Excerpt from CBRNE - Vomiting Agents: Dm, Da, Dc

Synonyms, Key Words, and Related Terms: vomiting agents, DM, diphenylaminearsine, adamsite, 10-Chloro-5,10-dihydrophenarsazine, DA, diphenylchlorarsine, diphenylarsinous chloride, DC, diphenylcyanoarsine, diphenylarsinous cyanide, chemical warfare, terrorism, riot control, riot-control agents, emesis-inducing agents

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Background: The chemical warfare agents diphenylchlorarsine (DA), diphenylcyanoarsine (DC), and diphenylaminearsine (DM, adamsite) belong to a group of chemicals classified as vomiting agents. DA appears as colorless crystals, DC as a white solid, and DM as light yellow-to-green crystals. DA and DM are odorless, and DC reportedly has an odor similar to garlic or bitter almonds. All 3 agents are insoluble in water.

The synthesis of these agents dates back to the early 20th century. In 1915, Wieland, a German chemist, synthesized the agent DM. Three years later, a US chemist, Robert Adams, independently developed this same compound and named it adamsite. Since that time, these agents have been produced for 2 purposes, as riot-control agents and as emesis-inducing agents to promote removal of personal protective gear during chemical warfare.

Pathophysiology: Vomiting agents typically are disseminated as aerosols. The primary route of absorption is through the respiratory system. Exposure also can occur by ingestion, dermal absorption, or eye impact.

The effects of the vomiting agents by any route of exposure are slower in onset and longer in duration than typical riot control agents (eg, CS). On initial exposure, vomiting agents are irritants. This irritation is delayed for several minutes after contact. As a result of this delay, less early warning properties are present for those exposed. By the time symptoms of irritation occur and personnel consider donning their protective equipment, significant contamination already may have occurred. Systemic signs and symptoms subsequently follow the initial irritation and consist of headache, nausea, vomiting, diarrhea, abdominal cramps, and mental status changes. Symptoms typically persist for several hours after exposure. Death has been reported with excessive exposure.

Frequency:

In the US: The use of vomiting agents within the United States against civilians never has been reported. Currently, the US government is funding numerous programs to prepare the nation for potential chemical terrorist attacks against its citizens and military.

Internationally: The use of vomiting agents has been reported during international conflicts. DA first was used by German troops in 1917. DA was not well filtered by the standard issue gas masks at that time. It resulted in nausea and vomiting, causing enemy troops to remove their masks. This rendered those personnel vulnerable to the toxic effects of other agents such as phosgene and chlorine gas. The Germans also produced DC and DM, but limited documentation exists for use of these agents during World War I. Questionable reports exist of vomiting agents used in other countries as riot control agents. No recent use of vomiting agents is documented.

Mortality/Morbidity: DM is the most toxic agent of this group, with an estimated LCt50 of 11,000 mg·min/m³ (eg, an estimated 50% lethality for a group of patients breathing air with a concentration of 11,000 mg/m³ for 1 min). Other factors also are important, such as the exposed patient's preexisting health status and the time from exposure to medical care. The dose at which vomiting reportedly begins for DM is estimated as 370 mg·min/m³.

Race: No published studies demonstrate a significant difference in effects of vomiting agents on various races.

Sex: No published studies demonstrate a significant difference in effects of vomiting agents by gender.

Age: Intuitively, those at the extremes of age would be less tolerant of exposure to these 3 chemical agents. However, no published studies prove this.