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Chemical Sampling Information (CSI)
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General Description

Synonyms: Azabenzene; Azine

OSHA IMIS Code Number: 2220

Chemical Abstracts Service (CAS) Registry Number: 110-86-1

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: UR8400000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 1282 129

NIOSH Pocket Guide to Chemical Hazards, Pyridine: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

OSHA Permissible Exposure Limit (PEL):

General Industry: 29 CFR 1910.1000 Z-1 Table -- 5 ppm, 15 mg/m3 TWA

Construction Industry: 29 CFR 1926.55 Appendix A -- 5 ppm, 15 mg/m3

Maritime: 29 CFR 1915.1000 Table Z-Shipyards -- 5 ppm, 15 mg/m3 TWA

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 1 ppm, 3.2 mg/m3 TWA; Appendix A3 - Confirmed Animal Carcinogen with Unknown Relevance to Humans

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 5 ppm, 15 mg/m3 TWA

Health Factors

Carcinogenic Classification:

International Agency for Research on Cancer (IARC) carcinogenic classification: Group 3, not classifiable as to its carcinogenicity to humans [103 KB PDF, 36 pages]

NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 1,000 ppm

Potential Symptoms: Irritation of eyes, skin, respiratory tract; cough, shortness of breath; headache, anxiety, dizziness, insomnia; nausea, anorexia; unconsciousness; dermatitis; liver, kidney damage; eye damage (on contact with liquid); SKIN ABS.: Redness; burning sensation; INGES. ACUTE: Abdominal pain, vomiting, diarrhea; weakness.

Health Effects: Cumulative liver, kidney and bone marrow damage (HE3) CNS effects (HE7); Irritation-Eyes, Nose, Throat, Skin---Moderate (HE15).

Affected Organs: Eyes, skin, CNS, liver, kidneys, GI tract


  1. Vapor/air mixtures of pyridine may be explosive.
  2. Pyridine is listed among FDA's "food additives permitted for direct addition to food for human consumption" (21 CFR 172.515).
  3. EPA's reference dose (RfD, daily oral exposure likely to be without an appreciable risk of deleterious effects during a lifetime) for pyridine is 0.001 mg/kg/day.
  4. Chronic oral ingestion of pyridine by mice in daily doses up to 70 mg/kg caused a dose-related increase in incidence of liver cancer, whereas rats receiving up to 36 mg/kg daily showed liver and kidney damage.
  5. Urinary metabolites of radiolabeled pyridine given orally to two volunteers included pyridine N-oxide (32% of the dose) and N-methylpyridinium ion (6-12% of the dose).

Date Last Revised: 09/14/2006

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Pyridine.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Pyridine.
  • U.S. EPA Integrated Risk Information System: Pyridine (CASRN 110-86-1).
  • Damani, L.A., Crooks, P.A., Shaker, M.S., Caldwell, J., D'Souza, J. and Smith, R.L.: Species differences in the metabolic C- and N-oxidation, and N-methylation of [14C]pyridine in vivo. Xenobiotica 12(8): 527-534, 1982.
  • National Toxicology Program: NTP toxicology and carcinogenesis studies of pyridine (CAS No. 110-86-1) in F344/N rats, Wistar rats, and B6C3F1 mice (drinking water studies). Nat. Toxicol. Program Tech. Rep. Ser. 470: 1-330, 2000.
  • Nikula, K.J. and Lewis, J.L.: Olfactory mucosal lesions in F344 rats following inhalation exposure to pyridine at threshold limit value concentrations. Fundam. Appl. Toxicol. 23(4): 510-517, 1994.
  • [No authors listed]: Pyridine [103 KB PDF, 36 pages]. IARC Monogr. Eval. Carcinog. Risks Hum. 77: 503-528, 2000.
  • Pohanish, R.P. (editor): Pyridine. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1988-1990.
Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Two XAD-7 tubes connected in series. Each tube has a 100 mg front section and a 50 mg back section. The 100 mg sections face forward when sampling. SKC 226-95 or equivalent.
    analytical solvent: Methanol
    maximum volume: 10 Liters
    maximum flow rate: 0.1 L/min
    current analytical method: Gas Chromatography; GC/FID
    method reference: OSHA Partially Validated Method (PV2295);
    method classification: Partially Validated

  • sampling media: Coconut Shell Charcoal (100/50 mg sections)
    analytical solvent: Methylene Chloride
    minimum volume: 18 Liters   
    maximum volume: 150 Liters   
    maximum flow rate: 1 L/min
    current analytical method: Gas Chromatography; GC/FID
    method reference: NIOSH Analytical Method (NIOSH 1613 [22 KB PDF, 4 pages])
    method classification: Fully Validated

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