ABSTRACT
In 1812 John Davy prepared phosgene (COCl 2,MW 98.92) by mixing equal volumes of carbon
monoxide and chlorine dried over calcium chloride. During World War I (WWI) phosgene (CAS 75-44-5) was produced as a result of passing carbon monoxide and chlorine over activated charcoal (CO Cl
2 → COCl 2 ). Once in solution phosgene produces carbon dioxide and hydrochloric acid via the following reaction:
COCl 2 H 2 O → CO 2 2HCl
The hydrolysis reaction rate of phosgene is exceptionally rapid with a half-life calculated to be 0.026 sec at 37ºC. The National Institute for Occupational Safety and Health (NIOSH)– established permissible exposure limit (PEL) and threshold limit values (TLV) are 0.1 ppm and 0.4 mg/m 3 , respectively (NIOSH, 1976). The physical characteristics of phosgene can be found in Table 20.1
For nearly 80 years, it has been known that phosgene has the capacity to cause severe lung injury. Phosgene has been known as an irritant as well as an asphyxiating gas based on the symptoms
observed in soldiers exposed during WWI. It was one of the weaponized respiratory threat agents in use during WWI and at times was also mixed with other gases such as chlorine. Battlefi eld exposure to gas mixtures was responsible for numerous casualties, approximately one-third of all casualties entering the hospital. In one instance, phosgene was directly responsible for more than 1100 casualties when 88 tons of gas was used against British soldiers at Wieltje, Belgium on December 19, 1915 (Spiers, 1986). Thereafter, it remained the war gas of choice during WWI and was used in shells, trench mortar bombs, and projector drums. It has been estimated that phosgene was responsible for nearly 85% of all respiratory-related deaths attributable to chemical weapons (Karalliedde et al., 2000). Based on military service medical records, phosgene gassing during WWI caused servicemen to lose 311,000 days due to hospitalization (Jackson, 1933).
