TRIMETHYLAMINE

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: 75-50-3; Chemical Formula: (CH₃)₃N

OSHA formerly had no exposure limit for trimethylamine. The ACGIH has a 10-ppm limit as an 8-hour TWA and a 15-ppm limit as a 15-minute STEL. The proposed PELs, with which NIOSH (Ex. 8-47, Table N1) concurs, were 10 ppm as an 8-hour TWA and 15 ppm as a 15-minute STEL. These limits are established in the final rule. Trimethylamine has a pungent, fishy odor and is a gas at room temperature.

Few toxicological data are available for trimethylamine. One study reports that the intravenous LD(50) for this substance is 90 mg/kg in mice (Dechezlepretre, Portet, and Cheymol 1967/Ex. 1-777). The ACGIH established the TLV for trimethylamine on the basis of its chemical similarity to dimethylamine, for which the current TLV-TWA is 10 ppm. Dimethylamine is a central nervous system depressant and causes methemoglobinemia. Only NIOSH commented on trimethylamine.

OSHA is establishing an 8-hour TWA limit of 10 ppm and a STEL of 15 ppm (15 minutes) for trimethylamine. Based on analogy with dimethylamine, the Agency concludes that these limits will protect workers exposed at previously unregulated levels from the significant risk of eye, mucous membrane, and upper respiratory tract irritation, which constitute material impairments of health.