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: 111-84-2; Chemical Formula: CH3(CH2)7CH3
Previously, OSHA had no limit for nonane. The ACGIH has a TLV-TWA of 200 ppm for this colorless liquid. The proposed PEL was 200 ppm; NIOSH concurs that this limit is appropriate (Ex. 8-47, Table N1). The final rule promulgates an 8-hour TWA PEL for nonane of 200 ppm.
The toxicity of nonane is approximately equal to that of VM&P naphtha. Naphtha has a 4-hour inhalation LC(50) for rats of 3400 ppm, while nonane has an LC(50) of 3200 ppm (Carpenter, Kinkead, Geary et al. 1975a/Ex. 1-302; Carpenter, Geary, Myers et al. 1978/Ex. 1-301). These investigators found a no-effect level of 590 ppm nonane for rats exposed six hours/day, five days/week for a 65-day period; under the same exposure conditions, a no-effect level of 560 ppm was reported for rats exposed to VM&P naphtha (Carpenter, Kinkead, Geary et al. 1975a/Ex. 1-302; Carpenter, Geary, Myers et al. 1978/Ex. 1-301). Earlier studies of octane and heptane have resulted in much higher LC(50) values for mice, i.e., 13,500 ppm and 16,000 ppm, respectively, for 30- to 60-minute exposures (Flury and Zernik 1931j/Ex. 1-994). Swann and associates (1974/Ex. 1-124) have reported similarly high LD(50) values in mice for octane and hexane; mice died from respiratory arrest after 3 to 5 minutes of exposure to 16,000 ppm of octane or to 48,000 ppm of hexane (Swann, Kwon, and Hogan 1974/Ex. 1-124). The AFL-CIO (Ex. 194) and the United Auto Workers (Ex. 197) favor a 10 ppm PEL for all petroleum solvents and urge OSHA to consider a lower PEL.
In the final rule, OSHA establishes an 8-hour TWA limit of 200 ppm for nonane. The Agency concludes that this limit will protect workers against the significant risk of narcosis, a material impairment of health that is associated with exposure to nonane at levels above the new PEL.