2,4-D review history and regulatory outcomes

Nomination for review

In 1995 2,4-D was nominated for review as part of the Existing Chemicals Review Program (ECRP) established to systematically review a number of Agvet chemicals that have been on the Australian market for some time. 2,4-D was nominated for review because concerns over its potential risk to public health, occupational health and safety, and the environment (including impacts on waterways, non-target animals and plants).

The review of 2,4-D has been split into two parts:

Part 1: contains the environmental risk assessment of high volatile 2,4-D (short-chain) esters
Part 2: contains the toxicological, occupational health and safety assessments and the environmental risk assessment of the low and non-volatile forms (acid, salt, and long-chain esters) of 2,4-D.

Currently only the Preliminary Review Findings (PRF) report for Part 1 is available. A report for Part 2 will be released after the initial assessments are completed.

Interim regulatory decision

The APVMA received reports of crop damage through its Adverse Experience Reporting Program, notably in cotton, grapes and other horticultural crops typical of a phenoxy-type herbicide and reportedly due to drift of 2,4-D.

A full investigation of these reports was conducted by the APVMA which concluded that the crop damage was due to off-target movement of 2,4-D, but that this could not directly be linked to a specific formulation of 2,4-D. The APVMA also concluded that additional instructions on 2,4-D product labels were warranted to assist users in managing the issue of spray drift at the time of application.

In October 2005 the APVMA released a label review under s.34A of the Act. In consultation with state authorities, the APVMA developed additional instructions to strengthen the existing label warnings in relation to minimising chemical spray drift. All registrants were required to update their product labels by 30 November 2005.

These changes are not the final outcome of the review of 2,4-D in relation to spray drift management. Further changes to approvals and registrations may also be required once the full toxicological, occupational health and safety, and environmental risks have been assessed.

Part 1: environmental risk assessment of 2,4-D short chain esters

Preliminary Review Findings Report

In April 2006 the APVMA released the 2,4-D Preliminary Review Findings Report (Environment) Part One: 2,4-D Esters.

The key preliminary finding was that short-chain ester (ethyl ester, butyl ester and isobutyl ester) forms of 2,4-D pose an unacceptable risk to crops and the environment (including non-target plants and aquatic organisms). Even when used according to label instructions it appears that these risks may not be able to be mitigated due to the highly volatile nature of the short-chain esters under certain environmental conditions, and the fact that 2,4-D vapour can drift for many kilometers off-target and affect vegetation downwind of the application site.

In the preliminary report the APVMA proposed cancelling all approvals and registrations relating to the short-chain esters forms (ethyl ester, butyl ester and isobutyl ester) of 2,4-D.

Suspension of 2,4-D short chain esters

However, rather than cancelling registrations and approvals of 2,4-D short chain esters, in October 2006 the APVMA suspended the registrations and label approvals of 24 products containing high volatile ester (short chain) forms of 2,4-D and issued new instructions for use until such time as further data is generated by registrants. Data on the physico-chemical properties of high-volatile esters was received by the APVMA and assessed. In May 2007 suspensions were extended until April 2009. During this period registrants will be expected to generate environmental fate and effects data.

Part 2: toxicological, occupational health and safety assessments and the environmental risk assessment of the low and non-volatile forms (acid, salt, and long-chain esters) of 2,4-D

The assessment of 2,4-D Part 2 is still in progress and a PRF report will be released after the assessment is completed.

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

For more information please contact the Chemical Review Program on (02) 6210 4749 or by email to chemrev@apvma.gov.au