Benzotrichloride and
benzoyl chloride are suspected to be causative agents of
lung cancer and maxillary
malignant lymphoma of workers employed in factories producing
benzoyl chloride. The present study was undertaken to evaluate the carcinogenicity in mice of inhaling
benzotrichloride and
benzoyl chloride. Mice inhaled
benzotrichloride and
benzoyl chloride vapor for 30 min/d for 2 d/wk for 5 months, and each animal was followed for several month without subsequent exposure.
Tumor developed in the lung, skin and lymphatic tissues at high incidences in mice inhaling
benzotrichloride. By
benzotrichloride vaporized at 50 degrees C, the incidence of pulmonary
tumors was 53.1% (17/32, p less than 0.001), that of skin
tumors was 25% (8/32, p less than 0.02), and that of
malignant lymphoma was 25% (8/32, p less than 0.02) observed at the 10th month after exposure. These are significantly higher than that observed in control mice. In mice exposed to
benzotrichloride vaporized at room temperature, the incidence of pulmonary
tumors was 81.1% (30/37), that of skin
tumors was 27.0% (10/37), and that of
malignant lymphoma was 10.8% (4/37) observed at the 15th month after exposure. On the other hand, by
benzoyl chloride vaporized at 50 degrees C, the incidence of pulmonary
tumors was 10.7% (3/28) and that of skin
tumors was 7.1% (2/28), but these incidences did not show any significant difference from the controls. These results suggest that the carcinogenicity of
benzotrichloride is much higher than
benzoyl chloride and that
benzotrichloride is the primary cause of
malignancies developing among workers engaged in manufacturing
benzoyl chloride.