SafeWork Australia Phosphine

Background

Work health and safety (WHS) ministers have agreed to the new WEL list and a transition period ending on 30 November 2026. This change comes after extensive work and consultation by SafeWork Australia (SWA) to revise the Workplace exposure standards for airborne contaminants (WES).

SWA have agreed to rename the Workplace exposure standards (WES) as Workplace Exposure Limits (WEL) to make it clear that these limits should not be exceeded, and for Australia to align with terms used internationally.

The WEL for each airborne contaminant is intended to protect the health of workers in Australia from both the short and long-term effects of exposure. A Code of Practice guidance document on WES is here.

8-hour time weighted average (TWA) – The TWA is the maximum average concentration of an airborne contaminant calculated for an eight-hour working day, based on a 5-day working week (40 hours). A worker must not be exposed to a level above the TWA over the course of an 8-hour working day. The TWA limit is intended to protect most workers from the long-term health effects of exposure to airborne contaminants.

The previously used Short-Term Exposure Limit (STEL) will alter to Peak Limit. A STEL is the time-weighted average maximum concentration of an airborne contaminant calculated over a 15-minute period. It is intended to protect most workers from the acute effects of exposure.

Phosphine Changes

For phosphine, the TWA will change from 0.3ppm to a WES of 0.05ppm.

In addition, the STEL of 1ppm will change to a Peak Limit of 0.15ppm.

There are a range of chemicals being changed with all changes outlined here. Existing regulations for comparison can be found here.

However, the main concern for the grain industry is phosphine. The evaluation report for phosphine can be found here.

Industry Response

The industry is responding to these changes via:

A Grains Research and Development Corporation (GRDC) investment to assist growers to implement these changes. A recent initial workshop was held, and a summary can be found here
GTA is working with GRDC, NWPGP and industry via a number of means including GTA Technical Committees to address post farmgate implementation of those SWA phosphine changes.

If required, please contact GTA for further information.