Chemical name: Cyclohexane, 1,2,3,4,5,6-hexachloro-, (1.alpha.,2.alpha.,3.beta.,4.alpha.,5.alpha.,6.beta.)-

Final regulatory action has been taken for the category: Pesticide

Final regulatory action: The chemical is Banned

Use or uses prohibited by the final regulatory action:

All uses are prohibited.

The final regulatory action was based on a risk or hazard evaluation: Yes

Summary of the final regulatory action:

The manufacture, supply, import and use of substances as well as products that contain substances listed under Annex 3.1 Number 3 of the Ordinance relating to Environmentally Hazardous Substances (Ordinance on Substances, Osubst). Articles (textiles and leather goods) which contain substances listed under Number 3, may not be imported as commercial goods.

Annex 3.1 Number 3 includes Lindane.

The exception concerning lindane as a seed dressing does not apply anymore. The use of

?-hexachlorocyclohexane in seed dressing for agricultural purposes has been revoked and no product or formulation containing lindane is/will be authorized by the Swiss Federal Office for Agriculture under the Ordinance relating to Plant Protection Products.

The reasons for the final regulatory action were relevant to: Environment

Summary of known hazards and risks to the environment:

Lindane is strongly adsorbed on soils that contain a large amount of organic matter; furthermore, it can move downward through the soil with water from rainfall or artificial irrigation. Volatilization appears to be an important route of its dissipation under the high-temperature conditions of tropical regions.

Lindane undergoes rapid degradation (dechlorination) in the presence of ultra-violet irradiation, to form pentachlorocyclohexenes (PCCHs) and tetrachlorocyclohexenes (TCCHs). When lindane undergoes environmental degradation under humid or submerged conditions and in field conditions, its half-time varies from a few days to three years, depending on type of soil climate, depth of application and other factors. In agricultural soils common in Europe, its half-time is 40-70 days. The biodegradation of lindane is much faster in unsterilized than in sterilized soils. Anaerobic conditions are the most favourable for its microbial metabolization. Lindane present in water is degraded mostly by microorganisms in sediments to form the same degradation products. Bacteria and fungi metabolize lindane to TCCH and PCCH. The rate of metabolic transformation in plants in low, and the main degradation pathway proceeds via PCCH to tr- and tetrachlorophenol and conjugates with beta-glucose and other, unknown compounds. There is no evidence that lindane is isomerized to alpha-HCH.

Limited amounts of lindane and gamma-PCCHs are taken up by and translocated into plants, especially in soils with a high content of organic matter. Residues are found mainly in the roots of plans, and little, if nay, is translocated into stems, leaves or fruits.

Rapid bioconcentration takes place in microorganisms, invertebrates, fish, birds and humans, but biotransformation and elimination are relatively rapid when exposure is discontinued. In aquatic organisms, uptake from water is more important than uptake from food. The bioconcentration factors in aquatic organisms under laboratory conditions ranged from approximately 10 up to 6000; under field conditions, the bioconcentration factors ranged from 10 to 2600.

Lindane is not very toxic for bacteria, algae, or protozoa: 1 mg/l., was generally the no-observed effect level (NOEL). Its action on fungi is variable, with NOELs varying from 1 to 30 mg/l., depending on the species. It is moderately toxic for invertebrates and fish, the L(E)C50 values for theses organisms being 20-90 µg/l.. In short-term and long-term studies with three species of fish, the NOEL was 9 µg/l.; no effect on reproduction was seen with levels of 2.1-23.4 µg/l. The LC₅₀ values for both freshwater and marine crustacean varied between 1 and 1100 µg/l. Reproduction in Daphnia magna was depressed in a dose-dependent fashion; the NOEL was in the range 11-19 µg/l.

Reproduction of molluscs was not adversely effected by a dose of 1 mg/l.

The LD₅₀ for honey-bees was 0.56 µg/bee.

Acute oral LD₅₀ values for a number of bird species were between 100 and 1000 mg/kg body weigh. In short-term studies with birds, doses of 4-10 mg/kg diet had no effect, even on egg-shell quality. Laying ducks treated with doses of lindane up to 20 mg/kg body weight, however, had decreased egg production.

Bats exposed to wood shavings that initially contained 10-866 mg/m² lindane, resulting from application at the recommended rate, all died within 17 days. No effect on mortality or reproductive success was seen in small field mammals given 20 mg/kg diet (the highest dose tested). No data were available on effects on populations and ecosystems.

Expected effect of the final regulatory action in relation to the environment:

Reduction of Lindane exposure to environmental organisms.

Date of entry into force of the final regulatory action: 01/01/2005