2-Butoxyethanol is widely used as a solvent in surface coatings, such as spray lacquers, quick-dry lacquers, enamels, varnishes, varnish removers, and latex paint (Leaf, 1985; Sax & Lewis, 1987). In surface coatings, it imparts blush resistance, gloss, and good flow-out. 2-Butoxyethanol is also used as a coupling agent in metal and household cleaners; as an intermediate in 2-butoxyethanol acetate production; and in herbicides, automotive brake fluids, printing inks, spot removers, and cosmetics (Leaf, 1985; ATSDR, 1996). In 1994, 176 900 tonnes of 2-butoxyethanol were produced in the USA (US ITC, 1996). Within the European Community, the total production capacity of 2-butoxyethanol was approximately 70 00090 000 tonnes in the same year (ECETOC, 1994; CEFIC, 1995). 2-Butoxyethanol may be released into air or water by facilities that manufacture, process, or use the chemical (ATSDR, 1996; US NLM, 1997). Products containing 2-butoxyethanol may also release the substance into the air. Solvent-based building materials such as silicone caulk will release 2-butoxyethanol to air as they dry. There is potential for the release of 2-butoxyethanol from hazardous waste sites, although quantitative data have not been identified. Based upon the detection of 2- butoxyethanol in samples of groundwater and surface water taken near municipal landfills and hazardous waste sites, 2-butoxyethanol may be released to water in leachates from these sites (ATSDR, 1996). Information on the total estimated release of 2-butoxyethanol into the environment in the USA was not identified. In Canada, emissions to the environment between 1992 and 1994 have been reported to range from 1.4 to 3.1 tonnes per year (Canadian Chemical Producers Association, 1996).
In the atmosphere, 2-butoxyethanol is expected to exist in the vapour phase. Owing to its water solubility, wet deposition is likely to be more important than dry deposition (ATSDR, 1996). The chemical will not persist in the atmosphere; it has an atmospheric half-life of approximately 17 h, based on an estimated rate constant for reaction with hydroxyl radicals (US NLM, 1997).
The miscibility of 2-butoxyethanol in water suggests that volatilization from water, adsorption, and bioconcentration are not important fate processes and that the chemical should not bioconcentrate in aquatic organisms. Based upon aerobic biodegradation rates, the half-life of 2-butoxyethanol in water is estimated to range from 1 to 4 weeks (Howard et al., 1991). 2-Butoxyethanol is not likely to undergo direct hydrolysis in the aquatic environment, and it is likely readily biodegraded (ATSDR, 1996). Five-day theoretical biological oxygen demand values range from 5% (without acclimation) to 73% (with acclimation); 10-day theoretical biological oxygen demand values range from 57% to 74%. The maximum theoretical biological oxygen demand value reported is 88% for 20 days (US NLM, 1997). Biodegradation is likely to be the most important mechanism for the removal of 2-butoxyethanol from aerobic soil and water.
Laboratory analysis for 2-butoxyethanol in environmental samples is usually by gas chromatography (GC) in combination with flame ionization detection (FID), electron capture detection (ECD), or mass spectrometric (MS) detection; infrared absorption spectrophotometry is also sometimes used. The detection limits of these analytical methods in air range from 0.031 ppm (0.15 mg/m3) for a 48-litre sample (OSHA, 1990) to 0.010.02 mg for 2- to 10-litre samples (NIOSH, 1994). Multidimensional GC-MS has been used to improve the detection limit to 57 mg per sample (Kennedy et al., 1990). Biological monitoring is a useful adjunct to environmental measurements in assessing human exposure to 2-butoxyethanol, as it accounts for both dermal and respiratory uptake.
A variety of GC methods combined with FID, ECD, or MS detection and high-performance liquid chromatography (HPLC) methods coupled with ultraviolet or radiochemical detection have been developed for the analysis of 2-butoxyethanol and its metabolite 2-butoxyacetic acid in the urine and blood of exposed workers or rats.
In general, these methods are based on either extraction or lyophilization of the blood or urine followed by derivatization and then analysis (Smallwood et al., 1984, 1988; Groeseneken et al., 1986, 1989; Johanson et al., 1986, 1988; Rettenmeier et al., 1993; Sakai et al., 1993, 1994; Corley et al., 1994). The detection limits range from 0.03 to 0.1 mg 2-butoxyacetic acid/litre. 2-Butoxyethanol and 2-butoxyacetic acid in rat and human blood can be analysed by a GC-MS derivatization method with a detection limit range of 1618 ng/g blood (Bormett et al., 1995). The National Institute for Occupational Safety and Health reviewed the available data and developed guidelines for biological monitoring of 2-butoxyacetic acid (NIOSH, 1990).
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