Alpha-HCH

The first commercially available HCH insecticide sometimes misleadingly called benzene hexachloride (BHC) was a mixture of isomers, principally alpha HCH (65-70%), beta HCH (7-10%), and gamma HCH (14-15%). Most of the insecticidal activity was due to the gamma isomer (Figure 5.1), a purified preparation of which (>99% pure) was marketed as lindane. In Western countries, technical HCH was quickly replaced by lindane, but in some other countries (e.g., China) the technical product, which is cheaper and easier to produce, has continued to be used. HCH has been used as a seed dressing, a crop spray, and a dip to control ectoparasites of farm animals. It has also been used to treat timber against wood-boring insects. 

Biosphere preserve IDDT ZHCH SDDT Gamma-HCH Alpha-HCH... 

Macdonald et al. (2000) found that global use of technical HCH and historical measurements of alpha-HCH concentration in the atmosphere of Arctic region showed two significant declines, one in 1983 when China banned the use of technical HCH and another around 1990 when India banned technical HCH usage in agriculture. In an experiment conducted at a paddy field in southern India Tanabe et al. (1991), Ramesh et al. (1991) and Takeoka et al. (1991) noticed rapid volatilization of HCHs, low residues in the soil and paddy plant when compared to their presence in the atmospheric levels and rapid removal to the atmosphere. Such experiments and surveys indicate the prominence of India in the contribution toward global pollution of toxic chemicals. 

Canton, J.H., Greve, P.A., Sloof, W., van Esch, G.J. (1975) Toxicity accumulation and elimination studies of alpha-hexacyclohexane (alpha-HCH) with fresh water organisms of different trophic levels. Water Res. 9, 1163-1169. 

Toose L, Woodfine DG, MacLeod M, Mackay D, Gouin J. 2004. BETR-World a geographically explicit model of chemical fate application to transport of alpha-HCH to the Arctic. Environ Pollut 128 223-240. 

Mossner, S. Spraker, T.R. Becker, P.R. BaUschmiter, K., Ratios of enantiomers of alpha-HCH and determination of alpha-, beta-, and gamma-HCH in brain and other tissues of neonatal Northern fur seals (Callorhinus ursinus) Chemosphere 1992, 24, 1171-1180. 

Hummert, K. Vetter, W. Luckas, B., Levels of alpha-HCH, lindane, and enantiomeric ratios of alpha-HCH in marine mammals from the northern hemisphere Chemosphere 1995, 31, 3489-3500. 

Duinker JC, Hillebrand MTJ. 1979. Behaviour of PCB, pentachlorobenzene, hexacMorobenzene, alpha-HCH, gamma-HCH, beta-HCH, dieldrin, endrin and p,p -DDD in the Rhine-Meuse estuary and the adjacent coastal area. Neth J Sea Res 13 256-281. 

SYNONYMS 1 -alpha,2-alpha,3-beta,4-alpha,5-beta,6-beta-hexachlorocylcohexane, ben-zene-trans-hexachloride, alpha-1,2,3,4,5,6-hexachlorocyclohexane, cyclohexane, 1,2,3,4,5,6-hexachloror-,alpha-isomer, alpha-lindane, alpha-hch, alpha-hexachlorane hexachlorocyclohex-... 

Jantunen, L.M. and T. Bidleman 1996. Air-water gas exchange of hexachlorocyclohexanes (HCHs) and the enantiomers of alpha-HCH in arctic regions. Journal of Geophysical Research—Atmospheres 101(D22) 28837-28846. 

Of the other HCH isomers, the alpha and beta forms are less toxic than the gamma form. However, the beta form is more persistent than the gamma form, and unacceptably high residues have sometimes been reported in foods originating from countries where technical HCH is still used (Environmental Health Criteria 123). 

A portion of pesticides administered is accumulated in an unaltered form, and a further fraction may undergo different biotransformations. For example, DDT can be partially metabolized to DDA, DDD or DDE depending on the organism. HCH is accumulated in the form of alpha, beta, gamma and delta isomers. The accumulation of compounds in the organism is also altered on changing their chemical structure. 

SYNONYMS benzenehexachloride, delta- HCCH, delta-HCH, TBH, 1-alpha,2-alpha,3-alpha,4-beta,5-alpha,6-beta-hexachlorocyclohexane, delta-bhc, delta-lindane... 

Wittlinger R, Ballschmiter K. 1990. Studies of the global baseline pollution XIII. C6-C14 organohalogens (Alpha- and gamma-HCH, HCB, PCB, DDT, 4,4 -DDE, cis- and frans-chlordane, frans-nonachlor, anisols) in the lower troposphere of the Southern Indian Ocean. Fresenius Journal of Analytical Chemistry 336 193-200. 

Whole-body autoradiographic studies on the distribution of alpha-, beta- and gamma-HCH indicated their relatively rapid urinary excretion 51.0, 8.5 and 1.5% of administered labelled gamma-HCH were excreted at the first, second, and third day after intraperitoneal injection to mice (Nakajima et al. 1970). Results of autoradiographic studies were presented by Kurihara (1973), also. 

Stein et al. (1977) (Fig. 3), supposed the HCH hydroxylation to hexachlorocyclohexanols (I) to explain the polychlorophenol formation from HCH. This alpha-chlorohydrin (I) that results would be expected to eliminate spontaneously HCl to form a ketone, 2,3,4,5,6-pentachloro-cyclohexanone-(l) (II). An elimination of two pairs of H C1 in alpha beta-position to the keto-function yielding a symmetrical trichlorocyclo-hexadienone (III) now could be imaginable. Intermediate (III) could be stabilized by tautomerization to 2,4,6-TCP. The authors stated a high extent of conjugation (in vivo 90% ) of this TCP. 

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