Potency of PCDD, PCDF, PCB mixture to produce salmonid developmental mortality compared to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
- Univ. of Wisconsin, Madison, WI (United States)
- Environmental Protection Agency, Duluth, MN (United States)
The combined presence of TCDD-like polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) in feral fish eggs can be expressed as TCDD equivalents (TEQs), assuming congeners interact additively. To test this assumption, early life stage (ELS) mortality was assessed following exposure of lake trout and rainbow trout eggs to control, 7 graded doses of TCDD, or 14 graded doses of a mixture containing 11 TCDD-like PCDDs, PCDFs, PCBs, and 3 nonTCDD-like PCBs, mimicking congener ratios in Lake Michigan lake trout eggs. Lake trout eggs were exposed to waterborne TCDD or mixture and egg congener concentrations determined by GC/MS. Rainbow trout eggs were injected with a known dose of TCDD or mixture. Egg TEQs were calculated as the sum of egg congener concentration multiplied by fish-specific toxic equivalency factors. For both species, dose response curves for ELS mortality versus egg TCDD dose and egg TEQ dose were parallel. However, the mixture dose-response curve was shifted to the right of that for TCDD by 1.5--1.8 fold. LD{sub 50}S for lake trout were 200 pg TCDD/g and 362 pg TEQ/g. Based on TEQs, developmental toxicity of the PCDD, PCDF, PCB mixture was less than additive.
- OSTI ID:
- 42915
- Report Number(s):
- CONF-9410273--
- Country of Publication:
- United States
- Language:
- English
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