Amosite asbestos

CAS RN: 12172-73-5

Toxicity Summary

IDENTIFICATION AND USE: Amosite is ash gray, greenish, yellowish or brown. The fibers are long, straight, coarse, and somewhat flexible (less so than chrysotile or crocidolite). Chrysotile, amosite, and particularly crocidolite all have extremely high tensile strengths and are used extensively as reinforcers in cements, resins, and plastics. Although chrysotile is most adaptable to industrial use, crocidolite and amosite are particularly useful in combination with chrysotile for adding specific properties, such as rigidity. HUMAN STUDIES: Occupational exposure to amosite increases the risk of lung cancer. Mesothelioma and digestive-tract cancer were observed in workers occupationally exposed to amosite. Co-exposure to asbestos and tobacco smoking increased the risk of lung cancer in a synergistic manner. ANIMAL STUDIES: Inhalation exposure to amosite, caused mesothelioma and lung cancer (carcinoma) in rats. Intrapleural injection of various types of asbestos caused mesothelioma in rats and hamsters, and intraperitoneal injection of amosite caused peritoneal tumors, including mesothelioma, in mice and rats. Oral administration of amosite did not cause tumors in rats and hamsters. Possible teratogenicity of amosite was assessed in mice. Dams on Day 9 of gestation were given a single intraperitoneal administration at dose of 40 mg/kg body weight of asbestos. Dams and fetuses were examined on Day 18 of gestation. The incidence of dams with early dead fetuses in the groups given amosite were increased. While no external or skeletal malformation was observed in the control group, the incidence of external malformation (mainly reduction deformity of limb) and the incidences of skeletal malformation (mainly fusion of vertebrae) were significantly increased in the group given amosite. Amosite induced transformation of Syrian hamster embryo cells. In cultured rodent cells, amosite induced chromosomal aberrations, and sister chromatid exchanges. It was inactive or weakly active in inducing mutation in rodent cells in vitro, and it was not mutagenic to bacteria.
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