Chlorpyrifos - Australian Review Outcomes and Current Regulatory Status


20 January 2006


Chlorpyrifos is a broad spectrum organophosphorus (OP) insecticide. It has been available for use in Australia for more than 30 years. Chlorpyrifos products are registered for the control of a broad range of insects in agriculture (mainly horticulture), for the control of pests such as cockroaches, termites and fleas in buildings, and as domestic animal and garden pesticides. In Australia, pre-construction termiticide products are restricted chemical products and can only be supplied to and used by appropriately authorised persons.

The APVMA initiated a review of chlorpyrifos in 1997 as part of its chemical review program which is examining a number of organophosphorus insecticides because of concerns about their relative lack of specificity against target pests and potential toxicity to both invertebrates (including beneficial insects) and vertebrates (including humans). The review of chlorpyrifos covered issues relating to public health, occupational health and safety, and the environment.

The Australian chlorpyrifos review was rigorous and extensive. Over three years it drew submissions from industry, community organisations, individuals and scientific bodies, saw the collection of information from Australian and international sources, and involved detailed scientific analysis of the available data.

The interim review report was published in 2000. The major findings of the review were:

  • Highly concentrated chlorpyrifos products available for purchase and use by householders posed an unacceptable risk to these users. Provided that householder access to these concentrated products was removed, uses in or around the home and garden, including termiticide use, would not pose a public health risk.
  • There were inadequate instructions on product labels with regards to safety directions, label warnings and the circumstances in which which the products could be used. Provided that label instructions and warnings were strengthened, continued use was not likely to pose a occupational health and safety risk or a risk to the environment.
  • There were some deficiencies in chlorpyrifos residue data for some agricultural commodities. Nevertheless, available data indicated very low residues in Australian produce, such that the population with the highest estimated exposure had a dietary intake which was only 3% of the Acceptable Daily Intake (ADI) for chlorpyrifos.

Key regulatory decisions made by the APVMA as a result of the review of all the available data at that time included:

  • cancellation of registration of household pesticides with chlorpyrifos concentrations greater than 50 g per litre and a warning on all products of higher strength that they were too hazardous for use by householders;
  • restrictions on use such that indoor spraying of exposed surfaces such as floors and walls was no longer permitted;
  • new requirements for labelling including detailed safety directions and new instructions concerning the times and conditions governing re-entry and re-occupation of treated areas;
  • clear advice on use practices that would reduce the potential for environmental contamination, with strengthening of label restraints by incorporating statements designed to minimise spray drift, surface run-off to waterways, and releases to urban drains. The Department of the Environment and Heritage was satisfied that, subject to these label changes and changes in uses, harmful effects on the animals or the environment were unlikely.

Finalisation of the review awaited the collection of further data on residue levels in commodities, in order to confirm or re-establish permanent Maximum Residue Limits (MRLs) for individual crops. This data has been submitted to the APVMA and its assessment is close to completion; a final review report is expected in 2006. The final review report will also take into consideration any other new information about chlorpyrifos that has become available since publication of the 2000 report, including its regulatory status in other countries.

US and International Status
The regulatory approach that the APVMA is taking is likely to achieve the same health and safety outcomes that the USA and other countries are seeking, through their own national review programs. Further information on the APVMA’s review in the context of international regulatory activity can be found in section 3.3 of the APVMA Review of Chlorpyrifos Review of Chlorpyrifos (September 2000).

Recently some concerns have been expressed in Australia about the fact that use of chlorpyrifos as a pre-construction termite protection barrier ceased in the USA from the end of 2005. This is not a new regulatory initiative in the USA but follows from regulatory action in 2000. Other US chlorpyrifos uses in agriculture are unaffected. Chlorpyrifos is also available as an agricultural pesticide in both Canada and the EU.

In Australia, chlorpyrifos products are still available for pre-construction use but they are restricted chemical products (RCPs), only available to authorised pest-control operators. The APVMA review concluded that data on this particular use of chlorpyrifos indicated that the exposure to chlorpyrifos vapour in the air of treated homes was low and that it did not pose an unacceptable health risk provided it was used according to directions.

In the USA, approvals for household uses of chlorpyrifos have been removed. In Australia low-strength domestic products continue to be allowed, noting that in the US, prior to its regulatory action, there was significantly higher reliance on this compound in the home garden (recommended regular treatment of lawns to kill insects and grubs) and in public health control of cockroach infestations in public and tenement housing) than there was in Australia.

With respect to dietary intake of chlorpyrifos residues in food, the public health intake standards in Australia have been established using the most sensitive biological effects of chlorpyrifos; thus the Australian Acceptable Daily Intake (ADI) value is lower than the international equivalent established by the World Health Organization (WHO) in 1999.

New technologies to protect buildings against termites
In Australia, new technologies to protect buildings against termites have also become available. An informative document about termiticides, including physical barrier technology and chemical bait stations (Information on termite treatments available in Australia, including hazard information on chemicals approved in Australia for use as termiticides) is available on the ‘Chemicals’ website of the Australian Government Department of Health and Ageing (DoHA) at http://www.tga.gov.au/docs/pdf/termite.pdf. This document was prepared in co-operation with the APVMA.



What is the Australian Pesticides and Veterinary Medicines Authority (APVMA)?

The APVMA is the Australian Government statutory authority responsible for the regulation of pesticides and veterinary medicines up to the point of retail sale.

All pesticides and veterinary medicines must be registered by the APVMA prior to being supplied, sold or used throughout Australia.

Pesticides include products that are used around the home garden and those used for commercial or agricultural purposes.

What is product registration?

Registration means that the pesticide or veterinary medicine has been rigorously assessed to ensure that it works, is safe for people, animals and the environment, has been manufactured to appropriate standards and does not pose an unacceptable risk to Australia’s trade with other countries.

All registered products have an approved label that includes instructions for correct use and relevant safety information. Only registered products have a distinguishing number on the label APVMA Approval no. xxxxx/ or NRA Approval No. xxxxx/.

What is a chemical review?

The APVMA has a program for reconsidering (reviewing) the registration of older chemicals that are currently on the market. Reviews are undertaken when there is new information that raises potential concerns about a chemicals ongoing use, suggesting that its registration should be reassessed. This is the process undertaken for arsenic based timber treatment products.

Reviews can be triggered by new research or other evidence that has raised concerns about one or more of the following:

  • the safety of people using the chemical or the product
  • an effect that is harmful to public health
  • an unintended effect that is harmful to animals, plants or to the environment;
    a prejudice to trade or commerce between Australia and places outside Australia
  • whether the product is effective when used as instructed by the label
    labels instructions for the safe and effective use of the product.

When the APVMA decides to reconsider the registration of a chemical it will call for any relevant new information from registrants and the public, it may also require registrants to conduct new studies. The APVMA then assesses all the information and publishes a review report that details its findings. The assessment also forms the basis for decision about the future availability of the chemical or how it is used.

There are three possible outcomes from a review:

  • The APVMA is satisfied that products are safe and effective and chemical use can continue based on existing instructions
  • The APVMA has identified that some aspect of the chemical or its use may not be safe and therefore makes changes to the conditions of registration and/or the label instructions; or
  • The APVMA is not satisfied that continued use of the chemicals will be safe and effective and suspends or cancels the chemical.