Assessment of Exposure to Ortho-Toluidine and Other Aromatic Amines in a Rubber Chemical Manufacturing Plant. Exposure Assessment Update, Documentation Report

摘要

In 1991 and 2000, the National Institute for Occupational Safety and Health (NIOSH) published the results of a retrospective cancer incidence study and a mortality study, respectively, of the 1,749 workers employed at a rubber chemical manufacturing plant in NY. These workers were believed to have been occupationally exposed to ortho-toluidine and aniline, suspected bladder carcinogens in animals. Thirteen cases of bladder cancer were observed versus 3.61 expected (standardized incidence ratio (SIR) = 3.6; 90 percent confidence interval (CI) = 2.1-5.7). Among workers considered to have definite exposure (DE) to ortho-toluidine and aniline, the bladder cancer excess risk was 6.5-fold, while for those with possible exposure (PE), the excess risk was nearly 4-fold. The risk of cancer was strongly associated with increased duration of employment in the department where ortho-toluidine was used, with a 27-fold excess risk among workers with 10 or more years of employment. The original exposure characterization for the cohort utilized a surrogate measure of exposure based on departments in which each worker was ever employed, comparing bladder cancer incidence among exposure groups within the cohort. The exposure assignments included: (1) Definitely Exposed (DE), workers who had ever worked in the department where ortho-toluidine and aniline were used, even if they had periods of employment outside of that department; (2) Possibly Exposed (PE), workers who had ever worked in maintenance, shipping, janitorial, or yard work; and (3) Probably Not Exposed (PNE), all other workers who were not likely to have been exposed to ortho-toluidine and aniline.