Estrogen Disrupting Pesticides in Nebraska Groundwater: Trends between Pesticide-contaminated Water and Estrogen-related Cancers in An Ecological Observational Study

Estrogen disrupting pesticides (EDP) are pesticides that modify estrogen activities in estrogen-producing vertebrates. A substantial amount of these pesticides has been detected in human tissues, and they function directly to disrupt estrogen synthesis or effector cells. This study examines EDP's ecological distribution across Nebraska counties and its association with estrogen-related cancers (ERC). To determine the ecological distribution of selected EDP, county-level choropleth maps were created. Moreover, EDP was tested in separate linear models with different ERC to determine the association between ERC and EDP across Nebraska counties. Exposure data for this county-level study was obtained from the quality assessed agrichemical contaminant Nebraska groundwater database between 1 January 1974 and 31 December 2012. Acetochlor, atrazine, and its metabolites, deethylatrazine (DEA), and de-isopropyl atrazine (DIA) were the most frequently detected EDP in Nebraska groundwater. Moreover, Nebraska county-level potential confounder for ERC such as physically unhealthy days, % adult smoking, % obese adult, % uninsured, and % binge drinking were obtained from County Health Rankings 2010. ERC, which is the outcome variable (breast cancer, uterine cancer, and prostate cancer), were obtained from the Nebraska State profile of the National Cancer Institute. This was expressed as county-level age-standardized incidence cancer rates between 1 January 2013 and 31 December 2017. Data characteristics were determined using percentages, mean, median, 25th and 75th percentile, minimum and maximum values. The relationship between county-level cancer rates and % wells positive for pesticides after adjusting for the county level potential confounders were analyzed in a linear regression model. Water supply wells positive for atrazine and DEA were observed to cluster in the South and South East counties of Nebraska. Furthermore, breast cancer and prostate cancer incidence rates were higher in the southeast of Nebraska with more atrazine and DEA. However, breast cancer and prostate cancer were not significantly associated in a linear regression model with any of the observed EDP. In contrast, uterine cancer was statistically associated with % water supply wells positive for acetochlor (beta = 4.01, p = 0.04). While consistent associations were not observed between ERC and EDP from the GIS and the linear regression model, this study's results can drive future conversation concerning the potential estrogenic effects of acetochlor, atrazine, and its metabolites on the incidence of breast, uterine and prostate cancer in the State of Nebraska.