What is White Phosphorus?

White phosphorus is a colourless-to-white waxy solid with a garlic-like smell that is flammable in the air and glows in the dark.

Phosphorus is a non-metallic chemical element with symbol P and atomic number 15. As a mineral, it is almost always present in its maximally oxidised state, as inorganic phosphate rocks. Elemental phosphorus exists in two major forms—white phosphorus and red phosphorus—but due to its high reactivity, phosphorus is never found as a free element on Earth.

Pure white phosphorus is a colourless-to-white waxy solid, but commercial white phosphorus is usually yellow. Therefore, it is also known as yellow phosphorus. White phosphorus is also called phosphorus tetramer and has a garlic-like smell. In air, it catches fire at temperatures l0–15 degrees above room temperature. Because of its high reactivity with oxygen in air, white phosphorus is generally stored under water. White phosphorus does not occur naturally. Industries produce it from naturally occurring phosphate rocks. White phosphorus glows in the dark (when exposed to oxygen) with a very faint tinge of green and blue.

What is White Phosphorus used for?

White phosphorus is mainly used to produce phosphoric acid and other chemicals, which are used in fertilisers, food and drink additives, and cleaning products. Small amounts are used in rat and roach poisons and fireworks. Formerly used in match production, it has been replaced by a less harmful chemical. White phosphorus is also used in military ammunition, such as mortar shells, artillery, and grenades.

White Phosphorus In The Environment

White phosphorus can enter the environment through manufacturing, military use, or accidental spills during transport. It can be found in water and sediment near facilities that produce or use it. In air, white phosphorus quickly reacts with oxygen to form harmless chemicals. In water, it breaks down within hours or days, but in low-oxygen water, it can form toxic phosphine gas, which eventually evaporates and transforms into less harmful substances. White phosphorus can accumulate slightly in fish, and in soil, it binds to particles and transforms into less harmful compounds within days. However, in deep or oxygen-poor soils, it can remain unchanged for years.

Sources and Routes of Exposure

Sources of Emission

• Breathing contaminated air near facilities using white phosphorus.
• Eating fish or game from areas with white phosphorus contamination.
• Drinking or swimming in contaminated water.
• Contacting contaminated soil.
• Working in industries using or producing white phosphorus or related munitions.

Routes of Exposure

White phosphorus enters the body through inhalation, ingestion, or skin contact. Systemic exposure via eye contact is unknown.

Health Effects

Acute Effects

• Ingestion: Acute oral exposure has three stages: gastrointestinal symptoms, a symptom-free period, then a rapid decline with severe gastrointestinal, kidney, liver, heart, and CNS effects.
• Inhalation: Causes respiratory irritation and coughing. Animal studies show effects on the respiratory system, liver, and kidneys.
• Skin Contact: Causes severe burns with a garlic-like odour and yellowish appearance.
• Animal Studies: Rats and mice exhibit extreme toxicity from oral exposure.

Chronic Effects

• Human Exposure: Chronic exposure can lead to jaw necrosis, known as "phossy jaw," which progresses from inflammation to jawbone destruction. Anaemia and leukopenia have been observed.
• Animal Exposure: Blood effects have been reported in animals after inhalation exposure.
• Reference Dose (RfD): Set at 0.00002 mg/kg/day based on reproductive effects. CalEPA’s inhalation reference level is 0.00007 mg/m³.
• Minimal Risk Level (MRL): For acute inhalation, set at 0.02 mg/m³ based on respiratory effects in humans.

Reproductive/Developmental Effects

• Human Studies: No available data.
• Animal Studies: High maternal mortality reported after oral exposure.

Cancer Risk

No available data on carcinogenicity in humans or animals. White phosphorus is classified as Group D by the EPA, meaning it’s not classifiable as to human carcinogenicity.

White Phosphorus Safety

First Aid Measures

• Inhalation: Move to fresh air. If not breathing, administer artificial respiration. Get emergency help if necessary.
• Skin Contact: Immerse affected areas in water and seek immediate medical attention. Remove contaminated items.
• Eye Contact: Rinse eyes with water for 15 minutes, ensuring thorough irrigation. Get immediate medical help.
• Ingestion: Do not induce vomiting. Give water, keep the airway clear, and get immediate medical attention.

Fire & Explosion Information

• Fire Hazard: White phosphorus is highly flammable and ignites upon air exposure. Contaminated water can ignite if dried.
• Extinguishing Media: Use foam, water, wet sand, or earth. Avoid alkaline agents.
• Firefighting: Move containers from the fire if safe. Cool containers with water spray. Avoid inhaling combustion products, and use a self-contained breathing apparatus.

Exposure Controls & Personal Protection

Engineering Controls

Use closed systems and exhaust ventilation to keep exposure below limits. Ensure proximity to emergency eye wash stations and showers.

Personal Protective Equipment

• Eye Protection: Splash-resistant goggles with a face shield.
• Skin Protection: Chemical-resistant clothing and rubber boots. In some cases, a full body suit may be required.
• Hand Protection: Chemical-resistant gloves.
• Respiratory Protection: Supplied air respirators are required unless there’s no phosphine or phosphorus pentoxide. Use a respirator with N95 filters if expected exposure exceeds limits. Follow a respiratory protection program as required.

Regulation

Occupational Exposure Limits

United States

EPA: The Environmental Protection Agency has listed white phosphorus as a Hazardous Air pollutant. The EPA requires that spills or accidental releases into the environment of 1 pound or more of white phosphorus be reported to the EPA.

The National Institute for Occupational Safety and Health (NIOSH), the Occupational Safety and Health Administration (OSHA), and the American Conference of Governmental Industrial Hygienists (ACGIH) have all set the inhalation exposure limit for white phosphorus in the workplace during an 8-hour workday at 0.1 milligram of white phosphorus per cubic meter of air (0.1 mg/m³).

Australia

Safe Work Australia: Safe Work Australia has set an 8-hour Time Weighted Average (TWA) concentration of 0.1 mg/m³.