Mirex in the Great Lakes

Eggs of the American crocodile (Crocodylus acutus) from the Florida Everglades contained up to 2.9mg/kg fresh weight of DDE and 0.86 mg/kg of polychlorinated biphenyls, but less than 0.02 mg mirex/kg. Livers of the deep-sea fish (Antimora rostrata), collected in 1971-74 from a depth of 2500 m off the U.S. east coast, contained measurable concentrations of DDT audits degradation products, and dieldrin, but no mirex. 

Between 1959 and 1975, 1.5 million kg of mirex were sold, of which 74% or more than 1.1 million kg were predominantly Dechlorane, a compound used in flame-resistant polymer formulations of electronic components and fabrics. The total amounts are only approximate because almost half the mirex sold from 1962 to 1973 could not be accounted for. Mirex loadings to Lake Ontario were estimated at 200.0 kg per year in 1960-62, which decreased to 28.0 kg in 1980. Mirex entered Lake Ontario mainly from the Niagara River and Oswego River. About 700.0 kg of mirex were present in the bottom sediments of Lake Ontario in 1968, 1600.0kg in 1976, and 1784.0 kg in 1981. All fish species in Lake Ontario were contaminated with mirex, and concentrations in half the species exceeded 

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Concentrations of PCBs in fish from each of the Great Lakes currently exceed the GLWQA objectives for the protection of aquatic life. Similarly, concentrations of some substances (e.g., PCBs, Hg, mirex, toxaphene) in Great Lakes fish continue to exceed acceptable guidelines for human consumption. Documented effects in the Great Lakes include reproductive failure, congenital abnormalities and induction of tumours in various aquatic, terrestrial and avian species (23). 

Mirex and its degradation products in herring gull eggs collected from the Great Lakes in 1977... 

Mirex (dodecachlorooctahydro-l,3,4-metheno-2H-cyclobuta [tv/] pentalene) has been used extensively in pesticidal formulations to control the red imported fire ant (Solenopsis invicta), and as a flame retardant in electronic components, plastics, and fabrics. One environmental consequence of mirex was the severe damage recorded to fish and wildlife in nine southeastern states and the Great Lakes, especially Lake Ontario. In 1978, the U.S. Environmental Protection Agency banned all further use of mirex, partly because of the hazards it imposed on nontarget biota. These included ... 

Sergeant, D.B., M. Munawar, P.V. Hodson, D.T. Benine, and S.Y. Huestis. 1993. Mirex in the North American Great Lakes new detections and their confirmation. Jour. Great Lakes Res. 19 145-157. 

Mirex has been detected in wet precipitation over rural areas at concentrations of less than 1 ng/L (ppt) (EPA 1981b). Rainfall samples collected at several sites in 1985-1986 as part of the Great Lakes Organics Rain Sampling Network contained from >0.2 to <0.5 ng/L (ppt) of mirex. Mirex was not detected consistently at many stations throughout the sampling period therefore, quantitative results for mirex were not presented (Strachan 1990). Air samples taken over southern Ontario in 1988 showed mirex in 5 of 143 samples, at an annual mean concentration of 0.35 pg/sol m (range, 0.1-22 pg/m ) with all of the positive samples detected in polluted environments (Hoff et al. 1992). 

Limited data are available on mirex worldwide except in the United States. The levels of mirex found in birds that were collected in the United States, except of those from the southeastern United States and the Great Lakes, were low and were considered nonhazardous in the 1970s (Cain Bunck, 1983). White (1979) investigated the wings of mallards and American black ducks (Anas rubripes) that were collected from four major flight pathways between 1976 and 1977 (Eisler, 1985 and the references therein). The results showed that Atlantic mallards had the highest detection frequencies of occurrence at 50% and the highest concentration of mirex (0.14 pg g-1 wet wt.). They were followed by Mississippi mallards at 29% and 0.03 pg g-1 wet wt., Central mallards at 14% and 0.06 pg g-1 wet wt., and Pacific mallards at 4% and 0.03 pg g-1 wet wt. (Eisler, 1985). 

The greatest concentration of mirex in the environment was found in Lake Ontario, Canada, where several factories dumped effluent containing mirex. Almost all of the mirex in North America was produced by the Hooker Chemical and Plastics Company of Niagara Falls, New York. A Canadian study found that although effluent runoff was isolated to Lake Ontario, mirex was found in sediment and fish samples from each of the Great Lakes 48a,48b This raises the question of how mirex is being transported upstream from Lake Ontario.54-56... 

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