Lewisite

Lewisite (L) is an organoarsenic compound. It was once manufactured in the U.S., Japan, Germany and the Soviet Union for use as a chemical weapon, acting as a vesicant (blister agent) and lung irritant. Although colorless and odorless, impure samples of lewisite are a yellow, brown, violet-black, green, or amber oily liquid with a distinctive odor that has been described as similar to geraniums. Lewisite (L) is an organoarsenic compound. It was once manufactured in the U.S., Japan, Germany and the Soviet Union for use as a chemical weapon, acting as a vesicant (blister agent) and lung irritant. Although colorless and odorless, impure samples of lewisite are a yellow, brown, violet-black, green, or amber oily liquid with a distinctive odor that has been described as similar to geraniums. The compound is prepared by the addition of arsenic trichloride to acetylene in the presence of a suitable catalyst: Lewisite, like other arsenous chlorides, hydrolyses in water to form hydrochloric acid and chlorovinylarsenous oxide (a less-powerful blister agent): This reaction is accelerated in alkaline solutions, and forms acetylene and trisodium arsenate. Lewisite will also react with metals to form hydrogen gas. It is combustible, but difficult to ignite. Lewisite is a suicide inhibitor of the E3 component of pyruvate dehydrogenase. As an efficient method to produce ATP, pyruvate dehydrogenase is involved in the conversion of pyruvate to acetyl-CoA. The latter subsequently enters the TCA cycle. Peripheral nervous system pathology usually arises from Lewisite exposure as the nervous system essentially relies on glucose as its only catabolic fuel. It can easily penetrate ordinary clothing and latex rubber gloves. Upon skin contact it causes immediate stinging, burning pain and itching that can last for 24 hours. Within minutes, a rash develops and the agent is absorbed through the skin. Large, fluid-filled blisters (similar to those caused by mustard gas exposure) develop after approximately 12 hours and cause pain for 2–3 days. These are severe chemical burns and begin with small blisters in the red areas of the skin within 2–3 hours and grow worse, encompassing the entire red area, for the ensuing 12–18 hours after initial exposure. Liquid lewisite has faster effects than lewisite vapor. Sufficient absorption can cause deadly liver necrosis. Those exposed to lewisite can develop refractory hypotension (low blood pressure) known as Lewisite shock, as well as some features of arsenic toxicity. Lewisite causes physical damage to capillaries, which then become leaky, meaning that there is not enough blood volume to maintain blood pressure, a condition called hypovolemia. When the blood pressure is low, the kidneys may not receive enough oxygen and can be damaged. Inhalation, the most common route of exposure, causes a burning pain and irritation throughout the respiratory tract, nosebleed (epistaxis), laryngitis, sneezing, coughing, vomiting, difficult breathing (dyspnea), and in severe cases of exposure, can cause fatal pulmonary edema, pneumonitis, or respiratory failure. Ingestion results in severe pain, nausea, vomiting, and tissue damage. The results of eye exposure can range from stinging, burning pain and strong irritation to blistering and scarring of the cornea, along with blepharospasm, lacrimation, and edema of the eyelids and periorbital area. The eyes can swell shut, which can keep the eyes safe from further exposure. The most severe consequences of eye exposure to lewisite are globe perforation and blindness. Generalised symptoms also include restlessness, weakness, hypothermia and low blood pressure.