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METHYL ALCOHOL

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: 67-56-1; Chemical Formula: CH3OH

OSHA's former 8-hour TWA limit for methyl alcohol was 200 ppm. The proposed limits were an 8-hour TWA of 200 ppm, a STEL of 250 ppm, and a skin notation. The final rule establishes these limits, which are consistent with those of the ACGIH. NIOSH previously recommended exposure limits for this substance of 200 ppm as a TWA and 800 ppm as a STEL; however, after reviewing the health evidence for methyl alcohol, NIOSH concurs with OSHA's final rule PELs for this substance (Ex. 8-47, Table N1). Methyl alcohol is a mobile, highly polar, flammable liquid that is widely used as an industrial solvent.

As stated in the proposal (53 FR 21061), workers exposed to concentrations of methyl alcohol between 200 and 375 ppm experience severe recurrent headaches, and at levels between 1200 and 8300 ppm, studies by Kingsley and Hirsch (1954/ Ex. 1-212) report that the visual capacities of exposed individuals are diminished. OSHA finds that a 250-ppm STEL is necessary because an 8-hour PEL of 200 ppm alone does not protect workers from exposure to short-term peaks at levels that cause eye irritation and severe, recurrent headaches in exposed workers. Although the skin LD(50) in rabbits is 20 g/kg, OSHA is adding a skin notation for methyl alcohol in the final rule (see Section VI.C.18 for a discussion of the Agency's policy on skin notations). The Agency's reason for establishing a skin notation for methyl alcohol despite this high dermal LD(50) in rabbits is that a dermal LD(Lo) of 500 mg/kg has been reported for this substance in monkeys (Dangerous Properties of Industrial Materials, 7th ed., Sax and Lewis 1989, p. 1377).

Several commenters submitted information to the record on methyl alcohol (Exs. 150 (Comments on Methyl Alcohol), 194, 3-661, 3-902, and 3-896). The Motor Vehicle Manufacturers Association (MVMA)(Ex. 3-902) presented no substantive comment with regard to methyl alcohol; instead, the MVMA listed 41 chemicals, including methyl alcohol, that, in the opinion of the MVMA, require "more review...to allow OSHA and industry additional time to properly assess...[the technological and economic] consequences" of revising the limit. Both the Eastman Kodak Company (Ex. 3-661) and the Chevron Corporation (Ex. 3-896) submitted specific comments on OSHA's proposal to add a STEL of 250 ppm to the existing 8-hour TWA of 200 ppm. Representing Chevron, Stanley Dryden stated:

  • We do not believe that the proposed 250-ppm STEL is justified by the discussion in [OSHA's] preamble (Ex. 3-896, p. 10).

According to Kodak, the study by Kingsley and Hirsch (1954/ Ex. 1-212) that was cited by OSHA in support of the STEL involved exposures to a duplicating machine fluid that contained between 5 and 98 percent methyl alcohol and 2 to 9 percent of an unidentified fluid(s). Kodak is of the opinion that the severe headaches experienced by exposed employees may have been related to the unidentified components of the fluid rather than to methyl alcohol, and further that these exposures may not have been the result of short-term exposures (Ex. 3-661).

OSHA finds Chevron's and Eastman Kodak's comments unpersuasive, for several reasons. First, the measured airborne levels of methyl alcohol reported in the Kingsley and Hirsch study (1954/Ex. 1-212) ranged from 200 to 375 ppm when employees were using direct process duplicating fluids; other studies also report that exposure to methyl alcohol at these levels causes headaches (Henson 1960, as cited in ACGIH 1986/Ex. 1-3, p. 372). Thus, the effects cited in the Kingsley and Hirsch study (1954/Ex. 1-212) are biologically plausible and consistent with those reported in other studies of the effects of this substance. Second, OSHA believes that a 250-ppm STEL is needed to ensure that workers are not exposed, even for short periods, to the elevated levels that have been shown to cause these effects. NIOSH has reevaluated the toxicological evidence for a STEL for methyl alcohol and concurs with the 250-ppm limit OSHA is establishing in the final rule. According to NIOSH (Ex. 150, Comments on Methyl Alcohol):

  • [T]here appears to be no justification for a ceiling of 800 ppm [the ceiling level formerly recommended by NIOSH]. It appears that data are more supportive of the OSHA and ACGIH STEL of 250 ppm...it seems reasonable to update the NIOSH recommended ceiling (Ex. 150).

Thus, OSHA has determined that the addition of a STEL is necessary to reduce the significant risk of disturbed vision and headaches to which workers could be and have been exposed in the absence of a limit on short-term exposures. As discussed above, NIOSH concurs with OSHA that a short-term limit of 250 ppm is appropriate for methyl alcohol; NIOSH described a recent study (Frederic et al. 1984, as cited in Ex. 150, Comments on Methyl Alcohol) that found that teachers' aides exposed to 80 to 3080 ppm of methyl alcohol while using duplicating machines experienced blurred vision, headaches, dizziness, and skin problems. The AFL-CIO (Ex. 194, p. A-12) supports the addition of a STEL and a skin notation for methyl alcohol.

The final rule promulgates an 8-hour TWA of 200 ppm, a STEL of 250 ppm, and a skin notation for methyl alcohol. OSHA concludes that the 8-hour TWA and 15-minute STEL will work together to reduce substantially the significant risk of headaches and blurred vision presented by short-term occupational exposures to methyl alcohol at concentrations above 250 ppm. The Agency finds that the headache, blurred vision, and other ocular effects associated with exposure to methyl alcohol constitute material impairments of health.

 
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  • Page last updated: September 28, 2011
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