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Chemical Sampling Information (CSI)
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General Description

Synonyms: N,N-Dimethylmethanamine; TMA [Note: May be used in an aqueous solution (typically 25%, 30%, or 40% TMA).]

OSHA IMIS Code Number: T127

Chemical Abstracts Service (CAS) Registry Number: 75-50-3

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: PA0350000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 1083 118 (anhydrous); 1297 132 (aqueous solution)

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

Exposure Limits

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 5 ppm, 12 mg/m3 TWA; 15 ppm, 36 mg/m3 STEL

American Industrial Hygiene Assocation (AIHA) Workplace Environmental Exposure Levels (WEEL): 1 ppm, 2.4 mg/m3 TWA

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 10 ppm, 24 mg/m3 TWA, 15 ppm, 36 mg/m3 STEL

Health Factors

Potential Symptoms: Irritation of eyes, skin, nose, throat, respiratory system; headache; cough, dyspnea (breathing difficulty); pulmonary edema (may be delayed); blurred vision, corneal necrosis; skin burns; frostbite (from liquid)

Health Effects: Irritation-Eye, Nose, Throat, Skin---Marked (HE14); Lung edema (HE11)

Affected Organs: Eyes, skin, respiratory system


  1. OSHA does not have a PEL for trimethylamine.
  2. Vapor/air mixtures of trimethylamine may be explosive.
  3. Trimethylamine is considered to be generally recognized as safe when used as a flavoring agent (Flavor and Extract Manufacturers Association number 3241; Joint FAO/WHO Expert Committee on Food Additives number 1610).
  4. Trimethylamine is excreted largely in the urine as trimethylamine N-oxide, except in individuals with inherited mutations of the enzyme flavin monooxygenase-3 (FMO3) or with transient reductions in the activity of this enzyme (e.g., during menstruation).
  5. A deficiency in FMO3 activity can cause excess trimethylamine in breath, sweat, urine and other body secretions that may affect an employee?s ability to work in close proximity to others, except for a small percentage of the population (5-7%) that has a substantially decreased ability to smell the fishy odor of trimethylamine (anosmia).
  6. Penetration of human skin in vitro by trimethylamine was linear over the 100-fold range of doses tested.
  7. Application of a 1.5% solution of trimethylamine in water for two 30-minute periods (separated by 3 hours) twice/day for 4 days on the skin of human volunteers caused significant disruption of the permeability barrier without significant irritation after the third day of application.

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Trimethylamine.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Trimethylamine.
  • Cashman, J.R., et al.: Biochemical and clinical aspects of the human flavin-containing monooxygenase form 3 (FMO3) related to trimethylaminuria. Curr. Drug Metab. 4(2): 151-170, 2003.
  • Amoore, J.E. and Forrester, L.J.: Specific anosmia to trimethylamine: the fishy primary odor. J. Chem. Ecology 2(1): 49-56, 1976.
  • Fluhr, J.W., et al.: Additive impairment of the barrier function and irritation by biogenic amines and sodium lauryl sulphate: a controlled in vivo tandem irritation study. Skin Pharmacol. Physiol. 18(2): 88-97, 2005.
  • Kenyon, S., et al.: The passage of trimethylamine across rat and human skin. Food Chem. Toxicol. 42(10): 1619-1628, 2004.
  • Mitchell, S.C. and Smith, R.L.: Trimethylamine and odorous sweat. J. Inherit. Metab. Dis. 26(4): 415-416, 2003.
  • Pohanish, R.P. (editor): Trimethylamine. Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 2275-2277.
  • Shimizu, M., Cashman, J.R. and Yamazaki, H.: Transient trimethylaminuria related to menstruation. BMC Med. Genet. 8: 2, 2007.

Date Last Revised: 02/28/2007

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Coated XAD-7 Tube (80/40 mg sections) Coating is 10% Phosphoric Acid
    analytical solvent: (50:50) Methanol: Deionized Water
    maximum volume: 20 Liters
    maximum flow rate: 0.2 L/min
    current analytical method: Gas Chromatography; GC/FID
    method reference: OSHA Analytical Method (OSHA PV2060)
    method classification: Partially Validated

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