Evaluating the atmospheric particulate concentrated carcinogenic potential: a lung cancer experimental study in two different mice models

Abstract

Introduction: Previous studies have linked exposure to pollution and cancer, have shown the role of dose-dependent promoters and polluted atmosphere in the progression of lung tumours. Objectives: To determine whether chronic exposure to particulate matter (PM) concentration 2.5, from the ambient air of the city of São Paulo, has carcinogenic potential. Methods: Of the 120 male Swiss and AJ mice, of four to ten weeks of age were exposed daily to the PM 2, 5 in a container, for two hours, for four months. Urethane was used as carcinogen for Swiss mice, in a dose of 3.0 mg/kg, while in the AJ 4 mice, NNK carcinogen was used in a dose of 200 mg/kg. Each strain was divided into four groups: two controls (Cr) containing saline and carcinogen and two exposed (Ex) and saline containing carcinogen. After euthanasia, the lungs were fixed and the number of lesions counted (nodules and hyperplasia). Results: The mean number of lesions in Swiss mice was greater in the exposed group with carcinogen(SWEx-U: 2.57, SD ±2.77) when compared with the control group (SwCr-U: 1.07, SD ±1.54), (P < 0.001) . Similar findings were seen in AJ mice, where the exposed group with NNK (ExNNKAJ: 9.14, SD ±7.70) had more lesions than the non exposed ones (CrNNKAJ : 4.94, SD ±3.54) (P < 0.001). Conclusion: We have evidence that chronic exposure to PM 2, 5 by air pollution in São Paulo has the potential to promote tumors in mice of two different strains.