Carcinogenicity Groups

NTP determined that there was clear evidence of carcinogenicity in male rats based on the increased incidence of renal neoplasms and no evidence of carcinogenic activity in female rats (NTP 1989). The EPA classified hexachloroethane as a possible human carcinogen (Group C). The slope factor calculated by EPA is 1.4xl0 2 (mg/kg/day) 1 for both the oral and inhalation routes of exposure (IRIS 1995). IARC has determined that hexachloroethane is not classifiable as to human carcinogenicity (Group 3). 

The EPA has determined that endrin is not classified as to its human carcinogenicity (Group D) because the available information is inadequate to allow the classification (IRIS 1995). No cancer classifications exist for the IARC (no adequate data) (IARC 1987). The National Toxicology Program (NIP) has assigned endrin the carcinogen code N (negative) (NTP 1995). 

Group 2B Possible human carcinogen Group B2 Probable human carcinogen... 

Group C Possible human carcinogen Group D Not classifiable as to human carcinogenicity... 

Morita, T., N. Asano, T. Awogi, Y. F. Sasaki, S.-I. Sato, H. Shimada, S. Sutou, T. Suzuki, A. Wakata, T. Sofuni, and M. Hayashi, Evaluation of the Rodent Micronucleus Assay in the Screening of IARC Carcinogens (Groups 1, 2A, and 2B). The Summary Report of the 6th Collaborative Study by CSGMT/JEMS-MMS, Mutat. Res., 389, 3-122 (1997). 

The EPA Office of Pesticide Programs reviewed the data for the tumorigenicity of triphenyltin hydroxide and classified it as a possible human carcinogen (Group B2) based on the tumors found in both rats and mice during chronic studies of carcinogenicity. The most appropriate estimate of the unit risk in human equivalents was a q1 of 2.8 (mg/kg/day) from the data on pituitary gland adenomas in female rats. 

Tetrachloroethylene is used as a solvent. It is highly volatile and, for this reason, has been found only in groundwaters. Its odor threshold in water is 300 pg L and it is classified by the EPA as a probable human carcinogen (Group B2). 

Epichlorohydrin has been shown to cause chromosomal aberrations in humans, and is classified as a probable human carcinogen (group 2A). 

Tumors may be formed as a consequence of repair in the damaged organs. EPA has classified it as a possible human carcinogen, group C. 

Chloracne has been reported in chronic occupational exposure to pentachlorophenol. However, commercial preparations are commonly contaminated with dioxins and furans, and chloracne may be linked to these compounds. In addition, hemolytic and aplastic anemia and weight loss have been reported in humans. Pentachlorophenol is classified as a probable human carcinogen (group 2B). 

Group 1. Proven human carcinogens Group 2A. Probable human carcinogens Group 2B. Possible human carcinogens. 

Cigarette smoke, the single most responsible cancer-causing agent known to man, contains numerous carcinogenic compounds. 17 These are listed in Table 32.3 by chemical type. The IARC carcinogenic groups, 1, 2A, and 2B are also included. 

Even if the bone marrow is a well-perfused tissue, chemically unstable compounds and/or metabolites may not reach it in sufficient quantities to induce detectable effects (Brambilla and Martelli 2004 Morita et al. 1997). In a large collaborative study of I ARC carcinogens (groups 1, 2A, and 2B), the in vivo bone marrow micronucleus test easily detected compounds able to induce tumors in hematopoietic tissues and lung. In contrast, it predicted only 40% of liver carcinogens (Morita et al. 1997). To solve this issue, chromosome damage, especially micronuclei, can be measured in tissues other than bone marrow and peripheral blood erythrocytes (Hayashi et al. 2007). 

Benzene is present at low concentrations in JP-8, generally at 0.1 -0.8 wt %. The International Agency for Research on Cancer (IARC) has classified benzene as a known human carcinogen (Group 1) on the basis of sufficient evidence that benzene causes leukemia in humans and sufficient evidence of carcinogenicity in animals (IARC 1987). 

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