A pilot simulation study of arsenic tracked from CCA-treated decks onto carpets

A controlled simulation experiment was performed to assess whether dislodgeable arsenic can be tracked onto carpets via foot traffic from chromated copper arsenate (CCA) pressure-treated decks. The pilot simulation study demonstrated that it is possible to track arsenic from CCA-decks onto carpets under the test conditions evaluated. A total of nine CCA-decks and two non-CCA-treated control surfaces were tested under wet and dry conditions. Five participants walked in a controlled manner (60 cycles, 11 steps per cycle) across decks and then walked over various lanes of carpet to simulate the tracking of arsenic indoors on the bottoms of shoes under heavy foot traffic conditions. To determine if arsenic was transferred from the CCA-treated wood to the carpet via shoes, laboratory analysis was performed on three different types of samples: (1) wipe samples of dislodgeable arsenic from a 46 cm2 area of carpet, (2) dust samples obtained from vacuuming a 7442 cm2 area of carpet, and (3) extractions of 13 cm2 carpet samples. Wipe samples were also taken directly from the deck lumber. Following digestion and extraction, the amount of arsenic in each sample was measured using Graphite Furnace Atomic Absorption Spectrometry. The mean arsenic concentration measured on the carpets was 2.52 μg/(100 cm2) and 2.05 μg/(100 cm2) with wipes for the dry and wet conditions, respectively, 4.69 μg/(100 cm2) and 0.68 μg/(100 cm2) with vacuumed dust for the dry and wet conditions, respectively, and 15.56 μg/(100 cm2) and 12.31 μg/(100 cm2) with carpet extractions for the dry and wet conditions, respectively. The mean arsenic concentration measured on the decks was 22.2 μg/(100 cm2) with wipes. Further research is needed to determine if indoor exposure to arsenic due to track-in from outdoor decks via foot traffic is significant compared to exposures from other sources.