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Chemical Sampling Information (CSI)
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General Description

Synonyms: Paraquat dichloride; 1,1'-Dimethyl-4,4'-bipyridinium dichloride; Paraquat dimethyl sulfate; 1,1'-Dimethyl-4,4'-bipyridinium bis (methylsulfate)

OSHA IMIS Code Number: 1982

Chemical Abstracts Service (CAS) Registry Number: 4685-14-7

Other Chemical Abstracts Service (CAS) Registry Numbers: 2074-50-2 (Paraquat dimethyl sulfate); 1910-42-5 (Paraquat dichloride)

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: DW2275000

NIOSH Pocket Guide to Chemical Hazards, Paraquat (Paraquat dichloride): chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

OSHA Permissible Exposure Limit (PEL):

General Industry: 29 CFR 1910.1000 Table Z-1 -- 0.5 mg/m3 TWA; Skin

Construction Industry: 29 CFR 1926.55 Appendix A -- 0.5 mg/m3 TWA; Skin

Maritime: 29 CFR 1915.1000 Table Z-Shipyards -- 0.5 mg/m3 TWA; Skin

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 0.5 mg/m3 TWA; 0.1 mg/m3 TWA - Respirable fraction

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 0.1 mg/m3 TWA; Skin

Health Factors

NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 1 mg/m3

Potential Symptoms: Irritation of eyes, skin, nose, throat, respiratory system; headache; cough; epistaxis (nosebleeds); lung edema; shortness of breath, labored breathing (lung fibrosis, may be delayed several days); dermatitis; fingernail damage; GI tract irritation; heart, liver, kidney damage; opacification of the cornea (upon direct eye contact); INGES ACUTE: Sore throat; ulceration of mouth and esophagus; abdominal pain; nausea, vomiting, diarrhea

Health Effects: Cumulative lung damage (HE10); Suspect dopaminergic neurotoxin---parkinsonism (HE7); Suspect teratogen (HE5); Irritation-Eye, Nose, Throat, Skin---Moderate (HE15)

Affected Organs: Eyes, respiratory system, heart, liver, kidneys, GI tract, CNS (nigrostriatal tract)


  1. The major cause of death is respiratory failure due to oxidative damage to lung alveolar epithelium with subsequent obliterating fibrosis.
  2. Chemically similar to MPP+ (1-methyl-4-phenylpyridinium) which was marketed as the herbicide cyperquat and found to cause Parkinson's disease.
  3. Epidemiological and animal studies with paraquat indicate a specific dopaminergic neurotoxicity that could potentially lead to parkinsonism.

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Paraquat (Paraquat dichloride).
  • International Chemical Safety Cards (WHO/IPCS/ILO): Paraquat dichloride.
  • Hertzman, C., Wiens, M., Bowering, D., Snow, B. and Caine D.: Parkinson's disease: a case-control study of occupational and environmental risk factors. Am. J. Ind. Med. 17(3): 349-355, 1990.
  • McCormack, A.L., et al.: Environmental risk factors and Parkinson's disease: selective degeneration of nigral dopaminergic neurons caused by the herbicide paraquat. Neurobiol. Dis. 10(2): 119-127, 2002.
  • Pohanish, R.P. (editor): Paraquat. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1784-1787.
  • Ranjbar, A., Pasalar, P., Sedighi, A. and Abdollahi, M.: Induction of oxidative stress in paraquat formulating workers. Toxicol. Lett. 131(3): 191-194, 2002.
  • Suntres, Z.E.: Role of antioxidants in paraquat toxicity. Toxicology 180(1): 65-77, 2002.

Date Last Revised: 07/09/2004

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Polytetrafluoroethylene (FA) Filter, 1.0 micron
    maximum volume: 1000 Liters
    maximum flow rate: 4.0 L/min
    current analytical method: High Performance Liquid Chromatography; HPLC/UV
    method reference: NIOSH Analytical Method (NIOSH 5003 [17 KB PDF, 3 pages])
    method classification: Fully Validated

Bulk Method:

  • Limit the amount of bulk submitted to one gram or one mL.

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