ABSTRACT
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was identified as the most potent anthropogenic animal carcinogen tested while 2,3,7,8-tetrachlorodibenzofuran (TCDF) would be one tenth as potent. In 1989, the Oregon Department of Environmental Quality listed the Willamette River as water-quality limited for TCDD based on dilution calculations. Additional in-stream monitoring was required to determine the effect of bleached kraft pulp mill discharge on downstream TCDD and TCDF concentrations in fish. TCDD and TCDF are hydrophobic, lipophilic compounds that are highly stable in the aquatic environment. Concern for TCDD and TCDF discharge to the aquatic environment has been elevated due to the potential for bioaccumulation and toxicity to humans consuming low concentrations in fish. Total organic halogen (TOX) was used as an additional measure of mill effluent presence. TOX, a measure of total organic halides, would indicate the organic chlorine discharge from the bleach kraft pulp mill which was not detected by TCDD or TCDF analysis.
