HEXYLENE GLYCOL

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: 107-41-5; Chemical Formula: (CH₃)₂-COHCH₂-CHOH-CH₃

OSHA previously had no limit for hexylene glycol. Based on the ACGIH recommendation, OSHA proposed a ceiling limit of 25 ppm for this liquid, which has a mild, sweetish odor. NIOSH (Ex. 8-47, Table N1) concurred with this proposed limit, and the final rule establishes it.

In mice, the LD(50) for hexylene glycol is reported to be 3.8 ml/kg, and it is reported to be 4.79 g/kg in rats. A single dose of 2.0 ml/kg induced hypnosis in mice. Undiluted hexylene glycol instilled into the rabbit eye caused irritation and corneal injury (Smyth and Carpenter 1948/Ex. 1-375).

The Shell Chemical Corporation has reported that oral administration of hexylene glycol can cause nervous system depression that is manifested by an initial state of excitation, followed by deep depression (Shell Chemical Corporation, as cited in ACGIH 1986/Ex. 1-3, p. 309). When the liquid is applied to the skin, mild to moderate irritation occurs, although skin absorption does not. At high concentrations, hexylene glycol vapors evoke a strong sensory response: a five-minute exposure at 1000 ppm produced eye irritation and throat and respiratory discomfort. At concentrations of 50 ppm for 15 minutes, slight eye irritation was reported (ACGIH 1986/Ex. 1-3, p. 309).

Mr. Melampy, Counsel to the ILMA, commented that the proposed 25-ppm ceiling limit “is far below the hazard levels found to exist…,” given that exposures to hexylene glycol concentrations of 50 ppm for brief periods of time cause only slight eye irritation. OSHA does not agree with the assessment that a 25-ppm ceiling limit is too low. As discussed earlier in this section, OSHA has determined that no employee should be subjected to mucous membrane or respiratory irritation caused by exposure to toxic agents and that this effect represents material impairment of health and adversely affects the well-being and functional capacity of employees. For hexylene glycol, 50 ppm represents an adverse-effect level, and establishing the limit at this level would not be sufficiently protective. OSHA also concludes that 25 ppm is a reasonable level at which to establish the PEL; this level provides some margin against this substance’s irritant effects. Therefore, OSHA finds that establishing a 25-ppm ceiling limit for hexylene glycol is necessary to reduce the risks of eye and respiratory irritation, which occur at exposure levels above the new PEL.