Phosgene (CG)

Phosgene-also called collognite or D-Stoff-was first used in the dye industry before it was used as a battlefield weapon. The first recorded use of phosgene was in the early hours of 19 December 1915, when the Germans released phosgene gas against British positions in Ypres, France. The attack resulted in 1,069 casualties, of which 116 were fatal. Within a year of the first attack with phosgene, the British were manufacturing supplies of phosgene gas at Porton Down. It was filled into artillery shells for British gunners for use in the Second Battle of the Somme in June 1916. By some estimates, over 80 percent of chemical agent fatalities in World War I were caused by phosgene. Phosgene gas will incapacitate a man within a few seconds if exposed to 100 parts per 10 million. Fatalities occur if he is exposed to concentrations of 200 parts per 10 million for one or two minutes. Phosgene kills any breathing thing by attacking the lung capillaries and then the membranes of the lung sacs, causing them to flood with watery fluids. Following exposure, death may follow within hours or up to a day. Phosgene is particularly dangerous because it does not detoxify naturally, has a cumulative effect on its victims and may persist in sheltered areas and buildings. Britain unilaterally destroyed its phosgene stocks after World War II. Phosgene was also produced and stockpiled by the Soviet Union and the United States. Egypt used Soviet-supplied phosgene stocks in the Yemeni civil war between 1963 and 1969.

The toxic action of phosgene is typical of a certain group of lung damaging agents. Phosgene is the most dangerous member of this group and the only one considered likely to be used in the future. Phosgene was used for the first time in 1915, and it accounted for 80% of all chemical fatalities during World War I.

Phosgene is a colorless gas under ordinary conditions of temperature and pressure. Its boiling point is 8.2°C, making it an extremely volatile and non-persistent agent. Its vapour density is 3.4 times that of air. It may therefore remain for long periods of time in trenches and other low lying areas. In low concentrations it has a smell resembling new mown hay.

The outstanding feature of phosgene poisoning is massive pulmonary oedema. With exposure to very high concentrations death may occur within several hours; in most fatal cases pulmonary oedema reaches a maximum in 12 hours followed by death in 24-48 hours. If the casualty survives, resolution commences within 48 hours and, in the absence of complicating infection, there may be little or no residual damage.

During and immediately after exposure, there is likely to be coughing, choking, a feeling of tightness in the chest, nausea, and occasionally vomiting, headache and lachrymation. The presence or absence of these symptoms is of little value in immediate prognosis. Some patients with severe coughs fail to develop serious lung injury, while others with little sign of early respiratory tract irritation develop fatal pulmonary oedema. A period follows during which abnormal chest signs are absent and the patient may be symptom-free. This interval commonly lasts 2 to 24 hours but may be shorter. It is terminated by the signs and symptoms of pulmonary oedema. These begin with cough (occasionally substernally painful), dyspnoea, rapid shallow breathing and cyanosis. Nausea and vomiting may appear. As the oedema progresses, discomfort, apprehension and dyspnoea increase and frothy sputum develops. The patient may develop shock-like symptoms, with pale, clammy skin, low blood pressure and feeble, rapid heartbeat. During the acute phase, casualties may have minimal signs and symptoms and the prognosis should be guarded. Casualties may very rapidly develop severe pulmonary oedema. If casualties survive more than 48 hours they usually recover.