Chlordecone applications

Dermal exposure of mice to 3.6 mg/kg of mirex, three times/week for 4 weeks, resulted in mild epidermal proliferation (Moser et al. 1992). Application of an unspecified amount of mirex to the skin of rabbits for 6-7 hours/day, 5 days/week for 9 weeks, resulted in slight erythema and scaling after day 5 (Larson et al. 1979a). This effect was reported to be reversible after 2 days without treatment. No signs of dermal irritation were observed in rabbits exposed to varying amounts of a 20% solution of chlordecone in corn oil (Larson et al. 1979b). 

As indicated in Section 2.3.2.1, studies in workers occupationally exposed to chlordecone have shown that it is absorbed, distributed to various tissues, and has a long retention time in the body (Cannon et al. 1978 Cohn et al. 1978 Taylor 1982, 1985). Since dermal exposures probably constituted a major portion of the exposure in these occupational studies, information presented in Section 2.3.2.1 is also applicable here. No studies were located regarding distribution in animals after dermal exposure to chlordecone. 

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). 

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. 

The most commonly used methods for measuring mirex in blood, tissues (including adipose tissue), milk, and feces are gas chromatography (GC) or capillary GC combined with electron capture detection (ECD) or mass spectrometry (MS). Tables 6-1 and 6-2 summarize the applicable analytical methods for determining mirex and chlordecone, respectively, in biological fluids and tissues. 

Methods exist for determining mirex and chlordecone in air (ambient and occupational), water, sediment and soil, biota and fish, and foods. Most involve separation by GC with detection by ECD or MS. Tables 6-3 and 6-4 summarize some of the applicable analytical methods used for determining mirex and chlordecone, respectively, in environment samples. 

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