There was no former OSHA exposure limit for acetylsalicylic acid. The ACGIH has a TLV of 5 mg/m3 as an 8-hour TWA. The proposed PEL was 5 mg/m3 as an 8-hour TWA. NIOSH (Ex. 8-47, Table N1) concurs with this limit, and this is the limit established by the final rule. Acetylsalicylic acid is a white crystal or powder that is essentially odorless and has a slightly bitter taste.
The work of O'Brien (1968/Ex. 1-47) reports that a normal therapeutic dose of 600 mg aspirin will interfere with platelet aggregation in subjects exposed for a period of five days or more. Hart (1947/Ex. 1-137) also reported that 150 mg is the smallest oral dose of acetylsalicylic acid that will produce this effect. Unpublished data from the Dow Chemical Company (cited in ACGIH 1986/Ex. 1-3, p. 10) indicate that aspirin concentrations exceeding 100 mg/m3 are tolerated except for occasional skin irritation. However, no data are available on the long-term effects on organ systems of inhalation exposure to aspirin. Secondary sources report that aspirin is an acute irritant to the gastric mucosa and respiratory tract. No comments other than that by NIOSH (Ex. 8-47) were received on this substance.
In the final rule, OSHA is establishing an 8-hour TWA of 5 mg/m3 for acetylsalicylic acid. The Agency concludes that this reduced limit will protect workers from experiencing the adverse blood effects and gastric and respiratory irritation, which constitute material impairments of health that are potentially associated with exposure to this substance at the previously uncontrolled levels.