Methyl parathion

  • Phosphorothioic acid, O,O-dimethyl O-(4-nitrophenyl) ester
  • O,O-Dimethyl O-4-nitrophenyl phosphorothioate
  • Metron
  • Metaphos
  • p-Nitrophenylthionophosphate
  • Parathion-Methyl
Formula
C8H10NO5PS
Structure
Description
Methyl parathion is a white crystalline solid.
Uses
It controls aphids, boll weevils, & mites esp well, although its spectrum for control of insects is nearly as broad as parathion.

Registry Numbers and Inventories.
CAS
298-00-0
EC (EINECS/ELINCS)
206-050-1
EC Index Number
015-035-00-7
EC Class
Very toxic; Toxic
RTECS
TG0175000
RTECS class
Agricultural Chemical and Pesticide; Tumorigen; Mutagen; Reproductive Effector
UN (DOT)
2783
Merck
12,6183
Beilstein/Gmelin
1914724
Beilstein Reference
4-06-00-01336
RCRA
P071
EPA OPP
53501
Swiss Giftliste 1
G-2517
Austrailia AICS
Listed
New Zealand
Listed

Properties.
Formula
C8H10NO5PS
Formula mass
263.21
Melting point, °C
36
Boiling point, °C
335
Vapor pressure, mmHg
0.00024 (25 C)
Vapor density (air=1)
1.358
Odor Threshold Odor threshold 0.1328 mg/m3
Density
1.358 g/cm3 (20 C)
Solubility in water
55 mg/L
Refractive index
1.56 (25 C)
Partition coefficient, pKow
2.86
Heat of vaporization
55.5 kJ/mol

Hazards and Protection.
Storage
Keep in a cool, dry, dark location in a tightly sealed container or cylinder. Keep away from incompatible materials, ignition sources and untrained individuals. Secure and label area. Protect containers/cylinders from physical damage.
Handling
All chemicals should be considered hazardous. Avoid direct physical contact. Use appropriate, approved safety equipment. Untrained individuals should not handle this chemical or its container. Handling should occur in a chemical fume hood.
Protection
Wear appropriate protective gloves, clothing and goggles.
Respirators
Wear positive pressure self-contained breathing apparatus (SCBA).
Small spills/leaks
Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. Cover with plastic sheet to prevent spreading. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. DO NOT GET WATER INSIDE CONTAINERS.
Stability
Moderate at 120 C, hazardous in xylene reactive only under extreme conditions.
Incompatibilities
It reacts violently with oxidizing agents. Avoid contact with strong oxidizers, water.
Decomposition
When heated to decomposition it emits very toxic fumes of nitrogen oxides, phosphorous oxides and sulfur oxides.

Fire.
Flash Point,°C
156
Fire fighting
SMALL FIRES: Dry chemical, carbon dioxide or water spray. LARGE FIRES: Water spray, fog or regular foam. Move containers from fire area if you can do it without risk. Dike fire control water for later disposal; do not scatter the material. Use water spray or fog; do not use straight streams. FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn.
Fire potential
May burn but does not ignite readily.
Hazards
Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form.
Combustion products
Poisonous gases are produced in fire and when heated.

Health.
Exposure limit(s)
TLV: 0.2 mg/m3 (as TWA) A4 (skin) (ACGIH 1997). NIOSH REL: TWA 0.2 mg/m3 skin
Poison_Class
2
Exposure effects
Fever, low heart rate and abnormally low blood pressure, or rapid heart rate and elevated blood pressure may occur. Headache, dizziness, muscle spasms and profound weakness are common. Alterations of level of consciousness, anxiety, paralysis, seizures and coma may occur. Seizures may be more common in children.
   Ingestion
Vomiting, hypersalivation, diarrhea, fecal incontinence and abdominal pain may occur.
   Inhalation
Dyspnea, rales, bronchorrhea, bronchospasm, or tachypnea may be noted. Noncardiogenic pulmonary edema may occur in severe cases. Chemical pneumonitis may be seen.
   Skin
Sweating is a consistent but not universal sign.
   Eyes
Constriction of the pupil, tearing, and blurred vision are common. Prolonged dialation of the pupils may occur in severe poisonings. Opsoclonus has been reported in one case. Salivation commonly occurs. Eye irritation may occur with direct contact.

First aid
 
   Ingestion
Seek medical assistance.
   Inhalation
Move victim to fresh air. Apply artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; induce artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult.
   Skin
Remove and isolate contaminated clothing and shoes. Immediately flush with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin.
   Eyes
Immediately flush with running water for at least 20 minutes.

Transport.
UN number
2783
Response guide
Hazard class
6.1
Packing Group
I; II; III
 
USCG CHRIS Code
MPT
 
Std. Transport #
4921443