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: 2238-07-5; Chemical Formula: C6H10O3
The former OSHA limit for diglycidyl ether (DGE) was 0.5 ppm as a ceiling concentration, and the ACGIH-recommended TLV is 0.1 ppm as an 8-hour TWA. NIOSH recommends a limit of 0.2 ppm for DGE as a 15-minute ceiling. OSHA proposed an 8-hour TWA of 0.1 ppm, and this limit is established in the final rule.
Both the previous ACGIH 0.5-ppm TLV and that organization’s current TLV are based on the results of an animal study reported by Hine and Rowe (1963b, as cited in ACGIH 1986/Ex. 1-3, p. 202) in which rats were administered repeated 4-hour exposures of 20, 3, or 0.3 ppm DGE. Rats exposed to 20 ppm of DGE showed respiratory irritation, loss of body weight, decreased leukocyte count, involution of the spleen and thymus, and hemorrhagic bone marrow. Residual hematopoietic effects were observed among rats exposed to 3 ppm, and no observed effects were noted among rats exposed to 0.3 ppm, even after as many as 60 exposures. The ACGIH’s previous TLV of 0.5 ppm as a ceiling value was based on the no-observed-effect level of 0.3 ppm reported in the Hine and Rowe (1963b, as cited in ACGIH 1986/Ex. 1-3, p. 202) study and on industrial experience. In 1979, the ACGIH reconsidered its limit for DGE, noting that, “in view of the seriousness of some of the effects produced [in the rat study], a TLV below the no-ill-effect level [of 0.3 ppm] would normally be adopted” (ACGIH 1986/Ex. 1-3). The ACGIH consequently revised the TLV to 0.1 ppm as an 8-hour TWA.
NIOSH concurs with this limit but notes that DGE may be a potential occupational carcinogen (Ex. 8-47), and the Workers Institute for Safety and Health (Ex. 116) objected to the establishment of a ceiling limit. No other comments were received on this substance.
In the final rule, OSHA concludes that the revised 8-hour TWA limit of 0.1 ppm will protect workers against the significant risk of hematopoietic and irritant effects, which constitute material health impairments and to which they were potentially exposed at OSHA’s former PEL. The risks of DGE exposure range from respiratory irritation to bone marrow effects. The final rule’s limit for DGE will reduce this risk substantially.