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Why do some chemical reviews take a long time to close?

13 August 2010

Some of the chemical reviews the APVMA initiates take a relatively long time to close. This happens because the APVMA is required to consider any new information presented to it and respond to new risks identified in the scientific literature once a review is commenced.

The APVMA can, however, make interim decisions and uses this ability to respond to any immediate risk a particular chemical may present. An on-going review does not mean that there is a tangible risk to the public. On the contrary, an on-going review can mean that there is a continuing evaluation of that chemical with the APVMA able to take timely action where there is the necessity to do so.

More information

After a chemical product has been registered, credible new scientific information may emerge suggesting the existence of a previously unrecognized risk to human health, the environment, efficacy and/or trade. In these cases the APVMA can initiate a review of the product.

Reviews provide an opportunity for the APVMA to have a close look at the issues of concern and to consider if the risks the product presents are being effectively managed.

If the risks are real, the APVMA and State and Territory governments can tighten controls to better manage the risk. If they cannot be effectively managed, the APVMA has the authority to remove a chemical from the market.

The review process can be very complex. Chemical manufacturers are typically required to produce new scientific information for the APVMA to assess. Some of these studies can take several years to complete, particularly those that relate to human health issues, the breakdown of chemicals in the environment or residues in treated commodities. Depending on the level of potential risk the APVMA may suspend registrations and/or restrict the use of a chemical during the time needed for new studies to be completed.

Once the APVMA has this information, it is able to assess the nature of the actual risk, and further, whether any amendments to existing health or environment controls are warranted. If so, the APVMA is required to work with manufacturers and users to try to identify practical ways to reduce any valid risk to the point where the APVMA can be satisfied that a product is likely to be safe for continued use.

While this process is taking place, two events can intervene. Firstly, new scientific information may emerge identifying a new concern. This can prompt a new round of assessments and warrant additional consideration of risk management strategies.

The second intervention that may occur is that manufacturers and/or users might need to generate data on crop residues, for instance, or investigate the feasibility of a proposed risk management strategy. Targeted scientific trials can take several growing seasons to complete, with additional time needed for the results to be evaluated and reported.

On occasion both of these events can happen in the one review! Instead of taking three or four years to close, some reviews can be ongoing for ten years or more.

This problem is not unique to the APVMA. Similar regulators in other countries experience similar issues.

For its part, the APVMA has progressively been introducing measures that enable it to better target the scope of a review and identify any regulatory measures that can be implemented sooner, rather than later in the review process. The APVMA aims to both minimise the chances of delays occurring and ensuring that any delays that do emerge in the course of a review are effectively managed.

There is a perception that an on-going review means that the risk that prompted the review is not addressed until the review is finalised. This is not the case. Interim regulatory actions (such as product suspensions with or without new instructions), and other measures (such as voluntary label amendments, product cancellations and/or formulation changes) are often undertaken prior to the start of a review or early in the review process to address specific areas of concern.

Those aspects of a review that remain uncompleted without any interim regulatory action are typically those where no sound basis for regulatory action has been established.  An uncompleted review does not translate to a tangible risk to the public.

Read more about the Chemical Review Program.

Some examples


The chlorpyrifos review commenced in 1996. All aspects of the chemical were reviewed including public health, occupational health and environmental risks. The APVMA finalised the review of all available information and proposed a substantial range of restrictions to use in 2000 that were implemented in 2001-2002.

In 2000 the APVMA also required new data to be generated to confirm maximum residue levels for a range of crops. These new data took five years to generate and another three or four years to assess. A Preliminary Review Findings (PRF) Report on the additional residues data was published in 2009 with the APVMA currently considering public comments received in response to that report.

All other aspects of the review of chlorpyrifos are considered as finalised, however, as with all chemicals, the APVMA keeps a watching brief on any new developments or information about chlorpyrifos.

Chlorpyrifos thus remains on the APVMA chemical review list as the APVMA determined that it required new residue data to confirm maximum residue limits.  While the review remains ‘open’ until this final component is completed, the restrictions implemented in 2001-2002 had addressed the concerns identified when chlorpyrifos was put under review in 1996.


The atrazine review commenced in 1995. All aspects of the chemical were reviewed including public health, occupational health and environmental risks. The APVMA finalised the review of all available information in 1997 and proposed a substantial range of restrictions to use that were implemented in 1998-1999.

In 1997 the APVMA also required additional environment and residue data to be generated to confirm environmental risk management strategies and maximum residue limits for a range of uses. When these data were generated they were reviewed by the APVMA and a draft final report published in 2002.

However, around this time the APVMA became aware of new studies that suggested that atrazine might cause adverse developmental and reproductive problems in frogs. In consequence, the APVMA delayed finalisation of the review in order to investigate these claims and reassess the toxicological and environmental risks of using atrazine.

In December 2004 the APVMA released a second draft final review report recommending additional restrictions. But again, as the APVMA prepared to implement these changes, further concerns about atrazine emerged.

In 2008 the APVMA decided to finalise the regulatory actions first proposed in 2004. All aspects of the review of atrazine were considered as finalised at that time.

The APVMA continues to monitor new developments or information about atrazine and in 2010 published a mode-of-action report detailing the regulatory implications of existing and ongoing research.

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Last updated on 17 August, 2010