Impact of Long-Term Weathering, Mobility, and Land Use on Chlordane Residues in Soil

The use of technical chlordane, a mixture of 147 separate components, and chlordane-containing products has been illegal in the United States since 1988. Technical chlordane is a member of the persistent organic pollutants (POPs), all of which exhibit remarkably long half-lives in the environment. Due to its persistence, its former use at extremely high application rates, and its toxicity, technical chlordane in soil may be present at levels of concern to public health. Concentrations at a site for which the date and rate of application of technical chlordane were recorded permit an accurate description of its weathering and an assessment of its vertical and horizontal movement during the past several decades. This site also allows computation of half-life as an average across the 147 components in soil 38 years after application using explicitly stated assumptions. Levels of technical chlordane in soils spanning a variety of land uses including agricultural sites, residential lawns and gardens, and foundation sites are also presented.