Arsenic and atrazine are two water contaminants of high public health concern in Iowa. Arsenic is found in soil from glacier deposits and atrazine is a commonly used herbicide. My questions were whether Iowans are exposed to higher levels of arsenic and atrazine from drinking water, whether Iowans have the same rates of cancers as the rest of the US, and whether higher levels of arsenic is some Iowa counties could lead to a higher risk for prostate cancer.

I investigated the occurrence of arsenic and atrazine in drinking water from Iowa private wells and public water systems. I found that detection and concentration of atrazine in drinking water decreased over time. However, the percentage of arsenic detections and concentrations higher than the current regulatory level increased over time in the public water systems. Therefore, arsenic was selected as a water contaminant for further study.

Cancer is the second leading cause of death in the US. However, cancer rates vary by different regions over time. In this study, the trends in cancers related to arsenic and atrazine exposures in Iowa were investigated and compared to 8 other states for white adults. I observed that the number of new overall cancer cases and death from them was lower in Iowa than the US, but different trends in major cancers were found between Iowa and the US. Importantly, prostate cancer was the most frequent type of cancer in men in both Iowa and the US and it was selected as a health outcome for further study.

Based on what I found in those previous studies, I conducted a county-level study comparing prostate cancer and arsenic in drinking water in Iowa. I estimated the risk of prostate cancer by the three range of arsenic level at a county level. The results of analysis showed that the risk of prostate cancer increased by 16 % and 28 % in the groups of counties with the medium and high arsenic level, compared to the group of counties with low arsenic level.

Together, these results indicate that the analysis of contaminants and regional occurrence of human diseases like cancer may be able to identify factors, like water contaminants, that have a negative effect on health. This knowledge can then be used to design methods to reduce or remove exposure to these contaminants.