Mirex degradation

No mirex degradation products were detected in whole fathead minnow or in hydrosoils under aerobic or anaerobic conditions (Huckins et al. 1982). In contrast, three metabolites were detected in coastal marshes after mirex bait application, one of which, photomirex, was accumulated by fish and oysters (Cripe and Livingston 1977). The fate and effects of mirex photoproducts in the environment are unclear and merit additional research. 

Aslanzadeh J, Hedrick HG. 1985. Search for mirex-degrading soil microorganisms. Soil Science 139(4) 369-374. 

Mirex degrades slowly in the environment. Residues can remain in soil and water for years. Mirex does not evaporate to any degree from surface water... 

No mirex degradation products were detected in whole fathead minnow or in hydrosoils under aerobic or anaerobic conditions. In contrast, three metabolites were detected in coastal marshes after mirex bait... 

Compounds that affect activities of hepatic microsomal enzymes can antagonize the effects of methyl parathion, presumably by decreasing metabolism of methyl parathion to methyl paraoxon or enhancing degradation to relatively nontoxic metabolites. For example, pretreatment with phenobarbital protected rats from methyl parathion s cholinergic effects (Murphy 1980) and reduced inhibition of acetylcholinesterase activity in the rat brain (Tvede et al. 1989). Phenobarbital pretreatment prevented lethality from methyl parathion in mice compared to saline-pretreated controls (Sultatos 1987). Pretreatment of rats with two other pesticides, chlordecone or mirex, also reduced inhibition of brain acetylcholinesterase activity in rats dosed with methyl parathion (2.5 mg/kg intraperitoneally), while pretreatment with the herbicide linuron decreased acetylcholine brain levels below those found with methyl parathion treatment alone (Tvede et al. 1989). 

Holmstead RL (1976) Studies of the degradation of mirex with an iron (II) porphyrin model system. J Agric Food Chem 24 620-624. 

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

Eggs of the American crocodile (Crocodylus acutus) from the Florida Everglades contained up to 2.9 mg/kg fresh weight of DDE and 0.86 mg/kg of polychlorinated biphenyls, but less than 0.02 mg mirex/kg (Hall et al. 1979). Livers of the deep sea fish (Antimora rostrata) collected from 1971 to 1974 from a depth of 2500 m off the U.S. east coast, contained measurable concentrations of DDT and its degradation products, and dieldrin, but no mirex (Barber and Warlen 1979). 

Modified from Norstrom, R.J., D.J. Hallett, F.l. Onuska, and M.E. Comba. 1980. Mirex and its degradation products in Great Lakes herring gulls. Environ. Sci. Technol. 14 860-866. 

Holloman, M.E., B.R. Layton, M.V. Kennedy, and C.R. Swanson. 1975. Identification of the major thermal degradation products of the insecticide mirex. Jour. Agric. Food Chem. 23 1011-1012. 

Mirex is a very persistent compound in the environment and is highly resistant to both chemical and biological degradation. The primary process for the degradation of mirex is photolysis in water or on soil surfaces photomirex is the major transformation product of photolysis. In soil or sediments, anaerobic biodegradation is also a major removal mechanism whereby mirex is slowly dechlorinated to the 10-monohydro derivative. Aerobic biodegradation on soil is a very slow and minor degradation process. Twelve years after the application of mirex to soil, 50% of the mirex and mirex-related compounds remained on the soil. Between 65--73% of the residues recovered were mirex and 3-6% were chlordecone, a transformation product (Carlson et al. 1976). 

Chlordecone has been primarily released to surface waters in waste waters from a manufacturing plant in Hopewell, Virginia, and may be released in activities associated with the disposal of residual pesticide stocks, and as a result of the direct use of mirex. Chlordecone has been released directly as a contaminant of mirex and indirectly from the degradation of mirex. 

Another source of chlordecone release to water may result from the application of mirex containing chlordecone as a contaminant and by the degradation of mirex which was used extensively in several southern states. Carlson et al. (1976) reported that dechlorinated products including chlordecone were formed when mirex bait, or mirex deposited on soil after leaching from the bait, was exposed to sunlight, other forms of weathering, and microbial degradation over a period of 12 years. Chlordecone residues in the soil could find their way to surface waters via runoff. 

Little information was found on the degradation of mirex in the atmosphere. Mirex is expected to be stable against photogenerated hydroxyl radicals in the atmosphere (Eisenreich et al. 1981). 

The degradation of mirex in water occurs primarily by photolysis. During the photodecomposition of mirex, the chlorine atoms are replaced by hydrogen atoms. The primary photoreduction product of... 

Under anaerobic conditions, mirex was slowly dechlorinated to the 10-monohydro derivative by incubation with sewage sludge bacteria for two months (Andrade and Wheeler 1974 Andrade et al. 1975 Williams 1977). The primary removal mechanism for mirex was anaerobic degradation as demonstrated by the 6-month stability of the compound in nine aerobic soils and lake sediments (Jones and Hodges 1974). 

Chlordecone is similar to mirex in structure and is also highly persistent in soils and sediments (halflife expected to be analogous to 10 years duration for mirex) because of its resistance to biodegradation, although some microbial metabolism of chlordecone has been reported (Lai and Saxena 1982 Ordorff and Colwell 1980). No evidence of microbial degradation was detected for chlordecone exposed to hydrosoils from a reservoir (not previously contaminated with chlordecone) and from Bailey Creek (contaminated with chlordecone) under either anaerobic or aerobic conditions for 56 days (Huckins et al. 1982). 

The most commonly used methods for measuring chlordecone and its degradation products in air, water, soil, sediment, fish, shellfish, and animal fat are similar to those used for mirex (i.e., GC/ECD techniques and confirmation by GC/MS). Because of the polar nature of chlordecone, the removal of... 

Carlson DA, Konyha KD, Wheeler WB, et al. 1976. Mirex in the environment Its degradation to Kepone and related compounds. Science 194(4268) 939-941. 

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