A study published in Environmental Epidemiology reveals that elevated levels of nitrate and disinfection by-products (DBPs) in drinking water may be associated with an increased risk of ovarian cancer. The research, conducted within the Agricultural Health Study cohort, focused on women in Iowa and North Carolina, many of whom rely on private wells for drinking water.

Key findings include:

• A 15% increased risk of ovarian cancer was observed for every 5 mg/L increase in nitrate-nitrogen levels in drinking water.
• Total trihalomethanes (TTHMs)—a class of DBPs formed during water disinfection—were also positively associated with ovarian cancer risk.
• Dietary nitrate intake was linked to an 8% increased risk of ovarian cancer per 10 mg/day consumed.
• No significant associations were found for dietary nitrite or DBPs known as haloacetic acids (HAA5).

The study is one of the first to evaluate ovarian cancer risk in relation to nitrate exposure from private wells, which are unregulated and more vulnerable to contamination in agricultural regions. Researchers used geospatial modeling to estimate nitrate levels in private wells and linked public water supply data to participant addresses.

The study also highlights the importance of monitoring water quality in private wells and public systems, especially in rural and agricultural communities.

The full article is available online at Environmental Epidemiology.