VOL.: 20 (1979) (p. 195)
b-HCH was tested in four experiments in mice by oral administration: two were inadequate, and another was inadequately reported but suggested hepatocarcinogenicity; in the fourth study, b-HCH induced benign and malignant liver tumours in animals of both sexes. Two feeding experiments in rats were considered to be inadequate.
Lindane was tested in six experiments in mice by oral administration: it produced benign and malignant liver tumours in animals of both sexes in two experiments, one of which involved only small groups of animals. The results of a third experiment suggested hepatocarcinogenicity but were inadequately reported. The results of a fourth experiment also suggested hepatocarcinogenicity but were considered inadequate because of the low number of control animals used. The other experiments were considered inadequate for an evaluation of carcinogenicity. Lindane was also tested in three feeding studies in rats: two were considered inadequate; in the other a slight excess of thyroid tumours was observed in females. Lindane was tested inadequately in mice by skin application and by subcutaneous and intraperitoneal administration.
Experimental data on the long-term effects of the d- and e-isomers were considered to be inadequate.
Technical HCH was tested in three experiments in mice by oral administration, producing liver tumours. A feeding experiment in rats was considered to be inadequate.
Lindane is embryotoxic. a- and b-HCH and lindane, when tested individually and/or as a mixture, were not mutagenic in bacteria, yeast or Drosophila. Lindane induces chromosome aberrations, polyploidy and mitotic arrest in a number of plant systems. It also induced chromatid breaks in human lymphocytes in vitro.
The only epidemiological study related to possible carcinogenic effects of HCH or lindane in humans involved exposure to many pesticides; the Working Group was thus unable to draw any conclusion specific to HCH or lindane.
The extensive production of HCH and lindane and their use in veterinary, agricultural and consumer products since the early 1950s indicate that widespread human exposure occurs. This is confirmed by many reports of their occurrence in the general environment and by reports of their presence in body fluids and tissues, both in the general population and in exposed workers.
For definition of the italicized terms, see Preamble Evaluation.
Previous evaluation: Vol. 5 (1974)
Subsequent evaluation: Suppl. 7 (1987)
See Also: Alpha- and beta-hexachlorocyclohexanes (EHC 123, 1992) Hexachlorocyclohexane (Mixed Isomers)