Methyl parathion

Synonyms & Trade Names

Azophos®, O,O-Dimethyl-O-p-nitrophenylphosphorothioate, Parathion methyl

CAS No.

298-00-0

RTECS No.

TG0175000

DOT ID & Guide

2783 152(solid)
3018 152(liquid)

Formula

(CH₃O)₂P(S)OC₆H₄NO₂

Conversion

IDLH

N.D.
See: IDLH INDEX

Exposure Limits

NIOSH REL

TWA 0.2 mg/m³ [skin]

OSHA PEL

none See Appendix G

Measurement Methods

NIOSH 5600;
OSHA PV2112
See: NMAM or OSHA Methods

Physical Description

White to tan, crystalline solid or powder with a pungent, garlic-like odor. [pesticide] [Note: The commercial product in xylene is a tan liquid.]

Molecular Weight

263.2

Boiling Point

289°F

Melting Point

99°F

Solubility

(77°F): 0.006%

Vapor Pressure

0.00001 mmHg

Ionization Potential

Specific Gravity

1.36

Flash Point

Upper Explosive Limit

Lower Explosive Limit

Combustible Solid

Incompatibilities & Reactivities

Strong oxidizers, water [Note: Explosive risk when heated above 122°F.]

Exposure Routes

inhalation, skin absorption, ingestion, skin and/or eye contact

Symptoms

irritation eyes, skin; nausea, vomiting, abdominal cramps, diarrhea, salivation; headache, dizziness, lassitude (weakness, exhaustion); rhinorrhea (discharge of thin nasal mucus), chest tightness; blurred vision, miosis; cardiac irreg; muscle fasciculation; dyspnea (breathing difficulty)

Target Organs

Eyes, skin, respiratory system, central nervous system, cardiovascular system, blood cholinesterase

Personal Protection/Sanitation

(See protection codes)
Skin:Prevent skin contact
Eyes:Prevent eye contact
Wash skin:When contaminated/Daily
Remove:When wet or contaminated
Change:Daily
Provide:Eyewash, Quick drench

First Aid

(See procedures)
Eye:Irrigate immediately
Skin:Soap wash immediately
Breathing:Respiratory support
Swallow:Medical attention immediately

Respirator Recommendations

NIOSH

Up to 2 mg/m³:
(APF = 10) Any air-purifying half-mask respirator with organic vapor cartridge(s) in combination with an N95, R95, or P95 filter. The following filters may also be used: N99, R99, P99, N100, R100, P100.
Click here for information on selection of N, R, or P filters.
(APF = 10) Any supplied-air respirator

Up to 5 mg/m³:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode
(APF = 25) Any powered, air-purifying respirator with an organic vapor cartridge in combination with a high-efficiency particulate filter.

Up to 10 mg/m³:
(APF = 50) Any air-purifying full-facepiece respirator equipped with organic vapor cartridge(s) in combination with an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters.
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister having an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters.
(APF = 50) Any powered, air-purifying respirator with a tight-fitting facepiece and organic vapor cartridge(s) in combination with a high-efficiency particulate filter
(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece

Up to 200 mg/m³:
(APF = 2000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode

Emergency or planned entry into unknown concentrations or IDLH conditions:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus

Escape:
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister having an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters.
Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

Methyl parathion

NIOSH REL

OSHA PEL

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