The carcinogenicity of inhalation exposure to antimony was investigated in rats. Wistar-rats were exposed by inhalation to 45 milligrams per cubic meter (mg/m3) antimony-oxide, 40mg/m3 antimony ore, or filtered air 7 hours per day, 5 days per week for 52 weeks. Five rats/sex/group were sacrificed at 6, 9 and 12 months, the rest at 20 weeks post exposure. Autopsies and histopathological examinations were performed on all animals. Tissues were analyzed for antimony, arsenic (7440382), and other inorganic elements by atomic absorption and proton induced X-ray emission. At 9 months, antimony in lungs of rats exposed to antimony-oxide was 5.4 to 5.7 times greater in males and females, and arsenic was 21 and 10.8 times greater, than in these respective groups exposed to antimony ore. Other tissues from females contained more arsenic than the same tissues from males. At final sacrifice, lungs from both exposure groups contained slightly elevated, confluent, white and yellow foci on the pleural surfaces of all lobes. Post exposure, alveolar particles were significantly decreased, but interstitial fibrosis continued to increase, affecting as much as 80 percent of the alveoli. No lung tumors were seen in control rats of either sex or in male rats exposed to either compound. Both antimony-oxide and ore exposed females developed lung neoplasms, the first lung tumor being seen after 41 weeks exposure to antimony ore or 53 weeks antimony-oxide exposure. Lung tumors were found in 27 percent of antimony-oxide exposed animals and 25 percent of those exposed to ore. Tumor types included squamous cell carcinomas, bronchoalveolar adenomas, bronchoalveolar carcinomas and scirrhous carcinomas. Multiple tumors were seen in six oxide and three ore exposed female rats. Both controls and exposed animals also developed a variety of tumors typical of this rat strain. The authors conclude that female rats are more susceptible to lung cancer induction by antimony-oxide and antimony ore than males. The significance of increased pulmonary arsenic concentrations is not clear.
Division of Biomedical and Behavioral Science, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, 41 pages, 16 references