Jonathon Polly (SFSU), Jennifer Beier (SFSU) and students from Burton and O'Connell High Schools
Chromated copper arsenate (CCA) is a chemical wood preservative containing chromium, copper and arsenic. CCA is used in pressure treated wood to protect wood from rotting due to insects and microbial agents. Since the 1970s, the majority of the wood used in the construction of outdoor play structures has been CCA-treated wood. In December 2003, the Environmental Protection Agency classified CCA as a restricted use product, for use only by certified pesticide applicators. Of the City of San Francisco’s 142 play structures, 92 are constructed with CCA pressure-treated wood. Eighty-five were tested by the City of San Francisco and 34 play structures tested positive for As by wipe tests of the play structures themselves. The SF-ROCKS high school outreach program hypothesized that we would find significant levels of As and Cr, in the sand or clay below each structure due to the weathering and flaking off of the CCA-treated wood. We visited 18 of the playgrounds that showed the highest levels of As and sampled the sand and soil beneath the structures for the presence of transported As and Cr. We collected 2-3 samples from varying depth at each of the 11 playgrounds that had not yet been replaced by the City of San Francisco. Sand and clay samples were then extracted and analyzed for As and Cr totals. This study outlines the As and Cr concentrations present in the sand and clay below each CCA-treated wood play structure we visited in San Francisco.
