Environmental context. The extent of perchlorate contamination in our environment is inadequately known. We examined perchlorate content in precipitation, soil water, soil cores and grass clippings in an urban lawn environment. Our results show that perchlorate is present in the lawn environment at concentrations that may adversely affect human health.

Abstract. Perchlorate contamination in groundwater is a concern owing to the likelihood that low concentrations of perchlorate may disrupt normal thyroid function. Lawns fertilized with perchlorate-containing fertilizers can adversely affect groundwater. We examined perchlorate concentrations from June 2006 to January 2007 in precipitation, grass clippings, soil cores and soil water at eight lawn environments in Suffolk County, NY, a county where lawns comprise more than 25% of the land use. Measured concentrations in soil waters were as high as 255 μg L^–1, with average concentrations of 69 μg L^–1 beneath sites treated with organic fertilizer, 1.2 μg L^–1 beneath sites treated with chemical fertilizer and 0.34 μg L^–1 beneath sites not fertilized. Although concentrations were dependent on the type of fertilizer applied, the patterns of leaching and grass uptake were similar at all sites.