80 °C. Safety Petroleum ethers are extremely volatile, have very low flash points, and present a significant fire hazard. Fires should be fought with foam, carbon dioxide, dry chemical or carbon tetrachloride. The naphtha mixtures that are distilled at a lower boiling temperature have a higher volatility and, generally speaking, a higher degree of toxicity than the higher boiling fractions. Exposure to petroleum ether occurs most commonly by either inhalation or through skin contact. Petroleum ether is metabolized by the liver with a biological half-life of 46–48 h. Inhalation overexposure causes primarily central nervous system (CNS) effects (headaches, dizziness, nausea, fatigue, and incoordination). In general, the toxicity is more pronounced with petroleum ethers containing higher concentrations of aromatic compounds. n-Hexane is known to cause axonal damage in peripheral nerves. Skin contact can cause allergic contact dermatitis. Oral ingestion of hydrocarbons often is associated with symptoms of mucous membrane irritation, vomiting, and central nervous system depression. Cyanosis, tachycardia, and tachypnea may appear as a result of aspiration, with subsequent development of chemical pneumonitis. Other clinical findings include albuminuria, hematuria, hepatic enzyme derangement, and cardiac arrhythmias. Doses as low as 10 ml orally have been reported to be potentially fatal, whereas some patients have survived the ingestion of 60 ml of petroleum distillates. A history of coughing or choking in association with vomiting strongly suggests aspiration and hydrocarbon pneumonia. Hydrocarbon pneumonia is an acute hemorrhagic necrotizing disease that can develop within 24 h after the ingestion. Pneumonia may require several weeks for a complete resolution. Intravenous administration produces fever and local tissue damage. Petroleum-derived distillates have not been shown to be carcinogenic in humans. Petroleum ether degrades rapidly in soil and water. References Hydrocarbon solvents Petroleum products