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: 768-52-5; Chemical Formula: C6H5NHCH(CH3)2
OSHA formerly had no limit for N-isopropylaniline. The ACGIH recommends a TLV-TWA of 2 ppm, with a skin notation, for this liquid. The proposed PEL was 2 ppm, with a skin notation; NIOSH (Ex. 8-47, Table N1) concurs. The final rule establishes an 8-hour TWA PEL of 2 ppm, and a skin notation, for N-isopropylaniline.
The oral LD(50) for rats exposed to N-isopropylaniline is between 0.25 and 0.5 g/kg. Slight irritation of the skin and eyes has been reported in animals as a result of direct contact with this chemical (Dow Chemical Company 1977k, as cited in ACGIH 1986/Ex. 1-3, p. 338). No other data concerning chronic toxicity or human exposure are available (ACGIH 1986/Ex. 1-3, p. 338).
Chemical analysis shows N-isopropylaniline to have toxicologic properties similar to those of its parent compound, aniline. The oral LD(50)s for the two chemicals are approximately equal. The ACGIH has established the 2-ppm TLV-TWA for N-isopropylaniline on the basis of its structural analogy with aniline (which has a 2-ppm TLV-TWA) and N,N-dimethylaniline (which has a 5-ppm TLV-TWA and a 10-ppm STEL); exposure to these substances has been shown to cause hemolytic and central nervous system effects in animals and humans. These substances are also toxic when absorbed through the skin. OSHA received only one comment, from NIOSH, on this substance.
In the final rule, OSHA is establishing an 8-hour PEL of 2 ppm for N-isopropylaniline, with a skin notation. The Agency concludes that this limit will protect exposed workers from the significant risk of irritation and systemic and hemolytic effects, all material health impairments that are caused by inhalation, ingestion, or dermal absorption of N-isopropyl-aniline.