Int. J. Environ. Res. Public Health 2010, 7 3619 Table 2. Common uses of pesticide-POPs and their properties on endocrine disrupting and carcinogenity. IARC b USNTP c EDCs a Pesticide-POPs Common uses carcinogenity carcinogenity -- d Aldrin Insecticide Listed Group 3 Chlordane Insecticide Listed Group 2B -- Chlordecone Insecticide Listed Group 2B Reasonable suspected DDT Insecticide Listed Group 2B Reasonable suspected Dieldrin Insecticide Listed Group 3 -- Endrin Insecticide Listed Group 3 -- Heptachlor Insecticide Listed Group 2B -- Hexachlorobenzene Bactericide Listed Group 2B Reasonable suspected α-Hexachlorocyclohexane Insecticide Listed Group 2B Reasonable suspected β-Hexachlorocyclohexane Insecticide Listed Group 2B Reasonable suspected Lindane Insecticide Listed Group 2B Reasonable suspected Mirex Insecticide Listed Group 2B Reasonable suspected Pentachlorobenzene Fungicide intermediate, -- -- -- fire retardant Toxaphene Insecticide Listed Group 2B Reasonable suspected a Listed in the endocrine disrupting chemicals (EDCs) by the Ministry of the Environment (Japan). b Overall evaluations of carcinogenicity to humans by the International Agency for Research on Cancer (IARC); Group 1: Carcinogenic to humans; Group 2A: Probably carcinogenic to humans; Group 2B: Possibly carcinogenic to humans; Group 3: Not classifiable as to carcinogenicity to humans. c United States National Toxicology Program (USNTP) by the Department of Health and Human Services; Reasonable suspected: Reasonably anticipated to be a human carcinogen. d Not listed. Regarding the chronic toxicity, carcinogenicity is the most important concern as compared to mutagenicity, tetragenicity, neurotoxicity and reproductive toxicity. As summarized in Table 2, the United States National Toxicology Program (USNTP) has listed chlordecone, DDT, hexachlorobenzene, hexachlorocyclohexane, lindane, mirex, and toxaphene as “reasonably anticipated to be a human carcinogen” based on sufficient evidence of carcinogenicity in experimental animals. To be in consistent with USNTP, the International Agency for Research on Cancer (IARC) has classified these pesticide-POPs and other POPs (i.e., chlordane and heptachlor) as “possibly carcinogenic to humans” (group 2B). By contrast, aldrin, dieldrin and endrin are considered as Group 3 (“not classifiable as to carcinogenicity to humans”). On the other hand, the carcinogenic toxicities of these pesticide-POPs are relatively less than those of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs), because these polychlorinated POPs are generally expressed as their toxic equivalent factors (TEF) relative to the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) [12]. It is well known that 2,3,7,8-TCDD is regarded as the most toxic substance among PCDDs, PCDFs and PCBs because it has been classified as Group 1 (IARC) and known to be a human carcinogen (USNTP).