CAUSE-OF-DEATH ASSIGNMENT AT THE NATIONAL CENTER FOR TOXICOLOGICAL RESEARCH

The system for assigning cause of death in animal studies of carcinoge nicity at the National Center for Toxicological Research (NCTR) is des cribed. An empirical study of the NCTR's experience with its current c ause-of-death assignment system based on selected representative exper iments is reported. Issues investigated include the degree of confiden ce associated with histologic cause-of-death assignment, potential age -, dose- and sex-related differences in assigned grades of certainty o f cause of death, and frequencies of identification of various organ-s pecific and systemic diagnoses as the cause of death. Implications for age-adjusted statistical tests of carcinogenicity that require cause- of-death data are discussed.