Urban air pollution enhances the formation of urethane-induced lung tumors in mice.

This paper investigates the association between air pollution and lung neoplasia in an animal model. The experimental exposures were done in two locations with different air pollution profiles: a polluted area (downtown São Paulo) and a "clean" environment (Atibaia). Swiss mice were employed and urethane (3 g/kg) was used as carcinogenic substance. Two experiments were performed: Experiment I was designed to verify whether air pollution acts as initiator and/or promoter of lung cancer, using 300 mice; Experiment II employed 250 animals and aimed to verify if the effects of air pollution on the development of lung tumors was dose dependent. A significant effect of air pollution in augmenting lung carcinogenecity induced by urethane was observed. This effect was shown to be dose-dependent and reproducible on two different occasions. In addition, morphometric studies revealed that pollution may influence tumor phenotype. These results support the hypothesis that air pollution plays a significant role in the development of lung tumors.