TOXAPHENE

Note: No definitive structure can be illustrated. Toxaphene is a complex mixture of at least 175 chlorinated camphenes; of this number, less than 10 structures are known (Casida et al., 1974). The following congeners were isolated from environmental samples: 2-exo,3-endo,5exo,9,9,10,10-heptachlorobornane, 3-exo,5-endo,6-exo,8,8,10,10-heptachlorobornane 2-endo, 3exo,5-endo,6-exo,8,8,10,10-octachlorobornane, and 2-exo,3-endo,5-exo,6-endo,9,9,10,10-octachlorobornane (Vetter et al., 2000). According to Pollock and Kilgore (1978), the average chlorine content is 67 to 69%. CASRN: 8001-35-2; DOT: 2761; DOT label: Poison; molecular formula: C10H10Cl8; FW: 413.82; RTECS: XW5250000; Merck Index: 12, 9693 Physical state, color, and odor: Yellow, waxy, nonflammable solid with a chlorine or terpene-like odor. Odor threshold concentration from water is 140 µg/L (quoted, Keith and Walters, 1992). Melting point (°C): 65-90 (IARC, 1979) 85 (Sims et al., 1988) Boiling point (°C): Decomposes at 120 (U.S. EPA, 1980a) Density (g/cm3): 1.6 at 20 °C (Melnikov, 1971) Flash point (°C): 28.9 in 10% xylene (quoted, Keith and Walters, 1992) Henry’s law constant (x 10-6 atm⋅m3/mol): 4.89 at 25 °C (gas stripping-HC, Warner et al., 1987) 0.99 at 10 °C, 3.56 at 20 °C, 6.81 at 30 °C, 8.49 at 35 °C, 14.8 at 40 °C (gas stripping, Jantunen

and Bidleman, 2000) Bioconcentration factor, log BCF: 3.53 (B. subtilis, Paris et al., 1977)

6.30 (Arctic cod, Kucklick et al., 1994) Soil organic carbon/water partition coefficient, log Koc: 3.18 using method of Kenaga and Goring (1980) Octanol/water partition coefficient, log Kow: 3.30 (Paris et al., 1977) 5.50 (Travis and Arms, 1988) 3.23 (Rao and Davidson, 1980) Solubility in organics: 120 g/L in alcohol at 25-30 °C (quoted, Meites, 1963) Solubility in water: ≈ 3 ppm at 25 °C (Brooks, 1974) 740 µg/L at 25 °C (extraction-GLC, Weil et al., 1974) 1.75 mg/L at 25 °C (quoted, Warner et al., 1987) 400 ppb at 20-25 °C (Weber, 1972) 550 µg/L at 20 °C (Murphy et al., 1987) Vapor pressure (x 10-6 mmHg): 33 at 20-25 °C (quoted, WHO, 1984a) 1 (Sims et al., 1988) 15.8 at 25 °C (2,2,5-endo-6-exo-8,9,10-heptachlorobornane, toxaphene component, Hinckley et

al., 1990) Environmental fate: Soil. Under reduced soil conditions, about 50% of the C-Cl bonds were cleaved (dechlorinated) by Fe2+ porphyrins forming two major toxicants having the molecular formulas C10H10Cl8 (Toxicant A) and C10H11Cl7 (Toxicant B). Toxicant A reacted with reduced hematin yielding two reductive dechlorination products (C10H11Cl7), two dehydrodechlorination products (C10H9Cl7), and two other products (C10H10Cl6). Similarly, products formed from the reaction of Toxicant B with reduced hematin included two reductive dechlorination products (C10H12Cl6), one dehydrochlorination product (C10H10Cl6), and two products having the molecular formula C10H11Cl5 (Khalifa et al., 1976). The reported dissipation rate of toxaphene from soil is 0.010/d (Seiber et al., 1979). 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 toxaphene in ice algae and phytoplankton collected from the Barrow Strait in the Canadian Archipelago were <5.38 and <5.46, respectively. Photolytic. Dehydrochlorination will occur after prolonged exposure to sunlight, releasing HCl (HSDB, 1989). Two compounds isolated from toxaphene, 2-exo,3-exo,5,5,6endo,8,9,10,10-nonachloroborane and 2-exo,3-exo,5,5,6-endo,8,10,10-octachloroborane, were irradiated with UV light (λ >290 nm) in a neutral aqueous solution and on a silica gel surface. Both compounds underwent reductive dechlorination, dehydrochlorination, and/or oxidation to yield numerous products including bicyclo[2.1.1]hexane derivatives (Parlar, 1988). Chemical/Physical. Saleh and Casida (1978) demonstrated that toxicant B (2,2,5-endo,6exo,8,9,10-heptachlorobornane), the most active component of toxaphene, underwent reductive dechlorination at the geminal dichloro position, yielding 2-endo,5-endo,6-exo,8,9,10-hexachlorobornane, and 2-exo,5-endo,6-exo,8,9,10-hexachlorobornane in various chemical, photo-

Toxaphene will slowly undergo hydrolysis resulting in the loss of chlorine atoms and the formation of HCl (Kollig, 1993). The hydrolysis rate constant for toxaphene at pH 7 and 25 °C was determined to be 8 x 10-6/h, resulting in a half-life of 9.9 yr. At 85 °C, experimentally determined hydrolysis half-lives were 9.8, 5.2, and 1.6 d at pH values of 3.24, 7.20, and 9.63, respectively (Ellington et al., 1987). Emits toxic fumes of chlorides when heated to decomposition (Lewis, 1990). Exposure limits (mg/m3): Potential occupational carcinogen. NIOSH REL: IDLH 200; OSHA PEL: TWA 0.5; ACGIH TLV: TWA 0.5, STEL 1 (adopted). Symptoms of exposure: Nausea, confusion, agitation, tremors, convulsions, unconsciousness, dry red skin (NIOSH, 1987) Toxicity: EC50 (48-h) for Daphnia magna 10 µg/L, Daphnia pulex 14.2 µg/L, Simocephalus serrulatus 19 µg/L (Mayer and Ellersieck, 1986), Chironomus plumosus 30 µg/L (Johnson and Finley, 1980). EC50 (24-h) for Daphnia pulex 23 µg/L, Simocephalus serrulatus 76 µg/L (Mayer and Ellersieck, 1986). LC50 (34-d) for bluegill sunfish 0.7 µg/L (Spehar et al., 1982). LC50 (7-d) for bluegill sunfish 1.4 µg/L (Spehar et al., 1982). LC50 (96-h) for fish (Cyprinodon variegatus) 1.1 µg/L, fish (Leiostomus xanthurus) 0.5 µg/L, decapod (Palaemonete pugio) 4.4 µg/L, decapod (Penaeus duorarum) 1.4 µg/L (quoted, Reish and Kauwling, 1978), bluegill sunfish 2.4 to 4.7 µg/L (Spehar et al., 1982); freshwater mussels (Anodonta imbecilis) 740 µg/L (Keller, 1993), Atherix variegata 40 µg/L, Claassenia sabulosa 1.3 µg/L, Gammarus fasciatus 26 µg/L, Pteronarcys californica 2.3 µg/L, Tipula sp. 18.0 µg/L, black bullhead 5.8 µg/L, brown trout 3.1 µg/L, carp 3.7 µg/L, channel catfish 13.1 µg/L, coho salmon 8 µg/L, fathead minnows 18 µg/L, goldfish 14 µg/L, green sunfish 13 µg/L, largemouth bass 2.0 µg/L, rainbow trout 10.6 µg/L, yellow perch 12 µg/L (Johnson and Finley, 1980). Acute oral LD50 for ducks 31 mg/kg, dogs 15 mg/kg, guinea pigs 250 mg/kg, mice 112 mg/kg, rats 55 mg/kg (quoted, RTECS, 1985). Drinking water standard (final): MCLG: zero; MCL: 3 µg/L. In addition, a DWEL of 10 µg/L was recommended (U.S. EPA, 2000). Uses: Nonsystemic pesticide used primarily on cotton, lettuce, tomatoes, corn, peanuts, wheat, and soybean. Its use was banned by the U.S. EPA in 1982.