1,1,2,2-TETRACHLOROETHANE

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: 79-34-5; Chemical Formula: CHCl₂CHCL₂

OSHA’s former PEL for 1,1,2,2-tetrachloroethane was 5 ppm as an 8-hour TWA, with a skin notation; a 1-ppm 8-hour TWA, also with a skin notation, was the level proposed by OSHA. NIOSH considers 1,1,2,2-tetrachloroethane to be a potential carcinogen but concurred with the limit proposed (Ex. 8-47, Table N6A). The final rule establishes a PEL of 1 ppm TWA and retains the skin notation for this colorless, nonflammable, heavy, mobile liquid with a sweet, chloroform-like odor.

One study by Jeney, Bartha, Kondor, and Szendrei (1957, as cited in ACGIH 1986/Ex. 1-3, p. 561) revealed identifiably adverse effects on the liver, including hepatitis, in humans exposed to concentrations of tetrachloroethane ranging from 1.5 to 247 ppm; liver damage was still evident after exposures were reduced to 15 ppm. An animal study by Schmidt, Binnewies, Gohlke, and Rothe (1972/Ex. 1-222) found “barely detectable” fatty infiltration of the liver in rats exposed to 2 ppm tetrachloroethane for 11 months.

The ACGIH (1986/Ex. 1-3, p. 561) cites some early studies that show that tetrachloroethane penetrates human skin; one fatality has been attributed to excess skin absorption. The New Jersey Department of Public Health (Ex. 144) urged OSHA to set the PEL for this substance on the basis of EPA’s IRIS data. The use of IRIS data is discussed in Section VI.A.

Based on this evidence, OSHA concludes that the former permissible exposure limit does not protect exposed workers against fatty infiltration of the liver or against more serious liver damage; these health consequences clearly constitute material health impairments and thus pose a significant occupational risk. OSHA finds that reducing the 8-hour TWA for 1,1,2,2-tetrachloroethane to 1 ppm will substantially reduce this significant risk, and in the final rule, OSHA is therefore establishing a 1-ppm 8-hour TWA, with a skin notation, for 1,1,2,2-tetrachloroethane.