4-METHOXYPHENOL

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: 150-76-5; Chemical Formula: CH₃OC₆H₄OH

Previously, OSHA had no limit for 4-methoxyphenol. The ACGIH has a TLV-TWA of 5 mg/m³ for this solid substance. The proposed PEL was 5 mg/m³; NIOSH (Ex. 8-47, Table N1) concurs with this limit. In the final rule, OSHA establishes an 8-hour TWA PEL of 5 mg/m³ for methoxyphenol.

In rats, the oral LD(50) for 4-methoxyphenol is between 1 and 2 g/kg; the skin absorption LD(50) is reported as greater than 1 g/kg in rabbits. Results of a two-month dietary study demonstrated no ill effects at 0.1 ppm (approximately 50 mg/kg/day). Direct contact of 4-methoxyphenol with the skin or eyes causes burns or moderate corneal damage (Hodge, Sterner, Maynard, and Thomas 1949/Ex. 1-41; Dow Chemical Company 1977n, as cited in ACGIH 1986/Ex. 1-3, p. 367). Only NIOSH commented on this substance.

To reduce the risk of dermal and ocular effects resulting from exposure to 4-methoxyphenol, a compound similar in chemical structure and toxicity to hydroquinone, OSHA is establishing a permissible exposure limit of 5 mg/m³ as an 8-hour TWA. The Agency concludes that this limit will protect workers against the significant risk of dermal and skin effects potentially associated with exposures to this substance at levels above the new PEL.