Immunotoxicology studies of sodium arsenate-effects of exposure on tumor growth and cell-mediated tumor immunity.

Exposure of mice to sodium arsenate (Na2HAs04) at levels of 2.5, 25 and 100 ppm As in the drinking water for 10-12 weeks increased the latent period and decreased the incidence of tumors induced by injection of MSB sarcoma cells. Tumor growth and regression induced by Moloney sarcoma virus (MSV) was not significantly affected by arsenic exposure. Cell mediated tumor immunity was either unaffected or enhanced by exposure to arsenic. Our results indicate that chronic exposure to sodium arsenate at arsenic levels as high as 100 ppm is not detrimental to mice in terms of tumor growth and immunosuppression.