To view this as a web page, click here



January 25, 2021
Safety Tip of the Week delivered to your inbox each Monday by

Fumigant Hazards

Phosphine has been used to fumigate grain storage structures since 1958. Available formulations include aluminum or magnesium phosphide.

Both penetrate deeply into stored grain, killing the target pests.

Phosphine Characteristics

Phosphine’s odor is often compared to dead fish or garlic. Phosphine also has a specific gravity in air of 1.214 (air=1 at standard temperature and pressure).

Since phosphine is heavier than air, it allows it to penetrate deep into grain.

This also means that phosphine can settle in low-lying interior areas without adequate natural or mechanical ventilation.

Phosphine gas is generated when aluminum or magnesium phosphide is exposed to heat or moisture. Inhalation is the most common type of exposure for affected employees.

The Occupational Safety and Health Administration sets the Permissible Exposure Level (PEL) for phosphine at 0.3 parts per million (ppm).

Exposures to concentrations above the PEL require NIOSH-certified respiratory protection, such as a full-face respirator with an appropriate canister or cartridge that protects against phosphine exposure.

Symptoms of Exposure

Symptoms of low-level exposure to phosphine may include general fatigue, ringing in the ears, nausea, or pressure in the chest.

Symptoms of exposure to greater quantities of phosphine may include fatigue, nausea, vomiting, diarrhea, and chest pain. Symptoms generally disappear when an affected person is removed from the exposure area to an area with fresh air.

Exposure Prevention

Licensed or certified applicators are required to post placards or warning signs at all entrances to the fumigated structure and the areas connected to the structure.

No unauthorized person should have access to areas that are in the process of being fumigated.

Once the fumigation process is complete, the fumigator will ensure that the structure is adequately aerated so that affected persons are not exposed to residual phosphine.

Areas adjacent to bins, silos, or fumigated structures should be ventilated using natural or mechanical ventilation.

This can be achieved by leaving tunnel access hatches, windows, and doors open or by providing artificial ventilation with fans or blowers.

Affected employees should be encouraged to use air monitoring equipment when entering areas that were fumigated recently.


Source: Joe Mlynek is president of Progressive Safety Services LLC, Gates Mills, OH:, and content creation expert for Safety Made Simple Inc., Olathe, KS;



Follow Our Safety News on Twitter

Receive Our Safety E-News Twice a Month

Safety Tip of the Week Archives


Safety Tip of the Week is edited by Managing Editor Tucker Scharfenberg and published each Monday by Grain Journal, Decatur, IL

800-728-7511 | Website: