Phosphine

Classification

Flammable gas, Category 1; Pyrophoric gas; Self-heating substance, Category 1; Gas under pressure (liquefied gas); Acute toxicity (inhalation), Category 1; Skin corrosion, Category 1B; Serious eye damage, Category 1; Hazardous to the aquatic environment (acute), Category 1 (per the Sigma-Aldrich SDS)

Hazard statements

• H220 Extremely flammable gas.
• H250 Catches fire spontaneously if exposed to air.
• H251 Self-heating; may catch fire.
• H280 Contains gas under pressure; may explode if heated.
• H314 Causes severe skin burns and eye damage.
• H330 Fatal if inhaled.
• H400 Very toxic to aquatic life.

Key precautionary statements

• P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
• P260 Do not breathe gas.
• P271 Use only outdoors or in a well-ventilated area.
• P280 Wear protective gloves, protective clothing, eye protection and face protection.
• P284 Wear respiratory protection.
• P304+P340+P310 IF INHALED: Remove person to fresh air and keep comfortable for breathing. Immediately call a POISON CENTER or doctor.
• P377 Leaking gas fire: Do not extinguish, unless leak can be stopped safely.
• P403+P233 Store in a well-ventilated place. Keep container tightly closed.
• P405 Store locked up.

The OSHA PEL is 0.3 ppm as an 8-hour TWA (29 CFR 1910.1000 Table Z-1). NIOSH recommends 0.3 ppm TWA with a 1 ppm STEL, and Cal/OSHA uses the same pair. ACGIH set a much lower TLV in 2017: 0.05 ppm TWA and 0.15 ppm STEL. The NIOSH IDLH is 50 ppm. No skin notation is assigned. Published odor thresholds vary and smell is not a reliable warning, so rely on instruments. State OSHA plans may set different limits.

• Appearance: Colorless gas, shipped as a liquefied compressed gas
• Odor: Fish- or garlic-like; not a reliable warning
• Molecular weight: 34.0
• Boiling point: -126°F (-88°C)
• Freezing point: -209°F (-134°C)
• Flash point: Not applicable (flammable gas); can ignite spontaneously in air
• Explosive limits: LEL 1.79%; UEL not established
• Vapor pressure: 41.3 atm
• Relative gas density: 1.18 (heavier than air)
• Water solubility: Slight

Inhalation

The main route of exposure. Causes nausea, vomiting, stomach pain, diarrhea, thirst, chest tightness, shortness of breath, muscle pain, chills and fainting. Higher exposures cause fluid in the lungs (pulmonary edema), which can be delayed, and can lead to coma and death.

Skin

Contact with the liquefied gas causes frostbite.

Eyes

Liquid contact causes frostbite. The supplier SDS classifies phosphine as causing serious eye damage.

Ingestion

Not a likely route for the gas. Swallowing metal phosphide pesticides releases phosphine inside the body and is a medical emergency.

Target organs

Respiratory system; NJDOH also notes possible liver and kidney damage

Long-term effects

Repeated exposure may cause bronchitis.

Where exposure happens

Phosphine is released when aluminum, magnesium or zinc phosphide pesticides contact moisture or acids, so fumigation of grain, ship holds, containers and buildings is a common source. See zinc phosphide exposure. It is also used as a dopant gas in semiconductor manufacturing.

Gloves

Chemical-resistant gloves chosen with the supplier's help. Use insulated gloves where liquefied gas could be contacted.

Eyes and face

Non-vented goggles; add a face shield where the liquid or a release could reach the face.

Respiratory

NIOSH lists supplied-air respirators at almost every level: any supplied-air respirator up to 3 ppm, continuous-flow supplied air up to 7.5 ppm, and full-facepiece gas masks with phosphine canisters, SCBA or supplied air up to 15 ppm. Above that, or at unknown levels, use a pressure-demand full-facepiece SCBA. Fumigant labels may set their own respirator rules. See respiratory protection.

Clothing

Flame-resistant, antistatic clothing where gas cylinders are handled.

Store cylinders upright and secured in a cool, dry, well-ventilated area away from moisture, heat and ignition sources, and protect them from damage. Ground and bond metal containers, use non-sparking tools, and use continuous gas detection where phosphine is used or generated.

Keep metal phosphide fumigants dry and sealed, because moisture or acid releases phosphine. Treat fumigated spaces such as silos, holds and containers as permit-required confined spaces until testing shows they are clear.

Keep away from

• Air and oxygen (may ignite spontaneously)
• Oxidizers, including chlorine and other halogens
• Acids, including nitric acid
• Moisture
• Halogenated hydrocarbons
• Copper

• Evacuate and isolate the area. Stay upwind and keep out of low areas.
• Remove all ignition sources; the gas may ignite on its own.
• Only trained responders wearing SCBA should approach a leak.
• Stop the flow if it is safe. If a cylinder cannot be stopped, move it outdoors to a safe place and let it empty or repair it.
• Keep gas out of sewers and confined spaces.
• Follow ERG Guide 119.

Suitable extinguishing media

• Do not put out a leaking gas fire unless the leak can be stopped safely
• Water spray or fog
• Regular foam
• Do not use halogenated extinguishing agents

Special hazards

Extremely flammable and may ignite on contact with air. Gas can travel to an ignition source and flash back. Cylinders may explode when heated. Fires produce toxic phosphorus oxides. Firefighters should wear SCBA and full protective gear.

• OSHA Hazard Communication (29 CFR 1910.1200): Hazardous chemical; SDS, labels and training required.
• OSHA Air Contaminants (29 CFR 1910.1000 Table Z-1): 0.3 ppm (0.4 mg/m³) TWA.
• OSHA Process Safety Management (29 CFR 1910.119 Appendix A): Threshold quantity 100 lb.
• CERCLA (40 CFR 302.4): Hazardous substance, reportable quantity 100 lb (RCRA waste P096).
• EPCRA Section 302 (40 CFR 355 Appendix A): Extremely hazardous substance, threshold planning quantity 500 lb, reportable quantity 100 lb.
• Clean Air Act 112(r) (40 CFR 68.130): Threshold quantity 5,000 lb. Also a listed hazardous air pollutant.
• Pesticide use: Phosphine-generating fumigants are EPA-registered pesticides; follow the product label and fumigation management plan.
• DOT (49 CFR 172.101): UN2199, Phosphine, Division 2.3 with subsidiary 2.1; Poison Inhalation Hazard, Zone A.

• NIOSH Pocket Guide: Phosphine
• OSHA Occupational Chemical Database: Phosphine
• Sigma-Aldrich SDS: Phosphine
• NJ Department of Health Hazardous Substance Fact Sheet: Phosphine (Spanish edition)
• NJ Department of Health Hazardous Substance Fact Sheet: Aluminum Phosphide
• CAMEO Chemicals: UN2199 (DOT and ERG data)
• 40 CFR 302.4, CERCLA hazardous substances