OSHA formerly had an 8-hour TWA limit of 3 ppm for ethanolamine. The ACGIH has the same TWA limit, along with a 15-minute STEL of 6 ppm. OSHA proposed to retain the 8-hour TWA PEL of 3 ppm and to supplement this limit with a 6-ppm STEL; NIOSH (Ex. 8-47, Table N1) concurred with the proposed limits, and the final rule establishes them. Ethanolamine is a colorless liquid with a mild smell like that of ammonia.
The health hazards associated with exposures to ethanolamine include irritation and necrosis of the skin and central nervous system depression. The oral LD(50) in rats is reported as 3.32 g/kg, and the intraperitoneal LD(50) in rats is 981 mg/kg (Hartung and Cornish 1968/Ex. 1-328). The dermal toxicity of ethanolamine is considerably higher, with an LD(50) of 1 mg/kg reported in the rabbit. Dermal application of the undiluted liquid also caused redness, swelling, and burns comparable to mild first-degree burns (Union Carbide Corporation, as cited in ACGIH 1986/Ex. 1-3, p. 235). The eye injury potential of ethanolamine is just slightly less than that of undiluted ammonia (Carpenter and Smyth 1946/Ex. 1-859). Rats fed 0.5 percent (320 mg/kg/day) ethanolamine in their food for 90 days (Smyth, Carpenter, and Weil 1951/Ex. 1-439) showed no adverse effects, but at 1.28 g/kg/day, fatalities occurred. Treon, Cleveland, Stemmer, and associates (1957/Ex. 1-1172) reported lung, liver, and kidney damage in various species exposed to high concentrations of the vapor and mist. In tests of various species, Weeks and co-workers (1960/Ex. 1-941) reported marked dermal effects from continuous exposures (24 hours/day, seven days/week, for from 24 to 90 days) at various concentrations of the vapor; at 12 to 26 ppm, dermal effects were less severe, but at 5 ppm, skin irritation was still evident. After 90 days of exposure to 5 ppm, dogs also experienced a slight and temporary weight loss as well as decreased activity and alertness (Weeks, Downing, Musselman et al. 1960/Ex. 1-941). Luck and Wilcox (1953/Ex. 1-917) demonstrated that a portion of low doses of ethanolamine is not excreted and is presumably retained in the body of cats, rats, and rabbits.
In studies of anesthetized dogs, Priddle (1954, as cited in ACGIH 1986/Ex. 1-3, p. 235) reported that sublethal doses of ethanolamine cause central nervous system stimulation, while lethal doses cause CNS depression. Ethanolamine's irritant and necrotic effects on the skin are not related to its alkalinity (Hinglais 1947/Ex. 1-909). OSHA received no comments, other than the one by NIOSH (Ex. 8-47), on this substance.
In the final rule, OSHA is establishing a PEL of 3 ppm as an 8-hour TWA and a 15-minute STEL of 6 ppm for ethanolamine. The Agency concludes that both of these limits are required to protect workers against the significant risk of irritation and neuropathic effects, which constitute material health impairments that are potentially associated with exposure to ethanolamine at levels permitted above the 8-hour TWA limit. The Agency has determined that these limits will substantially reduce this significant risk.