Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 110–91–8
NIOSH REL: 20 ppm (70 mg/m3) TWA, 30 ppm (105 mg/m3) STEL [skin]
Current OSHA PEL: 20 ppm (70 mg/m3) TWA [skin]
1989 OSHA PEL: 20 ppm (70 mg/m3) TWA, 30 ppm (105 mg/m3) STEL [skin]
1993-1994 ACGIH TLV: 20 ppm (71 mg/m3) TWA [skin]
Description of substance: Colorless liquid with a weak, ammonia- or fish-like odor.
LEL :. . 1.4% (10% LEL, 1,400 ppm)
Original (SCP) IDLH: 8,000 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by ILO  that 1 of 6 rats died following an 8-hour exposure to 8,497 ppm. The chosen IDLH is also supported by Patty  who reported that 1 hour was the maximum survival time for rats exposed to the saturated vapor (9,200 ppm); exposure of 6 rats to 8,000 ppm (calculated) for 8 hours resulted in no deaths [Smyth et al. 1954].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal concentration data:
|Rat||ILO 1972||LC17: 8,497||-----||8 hr||21,243 ppm (2.5)||2,124 ppm|
|Mouse||Toksikol Nov Prom Khim Vesh 1966||365||-----||2 hr||584 ppm (1.6)||58 ppm|
Lethal dose data:
|Adjusted LD||Derived value|
|Mammal||Bazarova & Miguekina 1975||oral||1,220||-----||2,359 ppm||236 ppm|
|Mouse||Patel et al. 1985||oral||525||-----||1,015 ppm||102 ppm|
|Rat||Smyth et al. 1954||oral||1,050||-----||2,030 ppm||203 ppm|
Other animal data: No deaths resulted from exposures of 6 rats to 8,000 ppm for 8 hours [Smyth et al. 1954].
Human data: Irritation of the nose has been reported after a 1-minute exposure to 12,000 ppm and coughing started after 1.5 minutes; it was suggested that this concentration would probable be intolerable for long periods [Shea 1939].
|Revised IDLH: 1,400 ppm [LEL]
Basis for revised IDLH: Based on health considerations and acute inhalation toxicity data in humans [Shea 1939] and animals [ILO 1972; Smyth et al. 1954], a value of 2,000 ppm would have been appropriate for morpholine. However, the revised IDLH for morpholine is 1,400 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 1.4%).
1. Bazarova LA, Miguekina NV . Comparative evaluation of the toxicity, hazard and effect of piperidine and morpholine. Toksikol Nov Prom Khim Vesh 14:90-95 (in Russian).
2. ILO . Morpholine. In: Encyclopaedia of occupational health and safety. 2nd ed. Vol. II (L-Z). Geneva, Switzerland: International Labour Office, pp. 915-916.
3. Patel VK, Venkatakrishna-Bhatt H, Patel NB, Jindal MN . Pharmacology of new glutarimide compounds. Biomed Biochim Acta 44(5):795-803.
4. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., pp. 2203-2204.
5. Shea TE Jr . The acute and sub-acute toxicity of morpholine. J Ind Hyg Toxicol 21(7):236-245.
6. Smyth HF Jr, Carpenter CP, Weil CS, Pozzani UC . Range-finding toxicity data: list V. AMA Arch Ind Hyg Occup Med 10:61-68.
7. Toksikol Nov Prom Khim Vesh ; 8:60-70 (in Russian).