When Science Isn't Enough: Wilhelm Hueper, Robert A. M. Case, and the Limits of Scientific Evidence in Preventing Occupational Bladder Cancer.

A recent outbreak of occupational bladder cancer in a Buffalo, New York, factory confirmed the carcinogenicity of ortho-toluidine, an aromatic amine that had first been implicated in human bladder cancer cases decades earlier. Events leading to this outbreak replicated the history of numerous earlier bladder cancer outbreaks among workers exposed to beta-naphthylamine and benzidine, two other aromatic amines that were widely used in the dye and rubber industries and that have been responsible for bladder cancer outbreaks in the United States, Germany, Switzerland, England, France, Italy, Austria, Czechoslovakia, the former Soviet Union, Poland, and China. The historic development of scientific knowledge of occupational bladder cancer prefigured many debates that later occurred around other environmental carcinogens; two of the giants of occupational medicine, Wilhelm Hueper and Robert A. M. Case, played seminal roles in the study of these chemicals. Examination of the history of worker exposure to aromatic amines and the subsequent development of bladder cancer at Du Pont, Allied Chemical, and other U.S. manufacturers demonstrates that these carcinogens were regulated only after cancer epidemics were recognized. Production and use of aromatic amines continues in developing countries; these nations will inevitably experience similar outbreaks unless steps are taken to eliminate exposure to these deadly chemicals. This paper chronicles the history of occupational bladder cancer in the United States, highlighting the roles of Hueper and Case in occupational cancer investigation and prevention.