HEXACHLOROBENZENE This substance was considered by previous working groups, in 1978 (IARC, 1979) and 1986 (IARC, 1987). Since that time, new data have become available, and these have been incorporated into the monograph and taken into consideration in the present evaluation. 1. Exposure Data 1.1 Chemical and physical data 1.1.1 Nomenclature Chem. Abstr. Serv. Reg. No.: 118-74-1 Chem. Abstr. Name: Hexachlorobenzene IUPAC Systematic Name: Hexachlorobenzene Synonyms: HCB; pentachlorophenyl chloride; perchlorobenzene 1.1.2 Structural and molecular formulae and relative molecular mass Cl Cl Cl Cl Cl Cl C6Cl6 Relative molecular mass: 284.78 1.1.3 Chemical and physical properties of the pure substance (a) Description: White needles (Lide & Milne, 1996; WHO, 1997; Budavari, 2000) (b) Boiling-point: 325 °C (Lide & Milne, 1996) (c) Melting-point: 231.8 °C (Lide & Milne, 1996) –493– 494 IARC MONOGRAPHS VOLUME 79 (d) Spectroscopy data: Infrared [prism (4545), grating (410)], ultraviolet and mass spectral data have been reported (Sadtler Research Laboratories, 1980; Lide & Milne, 1996). (e) Solubility: Practically insoluble in water (5 × 10–6 g/L at 25 °C); very soluble in benzene; soluble in chloroform and diethyl ether; slightly soluble in ethanol (Lide & Milne, 1996; WHO, 1997) ( f ) Volatility: Vapour pressure, 1.09 × 10–5 mm Hg [1.45 mPa] at 20 °C (Budavari, 2000) (g) Stability: Flash-point, 242 °C (Budavari, 2000) (h) Octanol/water partition coefficient (P): log P, 5.5 (WHO, 1997) 1.1.4 Technical products and impurities Technical-grade hexachlorobenzene was commercially available in the past as a wettable powder, liquid and dust. It was reported to contain about 98% hexachloro- benzene, 1.8% pentachlorobenzene and 0.2% 1,2,4,5-tetrachlorobenzene in the USA (IARC, 1979). Several other impurities have been detected, including hepta- and octa- chlorodibenzofurans, octachlorodibenzo-para-dioxin and decachlorobiphenyl (WHO, 1997). Trade names for hexachlorobenzene include Amatin, Anticarie, Bunt-Cure, Bunt- No-More, Co-op Hexa Granox NM, HexaCB, Julin’s Carbon Chloride, No Bunt, Sanocide, Smut-Go and Snieciotox. 1.1.5 Analysis Methods for the analysis of hexachlorobenzene in various matrices are summarized in Table 1. 1.2 Production Industrial synthesis of hexachlorobenzene involves the chlorination of benzene at 150–200 °C with a ferric chloride catalyst or distillation of residues from the pro- duction of tetrachloroethylene (WHO, 1997). Few recent data on the quantities of hexachlorobenzene produced are available. Worldwide production of pure hexachlorobenzene was estimated to be 10 000 t/year for the years 1978–81. Hexachlorobenzene was produced or imported in the European Community at 8000 t/year in 1978, and a company in Spain reportedly produced an estimated 150 t/year. Approximately 1500 t/year of hexachlorobenzene were manu- factured in Germany for the production of rubber chemicals, but this production was discontinued in 1993. Intentional production of hexachlorobenzene has declined as a result of restrictions on its use since the 1970s, but it may still be produced as an incidental by-product in some processes (see section 1.4) (WHO, 1997). HEXACHLOROBENZENE 495 Table 1. Methods for analysis of hexachlorobenzene Sample matrix Sample preparation Assay Limit of Reference procedure detection Air Trap on glass-fibre filter and HRGC/ 0.18 pg/m3 Hippelein et al. XAD-2; extract with toluene LRMS (1993) Adsorb on polyurethane foam; GC/ECD < 0.1 μg/m3 Lewis & extract with diethyl ether in MacLeod (1982) hexane Adsorb on polyurethane foam; GC/ECD Low pg/m3 Oehme & Stray extract with hexane; fractionate range (1982) by HPLC Adsorb on polyurethane foam or GC/ECD NR Billings & Tenax-GC resin; reflux with Bidleman (1980) dichloromethane; reflux with hexane; clean-up by alumina chromatography Adsorb on Amberlite XAD-2; GC/PID 0.815 mg/m3 Langhorst & desorb with carbon tetrachloride Nestrick (1979) Collect vapours on polyurethane GC/ECD NR Environmental foam; extract with 5–10% Protection diethyl ether in hexane Agency (1999a,b) [Methods TO- 04A, TO-10A] Collect on polyurethane foam; GC/ECD or 5 ng/m3 Hsu et al. (1988) Soxhlet extraction; concentrate GC/ECD and GC/MS Water Extract with hexane; inject GC/ECD 0.002 μg/L Environmental extract Protection Agency (1995a) [Method 505] Extract with dichloromethane; GC/ECD 0.001 μg/L Environmental isolate extract; dry; concentrate Protection with methyl tert-butyl ether Agency (1995b) (capillary column) [Method 508.1] Extract by passing sample GC/MS 0.049–0.13 Environmental through liquid–solid extractor; μg/La Protection elute with dichloromethane; Agency (1995c) concentrate by evaporation [Method 525.2] (capillary column) 496 IARC MONOGRAPHS VOLUME 79 Table 1 (contd) Sample matrix Sample preparation Assay Limit of Reference procedure detection Water (contd) Extract with methyl tert-butyl GC/ECD 0.001 μg/L Environmental ether or pentane Protection Agency (1995d) [Method 551.1] Strip from water with stream of GC/MS or 0.001 μg/L APHA/AWWA/ air; adsorb on activated carbon GC/FID WEF (1999a) filter; extract with carbon [Method 6040B] disulfide or dichloromethane Adjust pH; concentrate on GC/MS 0.1 μg/L Garrison & XAD-4; clean-up on silica gel Pellizzari (1987) Ground-water Solvent extraction; solvent GC/ECD 0.12 μg/L Munch et al. exchange (1990) [National Pesticide Survey Method 2] River water Centrifuge; digest with chromic GC/ECD NR Driscoll et al. acid; extract (1991) Soil, chemical Extract with hexane GC/ECD 10 mg/kg DeLeon et al. waste samples (1980) Municipal & Extract with dichloromethane; GC/ECD 0.05 μg/L Environmental industrial dry; exchange to hexane; Protection discharges concentrate Agency (1999c) [Method 612] Extract with dichloromethane; GC/MS 1.9 μg/L Environmental dry; concentrate (packed Protection column) Agency (1999d) [Method 625] Adjust to pH 11; extract with GC/MS 1.9 μg/L APHA/AWWA/ dichloromethane; dry; WEF (1999b) concentrate [Method 6410B] Add isotope-labelled analogue; GC/MS 10 μg/L Environmental extract with dichloromethane; Protection dry over sodium sulfate; Agency (1999e) concentrate [Method 1625] Liquid & solid Extract with dichloromethane GC/ECD NR Environmental waste (liquid); hexane:acetone (1:1) or Protection dichloromethane:acetone (1:1) Agency (1996a) (solid); clean-up [Method 8081A] HEXACHLOROBENZENE 497 Table 1 (contd) Sample matrix Sample preparation Assay Limit of Reference procedure detection Soil, waste & Extract with dichloromethane GC/ECD 5.6 ng/L Environmental water (liquid); dichloromethane:ace- (reagent water) Protection tone (1:1) (solid); clean-up Agency (1994a) [Method 8121] Air sampling Liquid–liquid extraction or GC/MS 10 μg/L Environmental media, soil, Soxhlet extraction or ultrasonic (aqueous); Protection solid waste & extraction or waste dilution or 660 μg/kg Agency (1996b) water direct injection; clean-up with (soil/sediment) [Method 8270C] Florisil or gel-permeation (EQL) (capillary column) Soil, sludge & Thermal extraction; concentrate; TE/GC/MS 0.01–0.5 mg/kg Environmental solid waste thermal desorption Protection Agency (1996c) [Method 8275A] Sediment, soil, Liquid–liquid extraction (water); GC/FT-IR 20 μg/L Environmental solid waste Soxhlet or ultrasonic extraction Protection and waste- (sediment, soil or waste) Agency (1994b) water [Method 8410] Soil Extract with light petroleum; GC/ECD NR Waliszewski & liquid–liquid partition; clean-up Szymczynski with sulfuric acid (1985) Sediment Extract with dichloromethane; GC/MS NR Lopez-Avila subject to acid fractionation; et al. (1983) subject base or neutral fraction to silica gel chromatography Microwave; extract; centrifuge; GC/ECD NR Onuska & Terry filter (1993) Fish tissue Grind with sodium sulfate; GC/ECD [∼ 0.05 μg/kg] Oliver & Nicol extract with hexane:acetone; (1982) clean-up on Na2SO4:alumina: silica gel:Florisil column followed by a H2SO4 column on silica gel Extract with hexane:isopropanol; GC/ECD NR Lunde & Ofstad solvent and sulfuric acid (1976) partitioning Macerate; Soxhlet extract; clean- GC/ECD 5 μg/kg (lipid Rahman et al. up with sulfuric acid:silica gel basis) (1993) 498 IARC MONOGRAPHS VOLUME 79 Table 1 (contd) Sample matrix Sample preparation Assay Limit of Reference procedure detection Fish tissue Sulfuric acid digestion; silica gel GC/ECD 10–15 μg/kg Lamparski et al. (contd) column chromatography; (1980) methylation; alumina column chromatography Homogenize; Soxhlet extract; GC/MS 12.5 μg/kg ATSDR (1998) GPC fractionate; silica gel fractionate Fish, aquatic Homogenize with solvent; GC/ECD 50 μg/kg wet Miskiewicz & biota solvent exchange; clean-up on weight Gibbs (1994) Florisil Aquatic Homogenize; Soxhlet extract; GC/ECD NR Shan et al. organisms GPC fractionate; SPE (1994) [USGS fractionate; solvent exchange method] Oyster tissue Extract with acetone:acetonitrile; GC/ECD NR Murray et al. partition into petroleum ether; (1980) clean-up with silica gel chromatography Adipose tissue Extract with hexane; subject to GC/ECD NR Watts et al. (chicken) Florisil clean-up and one- (1980) fraction elution Adipose tissue Extract; GPC clean-up; GC/MS 12 μg/kg Stanley (1986) fractionate on Florisil Soxhlet extraction; clean-up on GC/ECD 1 μg/kg Alawi & Florisil Ababneh (1991) Extract with solvent; remove HRGC/MS 12 μg/kg Stanley (1986) bulk lipid; fractionate on Florisil Extract with benzene:acetone; GC/ECD 0.12 μg/kg Mes (1992) filter; fractionate on Florisil SFE with alumina (to remove GC/ECD 10 μg/kg ATSDR (1998) lipids); purify by column chromatography Extract fat; dissolve