- 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
- National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): Use encapsulated form. Appendix A - NIOSH Potential Occupational Carcinogens
- Carcinogenic Classification:
- Environmental Protection Agency (EPA): Group B2, probable human carcinogen
- International Agency for Research on Cancer (IARC): Group 3, not classifiable as to its carcinogenicity to humans
- National Toxicology Program (NTP): Reasonably anticipated to be a human carcinogen (PDF)
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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).
- 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
- Limit the amount of bulk submitted to one gram or one mL.
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