Product Identification

Product Name

Sodium methylarsonate

Synonyms

Ansar
Ansar 6.6
Methanearsonic acid, monosodium salt
Monosodium methylarsonate
MSMA
Weed 108

CAS

2163-80-6

Formula

CH4AsNaO3

Molecular Weight

161.94999999999999

EINECS

218-495-9

RTECS

PA2625000

RTECS Class

Agricultural Chemical and Pesticide; Organometallic; Mutagen; Primary Irritant

Beilstein/Gmelin

3915729

Beilstein Reference

2-04-00-00996

Physical and Chemical Properties

Appearance

Odorless colorless solid. Solution may be red or green.

Solubility in water

1 kg/L @ 20 C

Melting Point

113-116 (sesquihydrate);132- 139(hexahydrate)

Density

1.535 g/cm3 (25 C)

pKa/pKb

9.02 (pKa)

Partition Coefficient

< 1

Heat Of Vaporization

Usage

Herbicide.

Odor threshold

Odorless

First Aid Measures

Ingestion

Seek medical attention. If individual is drowsy or unconscious, do not give anything by mouth; place individual on the left side with the head down. Contact a physician, medical facility, or poison control center for advice about whether to induce vomiting. If possible, do not leave individual unattended.

Inhalation

IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used.

Skin

IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. If symptoms such as redness or irritation develop, IMMEDIATELY call a physician and be prepared to transport the victim to a hospital for treatment.

Eyes

First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

Handling and Storage

Storage

Solid formulations are somewhat hygroscopic and should be stored in dry place. Methanearsonic acid

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.

Hazards Identification

Inhalation

Respiratory tract irritation may occur. Cardiogenic or noncardiogenic pulmonary edema and respiratory failure may develop in severe poisonings.

Skin

Skin findings may include hyperpigmentation, keratoses, and epidermoid carcinomas. Mee's lines of the nails are common. Trivalent arsenic compounds are corrosive to the skin. Arsenic trioxide and pentoxide are sensitizers.

Eyes

As(III) is corrosive to the eyes, mouth, and mucous membranes. Perforation of the nasal septum can occur.

Ingestion

Acute toxicity results in early symptoms of abdominal pain, severe vomiting and diarrhea, as well as dryness of the oral and nasal cavities.

Exposure Controls/Personal Protection

Personal Protection

Protective gloves rubber or neoprene, goggles, or face shield for eye protection, rubber apron. Long pants, long-sleeved shirt, impermeable gloves, boots for handling or applying. Mixer-loaders should wear an apron and full-face shield for handling, mixing concentrate. Flagmen should be fully protected during spray operations or use mechanical flagmen. Pilots and ground spray rig applicators should wear a mask or approved respirator.

Respirators

Use NIOSH/MSHA approved respirator appropriate for exposure of concern.

Exposure Effects

Abnormally low blood pressure and rapid heart rate are common early signs. Fever and rapid breathing may occur. Elevated blood pressure has been associated with chronic environmental arsenic exposure. Altered mental status, seizures, toxic delirium, encephalopathy, and delayed peripheral neuropathy are complications of acute arsenic poisoning. Inorganic arsenic crosses the placenta and may result in spontaneous abortion or stillbirth with either acute or chronic poisoning.

Exposure limit(s)

OSHA: PEL (8 h TWA): 0.5 mg/m3.

Poison Class

3

Fire Fighting Measures

Fire Fighting

Fires involving this compound should be controlled with a dry chemical, carbon dioxide or Halon extinguisher.

Fire Potential

Non-flammable.

Accidental Release Measures

Small spills/leaks

If you spill this chemical, you should dampen the solid spill material with water, then transfer the dampened material to a suitable container. Use absorbent paper dampened with water to pick up any remaining material. Seal your contaminated clothing and the absorbent paper in a vapor-tight plastic bag for eventual disposal. Wash all contaminated surfaces with a strong soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

Stability and Reactivity

Stability

Stable to hydrolysis.

Combustion Products

Toxic gases may be generated in fires.