OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.

CAS: 108-88-3; Chemical Formula: C6H5CH3

The former OSHA standard for toluene was 200 ppm as an 8-hour TWA limit, with a 300-ppm ceiling (not to be exceeded for more than 10 minutes in any eight-hour period), and a 500-ppm peak. The ACGIH has an exposure limit for toluene of 100 ppm as an 8-hour TWA and 150 ppm as a 15-minute STEL; NIOSH recommends a 100-ppm 8-hour TWA and a 10-minute ceiling of 200 ppm. The proposed PELs were 100 ppm as an 8-hour TWA and 150 ppm as a STEL; NIOSH (Ex. 8-47, Table N1) concurs with these limits, which are established in the final rule. Toluene is a flammable, colorless liquid with an aromatic hydrocarbon odor.

The acute toxicity of toluene in animals is greater than that of benzene. Patty (1963b, as cited in ACGIH 1986/Ex. 1-3, p. 578) reports that the lethal doses of toluene and benzene in mice are 10,000 and 14,000 ppm, respectively. The oral LD(50) for toluene in rats is 7.53 ml/kg (Smyth, Carpenter, Weil et al. 1969/Ex. 1-442). Exposure of rats to 2500 or 5000 ppm of toluene caused a temporary decrease in white cell count but no evidence of damage to the blood-forming organs or the liver. Fairhall (1957d, as cited in ACGIH 1986/Ex. 1-3, p. 578) stated that severe toluene exposure can cause a marked drop in the red blood cell count and partial destruction of the blood-forming elements of the bone marrow, but other researchers report that numerous animal studies indicate that toluene is not a bone marrow toxin (Gerarde 1960c, as cited in ACGIH 1986/Ex. 1-3, p. 578).

A study by Greenberg, Mayers, Heinmann, and Moskowitz (1942/Ex. 1-325) reported that painters exposed to toluene levels of 100 to 1100 ppm exhibited enlarged livers, a moderate decrease in red blood cell counts, enlarged red blood cells, and absolute lymphocytosis, but no leukopenia. Wilson (1943/Ex. 1-403) observed 1,000 workers exposed to toluene at levels ranging from 50 ppm to 1500 ppm for periods of one to three weeks. One hundred of these workers developed symptoms severe enough to require hospitalization. At levels less than 200 ppm, 60 of these employees experienced headache, fatigue, and lack of appetite. Those workers exposed to 200 to 500 ppm toluene experienced headache, nausea, bad taste in the mouth, lassitude, temporary amnesia, impaired coordination, and anorexia. Levels of exposure from 500 to 1500 ppm resulted in nausea, headache, dizziness, anorexia, marked loss of coordination, diminished reaction time, pronounced weakness, and heart palpitations. Red cell counts were also decreased, and two cases of aplastic anemia required lengthy hospital treatment; however, the author noted that he could not rule out the possibility that benzene contamination of the toluene was the cause of these effects. Aplastic anemia (including one fatal case) has been noted in six glue sniffers; toluene was the base solvent in the glue (Powars 1965/Ex. 1-433). A man who had inhaled toluene regularly at unspecified levels for 14 years developed permanent encephalopathy (Knox and Nelson 1966/Ex. 1-421).

von Oettingen, Neal, Donahue et al. (1942/Ex. 1-875) exposed human volunteers to toluene levels ranging from 50 ppm to 800 ppm for 8 hours/day. These authors report that exposures to 50 ppm cause drowsiness and headaches and that exposures at 100 ppm result in sleepiness, moderate fatigue, and headaches. At 200 ppm, effects included impairment of coordination and reaction times. Later studies by Ogata, Tomokuni, and Takatsuka (1970/Ex. 1-352) showed an increase in reaction time, a decrease in pulse rate, and a decrease in systolic blood pressure in humans exposed to 200 ppm toluene for seven hours.

The Chevron Corporation (Ex. 3-896) objected to the short-term exposure limit for toluene as being unjustified by either the discussion in the preamble or that in the ACGIH Documentation (1986/Ex. 1-3). Chevron also urged OSHA to clarify the proposal’s discussion of blood dyscrasias occurring as a result of toluene exposure because, according to Chevron:

  • [T]he majority of later studies show no such evidence [of blood dyscrasias]. Due to the tighter specifications for benzene contamination of toluene, we question whether blood dyscrasias will occur (Ex. 3-896, p. 14).

As discussed above in connection with octane and pentane, OSHA finds that a short-term exposure limit is necessary to ensure that workers are not exposed at the elevated levels possible with a TWA limit alone. Levels only slightly above the 8-hour TWA may cause incoordination and amnesia. For example, workers could be exposed to toluene at levels as high as several hundred ppm if the 8-hour TWA limit was promulgated alone. In addition, OSHA notes that the Agency has always had a short-term and ceiling limit for toluene, to protect against this substance’s narcotic and neuropathic effects; OSHA continues to find a short-term limit necessary to ensure that workers do not experience the effects seen at levels only slightly above 100 ppm. On the question of blood dyscrasias, OSHA noted in the preamble to the proposal that the author of the study in question (Wilson 1943/Ex. 1-403) himself noted that benzene contamination may have been the cause of these blood effects; OSHA agrees that this may have been the case.

NIOSH (Ex. 150, Comments on Toluene) reports that “[s]everal recent studies indicate measurable biological changes in liver function” as a consequence of exposures to 100 ppm (Seiji et al. 1987) but not at 46 ppm (Yin et al. 1987). NIOSH also states that volunteers’ performance on psychological test scores was reduced during 100-ppm exposures to toluene and that these volunteers expressed exposure-related complaints. NIOSH also notes that there is some evidence that toluene causes reproductive effects at levels currently being experienced in the workplace (NIOSH, Ex. 150, Comments on Toluene). NIOSH concluded that “there are significant health effects at the …[former] PEL of 200 ppm which will be reduced by the … [final rule] PEL of 100 ppm.” The New Jersey Department of Health, represented by Dr. Rebecca Zagriniski, also notes that there are more recent studies on toluene (Tr. 11-266).

In the final rule, OSHA is establishing an 8-hour TWA PEL of 100 ppm and a STEL of 150 ppm for toluene. The Agency concludes that studies clearly indicate that a significant risk of hepatotoxic, behavioral, and nervous system effects exists at toluene levels substantially at or only slightly above the Agency’s former PEL. OSHA finds that the new limits will protect workers against the significant risk of serious health effects that have been demonstrated to occur even during less than full-shift exposures to toluene.

Page last reviewed: September 28, 2011