RESUMEN
An outbreak of hematuria occurred from May 20 to May 23, 1975, among employees of a chemical packaging plant. Nine of 22 workers who packaged the insecticide chlordimeform in a separate shed became severely ill with abdominal pain, dysuria, urgency to void, or hematuria. None of 18 persons who worked in other areas of the plant were affected. Four additional workers who had packaged the chemical during the previous year had a history of similar symptoms. Bladder biopsy specimens from three affected persons showed severe hemorrhagic cystitis; chlordimeform and 2-methyl-4-chloroaniline, a metabolite of chlordimeform, were present in urine specimens collected three days after exposure. The illness lasted from one week to two months; the workers recovered completely. Chlordimeform that was injected subcutaneously into three cats produced similar, though less severe, changes in the bladders of two animals.