This rodenticide, when mixed with water, produces a highly toxic gas that inhibits oxidative respiration.
Zinc phosphide is classified as a highly toxic rodenticide because it has an LD50 of less than 50 mg/kg. It impairs oxidative respiration by inhibition of oxidative phosphorylation. It releases phosphine gas on contact with water or acid or in the GI tract. (Proudfoot AT. Aluminum and zinc phosphide poisoning. Clin Tox 2009; 47(2):89-100. doi: 10.1080/15563650802520675)