Laboratory investigation of a poisoning epidemic in Sierra Leone

In June 1986, an epidemic of poisoning occurred in Sierra Leone, West Africa; it involved 49 persons--with 14 deaths. Our laboratory's approach and investigation of this incident is described. Using positive chemical ionization mass spectrometry and nuclear magnetic resonance spectroscopy, the toxicant was identified as parathion, a highly toxic organophosphorus pesticide. Analysis of various items supported the epidemiologic hypothesis that bread was made from contaminated flour and that the flour became contaminated with parathion during a truck shipment. Modern analytical instruments played a major role in this laboratory investigation and effected the identification of the unknown toxicant within hours of receiving the initial bread sample. Close cooperation and clear communication between the epidemiologic and laboratory teams were important in this investigation.