US Dept of Labor

Occupational Safety & Health AdministrationWe Can Help

Ethylene Thiourea

General Description

  • Synonyms: 2-Mercaptoimidazoline; 4,5-Dihydroimidazole-2(3H)-thione; ETU; NA-22; Pennac CRA; Warecure C; 2-Imidazolidinethione; 1,3-Ethylene-2-thiourea; N,N-Ethylenethiourea; ETU; 2-Imidazolidine-2-thione
  • OSHA IMIS Code Number: 1159
  • Chemical Abstracts Service (CAS) Registry Number: 96-45-7
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: NI9625000
  • NIOSH Pocket Guide to Chemical Hazards, Ethylene Thiourea: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): Use encapsulated form. Appendix A - NIOSH Potential Occupational Carcinogens

Health Factors

  • Carcinogenic Classification:
  • Potential Symptoms: Irritation of eyes; in animals: thickening of the skin; goiter; teratogenic effects; [potential occupational carcinogen].
  • Health Effects: Irritation-Eye, Nose, Throat, Skin---Moderate (HE15)
  • Affected Organs: Eyes, skin, thyroid, reproductive system
  • Notes:
    1. Ethylene thiourea is an OSHA Select Carcinogen. Reclassification by the IARC of this chemical from Group 2B (possibly carcinogenic to humans) to Group 3 has remained controversial.
    2. EPA's oral reference dose (daily oral exposure likely to be without an appreciable risk of deleterious effects during a lifetime) is 0.00008 mg/kg/day.
    3. Based upon animal studies showing thyroid and/or liver tumors and alteration of thyroid function, a safe drinking water concentration of ethylene thiourea, as an environmental decomposition product (and urinary metabolite) of some agricultural fungicides, was proposed in 1988 to be 3 ppb.
    4. Measurement of urinary ethylene thiourea has been used as a marker for exposure of farmers in France to ethylene bisdithiocarbamate fungicides. Thyroid function or other potential health effects of exposure were not studied in these farmers.
    5. Evidence that ethylene thiourea has an effect like the antithyroid drug propylthiouracil, causing a low thyroxine level and a high TSH level in blood, was reported in a rubber manufacturing worker in the UK.
    6. Possible symptoms of exposure higher than that causing respiratory irritation include sweating, thirst, nausea, increased heart rate and blood pressure, and pulmonary edema (Pohanish, 2002).

    Literature Basis:

    • NIOSH Pocket Guide to Chemical Hazards: Ethylene Thiourea.
    • International Chemical Safety Cards (WHO/IPCS/ILO): 2-Mercaptoimidazoline.
    • EPA Air Toxics Website: Ethylene Thiourea. U.S. Environmental Protection Agency Technology Transfer Network.
    • No Author: Ethylene Thiourea (PDF). Report on Carcinogens (latest edition); U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program.
    • El Balkhi, S., Sandouk, P. and Galliot-Guilley, M.: Determination of ethylene thiourea in urine by HPLC-DAD. J. Anal. Toxicol. 29(4): 229-233, 2005.
    • Frakes, R.A.: Drinking water guideline for ethylene thiourea, a metabolite of ethylene bisdithiocarbamate fungicides. Regul. Toxicol. Pharmacol. 8(2): 207-218, 1988.
    • Huff, J.: IARC monographs, industry influence, and upgrading, downgrading, and under-grading chemicals: a personal point of view. International Agency for Research on Cancer. Int. J. Occup. Environ. Health 8(3): 249-270, 2002.
    • Pohanish, R.P. (editor): Ethylene Thiourea. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1102-1104.
    • Smith, D.M.: Ethylene thiourea: thyroid function in two groups of exposed workers. Br. J. Ind. Med. 41(3): 362-366, 1984.
  • Date Last Revised: 10/19/2005

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • Two Glass Fiber Filter (37 mm) in series. Sampled open face with filters separated by spacer.
  • analytical solvent: Water
  • maximum volume: 480 Liters
  • maximum flow rate: 2.0 L/min
  • current analytical method: High Performance Liquid Chromatography; HPLC/UV
  • method reference: OSHA Analytical Method (OSHA 95)
  • method classification: Fully Validated
Bulk Method:
  • Limit the amount of bulk submitted to one gram or one mL.

** All Trademarks are the property of their respective owners.

Search Chemical Sampling Information


By Name


By CAS Number
collage image - OSHA Salt Lake Technical Center

*Accessibility Assistance: Contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300 for assistance accessing PDF materials.

All other documents, that are not PDF materials or formatted for the web, are available as Microsoft Office® formats and videos and are noted accordingly. If additional assistance is needed with reading, reviewing or accessing these documents or any figures and illustrations, please also contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300.

**eBooks - EPUB is the most common format for e-Books. If you use a Sony Reader, a Nook, or an iPad you can download the EPUB file format. If you use a Kindle, you can download the MOBI file format.

Back to Top

Thank You for Visiting Our Website

You are exiting the Department of Labor's Web server.

The Department of Labor does not endorse, takes no responsibility for, and exercises no control over the linked organization or its views, or contents, nor does it vouch for the accuracy or accessibility of the information contained on the destination server. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. Users must request such authorization from the sponsor of the linked Web site. Thank you for visiting our site. Please click the button below to continue.