Illnesses and Injuries Associated with Exposures to Phosphine and Phosphine Decomposition Products

For 1982 1992, records from the California Pesticide Illness Surveillance Program (PISP) showed 210 cases associated with exposure to phosphine gas and solid formulations of aluminum and zinc phosphide and 205 cases had sufficient information to retain in the data analysis. Of the cases with sufficient information, 179 (87.3%) cases involved isolated exposure to aluminum phosphide and 3 involved isolated exposure to zinc phosphide. The remaining 23 cases involved exposures to multiple compounds including chlorophacinone and methyl bromide. Fumigation of agricultural commodities (grains, nuts, and fruit) accounted for 142 (69.3%) of the cases, rodent control applications accounted for 52 (25.4%), fumigation of non-agricultural products accounted for 6 cases (2.9%), and in 5 (2.0%) the fumigated product was not specified. Fifty-one (24.9%) of the cases involved fumigant handlers and 154 (74.1%) involved incidental exposures to nonhandlers. Twenty-six incidents (involving from 2 to 18 individuals) accounted for 139 (67.8%) of the total cases, including 16 (31.4%) of the 51 fumigant handler cases and 123 (79.9%) of the 154 non-handler cases. Among the handler cases, 2 (3.9%) were associated with accidental direct exposure, 32 (62.7%) with applications for which no violation of proper handling procedure was reported, 13 (25.5%) with documented violations of proper handling procedures, and 4 (7.8%) with phosphine fires or explosions. The latter included 2 cases of serious traumatic injury. Among the 154 non-handler cases, there was one inadvertent case of direct exposure to partially spent aluminum phosphide residue. Four cases (2.6%) were associated with drift exposures short distances off of the sites of application, 70 (45.5%) with reportedly proper fumigation and aeration of treated commodities, and 14 (9.0%) with documented failure to follow appropriate application and aeration procedures. Fifty-six cases (36.4%) were associated with phosphine fires or explosions, illegal fumigation in transit with 3 (1.9%), and 6 (3.9%) with inadvertent contact with fumigant containers. Of the non-handler cases, 123 (79.9%) were related to 22 separate illness clusters. Notable episodes included 4 large clusters occurring in spite of reported compliance with appropriate fumigation and aeration requirements; and 6 cluster episodes involved phosphine fires or explosions. The cases described demonstrate the potential for safety problems associated with handling phosphide fumigants. In addition to the risk of systemic phosphine poisoning, mishandling of phosphide fumigants may cause fires and explosions, leading to serious injuries in both handlers and non-handlers. Minimizing risk may be achieved by careful attention to handling procedures and monitoring of air levels associated with its use. The recurrent illness clusters occurring among packing/processing workers illustrate the importance of frequent work place monitoring and rapid response to safety concerns of employees working in the vicinity of phosphide fumigants.