National Toxicology Program

Selected toxicity information from HSDB, one of the National Library of Medicine's databases. ¹

Names (NTP)

• Asbestos, amosite
• Asbestos, amosite + Dimethyl hydrazine
• ASBESTOS, GRUNERITE

Human Toxicity Excerpts

• HUMAN EXPOSURE STUDIES: With regard to mesotheliomas, 1 study suggested a particularly high risk of combined exposure to chrysotile and amphiboles (risk ratio, 61), thus almost multiplying the risk ratios (6 and 12, respectively) of exposures to chrysotile and to amphibole alone. /Chrysotile and amphiboles/ [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. S7 107 (1987)]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: In humans, occupational exposure to... amosite... has resulted in high incidence of lung cancer... . Many pleural and peritoneal mesotheliomas have been observed after occupational exposure to... amosite... . [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 80 (1977)]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: Exposures to amosite in factory making insulation materials were reported... 10 mesotheliomas, and an increased risk of lung cancer in workers followed up for 20 yr or longer /were reported/. The excess lung cancer risk in the amosite workers was shown to increase with duration of employment. There was a 3.87 fold increase in lung cancer among those with less than 3 months' employment. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 67 (1977)]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: In a retrospective study of 914 men who had worked for various periods of time during World War II in plant manufacturing insulating materials from amosite for the US Navy... the group of 65 men who had worked for <1 month had an excess mortality from lung cancer (but not from all cancers or all causes) which became discernible only 30 yr after exposure. Excess mortality from lung cancer and all cancers that showed up after progressively shorter intervals after the exposure was reported in men who had worked for periods ranging from 1 month to more than 2 years. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 67 (1977)]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: All types of asbestos are known to cause inflammatory changes in lungs and pleurae... and lung cancer. However, there is experimental and epidemiologic evidence that there may be differences in the potential of different asbestos types to produce disease. ...It has been suggested that crocidolite has greatest potential to produce disease; chrysotile, the smallest; with amosite occupying an intermediate position. [American Conference of Governmental Industrial Hygienists. Documentation of Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices for 2001. Cincinnati, OH. 2001., p. 3]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: Gastrointestinal tract cancers increased in groups exposed occupationally to amosite and excess of cancer of the larynx was also observed in exposed workers. [DHHS/NTP; Fourth Annual Report On Carcinogens p.29 (1985) NTP 85-002 ]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: Examination of 326 household contacts of amosite asbestos workers /were studied/. Of these, 35% who had no occupational asbestos exposure had chest X-ray abnormalities, with a predominance of pleural changes, fibrosis, and calcification. Contact had presumably been through asbestos dust on the workers' clothing and hair. The level of airborne dust in the homes of workmen has been reported as 100-5000 ng/cu m. [Nat'l Research Council Canada; Asbestos p.46 (1979) NRCC No. 16452 ]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: The /prospective/ study of /17,800/ USA and Canadian insulators /exposed primarily to chrysotile... and amosite showed that/ lung tumors... accounted for... 21% of /2271/ deaths. 8% were from mesothelioma of the pleura or peritoneum, and 7%... from asbestos... 675 excess malignacies occurred, constituting 30% of all deaths. In addition... the incidences of cancers of the larynx, pharynx and buccal cavity, and kidney were significantly elevated. Other tumors... as a group... were significantly in excess. [Selikoff IJ et al; Ann NY Acad Sci 330: 91-116 as cited in USEPA; Asbestos Health Assessment Update (Draft) p.11-13 (1984) EPA-600/8-84-003A ]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: Cancers of the digestive tract (stomach, colon, rectum) were also linked to asbestos exposure. In a study of 623 asbestos workers, these cancers accounted for 41 deaths while only 13 were expected from experience with the general population. During processing of rice, the Japanese add talc which usually has asbestos as an impurity. There was a positive correlation between the incidence of stomach cancer and rice consumption in the Japanese. Futhermore, chrysotile and amphibole asbestos fibers were found in the gastric tumors. [Nat'l Research Council Canada; Effects of Asbestos in the Canadian Environ p.19 (1979) NRCC No. 16452 ]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: In 1973, amphibole asbestos fibers were discovered in the municipal water supply of Duluth, Minnesota. The entire city population of approximately 100,000 was exposed from the late 1950s through 1976 at levels of 1-65 million fibers/L of water. Surveillance of cancer incidence in residents was initiated to determine the health effect from ingestion of asbestos. Lung cancer in females was considered of biological significance. The mesothelioma incidence rate was no more than expected. /Amphibole asbestos/ [Sigurdson EE; Environ Health Perspect 53: 61-67 (1983) ]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: In 1998, ...the results of /a/ mortality study of 753 workers in Tyler, Texas who were exposed to probably only amosite fibers /was published/. The duration of employment ranged from 1 day to 17.3 years with an average of 12.7 months. Among the 222 deaths in the analytical group, there was a significant number of excess deaths from respiratory cancer in workers with exposure durations of less than 6 months. Six of the deaths were connected with mesothelioma: 4 pleural and 2 peritoneal. [Bingham, E.; Cohrssen, B.; Powell, C.H.; Patty's Toxicology Volumes 1-9 5th ed. John Wiley & Sons. New York, N.Y. (2001)., p. V1 500]**PEER REVIEWED**
  
• HUMAN EXPOSURE STUDIES: To determine predictors of progression of pleural and parenchymal disease on the chest radiographs of workers exposed to a short term, intense exposure of amosite asbestos. The first and last of a series of chest radiographs of 887 workers exposed to amosite was interpreted and coded according to International Labor Organization (ILO) standards by two physicians. Significant predictors of disease progression were found by a linear stepwise regression analysis from among such variables as smoking history, latency (time since first exposure), duration and intensity of exposure, and cytology. Although most radiographs remained normal, some showed progression of disease with about twice as many patients with abnormalities on the last film. Various combinations of age, intensity of exposure, and time between films were significant predictors of pleural and parenchymal disease and progression of such disease. No predominance of one sided disease was noted. Cytology and smoking were unreliable predictors of disease. Most disease progression was minor, usually of less than two scoring categories. An intense, yet short, exposure to amosite asbestos can produce pleural and parenchymal changes on chest radiographs. The number of those affected roughly doubled over a period spanning 10 to 20 years after exposure. Age and intensity of exposure are the most important predictors of disease. [Shepherd JR et al; Occup Environ Med 54 (6): 410-5 (1997) ]**PEER REVIEWED**
  
• CASE REPORTS: There is a single case report in the literature of a pleural mesothelioma occurring in a woman who was an office worker in a building whose ceiling material contained amosite asbestos, and considerable numbers of amosite fibers were identified in this patient's lung tissues. [Rom, W.N. (ed.). Environmental and Occupational Medicine. 2nd ed. Boston, MA: Little, Brown and Company, 1992., p. 264]**PEER REVIEWED**
  
• CASE REPORTS: Mesothelioma has been diagnosed in a 44 year old woman exposed to talc over a 12 year period; lung tissue revealed the presence of elevated levels of brown asbestos (amosite). [Barnes R, Rogers AJ; Med J Aust 140: 488-90 (1984) ]**PEER REVIEWED**
  
• EPIDEMIOLOGY STUDIES: In a cohort of USA and Canadian insulation workers, the lung cancer incidence rate was 2.5/1000 man years, 5 times the expected rate. Factory workers exposed to amosite asbestos (and not to other materials common to the construction industry) exhibited a six to sevenfold increase in lung cancer incidence over the general population (suggesting that asbestos fibers may have been the cause of the lung cancers in the previous two cohorts). The incidence of deaths among the factory workers was correlated with the duration of exposure to amosite (and hence presumably correlated to the total dose received). [Nat'l Research Council Canada; Effects of Asbestos in the Canadian Environ p.113 (1979) NRCC No. 16452 ]**PEER REVIEWED**
  
• EPIDEMIOLOGY STUDIES: To examine the causes of death among 1130 former workers of a plant in Tyler, Texas dedicated to the manufacture of asbestos pipe insulation materials. This cohort is important and unusual because it used amosite as the only asbestiform mineral in the production process. High level exposure of such a specific type was documented through industrial hygiene surveys in the plant. Deaths were ascertained through various sources including data tapes from the Texas Department of Health and the national death index files. As many death certificates as possible were secured (304/315) and cause of death assigned. After select exclusions, 222 death certificates were used in the analysis. Causes of death were compared with age, race, and sex specific mortalities for the United States population with a commercial software package (OCMAP Version 2.0). There was an excess of deaths from respiratory cancer including the bronchus, trachea, and lung (standardised mortality ratio (SMR) 277 with 95% confidence interval (95% CI) 193 to 385). Four pleural mesotheliomas and two peritoneal mesotheliomas were identified. The analysis also showed an increasing risk of respiratory malignancy with increased duration of exposure including a significant excess of total deaths from respiratory cancer with less than six months of work at the plant (SMR 268 with 95% CI 172 to 399). The importance of the cohort lies with the pure amosite exposure which took place in the plant and the extended period of latency which has followed. The death certificate analysis indicates the pathogenicity of amosite, the predominant commercial amphibole used in the United States. These data confirm a link between amosite asbestos and respiratory malignancy as well as mesothelioma. [Levin JL et al; Occup Environ Med 55 (3): 155-60 (1998) ]**PEER REVIEWED**
  

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Non-Human Toxicity Excerpts

• LABORATORY ANIMALS: Acute Exposure: All commercial types of asbestos have produced mesotheliomas in CD Wistar rats /by intrapleural admin/. A dose of 20 mg of the Union Internationale Contre le Cancer standard reference samples, crocidolite, amosite, anthophyllite, Canadian & Rhodesian chyrsotiles, produced various numbers of mesotheliomas /in rats by intrapleural admin; species not stated/. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 45 (1977)]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Acute Exposure: .../It was found that an intrapleural/ dose of 40 mg asbestos dust on gelatin coated fiber-glass pledgets... /of/ 3 of the Union Internationale Contre le Cancer samples, crocidolite, amosite and Rhodesian chrysotile, all produced mesotheliomas in about 60% of Osborne Mendel rats. ...Mesotheliomas in Sprague Dawley rats treated with a single /intrapleural/ dose of 67 mg of chrysotile, amosite, or crocidolite /were observed/. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V13 45 (1977)]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Acute Exposure: In groups of 50 hamsters given single intrapleural injection of... 1 or 10 mg amosite, 4/50 hamsters developed mesotheliomas at the highest dose only. .../No data for controls are given./ [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 50 (1977)]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Acute Exposure: The acute in vivo response of the visceral pleura following intratracheal instillation of amosite asbestos was examined by light microscopy and by transmission and scanning electron microscopy in the guinea pig model. Asbestos fibers were observed close to the pleura or subpleural regions proper. Thus, pleural changes occurred in the absence of direct fiber contact. Morphological changes in the pleural and subpleural areas were seen as early as 2 hr after exposure and were associated with pathological alterations of the underlying parenchyma. The normally squamous mesothelial cells became pleomorphic in experimental animals, ranging from slightly cuboidal, to protruding columnar-like cells, to more abnormal forms. Many organelles remained unaltered, an incr in vacuolization in portions of the pleura, indicated localized and advanced intracellular responses. Beginning at 4 hr post-exposure, varied numbers of particulate-free macrophages were observed on the pleural surface, and were considered an extension of the inflammatory response occurring in the underlying parenchyma. Early proliferation of mesothelial cells, in limited areas of the pleura, and cytoplasmic extensions into pleural space were also observed. Distortions of the basal lamina and smooth muscle bundles accompanied the morphological changes in the pleural cells. A trend towards normality was observed in the longer time frames, but some areas of pleural change persisted through 3 months post-exposure. [Dodson RF, Ford JO; J Toxicol Environ Health 15 (5): 673-86 (1985) ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Subchronic or Prechronic Exposure: Intratracheal injection of amosite dust in guinea pig lung at 40, 80, 120, and 160 days produced continuous increase in hexosamine and glucuronic acid throughout development of disease and initial increase and later decrease in sialic acid which indicate loci of asbestos toxicity. [Misra V et al; Environ Res 16 (1-3): 55-61 (1978) ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Subchronic or Prechronic Exposure: Pulmonary fibrogenic response in mice was investigated following intratracheal inoculation of amosite over 150 day period. Acute inflammatory reaction in lungs was observed at early periods with thick reticulum fibers developing later. No asbestos bodies were reported. [Sahu AP et al; Exp Pathol (JENA) 11 (1-2): 21-4 (1975) ]**PEER REVIEWED**
  
• ALTERNATIVE IN VITRO TESTS: ...Increased levels of intercellular adhesion molecule-1 (ICAM)-1 and monocyte chemoattractant protein-1 (MCP)-1 protein were measured following 24 or 48 hours exposure of cultured rat pleural mesothelial cells to amosite fibers (1.5 to 5.0 ug/sq cm). [Hill GD et al; Exp Lung Res 29 (5): 277-90 (2003) ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Subchronic or Prechronic Exposure: ...Increased levels of intercellular adhesion molecule-1 (ICAM)-1, monocyte chemoattractant protein-1 (MCP)-1, and macrophage inhibitory protein-2 (MIP)-2 protein were found in pleural lavage fluid from Fischer-344 rats exposed to amosite asbestos for 4 and 12 weeks and after a 12-wk recovery period (following the 12-wk exposure period). [Hill GD et al; Exp Lung Res 29 (5): 277-90 (2003) ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: ...Malignant tumors developed in 5 to 14% of the rats survived 18 months after exposure. ...Lung cancer and mesothelioma were also produced by exposure to amosite. [Reeves AL; Environ Res 8: 178-202 (1974) as cited in USEPA; Asbestos Health Assessment Update (Draft) p.77 (1984) EPA-600/8-84-003A ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: The potential carcinogenic effect of taconite tailings, amosite and diatomaceous earth in drinking water /was investigated/. Groups of 20-30 rats were supplied water with these various materials throughout their lifetime. A variety of malignancies were found in each exposure group, although none were attributable to asbestos exposure. However, a pleural mesothelioma was identified in a group exposed to amosite plus chrysotile and a peritoneal mesothelioma was identified in the diatomaceous earth exposed group. [Hilding AC et al; Arch Environ Health 36: 298-303 (1981) as cited in USEPA, Office of Drinking Water; Criteria Document (Draft): Asbestos p.V-12 (1985) ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: A study examined the carcinogenic effects of asbestos on groups of 22-24 animals fed 250 mg/week of amosite, crocidolite, or chrysotile in margarine for up to 25 months. No excess malignancies were found in the exposed group compared with the margarine or undosed control groups. [Bolton RE et al; Environ Res 29: 134-50 (1982) as cited in USEPA, Office of Drinking Water; Criteria Document (Draft): Asbestos p.V-12 to V-13 (1985) ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: /Intrapleural admin to CD Wistar and Osborne-Mendel rats/ all commercial types of asbestos have produced mesotheliomas in C/D Wistar rats. A dose of 20 mg of the five UICC standard reference samples produced mesotheliomas in varying numbers - crocidolite 61%, amosite 36%, anthophyllite 34%, Canadian chrysotile 30% and Rhodesian chrysotile 19%. With a dose of 40 mg of asbestos dust on gelatin-coated fibre-glass pledgets, /it was/ found that three of the UICC samples, crocidolite, amosite and Rhodesian chrysotile, all produced mesotheliomas in about 60% of their Osborne-Mendel rats. Induced mesotheliomas with 60 mg of Russian chrysotile. In all these studies there was a long latent period between inoculation and appearance of the tumors. Evidence that the response was dose related. Mesotheliomas have also been produced by other workers: in rats, in hamsters and in rabbits. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V2 27 (1973)]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: Carcinogenesis studies of amosite asbestos were conducted by administering diets containing 1% of the asbestos in pellets from the conception of the mothers through the lifetime of male and female Syrian golden hamsters. Control groups consisted of 127 male and 126 female hamsters and the amosite asbestos groups consisted of 252 male and 254 female hamsters. ...Under the conditions of these studies, the ingestion of amosite asbestos at a level of 1% in the diet for their lifetime was not toxic and did not cause a carcinogenic response in male and female Syrian golden hamsters. Levels of Evidence of Carcinogenicity: Male Hamsters: Negative; Female Hamsters: Negative. [Lifetime Carcinogenesis Studies of Amosite Asbestos in Syrian Golden Hamsters (Feed Studies). Technical Report Series No. 249 (1987) NTIS Publication No. PB87-133278/AS U.S. Department of Health and Human Services, National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: Carcinogenesis studies of amosite asbestos alone or in combination with the intestinal carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) were conducted in male and female rats. Amosite asbestos was administered at a concentration of 1% in pelleted diet for the entire lifetime of the rats, starting with the dams of the study animals. One group of amosite asbestos-exposed rats (amosite preweaning gavage) also received chrysotile asbestos via gavage during lactation. Group sizes varied from 100 to 250. Litter size was the same, but the offspring from mothers exposed to amosite asbestos were smaller at weaning than those from nonexposed mothers and remained smaller throughout their life. The DMH was administered by gavage at a dose of 7.5 mg/kg for males and 15 mg/kg for females every 14 days, starting at 8 weeks of age, for a total of five doses. The administration of DMH did not affect body weight gain either in amosite-exposed or nonexposed animals. The amosite-exposed rats showed enhanced survival compared with that of the nonexposed rats. ...Under the conditions of these feed studies, amosite asbestos was not overtly toxic, did not affect survival, and was not carcinogenic when ingested at a concentration of 1% in the diet by male or female F344/N rats. The cocarcinogenic studies using DMH were considered inadequate because of the high incidence of DMH-induced intestinal neoplasia in both the amosite asbestos-exposed and nonexposed groups. [Toxicology & Carcinogenesis Studies of Amosite Asbestos in F344/N Rats. Technical Report Series No. 279 (1990) NIH Publication No. 91-2535 U.S. Department of Health and Human Services, National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: ...Groups of 69 Charles River CD rats /were exposed by inhalation/ to ball milled... amosite... for 4 hr/day on 4 days/wk for 2 yr at mean concentration of about 50 mg/cu m. Two pleural mesotheliomas were observed. No tumors were observed in controls. (It is important to note that the material was comminuted by vigorous mechanical milling (ball milling for up to 240 hr), which undoubtably altered the fiber properties). [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 43 (1977)]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: ...Groups of CD Wistar rats /were exposed/ to 5 Union Internationale Contre le Cancer asbestos samples (amosite, anthophyllite, crocidolite, and Rhodesian and Canadian chrysotiles) at concentrations of about 12 mg/cu m respirable dust for 7 hr/day on 5 days/wk, for several lengths of exposure: 1 day (7 hr), 3 months, 6 months, 12 months, or 24 months. At the end of exposures, the amount of dust in the lungs of animals exposed to the 2 chrysotile samples was much less than that in animals exposed to the 3 amphibole samples. However, all types of fiber produced asbestosis, which was progressive after removal from the dust. Futhermore, whereas no carcinomas of the lung were found in the control group, carcinomas of the lung and mesotheliomas were demonstrated in the groups exposed to Canadian chrysotile and to the amphiboles. Only carcinomas of the lung were seen with Rhodesian chrysotile... an increasing incidence of neoplasms was observed with increasing exposures to each form of asbestos. Even as little as 1 day of exposure (providing the animals were allowed to survive and were observed) produced neoplasia. /Amphibole and chrysotile asbestos/ [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 44 (1977)]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: ...Ip injections of 20 mg amosite, crocidolite or chyrsotile /were given to/ groups of 11, 13, 13 Charles River CD rats, respectively. Three peritoneal mesotheliomas were observed with chrysotile, 3 with crocidolite and none with amosite, after 7-17 months. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 51 (1977)]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: Long term studies of respiratory function and lung morphology on control groups of guinea pigs and matched groups exposed by inhalation to aerosols of chrysotile or amosite asbestos containing large numbers of short fibers. No fibrotic reaction was seen during 70 wk of amosite experiments. [Hiett DM; Br J Ind Med 35 (2): 135-45 (1978) ]**PEER REVIEWED**
  
• LABORATORY ANIMALS: Chronic Exposure or Carcinogenicity: Rats were fed a diet supplemented with an asbestos/margarine formulation for periods up to 1 yr. Union Internationale Contre le Cancer standard reference samples of amosite were used. No evidence of asbestos retention within gut lumen, and no sign of cell penetration or damage to intestinal mucosa observed. [Bolton RE, Davis J MG; Ann Occup Hyg 19 (2): 121-8 (1976) ]**PEER REVIEWED**
  
• GENOTOXICITY: In cultured human cells... amosite... did not induce DNA strand breaks ... [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. S7 109 (1987)]**PEER REVIEWED**
  
• GENOTOXICITY: Amosite ... induced transformation of Syrian hamster embryo cells ... Neither amosite nor crocidolite transformed CH3 10T1/2 cells. In cultured rodent cells, amosite ... induced chromosomal aberrations, & ... induced sister chromatid exchanges ... Amosite, chrysotile & crocidolite were inactive or weakly active in inducing mutation in rodent cells in vitro; none was mutagenic to bacteria. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. S7 109 (1987)]**PEER REVIEWED**
  
• GENOTOXICITY: Amosite exposure can increase the sister chromatid exchange rate in Chinese hamster ovarian fibroblasts. [Livingston GK; J Environ Pathol Toxicol 4: 373-82 (1980) as cited in USEPA; Asbestos Health Assessment Update (Draft) p.77 (1984) EPA-600/8-84-003A ]**PEER REVIEWED**
  
• GENOTOXICITY: Chrysotile, amosite, and anthophyllite showed no mutagenic activity toward tester strains of Escherichia coli or Salmonella typhimurium. [Chamberlain M, Tarmy EM; Mutat Res 43: 159 (1977) as cited in USEPA; Health and Environmental Effects Profile for Asbestos p.12-11 (1979) ]**PEER REVIEWED**
  
• ALTERNATIVE IN VITRO TESTS: Viral interferon production was depressed in monkey kidney cells in vitro by exposure to asbestos fibers. A dose response relation was evident and amosite, anthophyllite, crocidolite, and chrysotile all exhibited similar depressant activities. [Nat'l Research Council Canada; Effects of Asbestos in the Canadian Environment p.19 (1980) NRCC No. 16452 ]**PEER REVIEWED**
  
• ALTERNATIVE IN VITRO TESTS: ...In human lung epithelial cells A549, long amosite fibers, more effectively than the short ones, initiate free radical reactions, inhibit the glucose 6-phosphate dehydrogenase activity and the pentose phosphate pathway, decrease the intracellular level of reduced glutathione, and increase the generation of thiobarbituric acid reactive substances and the leakage of lactate dehydrogenase in the extracellular medium. [Riganti C et al; Toxicol Appl Pharmacol 193 (1): 106-15 (2003) ]**PEER REVIEWED**
  
• ALTERNATIVE IN VITRO TESTS: The cell transforming ability of asbestos dusts (amosite and crocidolite asbestos) was investigated using C3H10T1/2 murine fibroblast cultures. The dusts were capable of augmenting the oncogenic effect of benzo(a)pyrene. This synergistic effect was evident when fibers and chemicals were added to cultures as simple mixtures and when benzo(a)pyrene was adsorbed to the surface of fibers. [Poole A et al; Environ Health Perspect 51: 319-24 (1983) ]**PEER REVIEWED**
  

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Human Toxicity Values

• None found

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Non-Human Toxicity Values

• None found

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Absorption, Distribution and Excretion

• The retention of different types of asbestos in rats following exposure to the same concentration of respirable dusts... /has been described/. For the amphiboles, there was a similar pattern with an almost proportional increase of lung dust with dose. Much less dust was found for the chrysotiles, and no increase of dust content was shown in the lungs. Dust in the lungs of animals with 6 months' exposure had been partially cleared 18 months after the inhalation period. About 74% of the amosite and crocidolite and 41% of the anthophyllite were eliminated. [IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work)., p. V14 58 (1977)]**PEER REVIEWED**
  
• Using a minute volume for the rat of 100 mL, it would appear that about 1% of the total amosite inhaled is permanently in the lung. [USEPA; Asbestos Health Assessment Update (Draft) p.74 (1984) EPA-600/8-84-003A ]**PEER REVIEWED**
  
• Rats fed chrysotile, crocidolite, or amosite exhibited no retention of fibers in the gut lumen and no penetration of the mucosa. The transit time for the majority of fibers was 48 hours, and there was no asbestos either in the feces or in the gut after 7-28 days. [Bolton RE, Davis JMG; Ann Occup Hyg 19: 121-8 (1976) as cited in Nat'l Research Council Canada; Asbestos p.66 (1979) NRCC No. 16452]**PEER REVIEWED**
  
• Asbestos may have effects on organs in addition to the lungs and gastrointestinal tract (which come into obvious contact with the fibers) if the fibers can penetrate from these main sites to the blood or lymphatic systems. Amosite fibers can penetrate epithelial cells in rat jejunum through the luminal surface and can make their way into the highly vascularized lamina propria. The blood or lymph systems may then be involved in the transport of these fibers. [Storeygard AR, Brown AL; Mayo Clin Proc 52: 809-12 (1977) as cited in Nat'l Research Council Canada; Asbestos p.68 (1979) NRCC No. 16452]**PEER REVIEWED**
  
• Twenty female CBA mice were injected subcutaneously in two sites. Each injection contained 10 mg fiber suspended in 0.4 mL saline. Each animal received three injections into each flank. The flank was chosen as a site well distant from the thorax. Three fiber types: crocidolite, amosite, and chrysotile, were tested to study their distribution. All three fiber types were found in the submesothelial tissues of the thorax and abdomen. In addition, extensive inflammatory changes and some sarcomas developed at the injection sites, while transport of fibers to submesothelial tissues culminated in mesothelioma. [Roe FJC et al; Int J Cancer 2: 628-38 (1967) as cited in USEPA, Office of Drinking Water; Criteria Document (Draft): Asbestos p.III-9 (1985) ]**PEER REVIEWED**
  
• Two human studies gave evidence for the penetration and migration of asbestos. ...Amphibole asbestos /has been detected/ in the urine of Minnesota residents who ingested drinking water contaminated with 5X10+7 fibers/L. ...Amphibole asbestos in lung > liver > jejunum of persons exposed to high oral intake of the mineral /has been observed/. /Amphibole asbestos/ [Seiler, H.G., H. Sigel and A. Sigel (eds.). Handbook on the Toxicity of Inorganic Compounds. New York, NY: Marcel Dekker, Inc. 1988., p. 604]**PEER REVIEWED**
  
• Rats were fed a diet supplemented with an asbestos/margarine formulation for periods up to 1 yr. UICC standard reference samples of amosite were used. There was no evidence of asbestos retention within gut lumen, and no sign of cell penetration or damage to intestinal mucosa were observed. [Bolton RE, Davis J MG; Ann Occup Hyg 19 (2): 121-8 (1976) ]**PEER REVIEWED**
  
• Fibers were detected in beverages (beer, wine and soft drinks) and were studied to see if such fibers consumed orally can pass through the intestinal wall and enter the bloodstream. A stock solution was made to contain fibers the same length as those found in beverages (0.5-2) and determined to contain 9.4x10+6 fibers/L. An aliquot (assumed to be 350 mL) was then administered intragastrically to rats (number, species and sex not known). Asbestos fibers were found to accumulate in the omentum surrounding the small intestine, brain and lung. ...Counts could not be made on the liver and kidneys. /Asbestos cmpd/ [Cunningham HM, Pontefract RD; J Assoc Off Anal Chem 56: 976 (1973) ]**PEER REVIEWED**
  

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Metabolism/Metabolites

• None found

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TSCA Test Submissions

• None found

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Footnotes

¹ Source: the National Library of Medicine's Hazardous Substance Database, 10/28/2007.