What is the pathophysiology of smoke inhalation caused by red phosphorus?

Updated: Oct 15, 2021
  • Author: Keith A Lafferty, MD; Chief Editor: Joe Alcock, MD, MS  more...
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Answer

After World War II, RP smoke was developed in an attempt to avoid the toxicity associated with the manufacturing of white phosphorus. RP is 95% phosphorus in a 5% butyl rubber base and provides an adequate tank screen on the battlefield.

When RP is oxidized, it forms a mixture of phosphorous acids. When these acids are exposed to water vapor, they in turn form polyphosphoric acids, which may be responsible for the toxic injuries to the upper airways. Most of these injuries are mild irritations. No human deaths have been reported from exposure to either white phosphorus or RP smokes.

Most of the pathologic consequences associated with phosphorus are from elemental white phosphorus fumes or vapor. Contact with elemental phosphorus can cause burns to body surfaces.

A well-described condition termed phossy jaw is associated with longer-term occupational exposures to airborne phosphorus fumes. This disease is a degenerative condition affecting the entire oral cavity including soft tissue, teeth, and bones. Massive necrosis of teeth, bone, and soft tissue can lead to life-threatening infections. Treatment typically consists of soft tissue and bone debridement, abscess drainage, and reconstructive surgery.

White phosphorus and RP smokes may cause respiratory tract irritation after 2-15 minutes of exposure. This probably is caused by the polyphosphoric acids that react with moist mucosal membranes. Respiratory tract irritation has been observed at concentrations of 187 mg phosphorus pentoxide equivalents per cubic meter for 5 minutes or longer. Intense congestion, edema, and hemorrhages were observed in lung tissue following a 1-hour exposure at varying concentrations in studies using rats, mice, and goats.


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