Maldison [malathion; diethyl (dimethoxythiophosphorylthio) succinate] is a broad-spectrum organophosphorus (OP) insecticide and acaricide used to control a wide range of agricultural and veterinary insect pests.

Maldison review

Status: review in progress

Maldison is considered to be one of the least toxic of all the OP compounds but it can contain some toxic impurities. These impurities may be formed during the manufacturing process or when maldison is stored, either for long periods or at high temperatures. The safety, efficacy and environmental impact of agricultural and veterinary products can be significantly affected by these impurities.

In 1978 a report of worker poisonings and deaths following the use of maldison indicated the cause was a toxic degradate, isomalathion. Several subsequent studies have identified other very toxic degradates, such as O,S,S–trimethylphosphorodithioate and O,O,S–trimethylphosphorothioate.

In 1995 maldison was nominated for review as part of the Existing Chemicals Review Program (ECRP) which was established to systematically review a number of Agvet chemicals which have been on the Australian market for some time.

In November 2000 the US EPA released an Interim Re-registration Eligibility Decision (IRED) document setting out the concerns of their review of maldison. These concerns related to the safety of workers who mix, load and apply maldison and to concerns over potential worker exposure when re-entering treated areas.

In February 2003 the APVMA began a review of maldison because of concerns about its toxicity and human health and safety. The review will provide the APVMA with information to determine whether the existing uses of maldison should continue in Australia.

The 2003 APVMA released the Maldison Review Scope Document (PDF, 156kb) which outlined the information needed to conduct a scientific assessment of maldison. The scope document included a call for public submissions. The period for public comments on the scope of the review and the submission of information for the review closed on 3 June 2003.

Following the assessment of maldison the APVMA will release a preliminary review findings (PRF) report outlining the proposed regulatory arrangements for the future use of maldison. There will be an additional public consultation period providing all members of the community with an opportunity to comment on this report before it is finalised.

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

Review Report Date
Maldison Scope Document (PDF, 156kb) Feb 2003


For more information contact:

Chemical Review

Phone: +61 2 6210 4749

Fax: +61 2 6210 4776


Product Search

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APVMA maldison archive
Title Date
Gazette Notice: reconsideration of approvals and registrations related to maldison Mar 2003

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