Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants Volume 2 (2008) / Chapter Skim
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Pages 184-213
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, or testosterone concentration; workplace toluene exposure concentrations monitored in 1993-1995 were 50-100 ppm (TWA) for a portion (24%)
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zooepidemicus infection, as was serial exposure to toluene at over 100 ppm 3 h/day for 4 weeks. "Pulmonary bactericidal activity" was decreased after toluene exposure at 2.5 ppm and 100-500 ppm but not 5-50 ppm.
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; when subjects were exercising, a steady state was achieved more rapidly. After a 90-min exposure of seven human subjects to toluene at 50 ppm, Benoit et al.
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Because of population variability in the time course and yields of metabolic reactions, monitoring of the urinary metabolites hippuric acid and cresols are best considered qualitative, rather than quantitative, markers of toluene exposure (Andersen et al. 1983; Baelum et al.
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. Toluene exposure may lead to a loss of outer hair cells in the ear; there may also be neural-cell membrane effects.
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Navy values are provided for comparison. The literature contains an abundance of human-exposure data derived from multiple clinical, monitoring, and metabolic studies carried out at toluene concentrations less than 1,000 ppm for various exposure durations and thus suitable for direct estimation of exposure guidelines.
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The gradual changes observed were from no effect on reaction time or perceptual speed after a 20-min exposure at 100 ppm to an increase in simple reaction time after 20 min at 100 ppm and 20 min at 300 ppm (an average of 200 ppm for 40 min) to an eventual decrease in perceptual speed after successive 20-min exposures at 100, 300, 500, and 700 ppm (with one 5-min break presumably at 0 ppm)
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. Although the investigators acknowledge the inability to determine toluene exposures over several decades, maximally exposed people are known to be printers and their helpers.
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of 50-100 ppm in the workplaces of the majority of printers. Nevertheless, neither those air concentrations nor blood toluene concentrations of 850-1,700 µg/L in the highest toluene-exposure group was "convincingly associated" with subjective complaints or alteration from the referent group on standard tests of psychophysiologic and psychomotor functions; all scores of the toluene-exposure group were within the referent ranges (Neubert et al.
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1972. Toluene exposure.
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1986. Toluene concentrations in the blood and alveolar air of workers during the workshift and the morning after.
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1999. Risk of chronic effects on the central nervous system at low toluene exposure.
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1994. Progressive hair cell loss induced by toluene exposure.
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1981. The effects of acute and repeated toluene exposure on operant behavior in mice.
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2003. Occupational toluene exposure and auditory function: Results from a follow-up study.
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1989. Single toluene exposure and changes of response latency in shock avoidance performance.
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1982. Acute behavioral effects of exposure to some organic solvents - psychophysiological aspects.
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The committee considered all that information in its evaluation of the Navy's current and proposed 1-h, 24-h, and 90-day exposure guidance levels for xylene. The committee's recommendations for xylene exposure guidance levels are provided at the conclusion of this chapter with a discussion of the adequacy of the data for defining them and research needed to fill the remaining data gaps.
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It is excreted almost exclusively in the urine of humans as methylhippuric acid isomers but in the urine of animals as methylhippuric acid isomers and toluic acid glucuronides. Elimination is biphasic; the elimination half-life for the first phase is about 1 h, and that for the second is about 20 h.
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At 110 ppm, one of six subjects experienced throat discomfort; at 230 ppm, one of seven subjects reported eye irritation, tears, and dizziness or light-headedness. None of those exposed at 110 or 230 ppm complained of throat irritation.
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The 3-h xylene exposure significantly increased simple reaction time and choice reaction time; no significant effects were observed in the other seven tests. Male student volunteers were divided into three groups and exposed to m-xylene at a fixed concentration of 200 ppm, m-xylene at a basal concentration of 135 ppm with 20-min peak concentrations of 400 ppm at the beginning of morning and afternoon sessions, or control air (Seppalainen et al.
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. Xylene exposures did not significantly affect blood pressure, pulse rate, flicker value, or reaction time as measured at the beginning and end of exposure.
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Dudek et al. Decreased performance in simple and choice reaction times; no significant effects on 1990 other 7 psychologic tests 135-400 3 h in morning, m- Healthy males (9)
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No effect on choice reaction time, simple reaction time, short-term memory, heart rate, 1985 or subjective symptoms Prepublication Copy 100, 200 3 or 7 h with 1- m-, p- Health males (23) , 4 or 5 per group Ogata et al.
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. Repeated Exposure and Subchronic Toxicity Rats, guinea pigs, monkeys, and dogs that were exposed to o-xylene at 78 ppm for 90 days or at 780 ppm for 6 weeks had no significant changes in body weight or hematology (Jenkins et al.
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. Immunotoxicity Workers exposed to xylene have manifested decreased lymphocytes and serum complement (Moszczynsky and Lisiewicz 1983, 1984)
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. The primary metabolic pathway in humans is side-chain dehydroxylation by hepatic mixed-function oxidases to toluic acids, which are then conjugated with glycine to form methlyhippuric acid isomers that are excreted in the urine (Ogata et al.
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Navy Values, ppm Exposure Level Committee Recommended Values, ppm Current Proposed EEGL 1-h 200 100 200 24-h 100 100 100 CEGL 90-day 50 50 50 Abbreviations: CEGL, continuous exposure guidance levels; EEGL, emergency exposure guidance level. 1-Hour EEGL Xylene vapor at low concentrations is an irritant of eyes and mucous membranes, and at higher concentrations it results in signs of CNS depression.
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. Nevertheless, xylene exposure at 100 ppm for 3 h resulted in reduced performance in two (simple reaction and choice reaction times)
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A study designed to determine the presence and degree of eye and throat irritation for exposure of 1 and 24 h would improve the level of confidence in the EEGL and CEGL values. Epidemiologic investigations of workers exposed to xylene or longer-term controlled exposure studies of xylene at 25-75 ppm would benefit derivation of the 90-day CEGL.
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