Carcinogenicity of multiple chemicals simultaneously administered.

The possibility that several carcinogens may act concurrently in organs such as the lungs and skin has assumed greater importance as the nec ognized possible agents increase for these sites. A wide range of effects, from inhibition through no effects to summation or even synergism must be considered. The dosage, type of agents, portal of entry, duration of exposure, site and type of tissue, species and strain of animal, and many other fac