Mirex bioaccumulation

Leatherland, J.F., R.A. Sonstegard, and M.V. Holdrient. 1979. Effect of dietary mirex and PCB s on hepato-somatic index, liver lipid, carcass lipid and PCB and mirex bioaccumulation in yearling coho salmon, Oncorhynchus kisutch. Comp. Biochem. Physiol. 63C 243-246. 

Mitex [2385-85-5] is l,2,3,4,5,5,6,7,8,9,10,10-dodecachloro-octahydro-l,3,4-metheno-2JT-cyclobuta-p,<7 -pentalene (37) (mp 485°C). The rat LD s are 306, 600 (oral) and >2000 (dermal) mg/kg. Mirex is extremely resistant to biodegradation and was once considered the perfect stomach poison iasecticide for use ia baits to control imported fire ants. However, even at doses of a few milligrams per 10 m it was found to bioaccumulate ia birds and fish and its registrations were canceled ia the United States ia 1976. 

Chlordecone [143-50-0] or decachloro-5-oxo-pentacyclo-[5.3.0.02,6,03,9,04,8]-decane (38) (mp 349°C dec) is the 2-keto analogue of mirex and is soluble in water to 4 g/L by hydration. The rat LD50s are 95,140 (oral) and >2000 (dermal) mg/kg. Chlordecone is a stomach poison used in baits for the control of cockroaches and ants and for the control of banana thrips. Because of bioaccumulation its registrations were canceled in the United States in... 

Environmental. The high lipophilicity of the cydodienes and the prolonged persistence of dieldrin and heptachlor epoxide (soil half-lives 2—10 yr) have resulted in severe environmental contamination. These compounds are bioaccumulated from water to fish up to 100,000- to 300,000-fold and are ubiquitous in human fat and milk. Oxychlordane [26880-48-8], mirex, and chlordecone are also bioaccumulative. The cydodienes are extremely toxic to fish with LC5Qs (ppm) to trout and bluegill of endrin, 0.001-0.002 endosulfan, 0.001-0.003 diddrin, 0.003-0.015 aldrin, 0.006-0.01 heptachlor, 0.03-0.026 and chlordane, 0.022—0.095. The LD5Qs to pheasant and mallard are aldrin 16.8 and 520, dieldrin 79 and 381, and endrin 1.6 and 5.6 mg/kg. As indicated by their rat oral LD - s, they are also extremdy toxic to small mammals in fact, endrin has been used as a rodenticide (see Pesticides). Compounds, eg, aldrin and heptachlor, which have unsubstituted double bonds, readily add oxygen to form epoxides in plant and animal tissues and are preferentially concentrated and stored in animal fats. Aldrin epoxide (dieldrin) and heptachlor epoxide are more stable (half-lives on alfalfa of seven to eight days) than aldrin and heptachlor (half-lives on alfalfa of less than one day). 

The Binational Toxics Strategy between the USA and Canada has identified 12 bioaccumulative substances (referred to as Level-1 substances) having significant persistency and toxicity to the Great Lakes system, with the goal of reducing the sources of these substances to achieve naturally occurring levels [23]. Six of the 12 Level-1 substances are OC pesticides aldrin/dieldrin, chlordane, DDT, HCB, mirex, and toxaphene. Several other OC pesticides, such as endrin, heptachlor/heptachlor epoxide, hexachloro-cyclohexanes, tetra- and penta-chlorobenzenes, and pentachlorophenol, have been identified as Level-2 substances. 

USEPA, US Environmental Protection Agency, 2001. Persistent bioaccumulative and toxic (PBT) chemical program. Available at http //www.epa.gov/opptintr/pbt/mirex.htm... 

In response to the continuing discovery of the persistence, bioaccumulative properties, and toxicity of POPs, regional, national and international policies ban the intentional production of compounds, such as polychlorinated biphenyls (PCBs), several organochlo-rine pesticides, such as mirex and dieldrin, and the brominated flame retardants poly-brominated diphenyl ethers (penta-BDE and octa-BDE, and most recently, deca-BDE). Policies and programs have also targeted the unintentional production and release of POPs such as polychlorinated dibenzodioxins and furans (PCDD/Fs). Evidence of the success of these policies has been seen in immediate reductions of air concentrations, followed by declining concentrations in water bodies, soils, biota and our food supplies... 

In Table 4, the equation to predict the bioaccumulation factor (BAFl) of relatively persistent chemicals in human (fat) is also presented [191, 192]. This equation is only valid for chemicals which are not or only minimal metabolized in human. It is also important to note that for super-hydrophobic chemicals, such as octachlorodibenzo-p-dioxin (OCDD) and Mirex, no steady-state BAF value is reached during the whole life. 

Cyclodienes (chlordane, aldrin, dieldrin, heptachlor, endrin, mirex, endosulfan, chlordecone). This new class of pesticides appeared on the scene following World War II. Most of them are very stable to sunlight and persistent in soil and they were used to control termites and other insects. Their effectiveness leads to insect resistance and bioaccumulation in the food chain and for these reasons their use was banned between 1984 and 1988. These compounds affect the CNS in the same way, causing tremors, convulsions, and prostration to the maximum extent, depending on the rate and time of exposure. 

Chlorinated hydrocarbons have also found wide use as flame retardant additives for polymers. Some of these may not be obvious as flame retardants since they were most commonly used as insecticides. Examples include chlordecone and Mirex. These are also toxic and bioaccumulative and have been banned from manufacture as a result. 

Leatherland, J.F., and R.A. Sonstegard. 1980. Effect of dietary Mirex and PCBs in combination with food deprivation and testosterone administration on thyroid activity and bioaccumulation of organochlorines in rainbow trout Salmo gairdneri Richardson. Journal of Fish Diseases 3 115-124. 

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