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Title: A CONGENER SPECIFIC EVALUATION OF TRANSFER OF CHLORINATED DIBENZO-P-DIOXINSAND DIBENZOFURANS TO MILK OF COWS FOLLOWING INGESTION OF PENTACHLOROPHENOL-TREATED WOOD

Author
item FRIES, GEORGE - 1265-70-00 (RETIRED)
item PAUSTENBACH, DENNIS - EXPONENT
item MATHER, DIPTI - EXPONENT
item LUKSEMBURG, WILLIAM - ALTA ANALYTICAL LAB

Submitted to: Journal of Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: It was proposed previously that animal exposure to pentachlorophenol treated wood is an important source of dioxins in milk and beef. Aspects of this hypothesis were examined by administering treated wood to cows and measuring the transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans to milk. The ground wood was administered to four cows for 56 6days. Maximum concentrations were reached in milk within the first 28 days of dosing, and these concentrations were stable through the end of the dosing period. The three furans without chlorine in the 4 and 6 positions were not transported to milk in significant amounts because absence of chlorines in these positions allow metabolism of the compounds. The remaining furans and all dioxins were transported to milk at rates that were inverse to the number of chlorines in the compound. Variations among cows in the bioconcentration of specific congeners were small, and were not trelated to body weight, dry matter intake, or production of milk and milk fat. Bioconcentration factors and other transfer coefficients calculated for the individual dioxin and furan congeners provide tools for identifying sources and for estimating human exposure under various scenarios. The more extensive set of transfer coefficient derived in this study will reduce the uncertainty in risk assessments.

Technical Abstract: The hypothesis that pentachlorophenol (PCP) treated wood is an important source of dioxins in milk and beef was examined by administering PCP- treated wood to cows and measuring the transfer of polychlorinated dibenzo- p-dioxins (PCDD) and dibenzofurans (PCDF) to milk. The 3 g/day dose of ground wood was administered to four cows for 56 days. This dose provided a aPCP intake of 4.8 mg/day, and PCDD/F intakes in the range of 0.3 ug/day fo 2,3,7,8-TCDD to 17,000 ug/day for 1,2,3,4,6,7,8,9-OCDD. Steady state with respect to excretion in milk was reached because concentrations of PCDD/Fs in milk fat were unchanged from Day 28 through Day 56. The PCDFs without chlorine in the 4 and 6 positions were not transported to milk in significant amounts. The other PCDFs and all PCDDs had intake adjusted concentrations in milk that were inverse to the number of chlorines. Variations among cows in concentrations of specific congeners were small, and were not related to body weight, dry matter intake, or production of milk and milk fat. Bioconcentration factors (BCFs) and other transfer coefficients calculated for the PCDD/Fs provide tools for identifying sources and for reducing uncertainty in risk assessments.