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Bulgaria - Final Regulatory Action
Methamidophos CAS number:
Date circular:

Chemical name: O,S-dimethyl phosphoramidothioate

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 formulations and uses are prohibited.

Pesticide use or uses that remain allowed:


The final regulatory action was based on a risk or hazard evaluation: No

Summary of the final regulatory action:

Endrin was excluded from the list of active substances authorized for use in plant protection products in 1969 under the Law on protection of plants against pests and blights. It has prohibited to production, use and place on the market all plant protection products containing Endrin according to annual adopted list of active ingredients banned for use in plant protection products under the Plant Protection Act since 2003. Endrin is designated as a PIC chemical. (Annex I of the Regulation on the import and export of certain dangerous chemicals on the Bulgarian territory). The chemical is listed in Annex II of the Regulation as prohibited for export from and import in the country.

The reasons for the final regulatory action were relevant to: Human health and environment

Summary of known hazards and risks to human health:

In a controlled study in which a combined dose of methamidophos and acephate was administered to groups of male and female volunteers, cholinesterase depression was observed predominantly in those receiving a higher methamidophos: acephate ratio (1:4 rather than 1:9). A higher total concentration (0.2 mg/kg), administered at the lower ratio (1:9), did not result in any depression of enzyme activity.
Excessive human exposure to methamidophos caused delayed polyneuropathy.

Expected effect of the final regulatory action in relation to human health:

To avoid exposure of the chemicals and the associated risks to human health.

Summary of known hazards and risks to the environment:

In mildly acidic or neutral aqueous solutions, methamidophos is stable at temperatures up to 80 C. Methamidophos is degraded in outdoor natural water systems with half-lives of 15.9 days in water and 7.5 days in silt. Although methamidophos was leached from soils, it also degraded rapidly in natural water systems.
It is degraded relatively rapidly in soils. Within 1 week, the residue dropped to 10% of the level measured on the day of application. Furthermore, there was no accumulation of the insecticide, even after several applications.
Methamidophos is moderately toxic for fish as evidenced by 96-h LC50s of 25 mg/litre for rainbow trout (Oncorhynchus mykiss), and approximately 100 mg/litre for goldfish (Carassius auratus) and carp (Cyprinus carpio). The LD50s for the mallard duck (Anas platyrhynchos), Japanese quail (Coturnix coturnix Japonica), and the hen (Gallus domesticus) are 29.5, 10, and 25 mg/kg, respectively. This insecticide can also be harmful to bees.

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

To avoid exposure of the chemical and the associated risks to environment.

Date of entry into force of the final regulatory action: 01/04/2003