Public Health Implications of Arsenic in Agricultural Soils: A Legacy of Historical Pesticide Application Practices Open Access
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Arsenic-based pesticides were used extensively, starting in the late-1800s and continuing into the mid-20th century. Although arsenical pesticides were used primarily on apple and other tree fruit crops, these pesticides were also used on a wide variety of row crops. This research looked at the presence of arsenic in soil on properties used during the first half of the 20th century for (non-orchard) farming. The research relied on existing arsenic surface soil sampling data collected by the U.S. Geological Survey (USGS) as part of the North American Soil Geochemical Landscapes Project. The current and historical land use at each of 180 USGS sampling location in the northeastern U.S. were determined based on historical aerial photographs, to classify each location as historically agricultural or non-agricultural. A higher average surface soil arsenic concentration was observed in the historical agricultural land use group compared to the non-agricultural land use (8.28 mg/kg vs. 6.06 mg/kg). A non-parametric statistical comparison indicated a significant difference (Z=3.34, p=0.0008) between the two data sets. Graphical representations of the data indicated apparent differences between the agricultural and non-agricultural data sets. Thus, the historical application of arsenical pesticides to crops appears to have resulted in a slight upward shift in the natural distribution of arsenic soil concentrations across the group of former agricultural properties. Moreover, typical pesticide application methods for row crops and subsequent tilling reduce the likelihood of localized hot spots as observed in historical orchard properties. This conceptual model makes it difficult to distinguish between naturally occurring arsenic and any contribution from past agricultural use of arsenical pesticides. A review of current public health policies relating to arsenic in soil from historical pesticide application for several New England states is provided and a decision analytic framework for evaluating potentially affected properties, as well as possible applications of the framework, are proposed.