α-BHC

Cl Note: α-BHC is a steroisomer of γ-HCH, the active ingredient of lindane. CASRN: 319-84-6; DOT: 2761; DOT label: Poison; molecular formula: C6H6Cl6; FW: 290.83; RTECS: GV3500000 Physical state, color, and odor: Brownish to white monoclinic prisms, crystalline solid or powder with a phosgene-like odor (technical grade). An odor threshold concentration of 88 µg/kg was reported by Sigworth (1964). Melting point (°C): 157.3 (Plato and Glasgow, 1969) Boiling point (°C): 288 (Weast, 1986) Density (g/cm3): 1.870 at 20 °C (quoted, Horvath, 1982) Diffusivity in water (x 10-5 cm2/sec): 0.50 at 20 °C using method of Hayduk and Laudie (1974) Entropy of fusion (cal/mol⋅K): 17.2 (Plato and Glasgow, 1969) Heat of fusion (kcal/mol): 7.400 (DSC, Plato and Glasgow, 1969) Henry’s law constant (x 10-6 atm⋅m3/mol): 1.68 at 10 °C, 4.24 at 20 °C, 9.08 at 30 °C, 15.0 at 35 °C, 21.8 at 40 °C (gas stripping, Jantunen

and Bidleman, 2000) 0.12 at 25 °C (thermodynamic method-GC/UV spectrophotometry, Altschuh et al., 1999) 0.938 at 5 °C, 1.48 at 10 °C, 3.85 at 20 °C, 8.39 at 30 °C, 12.8 at 35 °C (average of bubble

stripping and dynamic headspace techniques-GC, Sahsuvar et al., 2003) 0.888 at 5 °C, 1.58 at 15 °C, 2.27 at 20 °C, 2.96 at 25 °C, 6.02 at 35 °C; in 3% NaCl solution: 1.48

at 5 °C, 2.76 at 15 °C, 5.23 at 25 °C, 7.20 at 35 °C (gas stripping-GC, Cetin et al., 2006) Bioconcentration factor, log BCF: 3.20-3.38 (fish tank), 2.85 (Lake Ontario) (rainbow trout, Oliver and Niimi, 1985) 2.49 (Chlamydomonas, Canton et al., 1977)

3.04 (Brachydanio rerio, Devillers et al., 1996) 3.90-4.04 (Artemia salina), 4.23 (Lebistes reticulatus) (lipid basis, Canton et al., 1978) Soil organic carbon/water partition coefficient, log Koc: 3.279 (Karickhoff, 1981) 3.01, 3.10, 3.30, 3.31, 3.34 (lateritic soil), 3.12, 3.33 (Kari soil), 3.14 (sandy soil), 3.19, 3.46

(alluvial soil), 3.32 (Pokkali soil) (Wahid and Sethunathan, 1979) Octanol/water partition coefficient, log Kow: 3.81 at 22 °C (shake flask-GLC, Kurihara et al., 1973) 3.72 (Schwarzenbach et al., 1983) 3.776 at 25 °C (shake flask-GLC, de Bruijn et al., 1989) 3.75 at 45 °C (shake flask-GLC, Paschke and Schüürmann, 1998) 3.77 at 25 °C (shake flask-GLC, Paschke and Schüürmann, 2000) Solubility in organics: Soluble in ethanol, benzene, chloroform (Weast, 1986), cod liver oil, and octanol (Montgomery, 1993) Solubility in water (mg/L): 1.4 (salt water, Canton et al., 1978) At 28 °C: 1.48, 1.77 (0.05 µ particle size), 1.21, 2.03 (0.1 µ particle size) (Kurihara et al., 1973) 2.00 at 25 °C (extraction-GLC, Weil et al., 1974) 1.63 at 20 °C (Brooks, 1974) Vapor pressure (x 10-5 mmHg): 2.5 at 20 °C (Balson, 1947) 2.15 at 20 °C (Sims et al., 1988) 173 at 25 °C (subcooled liquid vapor pressure calculated from GC retention time data, Hinckley et

al., 1990) Environmental fate: Biological. Clostridium sphenoides biodegraded α-BHC to δ-3,4,5,6-tetrachloro-1-cyclohexane (Heritage and MacRae, 1977). In four successive 7-d incubation periods, α-BHC (5 and 10 mg/L) was recalcitrant to degradation in a settled domestic wastewater inoculum (Tabak et al., 1981). Soil. Under aerobic conditions, indigenous microbes in contaminated soil produced pentachlorocyclohexane. However, under methanogenic conditions, α-BHC was converted to chlorobenzene, 3,5-dichlorophenol, and the tentatively identified compound 2,4,5-trichlorophenol (Bachmann et al., 1988). Manonmani et al. (2000) isolated a microbial consortium from sewage and soil that could completely mineralize α-BHC in 14 d at 30 °C. The acclimated consortium could degrade up to 100 mg/L of α-BHC within 72 h at a degradation rate of 58 mg/L·day. Surface Water. Hargrave et al. (2000) calculated BAFs as the ratio of the compound tissue concentration [wet and lipid weight basis (ng/g)] to the concentration of the compound dissolved in seawater (ng/mL). Average log BAF values for α-BHC in ice algae and phytoplankton collected from the Barrow Strait in the Canadian Archipelago were 6.18 and 6.08, respectively. Photolytic. When an aqueous solution containing α-BHC was photooxidized by UV light at 9095 °C, 25, 50, and 75% degraded to carbon dioxide after 4.2, 24.2, and 40.0 h, respectively (Knoevenagel and Himmelreich, 1976). In basic, aqueous solutions, α-BHC dehydrochlorinates forming pentachlorocyclohexene before being transformed to trichlorobenzenes. In a buffered aqueous solution at pH 8 and 5 °C, the calculated hydrolysis half-life is 26 yr (Ngabe et al., 1993).

1990). α-BHC will hydrolyze via trans-dehydrochlorination of the axial chlorines resulting in the formation of HCl and the intermediate 1,3,4,5,6-pentachlorocyclohexene. The intermediate will undergo hydrolysis resulting in the formation of 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, and HCl (Kollig, 1993). Brubaker and Hites (1998a) investigated the gas-phase reaction of α-BHC with OH radicals in a helium gas filled quartz chamber at temperatures of 73, 92, and 113 °C. The measured OH reaction rate constants were extrapolated by the Arrhenius equation. The estimated rate constants at 4 and 25 °C were 1.0 and 1.4 x 10-13 cm3/sec. At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities were 303, 112, 41, and 15 mg/g, respectively (Dobbs and Cohen, 1980). Toxicity: EC50 (96-h) for guppies (Lebistes reticulatus) 1.31 mg/L (Canton et al., 1978). EC50 (48-h) for Daphnia pulex 680 µg/L (isomeric mixture, Johnon and Finley, 1980) LC10 (35-d) for Lebistes reticulatus 0.5 mg/L (Canton et al., 1978). LC50 (96-h) for Poecilia reticulata 1.49, Brachydanio rerio 1.11, Paracheirodon axelrodi 1.52 (Oliverira-Filho and Paumgarten, 1997), Lebistes reticulatus >1.4 mg/L, Artemia salina 0.5 mg/L (Canton et al., 1978); for isomeric mixture: cutthroat trout 9 µg/L, rainbow trout 18 µg/L, goldfish 348 µg/L, fathead minnow 125 µg/L, channel catfish 105 µg/L, bluegill sunfish 67 µg/L, largemouth bass 41 µg/L (Johnson and Finley). LC50 (72-h) values were 1.58, 1.11, and 1.52 mg/L for Poecilia reticulata, Brachydanio rerio, and Paracheirodon axelrodi, respectively (Oliverira-Filho and Paumgarten, 1997). LC50 (48-h) values of 1.95, 1.11, and 1.52 mg/L for Poecilia reticulata, Brachydanio rerio, and Paracheirodon axelrodi, respectively (Oliverira-Filho and Paumgarten, 1997). LC50 (24-h) values of 2.62, 1.41, and 1.64 mg/L for Poecilia reticulata, Brachydanio rerio, and Paracheirodon axelrodi, respectively (Oliverira-Filho and Paumgarten, 1997). Acute oral LD50 for rats 177 mg/kg (quoted, RTECS, 1985). Use: Not produced commercially in the U.S. and its sale is prohibited by the U.S. EPA.