Aniline and o-toluidine -- both compounds are aromatic amines -- are used in the manufacture of a variety of dyes, pharmaceuticals, pesticides, and chemicals employed in the manufacture of rubber. The primary routes of exposure to these compounds are inhalation and dermal contact. There is no doubt that o-toluidine and aniline are carcinogens -- agents that cause cancer.
Evidence reported by the National Institute for Occupational Safety and Health (NIOSH) clearly associates the occupational exposure to o-toluidine and aniline with an increased risk of bladder cancer among workers. The risk of bladder cancer is greatest among workers with possible and definite exposures to o-toluidine and aniline, and the risk increases with the duration of exposure.