Preliminary experimental study on carcinogenicity of arsenic trioxide in rat lung.

To investigate carcinogenic or cocarcinogenic properties, copper ore (Kinkaseki) and flue dust collected from a metal refinery and arsenic trioxide (As2O3) were administered into the lung of male Wistar-King rats by an intratracheal instillation method. No squamous cell carcinoma of the lung was found among the rats given three arsenical substances, while adenoma or adenocarcinoma was observed. Squamous cell carcinoma of the lung was observed in rats, when copper ore, flue dust, and arsenic trioxide were instilled into the lung together with benzo[a]pyrene (B[a]P. The incidence of squamous cell carcinoma of the lung in rats exposed to Kinkaseki, flue dust, and As2O3 in addition to B[a]P was higher than that in rats given B[a]P alone. The results of this study indicate that solid arsenical substances, such as arsenic trioxide, metal ore and flue dust from a metal refinery, seemed to act on the carcinogenicity of B[a]P in a cocarcinogenic manner.