Australian workplaces that use phosphine as a fumigant have less than six weeks to comply with a significantly tightened workplace exposure limit (WEL) that takes effect on 1 December 2026. Safe Work Australia (SWA) and the Australian Pesticides and Veterinary Medicines Authority (APVMA) issued a joint statement on 22 October confirming the new limit and urging employers to review their risk controls immediately.

The new time-weighted average (TWA) for phosphine drops from 0.3 parts per million (ppm) to 0.05 ppm — a sixfold reduction. The short-term exposure limit (STEL) has also been revised. The changes align Australian standards with updated international guidance and reflect growing evidence of health effects at lower concentrations than previously understood.

Why the Change?

Phosphine is a highly toxic, colourless gas used extensively in Australia for grain storage fumigation, as well as in some manufacturing and semiconductor processes. Exposure can cause headache, nausea, vomiting, pulmonary oedema, and in severe cases, death. The gas is particularly hazardous because its characteristic garlic-like odour may not be reliably detectable at concentrations now considered unsafe.

The downward revision follows a review of the evidence base by SWA’s Workplace Exposure Standards Advisory Committee, which considered data from more recent epidemiological and toxicological studies indicating adverse respiratory and neurological effects at sub-0.1 ppm concentrations with repeated exposure.

Who Is Affected?

The revised limit primarily affects operators in grain storage and transport (particularly bulk handlers, silo operators, and grain exporters), pest management businesses conducting structural or commodity fumigation, and some chemical manufacturing operations. The APVMA has indicated it will align label directions for registered phosphine products with the new WEL.

Importantly, the change affects not just direct fumigation operators but also workers who may re-enter fumigated spaces — including transport workers, grain receival staff, and port workers. Employers must ensure that clearance procedures and re-entry intervals reflect the new, more stringent limit.

What Employers Need to Do Before 1 December

SWA recommends employers undertake an immediate review of their phosphine risk assessments, air monitoring programs, and engineering controls. Key steps include:

• Reviewing current air monitoring data against the new 0.05 ppm TWA to determine whether existing controls remain adequate
• Ensuring gas detectors and personal monitors are calibrated and capable of reliably detecting concentrations at and below the new limit
• Reviewing and updating fumigation procedures, re-entry protocols, and emergency response plans
• Providing updated training to all workers potentially exposed, including those in adjacent roles
• Reviewing contracts with labour hire and subcontractors to ensure downstream compliance

Given the compressed timeframe, employers who have not yet commenced their review are encouraged to prioritise this immediately. The National Association of Testing Authorities (NATA) has flagged that demand for air monitoring services in the grain handling sector is expected to surge in the lead-up to the deadline.