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Benomyl not registered or approved in Australia

4 February 2009

Claims have been recently made in the media suggesting a possible link between the chemical benomyl and alleged chemical contamination in the Noosa area.

Benomyl is not registered in Australia and cannot be used. Information on benomyl and associated chemicals carbendazim and thiophanate methyl (both of which are registered) is available below.

Benomyl, carbendazim and thiophanate-methyl

Benomyl, carbendazim and thiophanate-methyl are fungicides that belong to the same chemical class (so-called benzimidazoles). Their registration status has been or is being reviewed by the Australian Pesticides and Veterinary Medicines Authority (APVMA) in response to their potential to cause birth defects effects by disrupting the process of cell division.

In animals, benomyl is rapidly converted to carbendazim. When given orally to laboratory animals in large single doses by stomach tube, benomyl and carbendazim can cause birth defects in animals, in particular small or absent eyes in rats (micro-ophthalmia and anophthalmia). However, when mixed in with the diet and fed to the animals, even very high doses of these two chemicals did not produce any evidence of this type of birth defect.

In contrast to benomyl and carbendazim, thiophanate-methyl did not induce birth defects in laboratory animals even following high oral doses administered by stomach tube. While thiophanate-methyl breaks down in the environment to form carbendazim, in mammals thiophanate-methyl appears to undergo only very limited metabolic conversion to carbendazim.


There are no products containing benomyl registered for use in Australia.

During the 1990s, allegations that benomyl products were damaging crops gave rise to legal action in the USA. Farmers and ornamental plant growers claimed their crops had been destroyed by defective batches of ‘Benlate’ (the market leading benomyl-based product) because the fungicide was contaminated with a weed killer. There were also some claims of crop damage in Australia.

The company manufacturing ‘Benlate’ was also subject to litigation in the USA relating to claims of a causal association between exposure of pregnant women to benomyl and eye defects found in their children at birth.

Because of these claims, the Australian Department of Health and Ageing (DoHA) reviewed benomyl in the mid-1990s and concluded that although it affected the development of the eyes in rats, these effects were only seen after giving animals single large doses by stomach tube. They were not present when the compound was mixed in with their food. This difference probably arises because a single large dose in the stomach cannot be detoxified by the liver or excreted from the body fast enough to prevent it from crossing the placenta and causing malformations in the developing foetus. However, animals exposed to a sustained dose in their diet are able to metabolise (detoxify) and excrete the chemical so that levels are not high enough to cross the placental barrier and thus affect the developing foetuses.

The developmental and reproductive effects seen in the laboratory animals resulted from high oral doses given by stomach tube. It is unlikely that during normal handing of the product, workers would be orally exposed to these levels. 

DoHA did not recommend cancellation of benomyl registrations but suggested to the APVMA that labels of benomyl products should bear the following warning statement: “Contains benomyl which causes birth defects in laboratory animals. Women of child bearing age should avoid contact with benomyl”.

Epidemiology studies with benomyl

Worldwide, a number of studies were initiated in the 1990s in response to media reports in England which suggested an association between claimed geographical ‘clusters’ of children born with small or absent eyes and maternal exposure to benomyl. In response, the authors of a large study in the UK found that the evidence for a causal link between exposure to pesticides (including benomyl) and small or absent eyes was weak, suggesting that other risk factors including maternal viral infection and hyperthermia were potentially more significant. In Italy an epidemiology study found that there was no positive association between benomyl use and the prevalence of small or absent eyes, and that agricultural workers did not have a greater proportion of children with eye deformities. A study in Norway did not produce any evidence that parental exposure to pesticides was associated with eye defects in their children, or that these defects were more prevalent among children whose parents lived or worked on farms where benomyl may have been applied.

In 2001 DuPont, the main producer of benomyl, withdrew benomyl products from the worldwide market, citing the high cost of litigation in the US courts (both claims of human birth defects and significant claims of crop damage due to possible contamination of the fungicide product with herbicides) as the primary reason for their decision. In Australia, DuPont Australia formally ceased sales of ‘Benlate’ from December 31, 2001 and voluntarily cancelled registration of the product in August 2003. In October 2003 the APVMA began a formal review of the remaining active constituent approvals and product registration of benomyl and moved to suspend benomyl product labels in order to add a precautionary birth defect warning. However, it did not continue with the review as the remaining active constituent approval holders and product registrant voluntarily cancelled their approvals and registration. This voluntary cancellation meant that there were no longer any registered benomyl products on the Australian market.


Carbendazim is used to control a broad range of fungal diseases on cereals, fruits, cotton, tobacco, turf, ornamentals and vegetables. It is also used in post-harvest food storage, as a seed pre-planting treatment and as a timber-treatment fungicide.

In February 2007 the APVMA began a review of carbendazim, based on advice from the Office of Chemical Safety (OCS) within DoHA that that because carbendazim and compounds that can form it (namely, benomyl and thiophanate-methyl) can cause birth defects in laboratory animals under certain conditions, their use in fungicide products might possibly pose a potential public and occupational health and safety risk.

The APVMA released the carbendazim and thiophanate-methyl Review Scope Document (February 2007) which outlined the information needed to conduct a comprehensive scientific assessment of carbendazim and included a call for public submissions. The period for public comments and the submission of additional information closed on 30 June 2007.

As with benomyl, the developmental and reproductive effects seen in the laboratory animals resulted from high oral doses.  It is unlikely that during normal handing of the product, workers would be orally exposed to these levels. 

However as a prudent measure at the commencement of the review the APVMA suspended the existing labels for carbendazim and issued new label instructions warning users  “Contains carbendazim which causes birth defects in laboratory animals. Women of childbearing age should avoid contact with carbendazim” and also amended the safety directions to decrease the risk of workers accidentally ingesting any product.

The general population is not at risk from registered uses of carbendazim because home garden use is not permitted, and there is no evidence of risk from dietary exposure.

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


Thiophanate-methyl is used in Australia to control soil-borne diseases in ornamental plants.

Thiophanate breaks down quite rapidly in the environment to form carbendazim. Therefore the use of thiophanate-methyl can lead to residues of carbendazim in treated commodities. For this reason the APVMA is conducting concurrent reviews of carbendazim and thiophanate-methyl.

In contrast to benomyl and carbendazim, thiophanate-methyl does not induce teratogenic effects in laboratory animals following high oral gavage doses. In mammals thiophanate-methyl appears to undergo only very limited metabolic conversion to carbendazim.