Summary

Description

Many of the pesticides detected at the pesticide storage site at Lake Minchumina could pose a serious threat to fish and wildlife. The 2,3,7,8TCDD isomer of dioxin, found in soils at the site, is the most toxic synthetic chemical ever tested under laboratory conditions, and has resulted in numerous mammal and bird deaths and reproductive failures elsewhere Eisler 1986: P. 1. The effects of DDE, a DDT metabolite, also present at the site, are also profound and include massive reproductive failures among certain bird species, especially raptors, due to eggshell thinning Stickel 197S. DDT and its metabolites are also slightly to severely toxic to invertebrates and fish depending on species EPA 1980; Mayer and Ellersieck 1986. No pesticides or dioxins were detected in any of burbot or northern pike examined see Appendix, with the exception of a trace amount, 0.02 mgkg 4,4DDE, in one fish. A similar amount of matrix blank contamination occurred, suggesting that even this small concentration was due to laboratory contamination and not actually present in the northern pike. Deficiencies in laboratory quality assurance do not enable an estimate of precision of these results. Also, lack of spike recovery data do not allow any conclusions regarding PCB or toxaphene concentrations of the fish. However, accuracy during spike recoveries was, for the most part, adequate to high for the remaining compounds examined. Although only five fish were examined, all findings were negative, suggesting that Lake Minchumina fish are not contaminated with organochlorine compounds. Apparently, contamination of the lake itself has been minimal. Alternately, dilution and degradation processes have been sufficient to minimize recent fish exposures to organochlorine compounds. These results agree with those obtained by E E 1987, which showed no organochlorine contamination of lake sediments, with the exception of lowlevel contamination by 2,4,5T 0.033 0.260 mgkg. Our analyses did not include analysis of this herbicide. When 2,4,5T is not contaminated by dioxin, it is of low toxicity to invertebrates and only slightly toxic to fish Mayer and Ellersieck 1986.