KAOLIN

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: None; Chemical Formula: H₂Al₂Si₂O₈H₂O

OSHA’s former limit for kaolin was 15 mg/m³, measured as total particulate; this was the Agency’s generic total particulate limit for all dusts and particulates. The ACGIH has a TLV-TWA of 10 mg/m³, measured as total dust. The Agency proposed an 8-hour TWA PEL of 10 mg/m³ for kaolin, and the final rule establishes this limit; the 5-mg/m³ limit for the respirable fraction is retained. Kaolin may be a white powder, or a white or yellow-white, earthy mass.

Exposure to excess amounts of kaolin dust may cause injury to the skin or mucous membranes (ACGIH 1986/Ex. 1-3). Although NIOSH (Ex. 8-47, Table N4) has not conducted an in-depth review of kaolin dust exposure, it notes that exposure to kaolin dust has been associated with respiratory effects (Lapenas and Gale 1983, as cited in Ex. 8-47). OSHA intends to monitor the developing toxicological literature on kaolin in the future. No other comments on this substance were received.

At this time, however, OSHA is establishing PELs of 10 mg/m³ (total particulate) and 5 mg/m³ (respirable particulate) as 8-hour TWA limits for kaolin. The Agency concludes that these limits will protect workers from the significant health risks associated with exposure to this substance. These risks include skin and mucous membrane injury, and, perhaps, irreversible respiratory effects, all of which constitute material health impairments.