AN INVESTIGATION OF ARSENIC GROUNDWATER CONTAMINATION FROM HISTORIC USE OF LEAD ARSENATE IN WESTON, CONNECTICUT

Arsenic is a potent carcinogen commonly found in groundwater in the Northeastern region of the United States whose origin is often presumed to be geologically sourced from leachable bedrock. However, it is well documented that lead arsenate (PbHAsO₄), a pesticide used to control the gypsy moth, Lymantria dispar (L.), was sprayed extensively on orchard fruit trees, first in the Northeast and then nationally, from the 1890s through the mid-1960s. Apple orchards, in particular, were treated more frequently and in higher concentrations throughout this time period. Focused in Weston, Connecticut, this study was designed to evaluate the potential for arsenic contamination in Connecticut’s groundwater to be the legacy of lead arsenate. Using 20 identified orchards in the Town of Weston in conjunction with our constructed database of 364 domestic well records, a spatial analysis was preformed using GIS software to determine the relationship between proximity to historic orchards and arsenic concentrations. This analysis determined that wells exceeding the arsenic standard for drinking water of 10 parts per billion (ppb) were found in higher frequencies within proximity to historic orchards and, notably, were often located along flowlines downgradient of historic orchards. An analysis of the association between arsenic contaminated wells and four local rock types in Weston indicated that, of the four rock types, only one had a higher frequency of occurrence of contaminated wells, but this rock formation also had a much higher prevalence of historic orchards. Prolonged exposure to arsenic poses potential human health risks. Studies of former or current orchard properties that were sprayed with lead arsenate pesticide can give insight into the identification of residential areas with increased risk of arsenic exposure. This includes risks associated with drinking groundwater, the use of groundwater for irrigation, and consumption of produce grown on contaminated land.