Long-term leaching of arsenic from pressure-treated playground structures in the northeastern United States

Wood used in playground structures built prior to 2004 was pressure-treated with chromated copper arsenate (CCA) which has been associated with negative health and environmental impacts. Given the prevalence and lack of maintenance of these aging play structures in rural northeastern US, the aim of this study was to determine the distribution of As (total, speciated and bioaccessible) in surface soil collected near and underneath four CCA-treated playground structures 16- and 26-years following installation. Note that one playground in southeastern MA was studied where surface soil samples were collected at various distances from the structures (0, 5, 15, and 30 cm). Total As in surface soil was measured by graphite furnace atomic absorption spectroscopy, whereas As speciation and bioaccessible As were determined by HPLC-ICPMS and in vitro SBRC-gastric assay, respectively. Near (≤5 cm) and underneath CCA-treated structures total As concentration in surface soil ranged from 143.4-213.5 mg/kg after 26 years of installation compared to 101.3-166.6 mg/kg ten years earlier. These concentrations exceeded the Massachusetts Residential Risk-Based Soil Standard by 5-10 times. In comparison, total As in background soil samples ranged from 4.6-6.6 mg/kg during the two study periods. While most of the As in surface soil were in the form of As(V), ≤29% was bioaccessible. Overall, our findings demonstrated that arsenic accumulation in soil surrounding aging playground structures continues to be a source of elevated exposure to children through contact with contaminated soil.