Phosphine gas Phosphine serves the purpose of eliminating insects, mice, and rats in grain and seed storage, and it is produced as a by-product in certain industrial manufacturing processes for chemicals, semi-conductors, welding, and metal alloys.
Breathing in phosphine gas is hazardous and can lead to illness or even death depending on the exposure level. Learn more about the legal obligations to manage phosphine gas exposure and ensuring worker safety.
What is phosphine gas? Phosphine is a highly toxic respirable poison. On farms, it is generated when fumigation tablets containing aluminum phosphide react with moisture in the air. Upon inhalation, the gas reacts further with the moisture in the lungs, forming an acid.
Phosphine, in its purest form, is a colorless, flammable gas with no distinctive odor. Occasionally, it may carry a scent of garlic or rotting fish due to contaminants, but relying on smell for phosphine detection is not advisable. Being heavier than air, it accumulates rapidly in poorly ventilated, enclosed, or low-lying areas. Phosphine has the potential to self-ignite and explode.
What are the risks of phosphine gas? Phosphine is easily inhaled and, upon lung absorption, affects the body's oxygen access and utilization. In smaller amounts, it can cause symptoms like headaches, respiratory issues, double vision, dizziness, fatigue, weakness, gastrointestinal problems, and more. Exposure to large amounts may result in delayed symptoms, including damage to organs, pulmonary edema, convulsions, and even death.
Repeated, long-term exposure to phosphine may lead to conditions such as anemia, bronchitis, gastrointestinal disorders, speech and motor disturbances, weakness, weight loss, spontaneous fractures, and swelling, toothache, and jawbone necrosis (never open tablet packets with your teeth).
Workplace exposure standards The workplace exposure standards (WES) for phosphine are:
- 0.3 ppm (0.42 mg/m3) (8-hour TWA*)
- 1 ppm (1.4 mg/m3) (STEL**)
*8-hour time-weighted average (TWA) represents the maximum average airborne concentration of a substance over an eight-hour working day for a five-day working week. **Short term exposure limit (STEL) denotes the time-weighted average maximum airborne concentration of a substance calculated over a 15-minute period.
Learn more about airborne contaminants.
How do I manage the risks? Workers and managers can collaborate to mitigate workplace hazards.
Adhere to safety instructions on products containing phosphides.
For workers As a worker, it is your responsibility to prioritize your health and safety and ensure your work doesn't negatively impact others. Read and follow safety instructions on fumigants, never rely on smell to detect phosphine, and avoid opening tablet packets with your teeth.
For businesses Employers or persons conducting a business or undertaking (PCBU) must manage phosphine gas risks per the Work Health and Safety Act 2011. Following the four-step risk management process is essential, and practical advice from the Managing risks of hazardous chemicals in the workplace code of practice 2021 (PDF, 1.21 MB) can be useful.