Children Playing With Poison: Arsenic Exposure From CCA-treated Wood

Deborah L. Baptist,RN, BSN; Nan S Leslie, PhD,RN,WHNP

Disclosures

Journal for Nurse Practitioners. 2008;4(1):48-53. 

In This Article

Pathway to Exposure

Arsenic is an element that occurs naturally in the Earth's crust, appearing as a steel gray metal-like material. In the environment, arsenic often appears in combination with other elements and, based on these combinations, can be classified as organic arsenic or inorganic arsenic. Of the two environmental forms, inorganic arsenic is considered more harmful than is organic arsenic.[5]

Inorganic arsenic is found both naturally in the environment and in man-made products such as pesticides. Although the United States no longer produces arsenic, it continues to import and use arsenic produced in other countries. In the early 1990s the Environmental Protection Agency (EPA) banned the use of pesticides formulated with inorganic arsenic for use in agriculture. However, the use of arsenic as a pesticide and wood preservative in the form of CCA continued until December of 2003 when the EPA removed CCA-treated wood from the residential marketplace.[6] Unfortunately, the ban on CCA-treated wood did not address the way to deal with wooden structures already in place in many residential settings and on playgrounds and other places frequented by children. According to the EPA, roughly 14% of public playgrounds have CCA-treated wooden structures, and 70% of single-family homes have decks and porches constructed from CCA-treated lumber.[7] Furthermore, a study undertaken to determine the effects of time and weathering on the chemical structure of arsenic and chromium in CCA-treated wood and the transport of these elements into the environment showed that the arsenic-chromium cluster has long-lasting stability as indicated in its presence in samples of new wood, aged wood, and wood residue.[3] The environmental implication of this long-term stability is that as the wood surface is rejuvenated by erosion, the surface arsenic concentrations are maintained.[3]

The problem with arsenic residues from CCA is found in the pathways through which children can be exposed, including dermal contact with both CCA-treated wood and CCA residues that have leached into the soil. Compounding the problem of dermal contact is the propensity for young children to put their hands in their mouths after touching CCA-treated structures and to eat CCA contaminated soil.[4]

The possibility of a child being exposed to arsenic from CCA residue by the dermal or the oral route prompted Kwon et al[7] to undertake a study in 2004 to examine the amount of arsenic on the hands of children who had contact with CCA-treated wood structures in playgrounds and with the sand beneath these structures. Results showed that the mean amount of water-soluble arsenic on the hands of children from the playgrounds with CCA-treated wood structures was significantly higher (P < 0.001) than the mean amount of water-soluble arsenic found on the hands of children from the playgrounds without CCA-treated wood. On the basis of these findings the investigators recommended that children wash their hands after playing on structures that have possibly been treated with CCA to decrease the potential for exposure to inorganic arsenic.

Based on safety concerns for children, raised by the general public and state regulatory agencies, EPA researchers undertook a probabilistic arsenic exposure assessment to evaluate the potential risk to children from CCA-treated wood.[4] An in-depth analysis of several independent variables that could potentially influence the total absorbed dose of inorganic arsenic was conducted. The study examined estimated arsenic exposure risk for children who washed their hands after contact with CCA-treated structures, for children who played on CCA-treated structures that had undergone residue reduction through the use of wood sealants, and for children who both washed their hands after CCA contact and who played on structures that had undergone residue reduction in their analysis. The investigators concluded that the most critical exposure pathways to arsenic residues from CCA-treated structures were residue ingestion and residue dermal absorption. Reductions in exposure were determined to be related to hand washing and the use of sealants on wood structures.[4]

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