Leachable and Dislodgeable Arsenic and Chromium from In-Service CCA-Treated Wood

Leachable and dislodgeable arsenic and chromium from CCA (chromated copper arsenate)treated wood were studied to evaluate the fate of these CCA-chemicals and possible human exposures when the chemicals have been released to the environment. To evaluate the leachable component, two full sized decks were constructed. One was made of CCA-treated wood, and the other was made of untreated wood. Rainfall, runoff water from the top surface of the deck, and infiltrated water through 70 cm of soil below the deck had been monitored for 408 days. Soil below the decks was collected 6 months and 13 months after deck installation. The results of the deck monitoring showed that a significant portion of arsenic could be leached to environment during the service life of the CCA-treated wood product when exposed to rainfall. During the monitoring period, the average concentration in the runoff water from the CCA-treated deck was 1,000 ug/L for arsenic and 99 ug/L for chromium. Release of these metals to the surface soil was also observed. The surface arsenic concentrations increased from 4.5 mg/kg for the 6 month soil sample to 11.5 mg/kg for the 13 month sample. The impacts of the releases were also observed in the infiltrated water samples collected