Temephos is a non-systemic organophosphorus (OP) insecticide and acaricide used to control ectoparasites on food producing animals and mosquito larvae in waterways.

The review of temephos was limited to the single product approved at the time for use on sheep because of concerns over occupational health and safety, toxicity and its potential risk to the environment. This product, Coopers Assassin Sheep Dip, was approved for use for the control of body lice (including synthetic pyrethroid resistant strains) on wet or dry short wool sheep by plunge or shower dipping and for the treatment of body lice on long wool sheep by hand jetting.

The review of temephos is separate from, but related to, the reviews of diazinon (another OP) and of selected sheep ectoparasiticides. While these reviews have been conducted separately, the outcomes of any review may be taken into consideration when conducting related reviews as they may have an impact on these assessments.

Temephos review

Status: review concluded as of June 2009


Temephos was nominated for review in 1995 as part of the Existing Chemicals Review Program (ECRP) which was established to systematically review a number of Agvet chemicals that had been on the Australian market for some time. Temephos was nominated because of concerns over occupational health and safety and its potential risk to the environment.

The APVMA commenced a review of temephos based on the findings and recommendations of the NRA Expert Panel on Organophosphate Sheep Dips (the Panel), which reported in 2000. The Panel reviewed the findings of the UK Institute of Occupational Medicine report, Epidemiological study of the relationship between exposure to organophosphate pesticides and indices of chronic peripheral neuropathy, and neuropsychological abnormalities in sheep farmers and dippers (July 1999). The Panel found that work practices and exposure risks differed between Australia and the UK. However, it could not completely rule out a link between OP exposure and long-term effects. The Panel recommended reducing worker exposure to OPs and that the APVMA review the uses of OPs on sheep.

The APVMA completed component evaluation reports on temephos in consultation with the Office of Chemical Safety and Environmental Health (OCSEH) within the Department of Health and Ageing, and the Department of Sustainability, Environment, Water, Population and Communities (previously the Department of the Environment, Water, Heritage and the Arts, or DEHWA), and provided these reports to the registrant for comment. However, the APVMA made no findings in relation to these component reports at that time. Rather, comment was sought from the affected registrant ahead of developing a review findings report. Users should be aware of the findings detailed in the attached component reports.

The occupational health and safety (OHS) assessment for the review of temephos was undertaken by OCSEH which considered all the OHS data and information submitted for the review. The OHS assessment concluded that the APVMA can be satisfied that the continued use of temephos products by portable plunge dipping, fixed plunge dipping or shower dipping would not be likely to be an undue hazard to the safety of workers, provided that they wear appropriate personal protective equipment (PPE) as indicated in the safety directions. However, the OSCEH was unable to conclude that the application method of hand jetting, even when PPE is worn, was not likely to lead to an unacceptable risk of exposure.

The environmental assessment for the review of temephos was undertaken by DEH, which considered all the environmental data and information submitted for the original registration of the product and additional data submitted for the review.

The environmental assessment raised concerns about the toxicity of temephos to aquatic invertebrates inhabiting waters close to the ocean outfall from wool scour sources. DEH was unable to conclude that continued use of the product on long wool sheep according to current label directions, even allowing for a three-month wool withholding period (WWP), would not be likely to have an unintended effect that is harmful to animals, plants or things or to the environment i.e. to aquatic invertebrates inhabiting waters close to the ocean outfall. DEH recommended that approved labels be varied to delete all instructions relevant to treatment of long wool sheep.

DEH also considered the issue of soil contamination from temephos dripping off treated sheep. Run-off from treatment areas should not be allowed to contaminate waterways. DEH recommended additional label statements be included on the current label to minimise the hazard posed to wildlife, fish, crustacea and environment from used or spent dip solution, or from drippings of treated sheep onto soil.

In January 2008, the APVMA approved amended label instructions which were voluntarily requested by the registrant. These amendments addressed the concerns identified in the OHS and environmental review reports.

Because the concerns that were the basis for the review of temephos have been addressed by the amended label instructions, the APVMA concluded that there was no need to continue the temephos review. However, users should be aware of the findings detailed in the attached component reports. Furthermore, any variation to the current label instructions for temephos, such as an extension of use to long wool, would need to be considered in the context of the concerns identified by the APVMA in the temephos review, particularly occupational health and safety concerns.

Review Report Date
Temephos Occupational Health and Safety Assessment (PDF, 262kb) April 2009
Temephos Environmental Assessment Report (PDF, 229kb) Sept 2003


For more information contact:

Chemical Review

Phone: +61 2 6210 4749

Fax: +61 2 6210 4776

Email: chemicalreview@apvma.gov.au

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