Hexachlorocyclohexane a-HCH

Canton, J.H., Wegman, C.C., Vulto, T.J.A., Verhoef, C.H., and van Esch, G.J. Toxicity, accumulation, and elimination studies of a-hexachlorocyclohexane (a-HCH) with saltwater organisms of different trophic levels. Water Res., 12(9) 687-690,1978. 

Unequivocal evidence for the re-emission of POPs has been demonstrated in an elegant study of the Great Lakes that border the USA and Canada. This study focused on the POP a-hexachlorocyclohexane (a-HCH), a chiral compound (Box... 

Fig. 7.29 The enantiomers of a-hexachlorocyclohexane (a-HCH). Bold wedge shaped bonds represent bonds rising from the plane of the page toward the viewer, and bonds represented by dashed lines are receding from the plane of the page away from the viewer. See also Box 7.3.

Finally, there is upwelling in cyclonic eddies. For example, enantiomer-specific analysis of a-hexachlorocyclohexane (a-HCH) showed that samples from the East Greenland Sea (75°N around the meridian) had much lower enantiomer ratios, such as typically encountered in deeper, older Arctic waters (Jantunen and Bidleman, 1996). This could be interpreted as surface waters from 75 N represented older/deeper water masses that had surfaced. 

Synonyms AI3-09232 Benzene hexachloride-a-isomer a-Benzene hexachloride BRN 3195880 CCRIS 327 EINECS 206-270-8 ENT 9232 a-HCH a-Hexachloran a-Hexachlorane a-EIexachlorcyclohexane a-Hexachlorocyclohexane 1,2,3,4,5,6-Hexachloro-a-cyclohexane la,2a,3p,4a,5p,6p-Hexachlorocyclohexane a-1,2,3,4,5,6-Hexachlorocyclohexane a-Lindane ... 

Illustrative Example 5.1 Deriving Liquid Aqueous Solubilities, Aqueous Activity Coefficients, and Excess Free Energies in Aqueous Solution from Experimental Solubility Data Problem Calculate the Cf (L), yf 1 and G of (a) di-n-butyl phthalate, (b) y-1,2,3,4,5,6-hexachlorocyclohexane (y-HCH, lindane), and (c) chloroethene (vinyl chloride) at 25 °C using the data provided in Appendix C. 

DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs) and hexachlorobenzene. Residues levels of industry-derived contaminants such as polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-/>-dioxins and dibenzofurans (PCDD/Fs) were also reviewed. Concentrations of these contaminants in different environmental compartments were expressed as unit equivalent to part-per-billion (ppb) level, unless otherwise specified. The cited values of concentrations from various literature sources were rounded to two significant digits for comparison. A number of factors can influence the concentrations in biological samples. Therefore, whenever possible, for biological samples the lipid normalized concentrations were cited for comparison. 

Figure 4.9 Depth profiles for concentrations of a-HCH and y-HCH (ng/L) and a-HCH enantiomer fractions (EFs) in the eastern Arctic Ocean (86° 25 N, 143° 32 E, sampled 5 August 1996). (Reproduced with permission from Environmental Science and Technology, Removal of a- and y-Hexachlorocyclohexane and Enantiomers of a-Hexachlorocyclohexane in the Eastern Arctic Ocean, by Tom Hamer, Henrik Kylin, Terry F. Bidleman and William M. J. Strachan, 33(8), 1157-1164. Copyright (1999) American Chemical Society)...

Wiherg, K. Brorstrdm-Lunden, E. Wiingberg, I. Bidleman, T.R Haglund, R, Concentrations and fluxes of hexachlorocyclohexanes and chiral composition of a-HCH in environmental samples from the southern Baltic Sea Environ. Set Technol. 2001, 35, 4739-4746. 

Figure 5.2 Air concentrations (pg/m ) of a-HCH (hexachlorocyclohexane), y-HCH, endo-sulfans (sum ofendo I, endo II andendosulfan sulfate) and chlordanes (sum of trans-chlordane, cis-chlordane, and trans-nonachlor) between December 2004 and March 2005 at GAPS sites around the world. (Reproduced with permission from Environmental Science and Technology, Toward a Global Network for Persistent Organic Pollutants in Air Results from the GAPS Study, by Karia Pozo, Tom Harner et a ., 40(16), 4867-4873. Copyright (2006) American Chemical Society)...

Hexachlorocyclohexane has been used as an insecticide for the control of agricultural pests, for dressing of cereal seed and for the control of parasites on farm animals since the 1960s. Its use has been banned in many countries but it still remains in extensive use in others. Hexachlorocyclohexane mainly exists in the form of three different isomers, a-(3- and y-hexachlorocyclohexane, appearing in a cmde mixture after manufacture. Only one of these isomers, the y form, expresses insecticidal activity, and the refined product containing about 99% y-hexachlorocyclohexane (y-HCH) is named lindane. 

Numerous individual substances were detected only in Ru04 extracts e.g. di- to pentachlorinated benzenes, 4-chlorobenzoic acid and 2,4-dichlorobenzoic acid 24, hexachlorocyclohexanes (a-,P-,y- and 5-HCH) 22, a technical mixture obtained during the synthesis of lindane, and the plasticizers alkylsulfonic acid phenylesters 23. These plasticizers were recently identified in riverine sediments (Franke et al. 1998). Furthermore, nitro-substituted benzoic acid and alkylated phenols 24 were observed. The occurrence of aromatic nitro compounds as a result of the oxidation of anilines can be excluded due to the contemporary appearance of amino compounds, e.g. 4-aminobenzoic acid or N-ethylaniline. However, the origin as well as the emission pathway of these compounds is still unknown. 

Synonyms Benzenehexachloride-a-isomer a-Benzenehexachloride ENT 9232 a-HCH a-Hexachloran a-Hexachlorane a-Hexachlorcyclohexane a-Hexachlorocyclohexane ... 

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