Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 110–86–1
NIOSH REL: 5 ppm (15 mg/m3) TWA
Current OSHA PEL: 5 ppm (15 mg/m3) TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 5 ppm (16 mg/m3) TWA
Description of substance: Colorless to yellow liquid with a nauseating, fish-like odor.
LEL: . 1.8% (10% LEL, 1,800 ppm)
Original (SCP) IDLH: 3,600 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty  that 2 of 3 rats died following a 6-hour exposure to 3,600 ppm [Fassett and Roudabush 1953].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal concentration data:
|Rat||Fassett & Roudabush 1953||LC66: 3,600||-----||6 hr||8,280 ppm (2.3)||828 ppm|
|Rat||Smyth et al. 1951||LC83: 4,000||-----||4 hr||8,000 ppm (2.0)||800 ppm|
|Rat||Vernot et al. 1977||9,000||-----||1 hr||11,250 ppm (1.25)||1,125 ppm|
Lethal dose data:
|Adjusted LD||Derived value|
|Rat||Biofax 1970||oral||891||-----||1,896 ppm||190 ppm|
|Mouse||Leslie et al. 1973||oral||1,500||-----||3,191 ppm||319 ppm|
|Rat||Smyth et al. 1951||oral||1,580||-----||3,362 ppm||386 ppm|
Human data: Nausea, headache, insomnia, nervousness, and low back or abdominal discomfort with urinary frequency have occurred in individuals exposed to concentrations averaging 125 ppm for 4 hours/day for 1 to 2 weeks [Patty 1963]. Chronic poisoning with mild symptoms of central nervous system injury occurred in workers at a plant where pyridine vapor concentrations ranged from 6 to 12 ppm [Tessinger 1948].
|Revised IDLH: 1,000 ppm
Basis for revised IDLH: The revised IDLH for pyridine is 1,000 ppm based on acute inhalation toxicity data in animals [Vernot et al. 1977].
1. Biofax . Data sheet 14. Northbrook, IL: Biofax Industrial Bio-Test Laboratories, Inc.
2. Fassett DW, Roudabush RL . Toxicity of pyridine derivatives with relationship to chemical structure. Unpublished paper presented to the American Industrial Hygiene Association Conference, Los Angeles, CA.
3. Leslie GB, Hanahoe THP, Ireson JD, Sturman G . Some pharmacological properties of pyridine. Pharmacol Res Commun 5(4):341-365.
4. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., pp. 2190, 2727-2731.
5. Smyth HF Jr, Carpenter CP, Weil CS . Range-finding toxicity data: list IV. AMA Arch Ind Hyg Occup Med 4:119-122.
6. Teisinger J . Mild chronic intoxication with pyridine. Czech Med J 39(1947); abstracted in J Ind Hyg Toxicol 30:58. [From ACGIH . Pyridine. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 1328-1330.]
7. Vernot EH, MacEwen JD, Haun CC, Kinkead ER . Acute toxicity and skin corrosion data for some organic and inor ganic compounds and aqueous solutions. Toxicol Appl Pharmacol 42(2):417-423.