The determination of selected polychlorinated dibenzo-p-dioxins and dibenzofurans in environmental samples from sites associated with the use of chlorophenolic wood preservatives

Graduation date: 1987Polychlorinated dibenzo-p-dioxins (PCDD's) and\ud dibenzofurans (PCDF's) are environmental pollutants associated with the production and use of a number of industrial\ud chemicals. In addition, PCDD's and PCDF's are produced\ud during low temperature combustion of wastes containing\ud polyvinylchloride (PVC), chlorophenols, and a number of\ud other chemical precursors.\ud A significant source of environmental contamination\ud by PCDD/PCDF in Oregon has been the use of technical\ud grades of pentachlorophenol (t-PCP) and 2,3,4,6-\ud tetrachlorophenol, and their sodium and potassium salts.\ud These compounds have been used extensively by the lumber industry as wood preservatives since the 1930's.\ud Environmental samples from five sites in Oregon and\ud Washington State were screened for 21 selected PCDD/PCDF\ud isomers. These included the most toxic laterally substituted isomers, that is those with chlorines in the\ud 2,3,7, and 8 positions, but lacking substituents in one or\ud more of the peri positions. The samples were taken from\ud sediments, soil, wood shavings from pressure treated lumber,\ud diptank sludge, fresh crystalline t-PCP, and tissues from\ud bovines and equines exposed to these chemicals in the environment. Three of the Oregon sites were associated with\ud chlorophenate salts used to prevent "sapstain" in finished\ud lumber. The fourth Oregon site served as a control. The\ud Eagle Harbor, Washington, site was located near a pressure\ud treatment facility long known to be a point source for\ud creosote in Eagle Harbor.\ud The soil and sediment samples were analyzed for PCDD/\ud PCDF with the intent of finding evidence for in-situ degradation, and perhaps acclimated microorganisms capable of\ud degrading these stable and persistent compounds. No\ud significant evidence of such processes occurring\ud under natural conditions was discovered. This tends to\ud support other work which suggests these compounds are highly\ud refractory to microbiological processes