Chemical name: Phosphorothioic acid, O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) ester

Final regulatory action has been taken for the category: Pesticide

Final regulatory action: The chemical is Severely Restricted

Use or uses prohibited by the final regulatory action:

All types of chlorpyrifos formulations for use in the agricultural sector are no longer allowed.

Pesticide use or uses that remain allowed:

Chlorpyrifos are still permitted for use in public health to control urban pests, such as cockroaches, termites, mosquitoes, ants, flies, and bugs.

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

Summary of the final regulatory action:

The Pesticides Board of Malaysia issued a Circular Letter dated April 28, 2021, informing the industry of the Board's decision to cancel the registration of all products containing chlorpyrifos for agricultural use effective from May 1, 2023.

This means that effective from May 1, 2023, chlorpyrifos will no longer be authorized as a plant protection product in agriculture. However, the registration of chlorpyrifos products for use in public health and urban pest control will continue.

Effective from the date of the Circular Letter, the Pesticides Board stopped accepting new applications and re-registrations of pesticide products containing chlorpyrifos for the agricultural sector. All new applications that were pending approval or in the process of evaluation were automatically cancelled.

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

Summary of known hazards and risks to human health:

The Department of Agriculture of Malaysia has revealed that food crops, including those intended for export, have consistently exceeded the national maximum limits for chlorpyrifos residues. This presents a potential risk to both workers and consumers who may be exposed to the pesticide.

Agricultural workers in Malaysia who have been exposed to chlorpyrifos have reported symptoms such as headaches, dizziness, and skin irritation. A study conducted in Sabak Bernam, Malaysia found that 7% of paddy farmers had chlorpyrifos in their blood, with a mean concentration of 7.29 nanograms per milliliter blood. Furthermore, 75% of the farmers in the study reported experiencing at least one pesticide exposure symptom.

In addition to its impact on human health, chlorpyrifos has been shown to cause neurotoxic symptoms in animals, including hypoactivity, lacrimation, salivation, foot splay, ataxia, and tremors. The lethal dose (LD50) for mammals (oral) ranges from 80 to 250 mg/kg/d, while the dermal LD50 for male rats is 202 mg/kg. The inhalational lethal dose is calculated to be 78 and 94 mg/kg for female mice and rats, respectively. However, rats have shown tolerance to prolonged and significant acetylcholinesterase (AChE) inhibition after subcutaneous injection.

In terms of genotoxicity, chlorpyrifos has been shown to induce micronuclei in erythroblasts and cause cytogenetic effects in human lymphoid cells. It has also produced significant increases in sister chromatid exchanges (SCEs), X chromosome loss, and sex-linked recessive lethality in Drosophila melanogaster.

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

Significant health risk reduction for farmers and consumers; being a high-volume pesticide, there will be significant reduction of chlorpyrifos exposure in consequence to this decision.

Date of entry into force of the final regulatory action: 01/05/2023