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: 109-59-1; Chemical Formula: (CH3)2CHOCH2CH2OH
OSHA had no former limit for 2-isopropoxyethanol. The ACGIH has a TLV-TWA of 25 ppm for this mobile liquid. The proposed PEL was 25 ppm as an 8-hour TWA, and the final rule establishes this limit.
2-Isopropoxyethanol has been demonstrated to produce systemic toxicity in laboratory animals. In studies of rats, 15 six-hour exposures at 1000 ppm caused hemoglobinuria, anemia, and lung congestion, but no fatalities (Gage 1970/Ex. 1-318). At 300 ppm, Gage reported transient hemoglobin and MCHC decreases and lung congestion after 15 exposures. Exposure at the 100-ppm level produced no effect (Gage 1970/Ex. 1-318). Another study reported a significant increase in the osmotic fragility of erythrocytes in female rats after a four-hour inhalation exposure to 62 ppm, but no effect was observed at 32 ppm (Carpenter, Pozzani, Weil et al. 1956/Ex. 1-303). Studies of four species exposed at concentrations of 200, 50, or 25 ppm for six hours/day for 26 weeks resulted in hematologic changes only in rats; increased osmotic fragility of erythrocytes was marked at 200 ppm, slight at 50 ppm, and minimal at 25 ppm (Moffett, Linnett, and Blair 1976, as cited in ACGIH 1986/Ex. 1-3, p. 235).
NIOSH (Ex. 8-47) did not concur with OSHA’s proposed limit of 25 ppm, noting that 25 ppm represented an effect level. Although “slight” increases in osmotic fragility were reported in animals subchronically exposed (Moffett, Linnett, and Blair 1976, as cited in ACGIH 1986/Ex. 1-3, p. 235), OSHA notes that a marked reaction did not occur until exposure was increased eightfold. Therefore, at this time, OSHA judges the 25-ppm PEL to be sufficiently protective.
OSHA is establishing an 8-hour TWA PEL of 25 ppm for 2-isopropoxyethanol in the final rule. The Agency concludes that this limit will substantially reduce the significant risk of hemolytic effects, which are material health impairments that are associated with exposure to this substance at levels above the new PEL.