FOLLOW-UP OF A GROUP OF WORKERS INTOXICATED WITH 4,4'-METHYLENEDIANILINE

4,4'-Methylenedianiline (MDA), an aromatic amine, is a known human hep atotoxin and an animal carcinogen but there is little information rega rding its chronic effects in humans. Between 1967 and 1976, 10 workers at a plant in Ontario that used MDA as an epoxy hardener developed ac ute jaundice. We followed this group from the date of intoxication thr ough to the end of 1991 for cancer incidence by matching with the Onta rio Cancer Registry. To date, one cancer, a pathologically confirmed b ladder cancer has developed (expected number based on provincial incid ence rates: 0.64 for all cancers, 0.05 for bladder cancer). This findi ng may be important because bladder cancer was a site of interest a pr iori; bladder cancers have been observed in two other occupationally e xposed groups (significantly higher than expected in one of these); in the National Toxicology Program bioassay, urinary bladder tumors occu rred in exposed animals but not in controls; and MDA has structural si milarity to known human bladder carcinogens such as benzidine. (C) 199 4 Wiley-Liss, Inc.