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Chemical Sampling Information |
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| Chlorpyrifos |
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General Description
Synonyms: Dursban®; O,O-Diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate; Phosphorothioic acid, O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) ester
OSHA IMIS Code Number: 0681
Chemical Abstracts Service (CAS) Registry Number: 2921-88-2
NIOSH, Registry of Toxic Effects (RTECS) Identification Number: TF6300000
Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 2783 152
NIOSH Pocket Guide to Chemical Hazards, Chlorpyrifos: chemical description, physical properties, potentially hazardous incompatibilities, and more
Exposure Limits
American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 0.1 mg/m3 TWA - Inhalable fraction and vapor; Skin; Appendix A4 - Not Classifiable as a Human Carcinogen
National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 0.2 mg/m3 TWA; 0.6 mg/m3 STEL; Skin
Health Factors
Potential symptoms: Wheezing, laryngeal spasms; salivation; bluish lips, skin (cyanosis); miosis, blurred vision; nausea, vomiting, abdominal cramps, diarrhea; sweating; dizziness, convulsions, unconsciousness.
Health Effects: Cholinesterase inhibition (HE6); LD50 (oral, rat) 82 mg/kg
Affected organs: Respiratory system, CNS, peripheral nervous system, plasma cholinesterase
Notes: 1) OSHA does not have a PEL for chlorpyrifos. 2) Chlorpyrifos can be absorbed through the skin. 3) A 1-year study of chlorpyrifos manufacturing workers found a 13% lower mean plasma butyrocholinesterase activity than in a reference group (p<0.002), but no persistent symptoms of weakness or sensory deficits were reported (Albers et al., 2004). In comparison, male human volunteers taking 0.1 mg/kg/day orally for nine days showed a mean inhibition of plasma cholinesterase of about 65% (EPA). 4) Persistent sensory neuropathy with or without memory impairment was reported in cases of prolonged moderate exposure in enclosed sites fumigated with chlorpyrifos (Kaplan et al., 1993). Cases of deficits in grip strength measured seven weeks or more following hospitalization for chlorpyrifos poisoning have also been reported (Meggs, 2003; Miranda et al., 2002). 5) Desulfuration by cytochrome P450 2B6 produces the biologically active oxon metabolite, whereas dearylation by cytochrome P450 2C19 detoxifies chlorpyrifos. Detoxification occurs more rapidly than activation in human liver microsomes (Sams et al., 2004). 6) Urinary excretion of 3,5,6-trichloro-2-pyridinol has been used as a marker of occupational exposure to chlorpyrifos (Albers et al., 2004).
Date Last Revised: 05/18/2005
Literature Basis:
- NIOSH Pocket Guide to Chemical Hazards: Chlorpyrifos.
- International Chemical Safety Cards (WHO/IPCS/ILO): Chlorpyrifos.
- U.S. Environmental Protection Agency Integrated Risk Information System: Chlorpyrifos (CASRN 2921-88-2).
- Albers, J.W., Garabrant, D.H., Schweitzer, S.J., Garrison, R.P., Richardson, R.J. and Berent, S.: The effects of occupational exposure to chlorpyrifos on the peripheral nervous system: a prospective cohort study. Occup. Environ. Med. 61(3): 201-211, 2004.
- Kaplan, J.G., Kessler, J., Rosenberg, N., Pack, D. and Schaumburg, H.H.: Sensory neuropathy associated with Dursban (chlorpyrifos) exposure. Neurology 43(11): 2193-2196, 1993.
- Meggs, W.J.: Permanent paralysis at sites of dermal exposure to chlorpyrifos. J. Toxicol. Clin. Toxicol. 41(6): 883-886, 2003.
- Miranda, J., et al.: Onset of grip- and pinch-strength impairment after acute poisonings with organophosphate insecticides. Int. J. Occup. Environ. Health 8(1): 19-26, 2002.
- Pohanish, R.P. (editor): Chlorpyrifos. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 602-604.
- Sams, C., Cocker, J. and Lennard, M.S.: Biotransformation of chlorpyrifos and diazinon by human liver microsomes and recombinant human cytochrome P450s (CYP). Xenobiotica 34(10): 861-873, 2004.
Monitoring Methods used by OSHA
Laboratory Sampling/Analytical Method:
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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 Analytical Method (OSHA 62)
method classification: Fully Validated
note: OSHA personnel may obtain sampling tubes from SLTC.
Wipe sampling: Yes, with Glass Fiber Filter.
Bulk method: Limit the amount of bulk submitted to one gram or one mL.
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