Chemical name: 1,4:5,8-Dimethanonaphthalene, 1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-,, 1,4:5,8-Dimethanonaphthalene, 1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-, (1.alpha.,4.alpha.,4a.beta.,5.beta.,8.beta.,8a.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 Isodrin.

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

Summary of known hazards and risks to the environment:

Release of isodrin to the environment is not expected to be significant since isodrin is no longer manufactured or used commercially in the United States. If released to soil, isodrin may undergo microbial oxidation to endrin by a mechanism analogous to the biooxidation of aldrin to dieldrin. The mobility of isodrin in soil may range from moderately mobile to immobile and isodrin is not expected to hydrolyze in moist soils or volatilize from soil surfaces. Based on experiamental data, the half-life of isodrin in soil has been estimated to range from 0.5 years to a maximum of 6 years. If released to water, isodrin may bioconcentrate in aquatic organisms, adsorb to suspended solids and sediments, volatilize (calculated half-life 5.4 days in rivers) and undergo very slow microbial transformation, possibly to endrin. Isodrin is not expected to hydrolyze since it contains no hydrolyzable functional groups. If released to air, isodrin should occur mostly adsorbed to particulate matter. It may undergo phototransformation possible forming photoisodrin or isodrin vapor may react with photochemically generated hydroxyl radicals (calculated vapor phase half-life 35.5 minutes).

TERRESTRIAL FATE: If released to soil, isodrin may undergo microbial oxidation to endrin by a mechanism analogous to the biooxidation of aldrin to dieldrin. The mobility of isodrin in soil may range from moderately mobile to immobile and isodrin is not expected to hydrolyze since it contains no hydrolyzable functional groups. Isodrin should not volatilize significantly from soil surfaces. The maximum degradation half-life of isodrin in soil has been estimated to be 6 years based on 85% removal in 14 years of 448 kg isodrin/hectare mixed uniformly throughout the profile of sandy loam soil. Based on other experimental data, the half-life of isodrin has been estimated to be 0.5 to 1.0 years. It is absorbed by roots of plants and is likely to be translocated to above ground parts of plants.

AQUATIC FATE: If released to water, isodrin may bioconcentrate in aquatic organisms, adsorb to suspended solids and sediments undergo very slow microbial transformation, possibly to endrin, volatilize (calculated half-life 5.4 days in rivers) and undergo phototransformation, possibly to photoisodrin. Isodrin is not expected to hydrolyze since it contains no hydrolyzable functional groups.

ATMOSPHERIC FATE: If released to air, isodrin may undergo phototransformation possibly forming photoisodrin or isodrin vapor may react with photochemically generated hydroxyl radicals (calculated vapor phase half-life 35.5 minutes).

Although not regulated as a persistent organic pollutant (POP) under UN agreements (like dieldrin and endrin) isodrin has similar properties of toxicity, persistence and tendency to bioaccumulate that characterise POPs.

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

It is the objective of the North Sea Conferences: "To aim for a substantial reduction in the quantities of pesticides reaching the North Sea and to this end, by 31 December 1992, to control strictly the use and application of pesticides and to reduce, where necessary, emissions to the environment. Special attention will be paid to:

i) the phasing out of those pesticides which are the most persistent, toxic and liable to bioaccumulate see part c) of Annex 1B);

ii) the establishment of approval systems specifying permitted pesticides and permitted uses".

The ban of Isodrin in Switzerland is intended to reach this objective.

Date of entry into force of the final regulatory action: 29/11/1995