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Potencies of Polychlorinated Dibenzo-p-dioxin, Dibenzofuran, and
Biphenyl Congeners, Relative to 2,3,7
,8-Tetrachlorodibenzo-p-dioxin, for Producing Early Life Stage
Mortality In Rainbow Trout (Oncorhynchus mykiss)
Walker, MK | Peterson, RE
Aquatic Toxicology AQTODG, Vol. 21, No. 3/4, p 219-238, December
1991. 3 fig, 4 tab, 58 ref. National Oceanic and Atmospheric
Administration, U.S. DOC and State of Wisconsin federal grant no.
NA90AA-D-SG469, Great Lakes Protection Fund FG6901038 and National
Institute of Environmental Health Sciences training grant ES07015.
The presence of polychlorinated dibenzo-p-dioxins (PCDDs),
dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in
feral lake trout eggs (Salvelinus namaycush) may increase the risk
of lake trout early life stage mortality in the Great Lakes. To
assess the combined toxicity of PCDDs, PCDFs, and PCBs to lake
trout early development, toxic potencies, relative to 2
,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), were determined
for individual PCDD, PCDF, and PCB congeners, based on rainbow
trout (Oncorhynchus mykiss) early life stage mortality. Newly
fertilized eggs were injected with graded doses of 2,3,7,7-TCDD,
or a PCDD, PCDF, or PCB congener. Median lethal dose values were
determined based on the egg dose that caused mortality from
hatching onset to swim-up. Toxic equivalency factors were
calculated as 2,3,7,8-TCDD median lethal dose/congener median
lethal dose. For PCDDs, fish-specific toxic equivalency factors
were 10 to 100-fold higher than toxic equivalency factors
determined in rat hepatoma cells, but were similar to toxic
equivalency factors determined in rat cells and toxic equivalency
factors proposed for risk assessment. The most significant
finding, however, was that for the coplanar PCBs and
mono-ortho-chlorinated analogues of the coplanar PCBs
fish-specific toxic equivalency factors were 1/14 to 1/80 less
than both those determined in rat cells and proposed for risk
assessment. Using these fish-specific toxic equivalency factors,
the risk associated with exposure of early life stages of lake
trout to complex mixtures of PCDDs, PCDFs, and PCBs in the Great
Lakes can be estimated. (Mertz-PTT) 35 048949002
 Descriptors: *Dioxins | *Fish | *Furans | *Mortality | *Polychlorinated biphenyls | *Toxicology | *Water pollution effects | Eggs | Great Lakes | Lake
trout | Rainbow trout | Reproduction | Risk assessment | Structure-activity relationships | Toxic equivalency factors
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