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Chemical Sampling Information (CSI)
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General Description

Synonyms: Phosphorodithioic acid o,o-diethyl s-[2-(ethylthio)ethyl] ester; O,O-Diethyl S-2-(ethylthio)-ethyl phosphorodithioate; Di-Syston®; Thiodemeton

OSHA IMIS Code Number: 2680

IMIS Name History: Disyston prior to 9/1/89

Chemical Abstracts Service (CAS) Registry Number: 298-04-4

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: TD9275000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 2783 152

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

Exposure Limits

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 0.05 mg/m3 TWA; Inhalable Fraction and Vapor; Skin; Appendix A4 - Not Classifiable as a Human Carcinogen; BEIA: see BEI® for Acetylcholinesterase Inhibiting Pesticides

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

Health Factors

Potential Symptoms: Eye, skin irritation, nausea, vomiting, abdominal cramps, diarrhea; salivation; headache, dizziness, lassitude (weakness, exhaustion); rhinorrhea (discharge of thin mucus), chest tightness; miosis, blurred vision; cardiac and blood pressure irregularities; muscle fasciculation; dyspnea (breathing difficulty); eye, skin burns; convulsions, unconsciousness

Health Effects: Cholinesterase inhibition (HE6); LD50 (oral, rat) 2-12 mg/kg

Affected Organs: Eyes, skin, respiratory system, CNS, cardiovascular system, blood cholinesterase


  1. OSHA does not have a PEL for disulfoton.
  2. EPA's oral reference dose (daily oral exposure likely to be without an appreciable risk of deleterious effects during a lifetime) is 0.00004 mg/kg/day.
  3. Disulfoton is metabolized to disulfoton sulfoxide by several hepatic cytochrome P450s, predominantly by CYP2C9 and CYP2C19.
  4. Disulfoton is also metabolized to disulfoton sulfoxide by the lung enzyme allele, flavin-containing monooxygenase FMO2*1.
  5. Biomarkers of exposure include measurement of cholinesterase activity in blood plasma and in red blood cells.

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Disulfoton.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Disulfoton.
  • US EPA Integrated Risk Information System: Disulfoton (CASRN 298-04-4).
  • Henderson, M.C., Krueger, S.K., Siddens, L.K., Stevens, J.F. and Williams, D.E.: S-oxygenation of the thioether organohosphate insecticides phorate and disulfoton by human lung flavin-containing monooxygenase 2. Biochem. Pharmacol. 68(5): 959-967, 2004.
  • Pohanish, R.P. (editor): Disulfoton. Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 991-993.
  • Usmani, K.A., Karoly, E.D., Hodgson, E. and Rose, R.L.: In vitro sulfoxidation of thioether compounds by human cytochrome P450 and flavin-containing monooxygenase isoforms with particular reference to the CYP2C family. Drug Metab. Dispos. 32(3): 333-339, 2004.

Date Last Revised: 08/01/2005

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: OSHA Versatile Sampler (OVS-2) - 13 mm XAD-2 tube (270/140 mg sections, 20/60 mesh) with Glass Fiber Filter enclosed
    maximum volume: 480 Liters
    maximum flow rate: 1.0 L/min
    current analytical method: Gas Chromatography; GC/FPD
    method reference: OSHA (In-House File)
    method classification: Partially Validated
    note: OSHA personnel may obtain sampling tubes from the Salt Lake Technical Center.

Conditions: Toluene extraction; (30 meter x 0.53 mm i.d.) DB-210 megabore Oven T = 150-200°C at 8 deg/min; Inj T = 200°C; Det T = 300°C; DL 0.6 ng/inj; C/P KM

Wipe Sampling Method:

  • sampling media: Glass Fiber Filter

Bulk method:

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

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