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Butyl mercaptan

General Description

  • Synonyms: Butanethiol; 1-Butanethiol; n-Butanethiol; n-Butyl Mercaptan; 1-Mercaptobutane
  • OSHA IMIS Code Number: 0480
  • Chemical Abstracts Service (CAS) Registry Number: 109-79-5
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: EK6300000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 2347 130
  • NIOSH Pocket Guide to Chemical Hazards, n-Butyl mercaptan: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

  • OSHA Permissible Exposure Limit (PEL):
  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 0.5 ppm, 1.8 mg/m3 TWA (TLV listed under n-Butyl mercaptan)
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 0.5 ppm, 1.8 mg/m3 Ceiling (15 Minutes)

Health Factors

  • NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 500 ppm
  • Potential Symptoms: Irritation of eyes, skin; cough, shortness of breath; dizziness, drowsiness; muscle weakness, malaise, sweating, nausea, vomiting, headache, confusion; skin rash; in animals: narcosis, incoordination, weakness, cyanosis; pulmonary irritation; liver, kidney damage
  • Health Effects: Irritation - Eye, Nose, Throat---Mild (HE16); Offensive Odor (HE20)
  • Affected Organs: Eyes, skin, respiratory system, central nervous system, liver, kidneys
  • Notes:
    1. Butyl mercaptan is a contaminant and degradation product of the restricted use cotton defoliants, DEF (tributyl phosphorotrithioate) and Folex (tributyl phosphorotrithioite, and it is described as having a potent skunk-like odor with a detection threshold as low as 0.0001 ppm.
    2. Butyl mercaptan is a flavoring agent (Flavor and Extract Manufacturers Association number 3478; Joint FAO/WHO Expert Committee on Food Additives number 511) which, at a concentration of 1 ppm in the flavor medium, has a taste described as "sulfureous, vegetative, savory meaty, garlic and onion."
  • Literature Basis:
    • NIOSH Pocket Guide to Chemical Hazards: n-Butyl mercaptan.
    • International Chemical Safety Cards (WHO/IPCS/ILO): n-Butyl mercaptan.
    • No authors listed: butyl mercaptan. The Good Scents Company.
    • Ames, R.G. and Gregson, J.: Mortality following cotton defoliation: San Juaquin Valley, California, 1970-1990. J. Occup. Environ. Med. 37(7): 812-819, 1995.
    • Pohanish, R.P. (editor): Butyl Mercaptan. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 418-419.
  • Date Last Revised: 11/07/2006

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • Chromosorb 104 Tube (150/75 mg sections)
  • maximum volume: 4 Liters
  • maximum flow rate: 0.05 L/min
  • current analytical method: Gas Chromatography; GC/FPD
  • analytical solvent: Acetone
  • method reference: NIOSH Analytical Method (NIOSH 2525 (PDF))
  • method classification: Fully Validated
  • Coated Glass Fiber Filter (37 mm Gelman Type A) Coating is Mercuric Acetate
  • maximum volume: 20 Liters
  • maximum flow rate: 0.2 L/min (TWA or Ceiling)
  • current analytical method: Gas Chromatography; GC/FPD
  • analytical solvent: (20 mL:5 mL) 25% Aqueous HCl:Methylene Chloride
  • method reference: NIOSH Analytical Method (NIOSH 2542 (PDF))
  • method classification: Fully Validated
  • note: Protect samples from light until analysis.

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