Characteristics of persons who report high pesticide exposure events (HPEE) were studied in a large cohort of licensed pesticide applicators from Iowa and North Carolina who enrolled in the Agricultural Health Study between December 1993 and December 1995. Fourteen percent reported having “an incident or experience while usinganypesticide which caused anunusuallyhigh personal exposure.” After taking into account total number of applications made and education, females (OR=0.76), applicators from NC (OR=0.65), and privately licensed applicators (OR=0.65) were less likely to have reported an HPEE. Work practices more common among both private and commercial applicators with an HPEE included delay in changing clothing or washing after pesticide application, mixing pesticide application clothing with the family wash, washing up inside the house after application, applying pesticides within 50 yards of their well, and storing pesticides in the home. Job characteristics more common among those with an HPEE included self-repair of application equipment and first pesticide use more than 10 years in the past. These job characteristics explained much of the difference in reported HPEE between males and females, but not between IA and NC subjects or between commercial or private applicators.

Chronic ingestion of excess sodium has been associated with high blood pressure, heart disease, and stroke. Limited research has suggested a relationship between increased sodium intake and the development of preeclampsia. This study investigated the association between elevated sodium in drinking water with preeclampsia using a hospital-based case-control study of 10,114 pregnant women in Iowa in the United States. Health records of women who delivered at the University of Iowa Hospitals and Clinics in Iowa City, Iowa, USA, between May 2009 and August 2020 were obtained from the Intergenerational Health Knowledgebase. Water quality data for community water systems from Safe Drinking Water Act compliance reporting and Consumer Confidence Reports (CCR) were used to estimate maternal exposure to sodium in drinking water. Logistic regression models were calculated to estimate the odds of preeclampsia based on median sodium concentrations reported by public water systems from 2000 to 2019. Preeclampsia was associated with a 38% increased odds (adjusted odds ratio (aOR) 1.38, 95% confidence interval (CI) 1.13-1.69) when women were exposed to concentrations between 20-69 milligrams per liter (mg/L), above EPA's recommendation for individuals on a very low sodium diet. Increased odds of 5% and 16% were also found at concentrations between 70-102 mg/L and greater than 256 mg/L but were not statistically significant. The lower odds at higher sodium concentrations may be due to consumers using alternative drinking water sources due to taste issues that are noted to arise between 30-60 mg/L. Preeclampsia diagnosis was strongly associated with gestational age, parity, newborn count, and body mass index. Better data on individual exposure through drinking water is needed to account for factors like home softeners, which can greatly increase sodium levels at the tap, or those users seeking out alternative water supplies (like bottled water) due to taste issues arising from greater salinity.

Across the Midwestern United States, Public Water Systems (PWSs) struggle with high levels of nitrate in source waters from intense agricultural activity. Leveraging a sensor network deployed across Iowa surface waters, we evaluated the potential of the Hach Nitratax SC Plus, which uses UV-light absorption to quantify dissolved nitrate-nitrite (NO_x-N) down to 0.1 mg-N L⁻¹, for real-time monitoring of NO_x-N in drinking water. For six different PWSs over multiple years, we compare NO_x-N levels in source waters (surface and groundwater under surface influence) to those measured via traditional methods (e.g., ion chromatography (IC)) for US EPA compliance monitoring. At one large PWS, we also evaluated sensor performance when applied to near-finished drinking water (filter effluent). We find good agreement between traditional analytical methods and in situ sensors. For example, for 771 filter effluent samples from 2006–2011, IC analysis averaged NO_x-N of 5.8 mg L⁻¹ while corresponding sensor measurements averaged 5.7 mg L⁻¹ with a mean absolute error of 0.23 (5.6%). We identify several benefits of using real-time sensors in PWSs, including improved frequency to capture elevated NO_x-N levels and as decision-support tools for NO_x-N management.

The Lead and Copper Rule (LCR) addresses lead in drinking water through utility-centric monitoring in high risk homes, corrosion control, and public education. These utility-centric activities, however, do not provide adequate information on lead concentrations in individual homes and leave an unknown number of consumers at risk from drinking water lead. To assess the number of consumers at risk from drinking elevated lead concentrations, we mined 166,554 lead samples taken for LCR compliance in Iowa and developed a new approach for estimating the number of consumers at risk. We estimate that 65,000 ± 14,000 people in Iowa are at risk from drinking water lead above the U.S. EPA action level of 15 parts per billion (ppb) each year. We further explored the average household sampling rates of community water systems (CWSs) of different population sizes, where, overall, 8.6% of homes in an Iowa CWS are sampled. Our estimates indicate that, even in the absence of a lead-in-water crisis, a significant number of people are at risk from lead concentrations exceeding available guidelines, raising concerns about the severity of baseline lead concentrations in drinking water nationwide. Our analysis highlights that consumer-centric lead in drinking water policies and avoidance strategies are needed to ensure public protection.

In the Agricultural Health Study, information on participant live births was largely provided by female partners of male private applicators. At the Iowa site, such information was available for 13,599 (42.9%) of 31,707 applicators. To improve identification of live births among Iowa participants, we used a probabilistic and deterministic approach to link available demographic data from 31,707 households and information on live births from 13,599 households with 1,014,916 Iowa birth certificates. Record linkage identified 16,611 (93.7%) of 17,719 reported live births and 17,883 additional live births, most (14,411 or 80.6%) not reported due to nonresponse by female partners. This record linkage produced an expanded cohort of live-born children among Iowa participants, which will facilitate improved study of the effects of agricultural exposures, including pesticides, on selected birth outcomes and childhood disease.

The authors conducted a population-based case-control study in Iowa of 375 brain cancer patients and 2, 434 controls. A postal questionnaire was used to gather information on lifetime residential history, sources of drinking water, beverage intake, and other potential risk factors. Exposure to chlorination byproducts in drinking water was estimated by combining questionnaire data with historical information from water utilities and trihalomethane levels in recent samples. The analysis included 291 cases (77.6%) and 1, 983 controls (81.5%), for whom water quality information was available for at least 70% of lifetime years. Proxies represented 74.4% of cases. The mean number and mean duration of places of residence were comparable between direct and proxy respondents, suggesting little contribution to bias. After multivariate adjustment, odds ratios for brain cancer were 1.0, 1.1, 1.6, and 1.3 for exposure to chlorinated surface water of 0, 1-19, 20-39, and ≥40 years (p trend = 0.1). Among men, odds ratios were 1.0, 1.3, 1.7, and 2.5 (p trend = 0.04), and among women, 1.0, 1.0, 1.6, and 0.7 (p trend = 0.7)). Similar findings were found with estimates of average lifetime level of trihalomethanes. The association was stronger among men with above-median tap water consumption. These observations deserve further attention, especially in view of increasing glioma rates. Am J Epidemiol 1999: 150: 552-60.

In 1988, the Iowa Department of Natural Resources, along withthe University of Iowa, conducted the Statewide Rural WellWater Survey, commonly known as SWRL. A total of 686private rural drinking water wells was selected by use of aprobability sample and tested for pesticides and nitrate. A subsetof these wells, the 10% repeat wells, were additionally sampledin October, 1990 and June, 1991. Starting in November, 1991,the University of Iowa, with sponsorship from the United StatesEnvironmental Protection Agency, revisited the 10% repeat wellsto begin a study of the temporal variability of atrazine and nitratein wells. Other wells, which had originally tested positive foratrazine in SWRL but were not in the 10% population, wereadded to the study population. Temporal sampling for a year-long period began in February of 1992 and concluded in Januaryof 1993. All wells were sampled monthly, a subset was sampledweekly, and a second subset was sampled for 14 day consecutiveperiods. Of the 67 wells in the 10% population tested monthly,7 (10.4%) tested positive for atrazine at least once during theyear, and 3 (4%) were positive each of the 12 months. Theaverage concentration in the 7 wells was 0.10 µg/L. Fornitrate, 15 (22%) wells in the 10% repeat population monthlysampling were above the Maximum Contaminant Level of 10 mg/L at least once. This paper, the second of two papers on thisstudy, describes the analysis of data from the survey. The firstpaper (Lorber et al., 1997) reviews the study design, theanalytical methodologies, and development of the data base.

The Iowa Department of Natural Resources and the University of Iowa (UI) Center for Health Effects of Environmental Contamination conducted a survey (a one-time sampling) of the quality of private drinking-water supplies used by rural Iowans. The State-Wide Rural Well-Water Survey (SWRL) was carried out between April 1988 and June 1989. The two primary objectives were to address: 1. What proportion of private rural wells in Iowa are affected by various environmental contaminants? and 2. What proportion of rural Iowa residents are utilizing well water containing these environmental contaminants?

To provide a statistically valid framework, a systematic sample, stratified by rural population density, was designed. A target of 698 sites was defined, based on statistical considerations, available funds and logistical constraints. The systematic framework was defined using every 5-minute intersection of latitude and longitude in the state; the intersections chosen for sampling sites were distributed proportionally through the population, based on county-level rural-population density. The drinking-water well closest to each chosen intersection was selected for sampling. Iowa Cooperative Extension Service county staff identified eligible participants, based on design criteria.

The effect of temporal variability in groundwater quality during the survey was addressed in two ways: 1. 10% of all sites were sampled a second time, but during a different season; 2. all sites within a county (or counties), typifying six general hydrogeologic regions in Iowa, were sampled quarterly. In addition, routine sampling was seasonally dispersed throughout the state.

Standardized procedures for field activities were employed during SWRL. An appointment was arranged for each site, so that a resident was available to interview. Information was compiled on items such as well construction, agricultural practices, water treatment, past water-quality problems, waste disposal practices, and the general health status of rural residents. The drinking water wells' construction and placement characteristics and proximity to point-sources of contamination were inventoried by field staff. Sampling points were chosen as close to the well as possible; the water-system was purged until tracking measurements stabilized. Samples for laboratory analysis were collected in pre-treated containers supplied by the laboratories. Field quality assurance and quality control (QA/QC) included blank, spiked, and duplicate samples. Custody forms tracked the movement of all sample containers.

All primary samples were analyzed for total coliform bacteria; nitrate (+ nitrite)-N, ammonia-N, and organic-N; major inorganic ions; 27 commonly-used pesticides; and selected pesticide metabolites. The participating laboratories had U.S. EPA QA/QC plans in place, and the SWRL plan utilized and verified their implementation. The method detection limits (MDL) for pesticide analyses were set as the minimum practical concentration quantitation limit for each analyte in a groundwater matrix, established through QA/QC procedures. Groundwater-matrix effects necessitated an increase in some SWRL MDLs, relative to a reagent water matrix. This may cause an increase in false negative detections, but should minimize false positive detections.

Overall completion criteria were established for the and were met successfully. For 1. site-inventory, sample collection and analysis, and 2. return of voluntary health questionnaires, criteria of 95% and 60%, respectively, were set. These criteria were met, at 98% and 85%. The final SWRL well-water sample was 686 sites. Sample and analysis completeness were also set for each county. County criteria were met with one exception, for inorganic ions: 92 counties (of 99) were sampled at 100% of the design; 94% of the 10% repeat sites were resampled; and 93% of the quarterly sites were sampled 4 times. In total, 1 ,048 well water samples were collected and analyzed. Of the 686 sites, 47% were the primary rural-residence selected (i.e., closest to the 5-minute intersection), and 79% were among the first three choices. The most common reason a selected residence was not sampled was the inability to contact a current resident (70%); < 8% of persons contacted were unwilling to participate.

Studies in Iowa have long documented the vulnerability of wells with less than 50 feet (15 meters) of confining materials above the source aquifer to contamination from nitrate and various pesticides. Recent studies in Wisconsin have documented the occurrence of viruses in untreated groundwater, even in wells considered to have little vulnerability to contamination from near-surface activities. In addition, sensitive methods have become available for analyses of pharmaceuticals and pesticides. This study represents the first comprehensive examination of contaminants of emerging concern in Iowa’s groundwater conducted to date, and one of the first conducted in the United States.

Raw groundwater samples were collected from 66 public supply wells during the spring of 2013, when the state was recovering from drought conditions. Samples were analyzed for 206 chemical and biological parameters; including 20 general water-quality parameters and major ions, 19 metals, 5 nutrients, 10 virus groups, 3 species of pathogenic bacteria, 5 microbial indicators, 108 pharmaceuticals, 35 pesticides and pesticide degradates, and tritium. The wells chosen for this study represent a diverse range of ages, depths, confining material thicknesses, pumping rates, and land use settings.

The most commonly detected contaminant group was pesticide compounds, which were present in 41% of the samples. As many as 6 pesticide compounds were found together in a sample, most of which were chloroacetanilide degradates. While none of the measured concentrations of pesticide compounds exceeded current benchmark levels, several of these compounds are listed on the U.S. Environmental Protection Agency’s Contaminant Candidate List and could be subject to drinking water standards in the future. Despite heavy use in the past decade, glyphosate was not detected, and its metabolite, aminomethylphosphonic acid, was only detected in two of 60 wells tested (3%) at the detection limit of 0.02 μg/L.

Pharmaceutical compounds were detected in 35% of 63 samples. Of the 14 pharmaceuticals detected, six had reported concentrations above the method reporting limit, with the maximum reported concentration of 826 ng/L for acetaminophen. Diphenhydramine was the only pharmaceutical to have two detections above the reporting limit, at 24.5 and 145 ng/L. Eight pharmaceuticals had confirmed detections at concentrations below the method reporting limit. Caffeine was the most frequently detected pharmaceutical compound (25%), followed by the caffeine metabolite, 1,7- dimethylxanthine (16%).

 Microorganisms were detected in 21% of the wells using quantitative polymerase chain reaction methodologies. The most frequently detected microorganism was the pepper mild mottle virus (PMMV), a plant pathogen found in human waste. PMMV was detected in 17% of samples at concentrations ranging from 0.4 to 6.38 gene copies per liter. GII norovirus, human polyomavirus, bovine polyomavirus, and Campylobacter were also detected, while adenovirus, enterovirus, GI norovirus, swine hepatitis E, Salmonella, and enterohemmorhagic E. coli were not detected. No correlations were found between viruses or pathogenic bacteria and microbial indicators.

Wells with less than 50 feet (15 meters) of confining material were shown to have greater incidence of surface-related contaminants; however, significant relationships (p<0.05) between confining layer thickness and contaminants were only found for nitrate and herbicides.

The Iowa Department of Natural Resources, in conjunction with the University of lowa, Center for Health Effects of Environmental Contamination, conducted the State-Wide Rural Well Water Survey (SWRL) between April 1988 and June 1989. The SWRL survey systematically selected and sampled 686 sites and provided a statistically valid assessment of the proportion of private rural wells and rural Iowa residents affected by various environmental contaminants. The SWRL design framework also systematically selected a subset of 10% (68) of all sites for repeat sampling, to assess temporal changes in water quality during the original survey. The 10% repeat sites yielded a very consistent representation of the statewide data, including proportionately representative detections of pesticides down to about a 1% occurrence interval. These sites provided a representative subset of SWRL for monitoring water quality over time as an indicator of temporal change. The first two samplings of this 10% subset of wells are termed SWRL 10-1 and 10-2, respectively (abbreviated as 10-1 and 10-2). The SWRL 10-1 was part of the full SWRL sampling, and therefore is used as the basis for comparison with subsequent samples.
The SWRL survey was conducted during the driest consecutive two-year period in Iowa's recorded history. The objective of the resampling studies was to resample the subset during more "normal" climatic conditions, and to assess changes in water-quality that may have occurred. The 10% subset was resampled in October 1990 (10-3) and June 1991 (10-4), after weather patterns in Iowa had changed from the drought conditions of 1988-1989, to more normal and wetter-than-normal conditions. Long-term monitoring has shown that a mid-fall period, such as October, often represents conditions near the annual average for many parameters, though typically fewer pesticide detections occur than in late-spring or summer, such as the 10-4 (June 1991) resampling. For cost and technical reasons fewer analytes were included in SWRL 10-3 and 10-4 than the full SWRL survey.
In June 1991, during 10-4, about 19% of the sites showed N03-N >10 mg/L; 57% were positive for total coliform bacteria and 24% positive for fecal coliform bacteria; 20% of wells had a detection of some herbicide compound, about 6% contained detectable atrazine (parent compound only), and about 11% showed detections of atrazine or one of two common metabolites. The pattern of greater nitrate and bacteria occurrences in samples from wells <IOO feet deep and lower contaminant levels in wells > 100 feet deep, continued to be statistically significant in the 10-3 and 10-4 sampling.
Using tritium (3H) analysis as a groundwater dating tool, wells > 100 feet deep were more likely to produce groundwater with <6+/-4 Tritium Units, which averages >20 years old, than wells <IOO feet deep. Groundwater containing detectable tritium showed much higher rates of nitrate, and total- and fecal-coliform contamination, as would be expected. The data indicate a relationship among shallow wells, relatively recently recharged groundwaters, and higher rates of contaminant occurrence. All of the wells > 100 feet deep that exhibited >10 T.U. (i.e., modem recharge water) are from east-central or northeastern Iowa, where the hydrogeologic conditions promote much greater depth of groundwater circulation, and, hence, the depth to which contaminants occur is much greater than elsewhere in the state. This tool provides further insights on the mechanisms of groundwater contamination and may be useful for evaluating pollution potential of well waters.
Relative to prior sampling, the proportion of sites positive for total coliform bacteria and those with any detection of total atrazine or other pesticide increased slightly. The percentage of wells with N03-N > 10 mg/L did not change, but the mean and median concentration did increase somewhat. The only water-quality changes and from the full SWRL and the 10-1 (1988-1989), the 10-3 (October 1990), and 10-4 (June 1991) samplings that were statistically significant as estimates for all rural well waters, statewide were: 1) the decline in the detection of dissolved organic-nitrogen in 10-3 and its increase again in 10-4; 2) the increase in fecal coliform positives in 10-3 and again in 10-4; 3) the decrease in NH4-N in 104; and 4) the increase in detections in 10-3, which subsequently declined in 10-4.

The change from drought to wetter than normal conditions did not affect the 10-3 and 10-4 sample results as noticeably or consistently as it did in long-term monitoring projects in the state. Atrazine (parent) detections increased significantly in 10-3, but declined again in 104. Detections of other herbicides and total atrazine (metabolites included) increased somewhat in the June 10-4 sampling, as might be expected from the seasonal patterns discerned in other Iowa studies. While mean nitrate concentrations increased slightly, the proportion of wells with N03-N > 10mgL, and total coliform detections were largely unchanged. Fecal coliform detections increased, but this increase was unrelated to trends in other contaminants. As a sample of wells state-wide, this less pronounced response might be expected because the 10% subset integrates a variety of well-depths, well types and hydrogeologic settings. The SWRL 10% sample may react more slowly to climatic change; one indication of this is the low tritium content and therefore, relatively old (>20 years) average age of almost half the well water sampled during SWRL 10-3 and 10-4. The change to wetter conditions may explain the increases in total coliform and fecal coliform bacteria positives. Other studies have noted that bacteria, similar to chemicals, may be rapidly transmitted to the water table by preferential flow through the soil. Also, as water tables rise during wet periods, they are closer to the land surface and into contact with soil horizons where coliform bacteria are more abundant and more likely to survive.

One sample was collected from a site using a rural water-supply (RWS) system for its home and farmwater. The RWS system uses surface water. Four herbicides were detected: alachlor (0.7 pg/L), atrazine (1.7 AWL), cyanazine (1.5 pg/L), and metolachlor (1.2 gg/L).

Immunoassay (IMA) methods for scans provided promising results. With further refinements, these methods may provide a tool for inexpensive screening of water supplies for triazine occurrence.

Functionalized nanomaterials hold tremendous promise for water treatment because their high surface area makes them ideal sorbents for pollutants like heavy metal ions that are pervasive in global water supplies. Here, a novel core/shell nanomaterial consisting of an electrospun hematite nanofiber core and a mesoporous silica shell of tunable thickness (from 20–60 nm) was prepared for the first time. The synthesis involved careful control of pH and sequential addition of the silica source to control the growth and ultimately, thickness of the mesoporous silica shell on the electrospun hematite nanofiber. The core/shell structure was subsequently tailored for heavy metal adsorption by grafting an aminopropyl functional group on the mesoporous silica surface. The resulting electrospun hematite/mesoporous silica core/shell nanomaterials were extensively characterized by energy dispersive spectroscopy (EDS) with high resolution transmission electron microscopy (HRTEM), and ζ potential measurements both before and after adsorption of the Cr(III), from aqueous solution. Notably, sorption capacities for Cr(III) exceeded those previously reported for other nanostructured sorbents for this metal. The advantages of these core/shell materials include controllable surface area through introduction of porosity and the option for facile surface modification to optimize physicochemical interactions for pollutant uptake. These nanocomposites also exhibit improved chemical resistance in harsh environments. At acidic pH values, for example, the core/shell nanomaterials were more chemically resistant to iron dissolution than the parent electrospun hematite nanofibers, which broadens the range of waste streams to which these sorbents can be applied.

Background
Pets are major contributors of endotoxin in homes, but whether they influence endotoxin association with respiratory outcomes is unclear.

Objective
To examine whether exposure and sensitization to dog and cat modify the relationship between endotoxin exposure and asthma and wheeze.

Methods
We analyzed data from 6051 participants in the 2005-2006 cycle of the National Health and Nutrition Examination Survey (NHANES). House dust from bedroom floor and bedding was evaluated for endotoxin and for dog (Canis familiaris 1) and cat (Feline domesticus 1) allergens. The NHANES also collected data on respiratory outcomes and measured IgE specific to allergens. Associations of log-endotoxin and pet exposure with respiratory outcomes were examined, adjusting for covariates including pet avoidance.

Results
Dog and cat ownership among participants was 48.3% and 37.5%, respectively. Endotoxin geometric mean (SE) was 15.49 (0.50) EU/mg. Endotoxin and pet allergen levels were significantly higher in households with a dog or cat. Overall, endotoxin was positively associated with wheeze (odds ratio [OR], 1.30; 95% CI, 1.04-1.62), but not with asthma. However, in participants nonsensitized to dog, the odds of endotoxin association with wheeze were higher with exposure to dog allergen (OR, 1.80; 95% CI, 1.27-2.53; P_interaction = .048). In participants sensitized to cat and exposed to cat allergen, endotoxin became positively associated with asthma (OR, 1.92; 95% CI, 1.21-3.0; P_interaction = .040). With coexposure to dog and cat allergens, endotoxin association with asthma and wheeze was exacerbated (OR, 2.00; 95% CI, 1.04-3.83; P_interaction = .012 and OR, 1.88; 95% CI, 1.32-2.66; P_interaction = .016, respectively).

Conclusions
Exposure to dog and cat allergens enhances the association of endotoxin with asthma and wheeze.

Background
Maternal exposure to drinking water disinfection byproducts (DBP)s may contribute to orofacial cleft (OFC) development, but studies are sparse and beset with limitations.

Methods
Population-based, maternal interview reports of drinking water filtration and consumption for 680 OFC cases (535 isolated) and 1826 controls were linked with DBP concentration data using maternal residential addresses and public water system monitoring data. Maternal individual-level exposures to trihalomethanes (THM)s and haloacetic acids (HAA)s (µg/L of water consumed) were estimated from reported consumption at home, work, and school. Compared to no exposure, associations with multisource maternal exposure <1/2 or ≥1/2 the Maximum Contaminant Levels (MCL)s for total THMs (TTHM)s and HAAs (HAA5) or Maximum Contaminant Level Goals (MCLG)s for individual THMs and HAAs (if non-zero) were estimated for all OFCs and isolated OFCs, cleft palate (CP), and cleft lip ± cleft palate (CL/P) using logistic regression analyses.

Results
Compared to controls, associations were near or below unity for maternal TTHM, HAA5, and individual THM exposures with all OFCs and isolated OFCs, CP, and CL/P. Associations also were near or below unity for individual HAAs with statistically significant, inverse associations observed with each OFC outcome group except CL/P.

Conclusions
This study examined associations for maternal reports of drinking water filtration and consumption and maternal DBP exposure from drinking water with OFCs in offspring. Associations observed were near or below unity and mostly nonsignificant. Continued, improved research using maternal individual-level exposure data will be useful in better characterizing these associations

The Lead and Copper Rule (LCR) addresses lead in drinking water through utility-centric monitoring in high risk homes, corrosion control, and public education. These utility-centric activities, however, do not provide adequate information on lead concentrations in individual homes and leave an unknown number of consumers at risk from drinking water lead. To assess the number of consumers at risk from drinking elevated lead concentrations, we mined 166,554 lead samples taken for LCR compliance in Iowa and developed a new approach for estimating the number of consumers at risk. We estimate that 65,000 ± 14,000 people in Iowa are at risk from drinking water lead above the U.S. EPA action level of 15 parts per billion (ppb) each year. We further explored the average household sampling rates of community water systems (CWSs) of different population sizes, where, overall, 8.6% of homes in an Iowa CWS are sampled. Our estimates indicate that, even in the absence of a lead-in-water crisis, a significant number of people are at risk from lead concentrations exceeding available guidelines, raising concerns about the severity of baseline lead concentrations in drinking water nationwide. Our analysis highlights that consumer-centric lead in drinking water policies and avoidance strategies are needed to ensure public protection.

Hydride generation (HG) is a sample introduction technique that provides enhanced sensitivity for metalloids and allows chemical speciation between selected arsenic (As) and selenium (Se) anion species. The present studies have demonstrated high sensitivity for As, Se, and antimony (Sb) using continuous flow HG-laser induced fluorescence (LIF) and HG-laser enhanced ionization (LEI) spectrometric techniques. The limits of detection (LODs) are 200, 90 and 300 fg ml⁻¹ for As, Se and Sb, respectively, using HG-LIF and 50 and 2 pg ml⁻¹ for As and Se, respectively, using HG-LEI approaches. Measurements performed using HG combined with LIF detection in an electrothermal atomizer resulted in LODs of 3 pg ml⁻¹ (6 pg absolute mass) and 20 pg ml⁻¹ (40 pg) for As and Se, respectively. All of the techniques are linear in their responses to at least 10 ng ml⁻¹ for the corresponding elements. Reliable chemical speciation of As(III/V) and Se(IV/VI) species has been obtained using the flame HG-LIF approaches. Selective determinations of Se(IV) and Se(VI) have been carried out using an on-line pre-reduction procedure, where selective HG of Se(IV) is performed in 31% HBr at room temperature, while HG of [Se(IV) + Se(VI)] is performed following pre-reduction in 31% HBr at 100°C. Selective HG of As species is accomplished by control of the solution pH, where selective HG of As(III) is performed at pH 6 and HG of [As(III) + As(V)] is performed at pH 0. The results obtained demonstrate that the HG approaches are selective and provide quantitative recoveries of the individual Se and As species at sub-ppb levels.

The application of hydride generation (HG) sample introduction combined with laser-induced fluorescence (LIF) detection in the inductively coupled plasma (ICP) and electrothermal atomizer (ETA) is reported. Far-ultraviolet excitation of As at 193.696 nm and Se at 196.026 nm is accomplished by using a tunable dye laser system with frequency doubling and stimulated Raman scattering. HG-ICP-LIF and HG-ETA-LIF techniques have been developed and demonstrate good sensitivity and good linearity at the ng/mL to sub-ng/mL level for both elements. The relative standard deviation of replicate measurements is on the order of 3-10% at the 5 ng/mL level for the HG-ICP-LIF technique and 5-35% at the 0.6 ng/mL level for the HG-ETA-LIF technique. Detection limits of 1 ng/mL (5 ng absolute mass) for As and 0.06 ng/mL (0.3 ng) for Se are reported for the HG-ICP-LIF technique and 0.04 ng/mL (0.2 ng) for As and 0.16 ng/mL (0.8 ng) for Se are reported for the HG-ETA-LIF technique. Lower than expected sensitivity and precision are observed in the ETA, which may be due to inefficient trapping of the hydrides in the procedure. Selective HG procedures have been demonstrated for the speciation and recovery of selected oxidation states of As and Se. The analytical capabilities of the HG-LIF techniques are compared to those of other HG techniques, and recommendations are made for improved performance of future HG-LIF approaches.

The estrogenic activity of municipal wastewater in aerated lagoon treatment facilities was evaluated using plasma concentrations of vitellogenin (Vtg) in male fathead minnows (Pimephales promelas). Caged fathead minnows were exposed for 10 to 12 d in three lagoons that are connected in series at each of 10 municipal wastewater treatment facilities in central Iowa. USA, during October and November 2000. Fathead minnows held in the laboratory served as unexposed controls. Pooled (n = 4–10 fish) plasma Vtg, quantified by enzyme‐linked immunosorbent assay (ELISA), was 1,702 ± 670 (mean ± standard error [SE]) μg/ml in the first lagoons (n = 9), 0.94 ± 0.36 μg/ml in the second lagoons (n = 10), and 0.04 ± 0.02 μg/ml in the third lagoons (n = 8). Differences in mean fish plasma Vtg concentration among lagoons were highly significant (p < 0.001). The mean concentration of plasma Vtg in fish in the third lagoons was not significantly different (p = 0.990) from that of the control fish (0.04 ± 0.02 μg/ml). Plasma Vtg concentrations of fish in the first lagoons were inversely correlated with wastewater retention time in the lagoons (p = 0.002, r = −0.877). Water temperatures of the final effluents during the study ranged from 9 to 12°C General treatment efficiency of lagoons has been shown to be dependent on temperature, so the potential exists for decreased removal of estrogenic activity when water temperatures are lower (e.g., winter months) than the present study. In conclusion, wastewater entering aerated lagoon systems was estrogenic to fish, but with serial passage through the lagoons, the estrogenic activity decreased to a level that was not sufficient to induce vitellogenesis in male fathead minnows in a 10‐ to 12‐d exposure.

Since the early 1990s, endocrine disrupting compounds have been recognized as an important environmental threat. Male fish exposed ro effluent from large, metropolitan municipal wastewater treatment facilities (WWTFs) have developed reproductive abnormalities including ovotestes and elevated levels of plasma vitellogenin (Vtg), a plasma protein typically produced by egg-laying females. In the summer of 2000, gonads and plasma Vtg concentrations were examined in feral male fathead minnows (Pimephales promelas) collected from lagoons of 11 small, rural municipal WWTFs and a reference site (a national wildlife refuge) in Iowa. Fathead minnows were captured in traps from five of the 33 lagoons (three per WWTF) sampled. No other fish species were captured. The five lagoons with fathead minnows were found at three WWTFs. Gonad histology indicated only one of 65 (1.5%) male fish living in the lagoons had ovotestes, which was similar to the incidence at a reference site (1 of 29, 3.4%). Plasma Vtg, however, was substantially higher in fish from four of the five lagoons than in fish from the reference site, indicating that fish in lagoons were exposed to estrogenic substances.

Bond distance is a common structural metric used to assess changes in metal‐ligand bonds, but it is not clear how sensitive changes in bond distances are with respect to changes in metal‐ligand covalency. Here we report ligand K‐edge XAS studies on Ni and Pd complexes containing different phosphorus(III) ligands. Despite the large number of electronic and structural permutations, P K‐edge pre‐edge peak intensities reveal a remarkable correlation that spectroscopically quantifies the linear interdependence of covalent M‐P σ bonding and bond distance. Cl K‐edge studies conducted on many of the same Ni and Pd compounds revealed a poor correlation between M‐Cl bond distance and covalency, but a strong correlation was established by analyzing Cl K‐edge data for Ti complexes with a wider range of Ti‐Cl bond distances. Together these results establish a quantitative framework to begin making more accurate assessments of metal‐ligand covalency using bond distances from readily‐available crystallographic data.

Synthetic musk fragrances are added to a wide variety of personal care and household products and are present in treated wastewater effluent. Here we report for the first time ambient air and water measurements of six polycyclic musks (AHTN, HHCB, ATII, ADBI, AHMI, and DPMI) and two nitro musks (musk xylene and musk ketone) in North America. The compounds were measured in the air and water of Lake Michigan and in the air of urban Milwaukee, WI. All of the compounds except DPMI were detected. HHCB and AHTN were found in the highest concentrations in all samples. Airborne concentrations of HHCB and AHTN average 4.6 and 2.9 ng/m³, respectively, in Milwaukee and 1.1 and 0.49 ng/m³ over the lake. The average water concentration of HHCB and AHTN in Lake Michigan was 4.7 and 1.0 ng/L, respectively. A lake-wide annual mass budget shows that wastewater treatment plant discharge is the major source (3470 kg/yr) of the synthetic musks while atmospheric deposition contributes less than 1%. Volatilization and outflow through the Straits of Mackinac are major loss mechanisms (2085 and 516 kg/yr for volatilization and outflow, respectively). Concentrations of HHCB are about one-half the predicted steady-state water concentrations in Lake Michigan.

Understanding the function of detoxifying enzymes in plants toward xenobiotics is of major importance for phytoremediation applications. In this work, Arabidopsis (Arabidopsis thaliana; ecotype Columbia) seedlings were exposed to 0.6 mm acetochlor (AOC), 2 mm metolachlor (MOC), 0.6 mm 2,4,6-trinitrotoluene (TNT), and 0.3 mm hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). In vivo glutathione (GSH) conjugation reactions of AOC, MOC, RDX, and TNT were studied in root cells using a multiphoton microscope. In situ labeling with monochlorobimane, used as a competitive compound for conjugation reactions with GSH, confirmed that AOC and MOC are conjugated in Arabidopsis cells. Reverse transcription-PCR established the expression profile of glutathione S-transferases (GSTs) and nitroreductases enzymes. Genes selected for this study were AtGSTF2, AtGSTU1, AtGSTU24, and two isoforms of 12-oxophytodienoate reductase (OPR1 and OPR2). The five transcripts tested were induced by all treatments, but RDX resulted in low induction. The mRNA level of AtGSTU24 showed substantial increase for all chemicals (23-fold induction for AOC, 18-fold for MOC, 5-fold for RDX, and 40-fold for TNT). It appears that GSTs are also involved in the conjugation reactions with metabolites of TNT, and to a lesser extent with RDX. Results indicate that OPR2 is involved in plant metabolism of TNT (11-fold induction), and in oxidative stress when exposed to AOC (7-fold), MOC (9-fold), and RDX (2-fold). This study comprises gene expression analysis of Arabidopsis exposed to RDX and AOC, which are considered significant environmental contaminants, and demonstrates the importance of microscopy methods for phytoremediation investigations.

Atrazine is a well-known contaminant of surface waters and has been implicated in point-source pollution at agrochemical dealerships in the Midwest. Although the fate of atrazine has been well documented in soil and water, little is known about the fate of this contaminant and its metabolites within a grassed system. In the present study, [U-ring-14C]atrazine was added to soil in closed systems to determine the fate of the parent compound and its metabolites in soil, including degradation and movement into plants and air. Soil was treated with 25 mg/kg [14C]labeled atrazine and allowed to age for 5 d. Four systems then were amended with a mixture of prairie grasses, and the remaining four chambers were maintained as unvegetated controls. Dissipation and distribution of parent compound and metabolites were recorded for 21 d. Plant uptake of [14C]residue was less than 0.5% of applied radioactivity. Approximately 2% of total applied [14C]atrazine was mineralized to [14C]CO2, with no differences between vegetated and unvegetated systems. Mass balance recoveries were 76% for grassed systems and 77.5% for unvegetated controls. Approximately 40% of applied radioactivity remained bound to the soil following extraction. The most prevalent extractable compound detected in the soil was the parent, atrazine; major metabolites in soil were deethylatrazine (DEA) and didealkylatrazine (DDA). Leaf tissue contained concentrations of atrazine and key metabolites, i.e., DEA, DDA, and deisopropylatrazine (DIA), above those allowed in forage grasses by the U.S. Environmental Protection Agency; another key metabolite, hydroxyatrazine, was the most prevalent compound identified in both leaf and root tissue.

Iron is ubiquitous in the environment, ranking fourth in abundance in the earth's crust. Iron is responsible for many environmental mechanisms including the distribution of plant nutrients and pollutants. Iron can exist in several minerals, including iron oxides. Arsenic is a naturally occurring metalloid which has been confirmed by the EPA as a carcinogen. Recently, an arsenic epidemic has unfurled in Bangladesh, poisoning an estimated 70 million people. Arsenic contamination does not exist only in the third world, but also in the United States, including Iowa. Due to the widespread distribution of arsenic and the potential for it to be leached into groundwater supplies, there has been a growing interest in establishing removal mechanisms.

Atomic absorption (AA) spectroscopy and inductively coupled plasma optical emission spectrometry (ICP-OES) have been used. There has been a shift in arsenic analysis methods with the advent of more sensitive methods such as the inductively coupled plasma mass spectrometer (ICP-MS). The geology department recently acquired a Thermo Scientific XSERIES ICP-MS, so an arsenic analysis method was developed in preparation for the research conducted in this study. The ICP-MS, however, only measures total arsenic concentration. As this study focused on the oxidation state of arsenic, an alternative means for determining oxidation state was developed. As(V)-selective cartridges were used to adsorb arsenate, while letting arsenite run through. This method was checked for effectiveness and used to determine aqueous arsenic oxidation state. X-ray absorption spectroscopy (XAS) was used to determine the oxidation state of arsenic adsorbed onto the surface of iron oxide.

Goethite (α-FeOOH) and magnetite (Fe₃O₄) are both known to strongly adsorb arsenic. In this work, the potential for As(III) oxidation and As(V) reduction by goethite was studied. As documented by Amstaetter et al., there was some evidence for adsorbed As(III) oxidation by an Fe(II)/goethite system. This study, however, also showed some evidence for oxidation of adsorbed arsenite in the presence of goethite alone. As(V) reduction by magnetite was also studied. Magnetite is capable of having different stoichiometries, or ratios of Fe(II) to Fe(III). Both an oxidized, x=0.27, and a near-stoichiometric, x=0.49, magnetite were studied for their ability to reduce arsenate. There was no evidence for As(V) reduction in the aqueous or adsorbed phase for either system.

Metolachlor is a point-source pollutant at agrochemical dealerships in the Midwest, as well as a non point-source contaminant of surface waters caused by runoff. Prairie grasses have been used in filter strips to control runoff and are also useful for phytoremediation; however, little is known about the fate of metolachlor and its metabolites within a grassed system. Effects of uptake by prairie grasses on the formation and fate of degradation products are not known. In this study, [U-ring-¹⁴C]metolachlor was added to enclosed systems to determine the fate of the parent compound and its metabolites in soil and plants. Mineralization and volatilization were monitored over the 97 day study and found to be 1.05 and 0.2%, respectively, for vegetated systems. At the end of the study, soil and plant material was evaluated for the presence of parent metolachlor and selected metabolites, as well as bound residues. Metolachlor ethane sulfonic acid was the dominant metabolite in soil and plant tissue. Over 7% of applied radioactivity was taken up by the grasses, and plant uptake/metabolism appeared to be the main mechanism for phytoremediation of metolachlor. Vegetation significantly reduced the amount of metolachlor in soil by 9%, indicating potential success as a remediation tool.

Nanocrystalline zeolites are porous nanomaterials with crystal sizes of less than 100 nm that possess unique external and internal surface reactivity. Nanocrystalline zeolites, such as silicalite, ZSM-5 and Y, were synthesized and extensively characterized by powder X-ray diffraction, nitrogen adsorption isotherms, dynamic light scattering, and electron microscopy. Spectroscopic characterization of the nanocrystalline zeolites by FTIR and solid-state NMR provided detailed structural information about internal and external surface sites. The nanocrystalline zeolites were also used as building blocks to form larger, hollow zeolite structures with encapsulated metal or organic species. The surface properties of nanocrystalline zeolites and hollow zeolite structures were tailored through functionalization of surface silanol groups. Applications of nanocrystalline zeolites and zeolite structures in the selective catalytic reduction of NO_x and the photoreduction of Cr(VI) to Cr(III) in aqueous solution were investigated. The unique properties and reactivity of nanocrystalline zeolites and the potential for future applications of these materials will also be discussed.

This research describes the development of a supercritical fluid extraction (SFE) method to recover aflatoxin B₁ from fortified soil. The effects of temperature, pressure, modifier (identity and percentage), and extraction type were assessed. Using the optimized SFE conditions, the mean recovery from air dried soil was 72%. The variables associated with changes in recovery of aflatoxin were co-solvents, static extraction, and temperature. Acetonitrile–2% acetic acid, used both in-cell and on-line, provided the most efficient recovery. The results indicate that desorption from the soil was the limiting factor in recovery and that the static phase was more important than the dynamic.

A novel sampling design is proposed that optimizes the spatial configuration of sampling sites and captures maximum intraurban variability in ambient air pollution with a minimum sample size. Unlike the classical sampling design, a deterministic approach is adopted and the redundancy in the site selection is minimized by controlling for spatial autocorrelation. The proposed design was tested and implemented in a medium-sized midwestern city. The analysis suggested that 32 sites were adequate to capture more than 95% of the total variance in airborne particulate 10 µm or less in aerodynamic diameter (PM₁₀). A list of 20 households was prepared around each of the 32 sites. Households were approached in order of their distance from these sites until one was recruited for intensive indoor and outdoor air pollution monitoring from spring through fall of 2008. Finally, 30 households located around the optimal sites participated in the study. One set of four photometric and gravimetric samplers was deployed for each indoor and outdoor environment. The average ambient PM₁₀ concentration (monitored from April to September 2008) at the selected locations was lower but statistically insignificant as compared with the PM₁₀ (computed using the data from mobile sampling in 2006) at the optimal sites.

Lead oxide (PbO₂) can be an important form of lead mineral scale occurring in some water distribution systems. It is believed to be formed by the oxidation of lead-containing plumbing materials by free chlorine. Its reactivity in water, however, has not been well studied. Iodide is also found in source drinking waters, albeit at low concentrations. Consideration of thermodynamics suggests that iodide can be oxidized by PbO₂. In this investigation, iodide ion was used as a probe compound to study the reduction of PbO₂ and the formation of iodoform, which has been predicted to be a carcinogen, in the presence of natural organic matter (NOM). The reduction of PbO₂ by iodide can be expressed as PbO₂ + 3I⁻ + 4H⁺ → Pb²⁺ + I₃⁻ + 2H₂O, and the reaction kinetics has been determined in this study. In the presence of NOM, I₃⁻ reacts with NOM to form iodoform and its concentration is proportional to the NOM concentration. Our results indicate that PbO₂ is a very powerful oxidant and can possibly serve as an oxidant reservoir for the formation of iodinated disinfection byproduct through a novel reaction pathway.

The focus of this dissertation is assessment of the potential impact of livestock production practices on terrestrial and aquatic ecosystems by studying the environmental fate and effects of two classes of veterinary antibiotics: macrolides (represented by tylosin) and sulfonamides (represented by sulfamethazine). These antibiotics are widely used in livestock production for disease treatment and prevention, as well as growth promotion. Each has also been widely detected in surface waters in the U.S. The work presented utilized laboratory experiments to study the fate (mobility, dissipation, binding,
and degradation) in soil columns and aquatic microcosms, and bioavailability to benthic invertebrates. Additionally, methodologies were developed for using a passive sampling, or biomimetic, device to estimate bioavailability in aquatic ecosystems. Results suggest the potential persistence of some antibiotic residues in sediments, and the level of bioaccumulation in Lumbriculus variegatus, an aquatic oligochaete, indicates that uptake by sediment-dwelling invertebrates may be a concern.

Nanoparticles and nanostructured aggregates of paratacamite are prepared in acidic solutions through the conversion of copper-based nanoparticles. Aged and oxidized copper nanoparticles with an average primary particle size of ∼15 nm, when combined with hydrochloric acid solutions in the range of 0.025 to 0.1 M, show interesting behavior yielding both a change in nanoparticle primary size, as measured by an electrospray scanning mobility particle sizer, and in chemical composition to produce a copper chloride hydroxide mineral identified as paratacamite (γ-Cu₂(OH)₃Cl) by powder X-ray diffraction of the dehydrated solid sample. Taken together, these data suggest that paratacamite nanoparticles in solution can aggregate to yield microporous paratacamite materials. Microporous paratacamite was characterized by several techniques including X-ray diffraction, transmission electron microscopy, energy dispersive X-ray analysis, electron energy loss spectroscopy, X-ray photoelectron spectroscopy and surface area measurements. Oxidation of these copper-based nanoparticles with molecular oxygen and the role of the oxidized layer in the formation of paratacamite have been investigated. Comparison to microscale copper particles showed there is unique oxidation behavior of nanoscale copper particles that results in unique reaction chemistry of oxidized nanoscale copper particles with hydrochloric acid solutions to form paratacamite. This study provides a new route for the formation of paratacamite nanomaterials that can be used in a wide range of chemically interesting applications including hydrogen storage materials and as a heterogeneous catalyst for the synthesis of green solvents such as dimethyl and diethyl carbonates. Additionally, this study suggests a potentially new pathway for the degradation of art objects and ancient artifacts as well as other cultural heritage materials containing small copper particles that has not been previously considered.

Rationale: β-D-Glucans are fungal cell wall polysaccharides that stimulate innate immune responses and are responsible for bioaerosol-induced respiratory symptoms in both indoor and occupational environments.

Methods: C3HeB/FeJ mice were exposed to pustulan (1®6)-β-D-linear glucan in the scheme shown in the Table below. At days 0 and 7 mice were injected intraperitoneally (i.p.) with bovine serum albumin conjugates (pustulan-BSA) with an adjuvant (25μg/ml of pustulan emulsified with 1mg/ml of alum in saline) or saline with/without alum. Negative control mice were injected with saline or alum. At days 14-16, 21-23, and 28-30 mice were challenged intranasally (i.n.) with pustulan (25 μg/mouse in 50μl). Control mice received saline.  Inflammation induced by pustulan was evaluated at day 31 by lung histology and evaluation of bronchoalveolar lavage fluid (BALF).

Results: Lung histology showed the highest degree of inflammation in mice pretreated with pustulan-BSA conjugate and i.n.-exposed to pustulan. Total BALF cells and cell types, are summarized below. Alum injection followed by pustulan or saline instillation produced an influx of monocytic cells to the lung. Pustulan instillation following saline injection also induced recruitment of monocytes. Significant neutrophilic influx was seen in all mice exposed to i.n. pustulan.

Conclusion: Pre-exposure to pustulan-protein conjugate is necessary for induction of neutrophilic inflammation upon inhalation of pustulan in mice.

Rationale: Iron induces growth in bacteria such as P. Aeruginosa. This is the most abundant transition metal in ambient particulate matter (PM). Since it has been reported that air pollution increases chronic obstructive pulmonary disease (COPD) exacerbations, we hypothesize that iron content in PM will induce an increase in bacterial growth.

Methods: P. Aeruginosa strain, PAO1 cultures were grown in the presence of different iron-containing particles and iron chelators. More specifically, iron-containing particles of various sizes, composition and iron solubility were used. These included alpha and gamma Fe2O3, metallic iron nanoparticles, Fly Ash and various iron chelators such as lactoferrin. Growth was observed over time by sampling cultures and determining colony forming units (cfu).

Results: After six hours, PAO1 cultures in the presence of iron-containing particles grew one log more than PAO1 in the presence of particles without iron. Iron chelation prevented the iron-containing particles from induced PAO1 growth increase. Furthermore, smaller iron-containing particles induced greater increased growth in PAO1 compared to larger particles

Conclusion: This study provides clear evidence that PM is a potential source of iron for bacteria. In addition, it seems that particle size affects the PM induced bacterial growth. These results are significant since 75% of COPD exacerbations are considered bacterial and they show that PM is a potential source of iron for bacterial growth.

The function of dipalmitoyl phosphatidylcholine (DPPC) Langmuir monolayers was studied after exposure to various concentrations of 200 nm carboxyl-modified polystyrene particles by a combination of surface pressure and surfactant microstructure studies. The presence of particles in the subphase at the lowest concentrations tested (10⁻⁵ to 10⁻⁴ g/L) did not influence the π–A isotherms. However, at the highest concentration (10⁻³ g/L), changes in the hysteresis areas of the isotherms were observed. The formation of LC domains during compression was significantly altered by the presence of the particles, resulting in the formation of smaller but more numerous domains. Fluorescence and atomic force microscopy images suggested that particles remained in the subphase but were closely associated with the condensed domains.

Air pollution is a risk factor for respiratory infections, and one of its main components is particulate matter (PM), which is comprised of a number of particles that contain iron, such as coal fly ash (CFA). Since free iron concentrations are extremely low in airway surface liquid (ASL), we hypothesize that CFA impairs antimicrobial peptides (AMP) function and can be a source of iron to bacteria. We tested this hypothesis in vivo by instilling mice with Pseudomonas aeruginosa (PA01) and CFA and determine the percentage of bacterial clearance. In addition, we tested bacterial clearance in cell culture by exposing primary human airway epithelial cells to PA01 and CFA and determining the AMP activity and bacterial growth in vitro. We report that CFA is a bioavailable source of iron for bacteria. We show that CFA interferes with bacterial clearance in vivo and in primary human airway epithelial cultures. Also, we demonstrate that CFA inhibits AMP activity in vitro, which we propose as a mechanism of our cell culture and in vivo results. Furthermore, PA01 uses CFA as an iron source with a direct correlation between CFA iron dissolution and bacterial growth. CFA concentrations used are very relevant to human daily exposures, thus posing a potential public health risk for susceptible subjects. Although CFA provides a source of bioavailable iron for bacteria, not all CFA particles have the same biological effects, and their propensity for iron dissolution is an important factor. CFA impairs lung innate immune mechanisms of bacterial clearance, specifically AMP activity. We expect that identifying the PM mechanisms of respiratory infections will translate into public health policies aimed at controlling, not only concentration of PM exposure, but physicochemical characteristics that will potentially cause respiratory infections in susceptible individuals and populations.

Environmental factors are likely to interact with genetic determinants to influence prostate cancer progression. The Agricultural Health Study has identified an association between exposure to organophosphorous pesticides including chlorpyrifos, and increased prostate cancer risk in pesticide applicators with a first-degree family history of this disease. Exploration of this potential gene-environment interaction would benefit from the development of a suitable animal model. Utilizing a previously described mouse model that is genetically predisposed to prostate cancer through a prostate-specific heterozygous PTEN deletion, termed C57/Luc/Pten^p+/−, we used bioluminescence imaging and histopathological analyses to test whether chronic exposure to chlorpyrifos in a grain-based diet for 32 weeks was able to promote prostate cancer development. Chronic exposure to chlorpyrifos in the diet did not promote prostate cancer development in C57/Luc/Pten^p+/− mice despite achieving sufficient levels to inhibit acetylcholinesterase activity in plasma. We found no significant differences in numbers of murine prostatic intraepithelial neoplasia lesions or disease progression in chlorpyrifos versus control treated animals up to 32 weeks. The mechanistic basis of pesticide-induced prostate cancer may be complex and may involve other genetic variants, multiple genes, or nongenetic factors that might alter prostate cancer risk during pesticide exposure in agricultural workers.

Recent interest in using submicrometer particles for industrial and therapeutic purposes has led to concerns about their interactions with biological membranes. The mechanisms of particle–membrane interactions are not well understood resulting in contradictory reports on the effects of particles on membrane interfacial properties. In this study, the interactions between negatively charged polystyrene particles (200 nm) and monolayers of dipalmitoyl phosphatidylcholine (DPPC) were investigated. Surface pressure, surface potential, and surfactant microstructure studies were conducted to monitor the interfacial properties of DPPC monolayers spread on a subphase in which particles were dispersed. At a concentration of 0.1 g/L, particles caused a partial collapse of the monolayer. DPPC monolayers spread on a particle-laden subphase also exhibited higher surface potential and increased ratio of ordered domains supporting the presence of a more compact monolayer. These results suggest that particles penetrated the air–water interface thereby altering monolayer packing at the interface. These findings are contrary to our previous work where particles injected into the subphase beneath a DPPC monolayer did not penetrate the interface confirming that the sequence of particle and monolayer addition can alter particle–monolayer interactions. These studies may partially explain the varying results reported in previous studies.

Zeolites and mesoporous silica nanoparticles are silicate or aluminosilicate nanomaterials with well-defined pore networks. Zeolites are widely used in industry for applications such as catalysis, separations and gas adsorption. Mesoporous silica nanomaterials have not been as extensively applied relative to zeolites due to the cost and reduced thermal stability, but are being intensively investigated for potential environmental and biomedical applications. In this article, zeolite and mesoporous silica nanomaterials are reviewed with emphasis on connections to the environment. Specifically, the topics of greener syntheses, environmental applications and biological toxicity will be addressed. Both of these materials are typically synthesized with a template, which is then removed to produce the pore volume. Synthetic strategies for the “greening” of the syntheses of zeolites and mesoporous silica will be discussed. Environmental applications including the adsorption of environmental contaminants and environmental catalysis will also be presented. Finally, the toxicity of zeolite and mesoporous silica nanomaterials will be considered.

Magnetic iron oxide/mesoporous silica nanocomposites consisting of iron oxide nanoparticles embedded within mesoporous silica (MCM-41) and modified with aminopropyl functional groups were prepared for application to Cr(III) adsorption followed by magnetic recovery of the nanocomposite materials from aqueous solution. The composite materials were extensively characterized using physicochemical techniques, such as powder X-ray diffraction, thermogravimetric and elemental analysis, nitrogen adsorption, and zeta potential measurements. For aqueous Cr(III) at pH 5.4, the iron oxide/mesoporous silica nanocomposite exhibited a superior equilibrium adsorption capacity of 0.71 mmol/g, relative to 0.17 mmol/g for unmodified mesoporous silica. The aminopropyl-functionalized iron oxide/mesoporous silica nanocomposites displayed an equilibrium adsorption capacity of 2.08 mmol/g, the highest adsorption capacity for Cr(III) of all the materials evaluated in this study. Energy-dispersive spectroscopy (EDS) with transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) experiments provided insight into the chemical nature of the adsorbed chromium species.

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Background: Recent studies have shown that colloidal particles can disrupt the interfacial properties of lung surfactant and thus key functional abilities of lung surfactant. However, the mechanisms underlying the interactions between aerosols and surfactant films remain poorly understood, as our ability to expose films to particles via the aerosol route has been limited. The aim of this study was to develop a method to reproducibly apply aerosols with a quantifiable particle dose on lung surfactant films and investigate particle-induced changes to the interfacial properties of the surfactant under conditions that more closely mimic those in vivo.

Methods: Films of DPPC and Infasurf^® were exposed to aerosols containing polystyrene particles generated using a Dry Powder Insufflator^™. The dose of particles deposited on surfactant films was determined via light absorbance. The interfacial properties of the surfactant were studied using a Langmuir-Wilhelmy balance during surfactant compression to film collapse and cycles of surface compression and expansion at a fast cycling rate within a small surface area range.

Results: Exposure of surfactant films to aerosols led to reproducible dosing of particles on the films. In film collapse experiments, particle deposition led to slight changes in collapse surface pressure and surface area of both surfactants. However, longer interaction times between particles and Infasurf^® films resulted in time-dependent inhibition of surfactant function. When limited to lung relevant surface pressures, particles reduced the maximum surface pressure that could be achieved. This inhibitory effect persisted for all compression-expansion cycles in DPPC, but normal surfactant behavior was restored in Infasurf^® films after five cycles.

Conclusions: The observation that Infasurf^® was able to quickly restore its function after exposure to aerosols under conditions that better mimicked those in vivo suggests that particle-induced surfactant inhibition is unlikely to occur in vivodue to an aerosol exposure.

To date, all studies of aflatoxin B₁ (AFB₁) transformation in soil or in purified mineral systems have identified aflatoxins B₂ (AFB₂) and G₂ (AFG₂) as the primary transformation products. However, identification in these studies was made using thin layer chromatography which has relatively low resolution, and these studies did not identify a viable mechanism by which such transformations would occur. Further, the use of methanol as the solvent delivery vehicle in these studies may have contributed to formation of artifactual transformation products. In this study, we investigated the role of the solvent vehicle in the transformation of AFB₁ in soil. To do this, we spiked soils with AFB₁ dissolved in water (93:7, water/methanol) or methanol and used HPLC-UV and HPLC-MS to identify the transformation products. Contrasting previous published reports, we did not detect AFB₂ or AFG₂. In an aqueous-soil environment, we identified aflatoxin B_2a (AFB_2a) as the single major transformation product. We propose that AFB_2a is formed from hydrolysis of AFB₁ with the soil acting as an acid catalyst. Alternatively, when methanol was used, we identified methoxy aflatoxin species likely formed via acid-catalyzed addition of methanol to AFB₁. These results suggest that where soil moisture is adequate, AFB₁ is hydrolyzed to AFB_2a and that reactive organic solvents should be avoided when replicating natural conditions to study the fate of AFB₁ in soil.

A range of chemical pollutants is present in drinking water sources, including organic compounds, (e.g., pharmaceuticals and pesticides) and heavy metals (e.g., arsenic and lead). To protect the health of consumers, particularly those with private drinking water wells and in urban areas with aging water distribution systems, drinking water treatment at the point of use (POU) is essential. Next-generation POU technologies must require minimal energy, efficiently remove a range of pollutants, and be simple enough to permit broad application across users. Nanomaterials are ideal candidates for such technologies, as they exhibit high reactivity within small physical footprints. However, concerns regarding pressure requirements and material release challenge their application in traditional reactor designs. To bridge the gap between potential and practical application of nanomaterials, this study utilizes electrospinning to fabricate composite nanofiber filters. In electrospinning, a high voltage draws a polymer precursor solution (which can contain nanomaterial additives) from a needle, depositing a non-woven nanofiber filter on a collector. Using electrospinning, we develop an optimized carbon nanotube-carbon nanofiber composite that achieves a key balance between material strength and reactivity towards organic pollutants. Additionally, we develop two optimized polymer nanocomposites with embedded iron oxide nanoparticles and/or ion exchange groups, and demonstrate their application for removal of a range of metal contaminants (e.g., arsenic, chromium, lead, copper, and cadmium). Outcomes of this work establish novel methods for nanocomposite fabrication, contributing to the responsible and effective deployment of nanomaterials in POU drinking water treatment.

Inflammation in adipose tissue is recognized as a causative factor in the development of type II diabetes. Adipocyte hypertrophy as well as bacterial and environmental factors have been implicated in causing inflammation in mature adipocytes. Exposure to persistent organic pollutants such as polychlorinated biphenyls (PCBs) has been associated with the development of type II diabetes. We show here that PCB126, a dioxin-like PCB, activates a robust proinflammatory state in fat cell precursors (preadipocytes). The response was found to be dependent on aryl hydrocarbon receptor (AhR) activation, although induction of the response was delayed compared to upregulation of CYP1A1, a classic AhR-responsive gene. Treatment of preadipocytes with a nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) inhibitor partially attenuated the PCB126-induced inflammatory response and partly, but not completely, ameliorated disruption of adipogenesis caused by PCB126. Our results indicate a role for PCB126 in mediating an inflammatory response through AhR in preadipocytes that interferes with adipogenesis.

Application of swine manure to agricultural land allows recycling of plant nutrients, but excess nitrate, phosphorus and fecal bacteria impact surface and drainage water quality. While agronomic and water quality impacts are well studied, little is known about the impact of swine manure slurry on soil microbial communities. We applied swine manure to intact soil columns collected from plots maintained under chisel plow or no-till with corn and soybean rotation. Targeted 16S-rRNA gene sequencing was used to characterize and to identify shifts in bacterial communities in soil over 108 days after swine manure application. In addition, six simulated rainfalls were applied during this time. Drainage water from the columns and surface soil were sampled, and DNA was extracted and sequenced. Unique DNA sequences (OTU) associated with 12 orders of bacteria were responsible for the majority of OTUs stimulated by manure application. Proteobacteria were most prevalent, followed by Bacteroidetes, Firmicutes, Actinobacteria, and Spirochaetes. While the majority of the 12 orders decreased after day 59, relative abundances of genes associated with Rhizobiales and Actinomycetales in soil increased. Bacterial orders which were stimulated by manure application in soil had varied responses in drainage waters over the course of the experiment. We also identified a “manure-specific core” of five genera who comprised 13% of the manure community and were not significantly abundant in non-manured control soils. Of these five genera, Clostridium sensu stricto was the only genus which did not return to pre-manure relative abundance in soil by day 108. Our results show that enrichment responses after manure amendment could result from displacement of native soil bacteria by manure-borne bacteria during the application process or growth of native bacteria using manure-derived available nutrients.

Background

Methods

Results

Conclusion

High quality spectra of Pseudomonas sp. strain ADP in the planktonic and biofilm state were obtained using Raman microspectroscopy. These spectra enabled the identification of key differences between free and biofilm cells in the fingerprint region of Raman spectra in the nucleic acid, carbohydrate, and protein regions. Scanning electron microscopy (SEM) enabled detailed visualization of ADP biofilm with confirmation of associated extracellular matrix structure. Following extraction and Raman analysis of extracellular polymeric substances, Raman spectral differences between free and biofilm cells were largely attributed to the contribution of extracellular matrix components produced in mature biofilms. Raman spectroscopy complemented with SEM proves to be useful in distinguishing physiological properties among cells of the same species.

RDX is a persistent and highly mobile groundwater contaminant that represents a major remediation challenge at numerous munitions manufacturing and load-assemblage-package facilities. This work presents proof of concept that permeable reactive iron barriers might be a viable approach to intercept and degrade RDX plumes. Specifically, RDX was rapidly reduced in aquifier microcosms amended with Fe(0) powder, and in flow-through columns packed with steel wool. The rate and extent of RDX degradation in microcosms was enhanced by anaerobic bacteria that feed on cathodic hydrogen (i.e., H2 produced during anaerobic Fe(0) corrosion by water). Apparently, the hydrogenotrophic consortium that exploits Fe(0) corrosion as a metabolic niche participated in the further degradation of heterocyclic intermediates produced by the reaction of RDX with Fe(0). Reductive treatment of RDX with Fe(0) also reduced its toxicity to microorganisms and enhanced its subsequent biodegradability under either anaerobic or anaerobic conditions. Therefore, a combined or sequential Fe(0)-biological treatment approach might improve treatment efficiency.

Evidence for enhanced microbial degradation of xenobiotic chemicals in the rhizosphere, a zone of increased microbial activity at the root-soil interface, continues to accrue, suggesting that vegetation may play an important role in facilitating bioremediation of contaminated surface soils. For sites tainted with pesticide wastes, such as at agrochemical dealerships, establishing vegetation may be problematic because of the presence of herbicide mixtures at concentrations severalfold above field application rates. Nonetheless, herbicide-tolerant plants exist that can survive in these environments, and they are ideal candidates for testing the influence of rhizosphere microbial communities on the degradation of pesticide wastes. Experiments in this laboratory have tested whether a commodity plant such as soybean could survive in soil from a pesticide-contaminated site containing a mixture of three predominant herbicides, atrazine, metolachlor, and trifluralin, and if its presence could enhance biodegradation. Although soybean survival in this soil was high, its presence did not enhance the degradation of the chemicals. Tests with nonvegetated soils and rhizosphere soils from Kochia sp., a herbicide-tolerant plant, showed enhanced degradation of these chemicals in rhizosphere soil. Also, Kochia sp. seedlings have emerged from rhizosphere soils spiked with additional concentrations of the three test chemicals, indicating the ability of these plants to survive in soils containing high concentrations of herbicide mixtures.

Perfluorooctane-1-sulfonic acid (PFOS) is emerging as an important persistent environmental pollutant. To gain insight into the interaction of PFOS with biological systems, the mixing behavior of dipalmitoylphosphatidylcholine (DPPC) with PFOS was studied using differential scanning calorimetry (DSC) and fluorescence anisotropy measurements. In the DSC experiments the onset temperature of the DPPC pretransition (T_p) decreased with increasing PFOS concentration, disappearing at X_DPPC ≤ 0.97. The main DPPC phase transition temperature showed a depression and peak broadening with increasing mole fraction of PFOS in both the DSC and the fluorescence anisotropy studies. From the melting point depression in the fluorescence anisotropy studies, which was observed at a concentration as low as 10 mg/L, an apparent partition coefficient of K = 5.7 × 10⁴ (mole fraction basis) was calculated. These results suggest that PFOS has a high tendency to partition into lipid bilayers. These direct PFOS–DPPC interactions are one possible mechanism by which PFOS may contribute to adverse effects, for example neonatal mortality, in laboratory studies and possibly in humans.

This work applied inexpensive passive sampling to measure airborne coarse particles with aerodynamic diameters between 2.5 and 10 μm (PM_10–2.5) over three 7-day periods at 33 sites in a medium-sized Midwest City (Iowa City, IA). The number of sites and their locations were selected using an optimal sampling design that captured 95% of the total variance in PM_10–2.5 as measured with real-time sampling equipment on a mobile sampling platform. Weekly averages of PM_10–2.5 were 15.9 μg m⁻³ (coefficient of variation between sites, CV=23%), 17.9 μg m⁻³ (CV=24%), and 6.1 μg m⁻³ (CV=30%). ANOVA showed that these means were statistically different (p<0.001), and that the spatial variability plus random error accounted for 29% of the total variability. The maximum coefficient of divergence between sites—a relative measure of uniformity—ranged from 0.21 to 0.36. These values indicate that PM_10–2.5 was heterogeneous even on the fine spatial resolution studied in this work (average distance between sites was 4.4 km). The spatial patterns of PM_10–2.5 measured with the passive samplers closely matched with those of mobile mapping and corresponded with known coarse particle sources in the area. This work demonstrates that passive sampling coupled with effective sampling design may enhance our ability to assess exposure to PM_10–2.5 at a local scale. Compared to exposure estimates made with data from centrally located, filter-based samplers, these highly spatially resolved estimates should reduce exposure misclassification errors in epidemiological studies.

Human exposure assessments require a linkage between toxicant concentrations in occupied spaces and the receptor's mobility pattern. Databases reporting distinct populations' mobility in various parts of the home, time outside the home, and time in another building are scarce. Temporal longitudinal trends in these mobility patterns for specific age and gender groups are nonexistent. This paper describes subgroup trends in the spatial and temporal mobility patterns within the home, outside the home, and in another building for 619 Iowa females that occupied the same home for at least 20 years. The study found that the mean time spent at home for the participants ranged from a low of 69.4% for the 50–59 year age group to a high of 81.6% for the over 80-year-old age group. Participants who lived in either one- or two- story homes with basements spent the majority of their residential occupancy on the first story. Trends across age varied for other subgroups by number of children, education, and urban/rural status. Since all of these trends were nonlinear, they indicate that error exists when assuming a constant, such as a 75% home occupancy factor, which has been advocated by some researchers and agencies. In addition, while aggregate data, such as presented in this report, are more helpful in deriving risk estimates for population subgroups, they cannot supplant good individual-level data for determining risks.

Veterinary antibiotics enter the environment through the application of organic fertilizers to cropland. In this study, the aerobic degradation of tylosin, a widely used antibiotic in the production of livestock and poultry, was conducted in water and in soil in an effort to further investigate its environmental fate. Tylosin is a macrolide antibiotic, which consists of four factors (A, B, C, D). Water and soil were sampled at selected times and analyzed for tylosin and its degradation products by high‐performance liquid chromatography (HPLC), with product identification confirmed by HPLC‐mass spectrometry. Tylosin A is degraded with a half‐life of 200 d in the light in water, and the total loss of tylosin A in the dark is 6% of the initial spiked amount during the experimental period. Tylosin C and D are relatively stable except in ultrapure water in the light. Slight increases of tylosin B after two months and formation of two photoreaction isomers of tylosin A were observed under exposure to light. However, tylosin probably would degrade faster if the experimental containers did not prevent ultraviolet transmission. In soil, tylosin A has a dissipation half‐life of 7 d, and tylosin D is slightly more stable, with a dissipation half‐life of 8 d in unsterilized and sterilized soil. Sorption and abiotic degradation are the major factors influencing the loss of tylosin in the environment, and no biotic degradation was observed at the test concentration either in pond water or in an agronomic soil, as determined by comparing dissipation profiles in sterilized and unsterilized conditions.

Forty-one homes of conventional design were studied to investigate the relationship between bioaerosols, building parameters, and season, and to determine if differences existed across health-based home categories. The homes were categorized as: those for which no indoor air problems were known (noncomplaint homes), noncomplaint homes of allergy patients (intervention homes), and complaint “sick” homes (complaint homes). Carbon dioxide and relative humidity were measured in the basement and main floor areas. CO₂ concentrations were elevated for complaint homes (mean 1190 ppm) but less than 1000 ppm for all noncomplaint homes (mean 550 ppm). Relative humidity was significantly lower for intervention homes than for complaint or noncomplaint homes. Viable and nonviable bioaerosol sampling was performed on the main floor, the basement, and outside. Outdoor viable fungi exhibited an 8.4-fold range when plotted by month, but respirable and nonrespirable indoor fungal concentrations did not differ significantly by season. Basement geometric mean concentrations of fungi exceeded twice outdoor levels for complaint homes but were half the outdoor concentration for noncomplaint homes. Analysis of variance of bioaerosol concentrations revealed higher contamination in complaint than in noncomplaint homes, and concentrations in intervention homes were significantly lower than the other two groups. Overall, 80% of total viable fungi and 55% of bacteria were respirable. The predominant genera were Cladosporium in noncomplaint and intervention homes, while Penicillium and Aspergillus dominated in basements of complaint homes. The presence of pets, having an unfinished basement, absence of central air conditioning, and decreased use of air conditioning were significantly associated with elevated levels of fungi. High-efficiency furnace filters and increased use of central air conditioning contributed significantly to lower fungal levels in intervention homes.

We report serologic evidence of avian influenza infection in 1 duck hunter and 2 wildlife professionals with extensive histories of wild waterfowl and game bird exposure. Two laboratory methods showed evidence of past infection with influenza A/H11N9, a less common virus strain in wild ducks, in these 3 persons.

Wild ducks, geese, and shorebirds are the natural reservoir for influenza A virus (1); all 16 hemagglutinin (H) and 9 neuraminidase (N) subtypes are found in these wild birds (1,2). Recently, the rapid spread of influenza A/H5N1 virus to new geographic regions, possibly by migrating waterfowl, has caused concern among public health officials who fear an influenza pandemic. Until now, serologic studies of the transmission of subtype H5N1 and other highly pathogenic strains of avian influenza have focused on humans who have contact with infected domestic poultry (3,4). In this cross-sectional seroprevalence study, we provide evidence of past influenza A/H11 infection in persons who were routinely, heavily exposed to wild ducks and geese through recreational activities (duck hunting) or through their employment (bird banding). To our knowledge, this study is the first to show direct transmission of influenza A viruses from wild birds to humans.

Background

Pandemic influenza strains originate in nonhuman species. Pigs have an important role in interspecies transmission of the virus. We examined multiple swine-exposed human populations in the nation' number 1 swine-producing state for evidence of previous swine influenza virus infection.

Methods

We performed controlled, cross-sectional seroprevalence studies among 111 farmers, 97 meat processing workers, 65 veterinarians, and 79 control subjects using serum samples collected during the period of 2002–2004. Serum samples were tested using a hemagglutination inhibition assay against the following 6 influenza A virus isolates collected recently from pigs and humans: A/Swine/WI/238/97 (H1N1), A/Swine/WI/R33F/01 (H1N2), A/Swine/Minnesota/593/99 (H3N2), A/New Caledonia/20/99 (H1N1), A/Panama/2007/99 (H3N2), and A/Nanchang/933/95 (H3N2).

Results

Using multivariable proportional odds modeling, all 3 exposed study groups demonstrated markedly elevated titers against the H1N1 and H1N2 swine influenza virus isolates, compared with control subjects. Farmers had the strongest indication of exposure to swine H1N1 virus infection (odds ratio [OR], 35.3; 95% confidence interval [CI], 7.7–161.8), followed by veterinarians (OR, 17.8; 95% CI, 3.8–82.7), and meat processing workers (OR, 6.5; 95% CI, 1.4–29.5). Similarly, farmers had the highest odds for exposure to swine H1N2 virus (OR, 13.8; 95% CI, 5.4–35.4), followed by veterinarians (OR, 9.5; 95% CI, 3.6–24.6) and meat processing workers (OR, 2.7; 95% CI, 1.1–6.7).

Conclusions

Occupational exposure to pigs greatly increases workers' risk of swine influenza virus infection. Swine workers should be included in pandemic surveillance and in antiviral and immunization strategies.

This article discusses the effects of various concentrations of the explosive 2,4,6‐trinitrotoluene (TNT) on the transpiration of hybrid poplar trees growing in hydroponic media. Transpiration was measured daily by gravimetric means. The rapid removal of TNT from hydroponic solutions was a result of plant uptake and required a daily dosage of TNT to ensure a relatively constant exposure over time. Transpiration decreased with increasing TNT concentrations ≥5 mg/L. Decreases in transpiration were accompanied by leaf chlorosis and abscission. A comparison between a laboratory study and a pilot‐scale experiment showed good scale‐up potential.

This article presents the results of a study assessing the physical and mental health of residents living in the vicinity of a large-scale swine confinement operation. Physical and mental health data were collected via personal interviews from a sample (n = 18) of all neighbors living within a two-mile radius of a 4,000-sow swine production facility. Results were compared to similar data collected from a random sample of demographically comparable rural residents (n = 18) living near minimal livestock production. Results indicate that neighbors of the large-scale swine operation reported experiencing significantly higher rates of four clusters of symptoms known to represent toxic or inflammatory effects on the respiratory tract. These clusters of symptoms have been well-documented among swine confinement workers. There was no evidence to suggest that neighbors of the large-scale swine operation suffered higher rates of psychological health problems manifested as anxiety or depression. A larger population-based study is needed to test the hypothesis that neighbors of large-scale swine operations experience elevated rates of physical health symptoms comparable to interior confinement workers.

Microbial concentrations of denitrifiers, pseudomonads, and monoaromatic petroleum hydrocarbon (BTX) degraders were significantly higher (p < 0.1) in soil samples from the rhizosphere of poplar trees than in adjacent agricultural soils, and atrazine degraders were found only in one rhizosphere sample. The relative abundance of these phenotypes (as a fraction of total heterotrophs) was not significantly different between rhizosphere and surrounding soils. Therefore, the poplar rhizosphere enhanced the growth of microbial populations that participate in natural bioremediation without exerting selective pressure for them.

An ecological study of lung cancer, cigarette smoking, and radon exposure was conducted in 20 Iowa counties. County-based lung cancer incidence data for white female residents of Iowa were stratified according to radon level and smoking status. Cancer incidence data for the period 1973-1990 were obtained from the State Health Registry of Iowa. Smoking level was determined from a randomly mailed survey. Radon level was determined according to an EPA supported charcoal canister survey. Within low smoking counties, rates for all lung cancer and small cell carcinoma were significantly lower (p < 0.05) in the high radon counties relative to the medium and low radon counties. However, within high smoking counties, rates for all lung cancer, adenocarcinoma, and small cell carcinoma were significantly higher (p < 0.05) in the high radon counties relative to the low radon counties. Variations in socioeconomic data for these counties, available through the 1980 and 1990 census, did not explain these results. Lung cancer rates also were significantly increased in urban counties even after holding smoking status constant. Multivariate analyses revealed significant interactions between smoking, urbanization, radon levels, and lung cancer. The results of this hypothesis generating study will be tested in a case/control study now ongoing in Iowa. Analysis will need to include separate evaluations by smoking status, radon level, and residence in urban or rural areas for the major morphologic types of lung cancer.

An intercomparison between trained professional and homeowner water collection techniques was conducted to assess the validity of using both inexperienced homeowner water collectors and mail‐in return of point‐of‐use water samples. The findings indicate that homeowner‐collected water samples obtained at the point of use inside the home and professionally collected water samples collected at an outside tap are comparable, especially if confounders, such as air bubbles in the sampling vials, are minimized.

The State-Wide Rural Well-Water Survey (SWRL) was conducted between April 1988 and June 1989 by the Iowa Department of Natural Resources and the University of Iowa Center for Health Effects of Environmental Contamination. SWRL was designed to provide a statistically valid assessment of the proportion of private rural wells and rural Iowa residents affected by various environmental contaminants. The survey was a systematic sample, stratified by rural population density. SWRL demographic data indicate the sample is clearly representative of rural Iowans.

Primary samples were analyzed for total coliform bacteria; nitrate (+ nitrite)-N, ammonium-N, and organic-N; major inorganic ions; 27 pesticides, and 5 pesticide metabolites. Existing agency and laboratory USEPA quality assurance, quality control plans were utilized and verified for SWRL. SWRL collected and analyzed 1,048 water samples from 686 sites.

SWRL was conducted during the driest consecutive two-year period on record in Iowa, with precipitation averaging 14 inches below normal. Monitoring studies indicate the drought limited the movement of contaminants to groundwater. Hence, the SWRL results may present a ‘best-case' water-quality situation because of the temporal coincidence with the drought.

The SWRL data provide a population-based summary of the drinking water used by rural Iowans, and a cross-section of the quality of Iowa groundwater. The variations in water quality exhibited in the SWRL data, both regionally and particularly with depth, show consistent and predictable geochemical patterns, related to contaminant sources, transport, and age effects. Iowa well waters are near neutral and dissolved ions are dominated by calcium, magnesium, bicarbonate, and in some cases, sulfate. Mean concentrations for all ions, except chloride (Cl) and nitrate (N03-N), increase or remain fairly constant with depth. The higher concentrations of Cl and N03-N at shallow depths are related to their surficial sources. State-wide, 1.3 % of private well waters exceeded the USEPA maximum contaminant level (MCL) for fluoride (F), and 2.5% exceeded the secondary standard of 2 mg/L. Private well water should be analyzed to assess the natural F content before a supplement is prescribed, to avoid problems with dental fluorosis.

About 18% of Iowa's private, rural drinking-water wells contained N03-N > 10 mg/L, the recommended health advisory level (HAL); 37% of wells have >3 mg/L, typically considered indicative of anthropogenic pollution. Approximately 14% of wells had detections of pesticides: 16 pesticide compounds were detected, including 11 parent compounds and 5 environmental metabolites; 16 pesticides were not detected. Atrazine and its metabolites were found in 8% of wells. Multiple residues were detected in all regions of the state. The mean concentrations were generally < 1 ug/L. Lifetime HALS were exceeded in 1.2 % of private, rural wells in Iowa.

Approximately 45% of sites were positive for total coliform bacteria. Total coliforms are ubiquitous constituents of soils, surface water, and shallow groundwater and cannot be equated to fecal coliforms. Only 7% of water systems were positive for fecal coliform bacteria. The only sound, general interpretation of a persistent presence of total coliforms is that the water system is allowing interaction with soil, soil-water, shallow groundwater, or possibly surface water. This can indicate that the system is prone to other forms of contamination.

Individually, or in combination, nearly 55% of rural water supplies exhibited total coliform positives, N03-N > 10 mg/L, and/or pesticide detections. Using fecal coliforms only, this reduces to about 30% of well-water supplies. Based on 1980 Census data, about 130,000 rural Iowa residents consume drinking water from private wells with > 10 mg/L, N03-N; 94,000 use water with one or more pesticides; 5,400 use water with a pesticide concentration above an HAL.

Statistical analyses show significant associations between many water-quality parameters but the associations are not strong predictors based on state-wide data. By far the most significant factor explaining water-quality variations is well depth. An apparent relationship among total coliforms, N03-N, and pesticides is primarily a function of their co-occurrence related to well depth. Total coliform bacteria are very poor predictors of these chemical contaminants. If a prediction were based on the presence of total coliform, the probability is better that they would not occur in the water supply.

Consistent relationships among N03-N, dissolved oxygen, and ammonium-N with well depth suggest that nitrate reduction and/or denitrification occurs with depth in groundwater systems in Iowa. It is not clear from these data if the deeper groundwater system has the capacity to denitrify the nitrate loads currently being delivered to the system, however.

The effects of sinkholes or agricultural drainage wells are not significant in a state-wide context. Sinkholes were identified in the vicinity of only 2.1% of sites and only 0.6% of sites were near agricultural drainage wells (ADW). No sites reporting ADWs had any pesticide detections or N03-N > 10 mg/L. Non-farm, suburban housing tracts exhibited the most significant association between land use and water quality; proportionately, these areas show substantially fewer wells with > 10 mg/L N03-N and total coliform bacteria. Wells <50 feet from septic systems, showed less nitrate and significantly fewer positives for total and fecal coliform bacteria.

Point source problems affect only a small proportion of wells state-wide. Wells located in feedlots showed significantly higher concentrations of nitrate, but not bacteria problems. Such sites comprise only about 3% of wells state-wide, and account for only about 1% of the wells with > 10 mg/L, N03-N. Sites where herbicides were mixed within 15 feet of the well showed greater pesticide detections, but again the proportion of wells is low, about 3%, state-wide. Wells located within 15 feet of chemical storage and handling areas are uncommon, occurring at <0.6% of rural sites, and none of these wells contained pesticides or N03-N > 10 mg/L.

About 5.5% of private water wells in Iowa have experienced a spill or back-siphoning accident with pesticides or fertilizers. These sites exhibit a greater proportion of pesticide detections and high nitrate concentrations than average, as expected, but at the majority of sites the pesticides detected were not those involved in the accident. The sites exceeding HALs for pesticides occurred throughout the state. The sites were dominated by shallow wells; one deep well was involved, and this was a point source case which could affect any depth of well. Two of the sites, 25%, are clearly point source cases, a spill and back-siphoning accident (alachlor and trifluralin); the majority, 62.5%, are probable nonpoint sources related to pesticide occurrences in shallow groundwater (alachlor and atrazine); 1 case, 12.5%, is equivocal (atrazine).

Well depth is a major variable related to well-water quality, affecting the potential for surficial contaminants to enter a well. The degree of contamination is far greater in shallow wells and significant contamination occurs in wells up to 100 feet deep. Wells < 100 feet deep comprise 50% of wells state-wide and account for 70% of total coliform positives, 80% of fecal coliform positives, 64% of pesticide detections and total atrazine detections, and 89% of wells with N03-N > 10 mg/L. In NE Iowa the depth of contamination is greater because of the deeper groundwater circulation. The greatest proportions of contaminated wells occur in the SC, SW, and NW regions, paralleling regional dependence on shallow wells. In these regions nearly 75% of wells are < 100 feet deep (dominantly seepage wells) because alternative water sources are limited.

Certain factors of well construction or placement may afford easy entry of shallow, contaminated groundwater. But these factors are not causes of contamination; if the contaminants were not in the environment they would not get into the soil water and groundwater, or the well. Remediation of well construction or replacing current wells with deeper wells would undoubtedly reduce nitrate and pesticide contamination in many locations, but this would not address the cause of the contamination. The sources of contamination must be addressed because these shallow groundwaters will be the recharge for deeper groundwater with time. Sanitary and structural improvements of private water systems are also needed.

Extrapolating from temporal samples provides an upper limit estimate of wells with likely detections, at sometime over the course of a year: 1. wells > 10 mg/L N03-N 21%; 2. wells with any pesticide detections 30%; 3. wells with atrazine detections 15%. The systematically selected 10% repeat sites provide a consistent representation of the state-wide data, including representative detections of pesticides down to a 1% occurrence interval. These wells can provide a subset for monitoring trends over time.

Transformation of pesticides is dependent on soil environmental conditions and knowledge of this is necessary to improve subsurface fate and transport pesticide models. Laboratory experiments were performed using ¹⁴C ring and isopropyl side-chain labeled atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) applied to three Iowa soils incubated in batch reactors under different environmental conditions. Mineralization of both the ring and isopropyl side chain carbons was proportional to the organic matter content of the soils and oxygen content. Atrazine ring carbon mineralization also increased with soil water content. Oxygen limitation in soils reduced the bio-transformation rate of atrazine, and mineralization was much slower under denitrifying conditions. Empirical models were developed to represent the mineralization rate of atrazine ring carbon and isopropyl side-chain carbon for varying soil organic matter, soil water content, temperature, and oxygen partial pressure.

Lead in maternal blood can cross the placenta and result in elevated blood lead levels in newborns, potentially producing negative effects on neurocognitive function, particularly if combined with childhood lead exposure. Little research exists, however, into the burden of elevated blood lead levels in newborns, or the places and populations in which elevated lead levels are observed in newborns, particularly in rural settings. Using ~2300 dried bloods spots collected within 1–3 days of birth among Iowa newborns, linked with the area of mother’s residence at the time of birth, we examine the spatial patterns of elevated (>5 μg/dL) blood lead levels and the ecological-level predictors of elevated blood lead levels. We find that one in five newborns exceed the 5 μg/dL action level set by the US Centers for Disease Control & Prevention (CDC). Bayesian spatial zero inflated regression indicates that elevated blood lead in newborns is associated with areas of increased pre-1940s housing and childbearing-age women with low educational status in both rural and urban settings. No differences in blood lead levels or the proportion of children exceeding 5 μg/dL are observed between urban and rural maternal residence, though a spatial cluster of elevated blood lead is observed in rural counties. These characteristics can guide the recommendation for testing of infants at well-baby appointments in places where risk factors are present, potentially leading to earlier initiation of case management. The findings also suggest that rural populations are at as great of risk of elevated blood lead levels as are urban populations. Analysis of newborn dried blood spots is an important tool for lead poisoning surveillance in newborns and can direct public health efforts towards specific places and populations where lead testing and case management will have the greatest impact.

Emerging evidence indicates that persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), are involved in the development of diabetes. Dysfunctional adipocytes play a significant role in initiating insulin resistance. Preadipocytes make up a large portion of adipose tissue and are necessary for the generation of functional mature adipocytes through adipogenesis. PCB126 is a dioxin-like PCB and a potent aryl hydrocarbon receptor (AhR) agonist. We hypothesized that PCB126 may be involved in the development of diabetes through disruption of adipogenesis. Using a newly developed human preadipocyte cell line called NPAD (Normal PreADipocytes), we found that exposure of preadipocytes to PCB126 resulted in significant reduction in their subsequent ability to fully differentiate into adipocytes, more so than when the cells were exposed to PCB126 during differentiation. Reduction in differentiation by PCB126 was associated with downregulation of transcript levels of a key adipocyte transcription factor, PPARγ, and late adipocyte differentiation genes. An AhR antagonist, CH223191, blocked this effect. These studies indicate that preadipocytes are particularly sensitive to the effects of PCB126 and suggest that AhR activation inhibits PPARγ transcription and subsequent adipogenesis. Our results validate the NPAD cell line as a useful model for studying the effects of POPs on adipogenesis.

The synthesis, coordination chemistry, and reactivity of two diphosphines containing the cyclic triaminoborane 1,8,10,9-triazaboradecalin (TBD) are described. To evaluate the ligand-centered reactivity of ^PhTBDPhos and ^iPrTBDPhos, the complexes (^PhTBDPhos)MCl₂ and (^iPrTBDPhos)MCl₂, where M = Ni and Pd, were prepared and characterized by elemental analysis, multinuclear NMR spectroscopy (¹H, ¹³C, ³¹P, and ¹¹B), and single-crystal X-ray diffraction (XRD). Despite very low boron Lewis acidity in the TBD backbone, (^PhTBDPhos)NiCl₂ (1) and (^PhTBDPhos)PdCl₂ (3) react with H₂O, alcohols, and hydrated fluoride reagents in the presence of NEt₃ to yield trans H–O or H–F addition across the bridgehead N–B bond. In contrast, ^iPrTBDPhos shows no appreciable reactivity when bound to NiCl₂ (2) and PdCl₂ (4), which is attributed to the sterically-bulky isopropyl substituents blocking substrate access to boron in the TBD backbone. The new complexes {[(^PhTBDPhos-H₂O)Ni]₂(μ-OH)₂}Cl₂ (5), {[(^PhTBDPhos-H₂O)Pd]₂(μ-OH)₂}Cl₂ (6), (^PhTBDPhos-MeOH)NiCl₂ (7), (^PhTBDPhos-MeOH)PdCl₂ (8), (^PhTBDPhos-C₃H₅OH)PdCl₂ (9), and {[(^PhTBDPhos-HF)Ni]₂(μ-OH)₂}Cl₂ (10) were isolated, and all but 6 were structurally characterized by single-crystal XRD. Multinuclear NMR studies revealed that isolated, crystallographically-authenticated samples of 5–9 lose ligand-bound water or alcohol with reappearance of starting materials 1 and 3 when dissolved in NMR solvents. Addition of NEt₃ attenuated the water and alcohol loss from 5–9 to allow ¹H, ¹³C, ³¹P, and ¹¹B NMR data to be collected for all the compounds, confirming the determined structures. Additional reactivity experiments with NaOMe and fluoride reagents suggested that participation of the bridgehead nitrogen in the TBD backbone is important for promoting reactivity at boron when ^PhTBDPhos is bound to Ni and Pd. The term “cooperative ligand-centered reactivity” (CLR) is proposed to define chemical reactions that appear to require participation of more than one atom on the ligand, such as those reported here.

Neonicotinoid insecticides are widespread in surface waters across the agriculturally intensive Midwestern United States. We report for the first time the presence of three neonicotinoids in finished drinking water and demonstrate their general persistence during conventional water treatment. Periodic tap water grab samples were collected at the University of Iowa over 7 weeks in 2016 (May–July) after maize/soy planting. Clothianidin, imidacloprid, and thiamethoxam were ubiquitously detected in finished water samples at concentrations ranging from 0.24 to 57.3 ng/L. Samples collected along the University of Iowa treatment train indicate no apparent removal of clothianidin or imidacloprid, with modest thiamethoxam removal (∼50%). In contrast, the concentrations of all neonicotinoids were substantially lower in the Iowa City treatment facility finished water using granular activated carbon (GAC) filtration. Batch experiments investigated potential losses. Thiamethoxam losses are due to base-catalyzed hydrolysis under high-pH conditions during lime softening. GAC rapidly and nearly completely removed all three neonicotinoids. Clothianidin is susceptible to reaction with free chlorine and may undergo at least partial transformation during chlorination. Our work provides new insights into the persistence of neonicotinoids and their potential for transformation during water treatment and distribution, while also identifying GAC as a potentially effective management tool for decreasing neonicotinoid concentrations in finished drinking water.

We describe drinking water sources and water quality for a large agricultural cohort. We used questionnaire data from the Agricultural Health Study (N = 89,655), a cohort of licensed pesticide applicators and their spouses in Iowa (IA) and North Carolina (NC), to ascertain drinking water source at enrollment (1993–1997). For users of public water supplies (PWS), we linked participants’ geocoded addresses to contaminant monitoring data [five haloacetic acids (HAA5), total trihalomethanes (TTHM), and nitrate-nitrogen (NO₃-N)]. We estimated private well nitrate levels using random forest models accounting for well depth, soil characteristics, nitrogen inputs, and other predictors. We assigned drinking water source for 84% (N = 74,919) of participants. Among these, 69% of IA and 75% of NC participants used private wells; 27% in IA and 21% in NC used PWS. Median PWS nitrate concentrations (NO₃-N) were higher in IA [0.9 mg/L, interquartile range (IQR): 0.4–3.1 mg/L] than NC (0.1 mg/L, IQR: 0.1–0.2 mg/L), while median HAA5 and TTHM concentrations were higher in NC (HAA5: 11.9 µg/L, IQR: 5.5–33.4 µg/L; TTHM: 37.7 µg/L, IQR: 10.7–54.7 µg/L) than IA (HAA5: 5.0 µg/L, IQR: 3.7–10.7 µg/L; TTHM: 13.0 µg/L, IQR: 4.2–32.4 µg/L). Private well nitrate concentrations in IA (1.5 mg/L, IQR: 0.8–4.9 mg/L) and NC (1.9 mg/L, IQR: 1.4–2.5 mg/L) were higher than PWS. More private wells in IA (12%) exceeded 10 mg/L NO₃-N (regulatory limit for PWS) than NC (<1%). Due to the proximity of their drinking water sources to farms, agricultural communities may be exposed to elevated nitrate levels.

Dichloroacetamide safeners are common ingredients in commercial herbicide formulations. We previously investigated the environmental fate of dichloroacetamides via photolysis and hydrolysis, but other potentially important, environmentally relevant fate processes remain uncharacterized and may yield products of concern. Here, we examined microbial biotransformation of two dichloroacetamide safeners, benoxacor and dichlormid, to identify products and elucidate pathways. Using aerobic microcosms inoculated with river sediment, we demonstrated that microbial biotransformations of benoxacor and dichlormid proceed primarily, if not exclusively, via cometabolism. Benoxacor was transformed by both hydrolysis and microbial biotransformation processes; in most cases, biotransformation rates were faster than hydrolysis rates. We identified multiple novel products of benoxacor and dichlormid not previously observed for microbial processes, with several products similar to those reported for structurally related chloroacetamide herbicides, thus indicating potential for conserved biotransformation mechanisms across both chemical classes. Observed products include monochlorinated species such as the banned herbicide CDAA (from dichlormid), glutathione conjugates, and sulfur-containing species. We propose a transformation pathway wherein benoxacor and dichlormid are first dechlorinated, likely via microbial hydrolysis, and subsequently conjugated with glutathione. This is the first study reporting biological dechlorination of dichloroacetamides to yield monochlorinated products in aerobic environments.