Carcinogens in the workroom air in the rubber industry

Only a few data are available on the occurrence of carcinogenic compounds in the air at workplaces in the rubber industry, with the exception of data on total particulates and solvents. The available information allows the indication of some specific workplaces with elevated exposure levels. Recent investigations of nitrosamines in the rubber industry indicate the widespread occurrence of considerable levels of nitrosodimethylamine and nitrosomorpholine. In an effort to elucidate the origin and formation of nitrosamines in this industry, chemicals as well as the air in various areas were analyzed. All chemicals used for rubber compounding contain nitrosamines if they are derivatives of secondary amines, eg, tetramethylthiuram, zinc diethyldithiocarbamate or N-oxydiethylene benzothiazolylsulfenamide. Accordingly, variable concentrations of airborne nitrosamines could be detected at places where rubber products are manufactured or stored. The nitrosamines found correspond to the compounded chemicals. The original nitrosamine level in rubber chemicals is not high enough to explain the amounts found in rubber products and in air. Therefore additional nitrosation had to be considered. The responsible nitrosating agents are described. Preliminary results show that, in most cases, either by elimination of the nitrosating agent or by the exchange of rubber chemicals nitrosamine levels in the work area can be drastically reduced.