Public Health Hazards Involved in the Use of Organic Phosphorus Insecticides in Cotton Culture in the Delta Area of Mississippi1

Abstract

During the summer of 1957, suspected cases of poisoning by cotton insecticides were investigated in the Mississippi Delta area. Blood cholinesterase levels of cases and of workers with maximal exposure to organic phosphorus insecticides were determined. In addition, the decay rates of insecticides and the exposure of workers were measured. Ninety-one illnesses suspected of being poisoning due to insecticides were evaluated. Evidence was found to definitely incriminate organic phosphorus compounds as a cause of illness in two workers in formulating plants. A diagnosis of poisoning must be considered in three pilots. One fatality and one other illness were attributed to the ingestion of chlorinated hydrocarbons. In 7 of 11 crashes or disturbances of the pilot’s performance about which enough information was available, three appeared to represent pilot error, one was myocardial infarction, and three—mentioned above–appeared to be mild poisoning with consequent interference with flying ability. An epidemic characterized by fever and respiratory symptoms accounted for the majority of cases suspected of being poisoning. Epidemiologic and toxicologic investigation of this epidemic established infection and ruled out insecticides as the cause of these illnesses. Groups of persons selected because of their exposures to methyl parathion or to Guthion resulting from their occupation or from their residing in treated areas were studied for evidence of poisoning. No clinical evidence of poisoning or significant cholinesterase depletion was found. The half-life for methyl parathion on cotton leaves was found to be less than 1hour. Exposure studies on checkers corroborated this rapid decay rate. Most of the residue exposure was on the hands. The half-life of Guthion spray and dust on cotton leaves appeared to be about 2 to 4 days. Exposure studies indicated that most of the residue exposure was to the hands.