Chronic health effects among sheep and humans surviving an aldicarb poisoning incident.

Aldicarb is a granular carbamate insecticide, acaricide and nematocide applied to soil. In 1989, a large scale aldicarb poisoning of grazing sheep occurred in south central Washington State. Among 1600 animals in 3 different groups, 288 of 318 sheep in 1 group died within a very short time. An investigation by the Washington State Department of Agriculture concluded that aldicarb poisoning was the cause of the acute sheep deaths. Within 3 w of the incident, all the 30 sheep which survived the initial exposure from the 1 group had died or were near death and euthanized. Among the approximately 1300 sheep nearby but not affected by the acute incident, low fertility and poor health were apparent over the next 3 y. These sheep also suffered more deaths than expected, and lambs born to the sheep had a higher frequency of limb and gastrointestinal malformations than usual. All of the 6 men present in the field the day of the acute sheep deaths complained of acute symptoms. Three men were hospitalized the night of the sheep deaths and 2 were seen by a physician the next day. All men were healthy prior to the sheep deaths. Within a few days 4 of the 6 men developed a productive cough and 1 reported right-sided abdominal pain. Three years after the incident 5 of the men were still seeking medical attention or reporting symptoms they felt associated with the acute exposure. The chronic health effects in the sheep and men are not expected following exposure to aldicarb. No explanation exists for the chronic health effects, nor have such effects been previously reported in aldicarb poisonings.