Int. J. Environ. Res. Public Health 2010, 7 3618 these pesticide-POPs are semi-volatile with extraordinarily low vapor pressure, but tend to diffuse from water phase (i.e., so-called fugacity, or escaping tendency) to the air phase due to their low solubilities in water. Although human exposure to OCPs can also occur via inhalation or by dermal absorption, ingestion is the major route of exposure in view of the health risks. Table 1. Chemical and physical information on pesticide-POPs a. Pesticide-POPs CAS No. foMrmoul.la MW M(°Cp)a (VPPab) (Pa-mH3/cmol) (mSgw/dL) Aldrin 309-00-2 C12H8Cl6 364.9 104 0.005 (25 °C) 50.3 (25 °C) 0.02 (20 °C) 6.5 Chlordane (technical) 12789-03-6 C10H6Cl8 409.8 ~105 0.06 (25 °C) 4.9 (25 °C) 0.1 (25 °C) 5.5 Chlordecone 143-50-0 C10Cl10O 490.6 350 ＜0.03 (25 °C) 0.003 (25 °C) 7.6 (25 °C) 4.5 DDT 50-29-3 C14H9Cl5 354.5 108.5 3×10 −5 (25 °C) 1.3 (25 °C) 0.0055 (25 °C) 6.2 Dieldrin 60-57-1 C12H8Cl6O 380.9 ~175 0.0005 (20 °C) 5.9 (25 °C) 0.17 (20 °C) 4.3 Endrine 72-20-8 C12H8Cl6O 380.9 ~228 0.0004 (20 °C) 0.8 (25 °C) ＜10 −6 (25 °C) 4.6 Heptachlor 76-44-8 C10H5Cl7 373.4 ~95 0.05 (25 °C) 150 (25 °C) 0.18 (20 °C) 5.3 Hexachlorobenzene 118-74-1 C6Cl6 284.8 228.8 0.0025 (20 °C) 35.1 (20 °C) 0.005 (25 °C) 5.5 α-Hexachlorocyclohexane 319-84-6 C6H6Cl6 290.8 158 0.006 (25 °C) 1.1 (25 °C) 2.0 (25 °C) 3.8 β-Hexachlorocyclohexane 319-85-7 C6H6Cl6 290.8 309 0.06 (25 °C) 0.07 (25 °C) 0.7 (20 °C) 3.8 Lindane 58-89-9 C6H6Cl6 290.8 113 0.007 (25 °C) 0.3 (25 °C) 2 (25 °C) 3.6 Mirex 2385-85-5 C10Cl12 545.5 485 0.0001 (20 °C) 43.3 (20 °C) 0.2 (24 °C) 5.3 Pentachlorobenzene 608-93-5 C6HCl5 250.3 86 1.0 (25 °C) 70 (25 °C ) 0.56 (25 °C) 5.2 Toxaphene 8001-35-2 ~C10H10Cl8 413.8 65–90 0.0009 (25 °C) 0.6 (20 °C) 0.55 (20 °C) 4.8 a Melting point. b Vapor pressure. c Henry’s law constant. d Solubility in water. e Octanol/water partition coefficient (as logarithmic scale). Kow e 2.2. Carcinogenity of Pesticide-POPs The pesticide-POPs under discussion consist of aromatic and/or alicyclic rings, and also contain carbon-halogen bonds to a different degree, suggesting that these chemicals are stable in the environment and should not be acutely toxic to living organisms. However, even when they are present in very low concentration, these POPs may pose high toxicity for their long-term and chronic effects because they are characterized as highly lipid soluble and thus bioaccumulate to a significant degree. It should be noted that these compounds are xenobiotic chemicals that may induce the hormone-like effects on the endocrine systems of wildlife and humans. The endocrine and reproductive effects of these pesticides are believed to mimic or disrupt the effect of endogenous estrogens. In the Strategic Programs on Environmental Endocrine Disruptors ’98 (SPEED ’98) by the Ministry of the Environmental Government of Japan, the pesticide-POPs except for pentachlorobenzene have been incorporated into the endocrine disrupting chemicals (EDCs) class, as shown in Table 2.