Phosphine has no adverse effects on seed germination when applied according to label directions and at labeled rates. Phosphine does react with certain metals such as copper, brass, bronze, gold, and silver. Reactions result in discoloration and corrosion. This is a problem with electrical and mechanical systems that utilize these metals. This problem apparently only occurs when there are high concentrations of phosphine in combination with high humidity and temperature.
If the liberation of hydrogen phosphide occurs in a confined area an explosion or fire may result. Aluminum phosphide has been formulated with ammonium carbamate or aluminum stearate and calcium oxide to control the release and lower the combustibility. In addition to controlling the reaction, formulations that contain ammonium carbamate release a garlic odor that serves as a warning odor. The time required for phosphine release is shorter under warm, humid conditions and longer under cool, dry conditions. Since the gas diffuses through the grain rapidly, structures must be sealed properly, especially under cooler conditions.
