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: 121-44-8; Chemical Formula: (C2H5)3N

OSHA previously had a limit of 25 ppm TWA for triethylamine. Based on the ACGIH recommendation, the Agency proposed revising this limit to 10 ppm as a TWA and 15 ppm as a 15-minute STEL for this colorless liquid with a strong, ammonia-like odor. NIOSH (Ex. 8-47, Table N1) concurred with this proposal, and OSHA is establishing these limits for triethylamine.

Exposure to triethylamine is associated with pulmonary, skin, and eye irritation and central nervous system effects. Guinea pigs exposed for 30 minutes to a concentration of 2000 ppm triethylamine survived, but four of six animals died when exposed to this level for two hours; two of six guinea pigs died during a four-hour exposure to a concentration of 1000 ppm, but all survived similar exposures at the 250- and 500-ppm levels (Carpenter, Smyth, and Shaffer 1948/Ex. 1-892). The single-dose oral LD(50) value in rats is 0.46 g/kg (range: 0.25 to 0.85) (Smyth, Carpenter, and Weil 1951/Ex. 1-439). These investigators also reported that triethylamine readily penetrated rabbit skin on contact, with an LD(50) value of 0.57 ml/kg (range: 0.36 to 0.90); skin irritation and eye injury were also noted from contact with the liquid. One of six rats died from an acute four-hour inhalation exposure to 1000 ppm triethylamine (Smyth, Carpenter, and Weil 1951/ Ex. 1-439). Rabbits exposed repeatedly to a level of 50 ppm exhibited marked irritation of the cornea and of pulmonary tissue (Brieger and Hodes 1951/Ex. 1-408; Carpenter and Smyth 1946/Ex. 1-859). The effects of repeated triethylamine exposure correspond to those of ethylamine and diethylamine (Brieger and Hodes 1951/Ex. 1-408). Triethylamine was also found to inhibit monoamine oxidase activity, resulting in central nervous system stimulation (De Bruin 1976/Ex. 1-895).

OSHA received a comment on its proposal to revise the limit for triethylamine from Mr. H.K. Thompson, Corporate Industrial Hygienist for Caterpillar, Inc. (Ex. 3-349), who agreed that the 25-ppm PEL is too high, but recommended that OSHA establish a 15-ppm TWA and a 25-ppm STEL. He stated that, in his experience, where triethylamine is used as a catalyst in the making of foundry cores, 16 ppm “produces no irritation or `halo’ effect.”

OSHA appreciates the suggestion made by Mr Thompson; however, the Agency is concerned that his suggested STEL of 25 ppm is not sufficiently protective, given that rabbits exposed repeatedly to 50 ppm exhibited marked irritation of the cornea and pulmonary tissue. OSHA judges that a somewhat greater margin of safety is called for to protect employees who may regularly be exposed to short-term elevated concentrations of triethylamine. Therefore, OSHA is establishing the limits originally proposed for trimethylamine, which are 10 ppm as an 8-hour TWA and 15 ppm as a 15-minute STEL. The Agency believes that these limits are necessary to reduce the significant risk of irritation, which constitutes a material impairment of health that is associated with exposure to this substance.

Page last reviewed: September 28, 2011