Inhalation of NO2and Blood Borne Cancer Cell Spread to the Lungs

Abstract

An experimental model was designed where the frequency of blood-borne cancer cell metastases to the lungs of animals was used as an indicator to detect adverse effects of inhaled nitrogen dioxide (NO₂). Animals were exposed to air containing 0.40 ± 0.05 ppm or 0,80 ± 0.05 ppm of NO₂. After the appropriate exposure periods, the animals were infused intravenously with B16 mouse melanoma cells. At 3 wk post-infusion the animals were killed and the lungs were examined for melanoma nodule development. The lungs of the NO₂-exposed animals contained a significantly higher number of melanoma nodules than the lungs of control animals (P < .0025). These results indicate that inhalation of ambient or near ambient levels of NO₂ influences the metastasis of blood-borne cancer cells. This raises the possibility that similar events may occur in the human population.