OSHA previously had a PEL of 2 ppm TWA for allyl alcohol, with a skin notation. OSHA proposed to supplement this TWA limit with a STEL of 4 ppm and to retain the existing skin notation. NIOSH (Ex. 8-47, Table N1) concurred with this proposal. The final rule establishes a 2-ppm TWA limit, a 4-ppm STEL, and a skin notation for allyl alcohol, which is consistent with the ACGIH (1986/Ex. 1-3) recommendation. Allyl alcohol is a colorless liquid with a pungent, mustard-like odor.
The most important adverse effects of occupational exposures to allyl alcohol are upper-respiratory-tract irritation and burns of the eyes. In a controlled human sensory response study (Dunlap, Kodama, Wellington et al. 1958/Ex. 1-630), a five-minute exposure to 25 ppm resulted in severe eye irritation. Milder irritation has been reported to occur at 5 ppm (McCord 1932, as cited in ACGIH 1986/Ex. 1-3, p. 18). Necrosis of the cornea and temporary blindness occurred in one individual exposed to allyl alcohol at a level irritating to the eyes and nose (Smyth 1956/Ex. 1-759). Skin absorption may lead to serious systemic injury (visceral congestion, periportal congestion of the liver, hematuria, and nephritis); in addition, when evaporation from the skin is prevented or reduced, skin contact causes burns (ACGIH 1986/Ex. 1-3, p. 18).
Exposure to airborne concentrations of allyl alcohol causes a series of characteristic effects, including lacrimation, photophobia, blurred vision, and retrobulbar pain (Dunlap, Kodama, Wellington et al. 1958/Ex. 1-630). Exposed individuals do not develop a tolerance for this substance, and they also do not become sensitized (Kodama and Hine 1958/Ex. 1-1088).
The New Jersey Department of Public Health (Ex. 144, 144A) urged OSHA to set its limits for allyl alcohol on the basis of EPA's IRIS data. The use of such an approach is discussed in Section VI.A of the preamble.
In a prehearing comment, Dr. Lawrence Hecker of Abbott Laboratories (Ex. 3-678) stated that a STEL did not appear to be warranted for allyl alcohol, based on his review of the literature. However, Dr. Hecker did not specifically discuss the evidence or rationale underlying this contention. In reviewing the evidence for allyl alcohol, OSHA notes that severe eye irritation has been reported to occur in human subjects exposed to 25 ppm for as short an interval as five minutes (Dunlap, Kodama, Wellington et al. 1958/Ex. 1-630); such an exposure would be permitted under the current limit of 2 ppm as an 8-hour TWA. OSHA also notes that short-term exposure to allyl alcohol produces characteristic effects more severe than those caused by other sensory irritants; these effects include photophobia and blurred vision. OSHA considers the effects of sensory irritation and disturbed vision to constitute material impairments of health or functional capacity. Sax and Lewis (1989) report that the dermal LD(50) in rabbits is 53 mg/kg, indicating that allyl alcohol readily permeates the skin and causes systemic toxicity.
OSHA concludes that the scientific evidence clearly shows a significant health risk associated with short-term exposure to the levels of allyl alcohol that would be permitted under the former standard; accordingly, the Agency is establishing a 4-ppm 15-minute STEL to supplement its 8-hour TWA limit of 2 ppm. The final rule retains the skin notation for this substance to protect workers from dermal absorption.