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: 123-19-3; Chemical Formula: (CH3CH2CH2)2CO
OSHA formerly had no limit for dipropyl ketone. The ACGIH has a TLV of 50 ppm TWA for this colorless liquid with a penetrating odor. The proposed PEL was 50 ppm as an 8-hour TWA, and NIOSH (Ex. 8-47, Table N1) concurs with this limit, which is established by the final rule.
Dipropyl ketone has a moderate oral and inhalation toxicity (Dangerous Properties of Industrial Materials, 6th ed., Sax 1984). In rats, the oral LD(50) is 3.35 g/kg, and the dermal LD(50) in rabbits is 9.5 g/kg. Tests have indicated that rats inhaling 2000 ppm for 4 hours survived, but at 4000 ppm all animals died (Carpenter, Weil, and Smyth 1974/Ex. 1-304). Methyl isobutyl ketone (MIBK) has a similar acute toxicity (ACGIH 1986/Ex. 1-3, p. 221); OSHA is establishing a 50-ppm 8-hour TWA and a 75-ppm STEL for MIBK. Only NIOSH submitted comments on dipropyl ketone.
In the final rule, OSHA is establishing an 8-hour TWA PEL of 50 ppm TWA for dipropyl ketone. The Agency concludes that this limit is necessary to protect workers from the significant risk of narcosis and irritation, both material health impairments that are associated with exposures at levels above the new PEL.