Dichlorvos review history and regulatory outcomes

Nomination for review

In December 1994 dichlorvos was nominated for review as part of the Existing Chemicals Review Program (ECRP) established to systematically review a number of Agvet chemicals that had been on the Australian market for some time.

In June 1996, the US Environmental Protection Agency (EPA) released an Interim Re-registration Decision (IRED) document setting out their concerns of their review of dichlorvos. As an outcome of the review the EPA cancelled some uses of dichlorvos including crack and crevice, home garden, and fogging applications.

In December 1996 the APVMA began a review of dichlorvos because of concerns relating to public and occupational health and safety, the environment, residues and trade. This action was based on reports of adverse experiences, regulatory action by the US EPA, and residue violations in cereals and cereal products.

Draft (Preliminary Review Findings) Report

In July 2000 the APVMA released the Dichlorvos Draft (Preliminary Review Findings) Report*. The APVMA found that:

• there were significant occupational health and safety and residue data gaps for some uses of dichlorvos
• the existing data were inadequate to establish or maintain Maximum Residue Limits (MRLs)
• the use of dichlorvos may pose a potential risk to birds, bees, fish and invertebrate aquatic organisms
• there was a potential risk to workers from some dichlorvos application methods
• product labels did not contain adequate instructions or warnings for the safe use of dichlorvos.

The APVMA requested more information from registrants on occupational health and safety and on residue levels to assess any potential risks from the use of dichlorvos.

In the preliminary report the APVMA proposed:

• varying product labels to include stronger first aid and safety directions and warnings to minimise the exposure of humans, birds, bees and aquatic organisms
• increasing withholding periods for grain (7 days for grain treated at 6 ppm and 28 days for grain treated at 12 ppm)
• setting temporary MRLs for a number of commodities until further residue data were generated. These include: cocoa beans, coffee beans, edible meat and offal (mammalian), eggs, fruits, milks, mushrooms, peanut, poultry meat and offal, tomato, tree nuts and vegetables.
• setting an MRL for rice hulls of 50 mg/kg.

The APVMA noted that the Office of Chemical Safety (OCS) recommended an increase in the ADI for dichlorvos from 0.0005 to 0.001 mg/kg bw/day. This is based on a NOEL for plasma cholinesterase inhibition of 0.013 mg/kg bw/day in human volunteers in a 28-day oral administration study, and using a 10-fold safety factor (to account for variability in human sensitivity).

The APVMA will issue a final report once the assessment of all available data is completed.

For more information please contact the Chemical Review Program on (02) 6210 4749 or by email to chemrev@apvma.gov.au

* Contact the APVMA for copies of this document.