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APPLIED STUDIES
Chemical pesticide treatment enables relatively nonresistant woods to be used in outdoor construction projects. The most prevalent procedure used to protect these woods is pressure treatment with chromium, copper, and arsenic (CCA). This pilot study examined the airborne concentration and particle size distribution of wood particles, chromium, copper, and arsenic at both outdoor (measured over the whole work day) and indoor (measured during the performance of specific tasks) work sites. At the outdoor residential deck construction sites, the arithmetic mean total dust concentration, measured using personal filter cassette samplers, was 0.57 mg/m^sup 3^. The mass median aerodynamic diameter (da) of the outdoor wood dust was greater than 20 (mu)m. Indoor wood dust concentrations were significantly greater than those measured outdoor and were job category-dependent. The highest mean breathing zone dust concentration, 49.0 mg/m^sup 3^, was measured at the indoor sanding operation. Personal impactor sampling demonstrated that the mean total airborne concentration of arsenic, but not chromium or copper, was consistently above recommended occupational exposure levels at the indoor work site, and occasionally at the outdoor work sites. At the indoor sanding operation, the mean total chromium, copper, and arsenic concentrations were 345, 170, and 342 (mu)g/m^sup 3^, respectively. Thus, significant exposure to airborne heavy metals can occur as a result of indoor and outdoor exposure to CCA pressure-treated wood dust. Therefore, current standards for wood dust may not adequately protect workers from the heavy metals commonly used in CCA pressure-treated wood.
Keywords: arsenic, chromium, metals, occupational exposure, pressure-treated wood, wood dust
To prolong the life of wood used in the outdoor construction and fabrication industries, chemical agents have been used since the 1930s to impregnate and preserve wood products. These chemicals have been highly successful in protecting wood against termites, other insects, fungus, and rot. Nearly 600 million cubic feet of pressure-treated wood are produced and used each year in the United States alone.(1) About 468 million cubic feet of the pressure-treated wood are treated with waterborne preservatives. The majority of the waterborne treatments utilize the impregnation of softwood with chromated copper arsenate (commonly referred to as CCA). Although these metals possess a wide range of toxic properties, the U.S. Environmental Protection Agency ruled in 1986 that CCA pressure-treated wood...