Chemical of the Week Part 2 - Methyl Parathion

Hazard Profile

Chemical Name and Pseudonyms

Methyl Parathion, O,O-Dimethyl-O-(p-nitrophenyl) phosphorothioate, phosphorothioic acid, Azophos, Parathion Methyl

UN Number

2783 (solid), 3018 (liquid)

Chemical Formula

(CH₃O)₂P(S)OC₅H₄NO₂

Hazards

Toxic

PPE Considerations

SFPC, Splash Protective Garment, multi-threat ensemble with SCBA

Fire Fighting Considerations

Water, CO ₂, dry chemical. Control runoff.  Consider non-extinguishment / non-intervention if involved in fire.

Decontamination

Soap and water

Detection and Monitoring

Colormetric, chemical/physical reactive assessment

Chemical and Physical Properties

Physical State

White-tan crystal solid or powder with a pesticide-like odor

Vapor Pressure

~.00001 mmHg

Boiling Point

~289^oF

Vapor Density

~9.1

Specific Gravity

~1.5

Miscibility

Soluble in water

Flash Point

N/A, but may be dissolved in solvents that have flash point

LEL/UEL

N/A, but may be dissolved in solvents that have LEL/UEL

Autoignition Temp

-

pH

-

Toxicity

IDLH

~25 ppm

PEL/REL/STEL

.02 mg/m³ /.2 mg/m³ /-

LD50

50 mg/kg

LC50

-

Radioactive (Yes/No)

No

Medical

Toxicological Considerations

Toxic by all routes. 

Signs/Symptoms of Exposure

Salivation, vomiting, abdominal pain, CNS, blurred vision, fasciculations, miosis, cardiac (SLUDGEM/DUMBBELLS)

Medical Treatment

Fresh air and treat symptomatically, flush areas of contact with water, organophosphate toxidrome protocol

Other Information

Strong oxidizers, water.  Explosive risk if heated.

Chemical Structure

https://pubchem.ncbi.nlm.nih.gov/compound/Methyl-parathion