Chemicals in the News: Paraquat
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Last updated 24 September 2012
Paraquat is a widely-used, non-selective contact herbicide used for the control of broadleaf weeds and grasses and as a defoliant and desiccant in crops such as cotton and sugar cane. There are approximately 65 registered paraquat products in Australia.
Paraquat is approved for use in Australia but is heavily regulated because of its acute toxicity. It is particularly dangerous if swallowed because there is no specific antidote to its effects. It causes irreversible damage to the lungs which may lead to death.
It is listed as a Schedule 7 Dangerous Poison (external site). Special regulations restrict its availability, possession, storage and use. It is only available, for example, to trained users who have the skills necessary to handle it safely. It is not supplied for home and garden use.
Additionally, paraquat labels must contain the additional headings (clearly visible in large bold type on the label):
KEEP OUT OF REACH OF CHILDREN
READ SAFETY DIRECTIONS BEFORE OPENING OR USING
CAN KILL IF SWALLOWED
DO NOT PUT IN DRINK BOTTLES
KEEP LOCKED UP
Paraquat products must also contain sufficient stenching agent to produce an offensive smell and a blue or green colourant.
The APVMA commenced a review of paraquat in 1997 because of concerns over the potential risk to occupational health and the environment.
An initial toxicology assessment from the Office of Chemical Safety (OCS) in the Australian Government Department of Health and Ageing (DOHA) did not identify any issues of major concern regarding the continued availability of the chemical, noting that the existing strict controls in place are generally adequate to manage the risks of acute poisoning.
However, the APVMA notes the concerns about possible links between long-term or chronic exposure to low doses of paraquat and the increased risk of Parkinson's Disease. To this end, in 2010 it commissioned the OCS to prepare a targeted report looking at the experimental and epidemiological evidence for the neurotoxicity concern. A draft report was prepared by the OCS and has been externally peer reviewed. In late March 2011, OCS was requested to amend the report in line with the comments provided.
The OCS amended report of June 2011 concluded that, in order to be satisfied that the health and safety of workers and the public can be adequately assured, an appropriate study of regulatory standard is required to assign a No Adverse Effect Level (NOEL) (PDF, 313kb) value for the neurological effects of paraquat.
The APVMA has not officially requested such a study but is aware that specific research has been conducted to address this issue. The APVMA hopes to be able to access and review this work in the near future.
In 2011, the APVMA sought additional advice from DOHA on any scientific literature relating to paraquat and Parkinson’s Disease and more recently sought an update review of any information that may have emerged in recent months.
While the APVMA continues to review the science suggesting a possible link, there is not currently a scientific consensus on the issue. Without such a consensus, there are limited grounds for imposing additional regulatory restrictions.
Paraquat is approved for use in many countries around the world including Canada, the United States and New Zealand and has been for many decades.
Paraquat was approved for use in the European Union in 2003 subject to certain conditions as part of a broad re-registration process for plant protection products. This approval was rescinded in 2007 following successful legal argument that the 2003 approval process was procedurally flawed. The decision had the effect of disallowing its use. It is important to note that paraquat was not found to be unsafe by this decision.
- Is there a link between paraquat and Parkinson’s Disease?
- Search the PUBCRIS database for registered products that contain paraquat. Search hint: in the Active Constituent 1 field enter paraquat