White phosphorus (weapon)

This article is about the military applications of white phosphorus. For more general information, see Phosphorus.

White phosphorus is a common allotrope of the chemical element phosphorus which has found extensive military application as an incendiary agent , smoke-screening agent, and as an antipersonnel flame compound capable of causing serious burns. It has been called a chemical weapon by many people and organizations. It is commonly referred to in military jargon as "WP". The Vietnam War era slang "Willy(ie) Pete" or "Willy(ie) Peter" is still occasionally heard.

Applications

Smoke-screening agent

Weight-for-weight, phosphorus is the most effective smoke-screening agent known, for two reasons:

It absorbs most of the screening mass from the surrounding atmosphere; and
The smoke particles are actually an aerosol, a mist of liquid droplets which are close to the ideal range of sizes for Mie scattering of visible light. This effect has been likened to three dimensional textured privacy glass—the smoke cloud does not obstruct an image, but thoroughly scrambles it. It also absorbs infrared radiation.

When phosphorus burns in air, it first forms phosphorus pentoxide (which exists as tetraphosphorus decoxide except at very high temperatures):

P₄ + 5 O₂ → P₄O₁₀

However phosphorus pentoxide is extremely hygroscopic and quickly absorbs even minute traces of moisture to form liquid droplets of phosphoric acid:

P₄O₁₀ + 6 H₂O → 4 H₃PO₄ (also forms polyphosphoric acids such as pyrophosphoric acid, H₄P₂O₇)

Since an atom of phosphorus has an atomic mass of 31 but a molecule of phosphoric acid has a molecular mass of 98, the cloud is already 68% by mass derived from the atmosphere. (To put that another way, you have 3.2 kilograms of smoke for every kilogram of WP you started with.) But it can still absorb more; phosphoric acid itself and the various polyphosphoric acids are hygroscopic. Given time, the droplets will continue to absorb more water, growing larger and more dilute, until they reach equilibrium with the local water vapour pressure. In practice the droplets quickly reach a range of sizes very suitable for scattering visible light, and then start to dissipate due to wind or convection.

Because of the great weight efficiency of WP smoke, it is particularly suited for applications where weight is highly restricted, such as hand grenades and mortar bombs. An additional advantage for hand smoke grenades—which are more likely to be used in an emergency—is that the WP smoke clouds form in a fraction of a second. Because WP is also pyrophoric, most munitions of this type have a simple burster charge to split open the casing and spray fragments of WP through the air, where they ignite spontaneously and leave a trail of rapidly thickening smoke behind each particle. The appearance of this cloud forming is easily recognised; one sees a shower of burning particles spraying outward, followed closely by distinctive streamers of white smoke, which rapidly coalesce into a fluffy, very pure white cloud (unless illuminated by a coloured light source).

Various disadvantages of WP are discussed below, but one which is particular to smoke-screening is "pillaring". Because the WP smoke is formed from fairly hot combustion, the gasses in the cloud are hot, and tend to rise. Consequently the smoke screen tends to rise off the ground relatively quickly and form aerial "pillars" of smoke which are of little use for screening. Tactically this may be counteracted by using WP to get a screen quickly, but then following up with emission type screening agents for a more persistent screen. Some countries have begun using red phosphorus instead. Red phosphorus ("RP") burns cooler than WP and eliminates a few other disadvantages as well, but offers exactly the same weight efficiency. Other approaches include WP soaked felt pads (which also burn more slowly, and pose a reduced risk of incendiarism) and PWP, or plasticised white phosphorus.

Effects on humans

Effects of exposure to WP weapons

Incandescent particles of WP cast off by a WP weapon's initial explosion can produce extensive, deep (second and third degree), painful burns. Phosphorus burns carry a greater risk of mortality than other forms of burns due to the absorption of phosphorus into the body through the burned area, resulting in liver, heart and kidney damage, and in some cases multi-organ failure. ^* These weapons are particularly dangerous to exposed people because white phosphorus continues to burn unless deprived of oxygen or until it is completely consumed, in some cases burning right down to the bone. In some cases, burns may be limited to areas of exposed skin because the smaller WP particles do not burn completely through personal clothing before being consumed. According to GlobalSecurity.org, quoted by "The Guardian", "White phosphorus results in painful chemical burn injuries" .

Exposure and inhalation of smoke

Burning WP produces a hot, dense white smoke. Most forms of smoke are not hazardous in the kinds of concentrations produced by a battlefield smoke shell. However, exposure to heavy smoke concentrations of any kind for an extended period (particularly if near the source of emission) does have the potential to cause illness or even death.

WP smoke irritates the eyes and nose in moderate concentrations. With intense exposures, a very explosive cough may occur. However, no recorded casualties from the effects of WP smoke alone have occurred in combat operations and to date there are no confirmed deaths resulting from exposure to phosphorus smokes. The Agency for Toxic Substances and Disease Registry has set an acute inhalation Minimum Risk Level (MRL) for white phosphorus smoke of 0.02mg/m³, the same as fuel oil fumes. (By contrast, the chemical weapon mustard gas is 30 times more potent: 0.0007 mg/m³.)

Oral ingestion

The accepted lethal dose when white phosphorus is ingested orally is 1 mg/kg, although the ingestion of as little as 15 mg has resulted in death. It may also cause liver, heart or kidney damage. There are reports of individuals with a history of oral ingestion who have passed phosphorus-laden stool ("smoking stool syndrome").

Arms control status

Use of white phosphorus against military targets (outside civilian areas) is not specifically banned by any treaty. However, there is a debate on whether white phosphorus should be considered a chemical weapon and thus be outlawed by the Chemical Weapons Convention (CWC) which went into effect in April of 1997. The Convention is meant to prohibit weapons that are "dependent on the use of the toxic properties of chemicals as a method of warfare" (Article II, Definitions, 9, "Purposes not Prohibited" c.). The Convention defines a "toxic chemical" as a chemical "which through its chemical action on life processes can cause death, temporary incapacitation or permanent harm to humans or animals".(CWC, II). Because its effects are physical and not chemical, WP was not included in the CWC's original annex listing chemicals that fell under this definition for purposes of verification.CWC: Annex on Chemicals on a USDOD web site

However, in 2005, interviewed by the RAI, Peter Kaiser, spokesman for the UN Organisation for the Prohibition of Chemical Weapons, which oversees the CWC, publicly questioned whether the weapon should fall under the convention's provisions: "No it's not forbidden by the CWC if it is used within the context of a military application which does not require or does not intend to use the toxic properties of white phosphorus. White phosphorus is normally used to produce smoke, to camouflage movement. If that is the purpose for which the white phosphorus is used, then that is considered under the Convention legitimate use. If on the other hand the toxic properties of white phosphorus are specifically intended to be used as a weapon, that of course is prohibited, because the way the Convention is structured or the way it is in fact applied, any chemicals used against humans or animals that cause harm or death through the toxic properties of the chemical are considered chemical weapons."

Some opponents have argued that because of its incendiary effects, WP is potentially restricted by the 1980 Convention on Conventional Weapons (Protocol III), which prohibits the use of air-delivered incendiary weapons against civilian populations or indiscriminate incendiary attacks against military forces co-located with civilians. However, that protocol also specifically excludes weapons whose incendiary effects are secondary, such as smoke grenades. This has been often read as excluding white phosphorus munitions from this protocol, as well. In any case, the third protocol has not been signed by the United States.David Charter, Michael Evans and Richard Beeston Phosphorus was used for Fallujah bombs, admits US in The Times November 17, 2005

Military regulations

According to the US Army field manual on the Rule of Land Warfare, "The use of weapons which employ fire, such as tracer ammunition, flamethrowers, napalm and other incendiary agents, against targets requiring their use is not violative of international law." However, there is some conflicting guidance given by the US Command and General Staff College at Fort Leavenworth. ST 100-3 Battle Book, a student text, states that "It is against the law of land warfare to employ WP against personnel targets." This seems at odds with other field manuals which discuss the use of white phosphorus against personnel . One blog has reported that The US Marine Corps has recently issued guidance against using "flame weapons" (including white phosphorus) against personnel.

History

WP is believed to have been first used by Fenian arsonists in the 19th century in the form of a solution of WP in carbon disulfide. When the carbon disulfide evaporated, the WP would burst into flames, and probably also ignite the highly flammable carbon disulfide fumes. This mixture was known as "Fenian fire" and allegedly was also used by I.W.W. activists in the early 20th century.

Britain's army introduced its first factory-built WP grenades in late 1916. In World War II, white phosphorus mortar bombs, shells, rockets and grenades were used extensively by American, Commonwealth, and to a lesser extent Japanese forces, as well, in both the smoke-generating and antipersonnel roles. At the start of the Normandy campaign, 20% of American 81mm mortar rounds were WP. At least five American Medal of Honor citations mention their recipients using white phosphorus grenades to clear enemy positions. In the 1944 liberation of Cherbourg alone, a single U.S. mortar battalion, the 87th, fired 11,899 white phosphorus rounds into the city.

In 1940, when the invasion of Britain seemed imminent, the phosphorus firm of Albright and Wilson suggested that the British government use a material similar to Fenian fire in several expedient incendiary weapons. The only one fielded was the Grenade, No. 76 or Special Incendiary Phosphorus grenade, which consisted of a glass bottle filled with a mixture similar to Fenian fire, plus some latex (c.f. Molotov cocktail, Greek fire). It came in two versions, one with a red cap intended to be thrown by hand, and a slightly stronger bottle with a green cap, intended to be launched from the Northover projector (a crude 2.5 inch blackpowder grenade launcher). Instructions on each crate of SIP grenades included the observations, inter alia:

Store bombs (preferably in cases) in cool places, under water if possible.

Stringent precautions must be taken to avoid cracking bombs during handling.

It was generally regarded as overly dangerous to its own operators.

WP munitions were also used extensively by both sides in the Korean War and again in Vietnam. According to GlobalSecurity.org, "In the December 1994 battle for Grozny in Chechnya, every fourth or fifth Russian artillery or mortar round fired was a smoke or white phosphorus round."

Disposal at sea

Following World War II, the United States disposed of tons of white phosphorus munitions by dumping them into the ocean. In 1989, the Army Chemical Materials Agency prepared a report entitled Summary of Some Chemical Munitions Sea Dumps by the United States which detailed the history of dumping incidents for weapons that included mustard gas, lewisite, cyanide and white phosphorus. In 2001, another report, entitled Offshore disposal of chemical agents and weapons conducted by the United States, corroborated the dumping. Other countries have also dumped white phosphorus at sea.

Use in Iraq

Main article: White phosphorus use in Iraq

On November 15, 2005, Dept. of Defense spokesman Lieutenant-Colonel Barry Venable confirmed to the BBC that WP had been used as an antipersonnel weapon in Fallujah:

On November 30, 2005, General Peter Pace justified use of WP, declaring that WP munitions were a "legitimate tool of the military", used to illuminate targets and create smokescreens, adding: "It is not a chemical weapon. It is an incendiary. And it is well within the law of war to use those weapons as they're being used, for marking and for screening". Peter Pace then made the point that conventional weapons can be more dangerous than non-conventional weapons: "A bullet goes through skin even faster than white phosphorus does".

External links

Globalsecurity.org on WP (including use during the Battle of Fallujah and during the December 1994 battle for Grozny during the First Chechen War)
TF 2-2 IN FSE AAR: Indirect Fires in the Battle of Fallujah (PDF) Field Artillery Magazine (March-April 2005)
December 9, 2004 U.S. Denial of Using Illegal Weapons in Fallujah AND November 10, 2005 note - following RAI doc - recognizing WP use for screening purposes and as a "potent psychological weapons" in "shake&bake" operations
White phosphorus chemical backgrounder

Notes

Incendiary weapons

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