Cleaning-induced arsenic mobilization and chromium oxidation from CCA-wood deck: Potential risk to children

• Wet wood treated with chromated copper arsenate (CCA) had > 3–4 times more dislodgeable As and Cr than dry one.
• Cleaning CCA-wood did not reduce the amounts of dislodgeable As and Cr on wood surface.
• Cleaning CCA-wood using bleach resulted in 110–170 μg/L CrVI and>300 μg/L As in leachate.
• 699-2473 mg As was released into soil from cleaning an 18.6 m2 CCA-wood deck.
• Estimated As doses in children aged 1–6 after 1 h of contact with wet CCA-wood were 0.25–0.60 μg/kg.

Concern about children's exposure to arsenic (As) from wood treated with chromated-copper-arsenate (CCA) led to its withdrawal from residential use in 2004. However, due to its effectiveness, millions of American homes still have CCA-wood decks on which children play. This study evaluated the effects of three deck-cleaning methods on formation of dislodgeable As and hexavalent chromium (CrVI) on CCA-wood surfaces and in leachate. Initial wipes from CCA-wood wetted with water showed 3–4 times more dislodgeable As than on dry wood. After cleaning with a bleach solution, 9.8–40.3 μg/100 cm2 of CrVI was found on the wood surface, with up to 170 μg/L CrVI in the leachate. Depending on the cleaning method, 699–2473 mg of As would be released into the environment from cleaning a 18.6-m2-deck. Estimated As doses in children aged 1–6 after 1 h of playing on a wet CCA-wood deck were 0.25–0.41 μg/kg. This is the first study to identify increased dislodgeable As on wet CCA-wood and to evaluate dislodgeable CrVI after bleach application. Our data suggest that As and CrVI in 25-year old CCA-wood still show exposure risks for children and potential for soil contamination.

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