Systemic uptake of inhaled arsenic in rabbits

Human occupational exposure to sufficiently high levels of arsenic in air has been associated with lung cancer, but generally not other types of cancer. Thus, a better understanding of the relationship between airborne arsenic exposures and systemic uptake is essential. In this study, rabbits were exposed to one of four levels of arsenic trioxide in air for 8 h/day, 7 days/week, for 8 weeks (0.05, 0.1, 0.22, or 1.1 mg/m3). Plasma levels of inorganic arsenic, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were measured following the last exposure. Although there was a dose-related increase in plasma levels of methylated arsenic metabolites, statistically significant increases in mean inorganic arsenic levels in plasma were observed only in male rabbits exposed to 0.22 mg/m3, and in both males and females exposed to 1.1 mg/m3. Mean inorganic arsenic levels in plasma in males and females exposed to 0.05 and 0.1 mg/m3, and females exposed to 0.22 mg/m3, were not significantly elevated compared to controls. These results suggest that arsenic inhalation has a negligible impact on body burden of inorganic arsenic until air levels are significantly elevated. Based on plasma measurements of inorganic arsenic, the two lowest exposure levels in this study (0.05 and 0.1 mg/m3) are indistinguishable from background.