The Development of a Standard Hand Method and Correlated Surrogate Method for Sampling CCA (Pressure)-Treated Wood Surfaces for Chemical Residue

Abstract

The U.S. Consumer Product Safety Commission (CPSC) staff completed a series of investigations that estimated the potential exposure and risk of young children to arsenic while playing on playground equipment composed of CCA (chromated copper arsenate)-treated wood. Prior to sampling in-use field structures composed of CCA-treated wood, studies were undertaken to create a standard sampling protocol for quantifying arsenic migration from CCA-treated wood and to establish a correlation between the amount of chemical removed by a human hand and a cloth surrogate. These studies resulted in: 1) the development of an efficient extraction method for chemical residues collected on a human hand, 2) the development of a sampling device for consistent surrogate measurements, 3) establishment of a correlation between surrogate and hand measurements, and 4) the development of a standard human hand and surrogate sampling protocol for quantifying arsenic migration from CCA-treated wood. These studies also examined factors such as approaching a maximum hand load, effects of re-rubbing the same area of a board, and comparison of surrogate materials. The results from sampling CCA-treated wood with methods described in this article were later employed to obtain field data used in exposure and risk assessments.These videos were made several years ago by CPSC for a different issue concerning playground equipment.

Estimating dermal transfer of copper particles from the surfaces of pressure-treated lumber and implications for exposure

“…Each board was divided into four sections: three for total copper analysis (9 replicates per formulation) and one for particulate analysis (3 replicates per formulation). Each section was sampled periodically at 0, 14, 34, 70, 97, 140, 260, and 399 days using a polyester cloth, as defined by the wipe sampling method developed by the CPSC (Cobb, 2003;Thomas et al, 2004). The samples collected from the first three sections of each board were processed and analyzed for total copper, while the samples from the fourth section were preserved for microscopy and X-ray adsorption fine structure spectroscopy (XAFS).…”

“…The method was developed by the CPSC and is described in detail elsewhere (Cobb, 2003;Thomas et al, 2004). In brief, a piece of polyester fabric (cloth) (Texwipe TX 1099), approximately a 10 cm square, was soaked with 2 mL of 0.9% NaCl solution and left overnight.…”

“…Therefore, the use of the material in outdoor wooden structures represents a potential biocidal exposure pathway to human through contact with the wood surface. Previous work by the U.S. Consumer Product Safety Commission (CPSC) suggested the greatest potential exposure route for children is hand-tomouth ingestion (Thomas et al 2004).…”

“…In 2003, the wood industry voluntarily stopped producing copper chromated arsenate (CCA) lumber for residential applications in favor of an ionic copper based treatment. The transition resulted from research, by the CPSC, into the potential for children to be exposed to elevated levels of arsenic during play activities on CCA treated equipment (Thomas et al, 2004). More recently, the industry has shifted from the ionic copper treatment formulation to a micronized copper formulation (Leach and Zhang, 2006).…”

“…Therefore, an investigation was conducted to characterize and evaluate the amount of 6 copper and copper micro/nanoparticles, primarily copper carbonate, transferred during physical contact with the wood surface. This research focuses on the copper released and available for potential ingestion through hand-to-mouth contact using surrogate dermal transfer methods developed previously for evaluating CCA lumber for arsenic (Cobb, 2003;Thomas et al, 2004).…”