N-nitrosamines have been found to be carcinogenic on animals and it is very probable that they possess the same activity in humans. The presence of N-nitrosamines has been also confirmed in the rubber industry. They are predominantly formed from vulcanization accelerators with the structural elements of secondary amines. Secondary amines (which can be nitrosated) are produced as by-products during the vulcanization. The elimination or reduction of N-nitrosamines in rubber products and also in the atmosphere of production plants can be achieved by the application of amine accelerators containing hindered substituents which lead to resonance-stabilized cations. These cations virtually do not participate in carcinogenic processes. Another way is the application of amine-free accelerators.