Soils chlordane, termite control

Cyclodienes. These are polychlorinated cycHc hydrocarbons with endomethylene-bridged stmctures, prepared by the Diels-Alder diene reaction. The development of these insecticides resulted from the discovery in 1945 of chlordane, the chlorinated adduct of hexachlorocyclopentadiene and cyclopentadiene (qv). The addition of two Cl atoms across the double bond of the ftve-membered ring forms the two isomers of chlordane [12789-03-6] or l,2,4,5,6,7,8,8-octachloro-2,3,3t ,4,7,7t -hexahydro-4,7-methano-lJT-indene, QL-trans (mp 106.5°C) and pt-tis (32) (mp 104.5°C). The p-isomerhas signiftcantiy greater insecticidal activity. Technical chlordane is an amber Hquid (bp 175°C/267 Pa, vp 1.3 mPa at 25°C) which is soluble in water to about 9 fig/L. It has rat LD qS of 335, 430 (oral) and 840, 690 (dermal) mg/kg. Technical chlordane contains about 60% of the isomers and 10—20% of heptachlor. It has been used extensively as a soil insecticide for termite control and as a household insecticide. 

Heptachlor was in extensive use until the 1970s for the control of certain soil-inhabiting insects that attack com and other field crops, cotton insects, grasshoppers, and for the treatment of crop seeds. Along with other cyclodiene insecticides, heptachlor is uniquely suited for termite control. Since 1988, it has not been used for the control of termites, but it is permitted for commercial use in the United States for fire ant control in power transformers.24 Nonachlor is a by-product created during the manufacture of chlordane and heptachlor. 

Heptachlor [76-44-8], another cyclodiene insecticide of chemical structure similar to chlordane is a chlorination product of chlordane. Technical grade heptachlor contains about 73% heptachlor, 22% fran -chlordane and 5% nonachlor. This pesticide was extensively used until 1970s for the control of soil insects, cotton insects, grasshoppers and termite control. The use of this pesticide for underground termite control was banned in the United States in 1988. Its application after that was restricted to controlling fire ant in power transformers. The U.S. EPA has classified heptachlor as a Group B2 probable human carcinogen. 

Leidy RB, Wright CG, Dupree Jr HE, et al. 1985. Subterranean termite control Chlordane residues in soil surrounding and air within houses. American Chemical Society Symposium Series 273 265-277. 

Subterranean Termite Control Chlordane Residues in Soil Surrounding and Air Within Houses... 

Uses Heptachlor was first isolated from technical chlordane in 1946. Its extensive use from 1960 to 1970 was primarily for the control of termites, ants, and soil insects. Different formulations such as dusts, wettable powders, emulsifi-able concentrates, and oil solutions were in use for pest management before the imposition of its use. Heptachlor has both nonsystemic stomach action and contact action. Heptachlor epoxide is the principal metabolite (oxidation product) of heptachlor and is formed by different plants and animals. 

Pesticides are also used indoors, from which release to outdoors occurs via ventilation (see Chapter 7). Indoor use of pesticides often results in indoor air and dust concentrations 10-100 times greater than that in outdoor air and surface soil because of minimal degradation indoors. Chlordane is still released via indoor air as a result of its application to house foundations to control termites in urban areas from the 1940s to its ban in the US in 1988 and global discontinuation of production in 1997 (Leone et al, 2000 Offenberg et al, 2004). 

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. 

From 1983 until 1988, chlordane s only approved use was to control termites in homes. The pesticide was applied underground around the foundation of homes. When chlordane is used in the soil around a house, it kills termites that come into contact with it. 

---