N-Ethylmorpholine

CAS number: 100–74–3

NIOSH REL: 5 ppm (23 mg/m³) TWA [skin]

Current OSHA PEL: 20 ppm (94 mg/m³) TWA [skin]

1989 OSHA PEL: 5 ppm (23 mg/m³) TWA [skin]

1993-1994 ACGIH TLV: 5 ppm (24 mg/m³) TWA [skin]

Description of Substance: Colorless liquid with an ammonia-like odor.

LEL:. . Unknown

Original (SCP) IDLH: 2,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement that 1 of 6 rats died following a 4-hour exposure to 2,000 ppm [Smyth et al. 1954 cited by ACGIH 1971].

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA

Lethal concentration data:

Species	Reference	LC50 (ppm)	LCLo (ppm)	Time	Adjusted 0.5-hr LC (CF)	Derived value
Rat	Smyth et al. 1954	LC17: 2,000	-----	4 hr	4,000 ppm (2.0)	400 ppm

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived value
Rat Mouse	Smyth et al. 1954 Timofievskaya 1979	oral oral	1,780 1,200	----- -----	2,601 ppm 1,754 ppm	260 ppm 175 ppm

Human data: Exposures to 100 ppm for 2.5 minutes have resulted in olfactory fatigue and irritation of the eyes, nose, and throat; irritation was slight after 25 minutes at 50 ppm and absent at 25 ppm [Smyth 1964]. Corneal edema has been noted in workers exposed to concentrations greater than 40 ppm for several hours [Dernehl 1966]. In another study, workers exposed to concentrations as high as 11 ppm but averaging about 3 to 4 ppm complained of drowsiness, optical halos, and foggy vision [Woewicki 1968].

Revised IDLH: 100 ppm Basis for revised IDLH: The revised IDLH for N-ethylmorpholine is 100 ppm based on acute inhalation toxicity data in humans [Dernehl 1966; Smyth 1964]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 100 ppm.

REFERENCES:

1. ACGIH [1971]. N-Ethylmorpholine. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 113.

2. Dernehl CU [1966]. Health hazards associated with polyurethane foams. J Occup Med 8:59-62.

3. Smyth JF Jr [1964]. Personal communication to ACGIH TLV Committee (November 24, 1964). [From ACGIH [1991]. N-Ethyl morpholine. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 638-639.]

4. Smyth HF Jr, Carpenter CP, Weil CS, Pozzani UC [1954]. Range-finding toxicity data: list V. AMA Arch Ind Hyg Occup Med 10:61-68.

5. Timofievskaya LA [1979]. Comparative evaluation of the toxicity of piperazine and N-methyl piperazine. Toksikol Nov Prom Khim Vesh 15:116-123 (in Russian).

6. Woewicki A [1968]. Personal communication to ACGIH TLV Committee. [From ACGIH [1991]. N-Ethyl morpholine. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 638-639.]