Toxicologic agents of concern for search-and-rescue dogs responding to urban disasters.

H ighly trained search-and-rescue (SAR) dogs are indispensable members of urban SAR teams responding to a variety of natural and man-made disasters. A large-scale disaster could result in the release and mixing of dozens or even hundreds of chemical agents. Therefore, urban disaster sites should be considered potentially contaminated with many dangerous chemicals and substances. In a previous report, 1 general toxicologic hazards for SAR dogs responding to urban disasters were discussed. The purpose of the present article is to raise awareness of some of the specific common substances that may be found at urban disaster sites and their potential for short-and long-term health effects. Hydrocarbons The term hydrocarbon refers to any compound consisting of carbon and hydrogen. The most common classes of hydrocarbons include petroleum distillates 2 The large number of motor vehicles typically found in an urban disaster site can be a source of many hydrocarbon chemicals, including gasoline, motor oil, and transmission fluid. Many of these substances are a mixture of hydrocarbons. For instance, gasoline may typically contain 150 hydrocarbon compounds in addition to various additives and blending agents. 3 Depending on the nature of the disaster, specific hydrocarbons may be of greater or lesser concern. For instance, at the World Trade Center and the Pentagon disaster sites in September 2001, jet fuels were involved. On the other hand, a study 4 of volatile organic compounds at municipal structural fires revealed that benzene dominated, along with toluene and naph-thalene. Hydrocarbons can be absorbed following respiratory , oral, or dermal exposure. Inhalation may occur as a result of exposure to dust, particles, vapors, or aerosols. Absorption following dermal exposure is slower and less extensive than that following respiratory or oral exposure. Preferential distribution to fatty tissues occurs, especially with the aliphatic hydrocarbons , and neurotoxicoses are thought to occur when lipophilic hydrocarbons dissolve in nerve cell membranes and disrupt membrane protein function. Metabolism of hydrocarbons is predominantly through oxidation by cytochrome P-450 isoenzymes and conjugation to more water-soluble compounds. Metabolism in the liver may represent an activation pathway for some hydrocarbons and a detoxification pathway for others. Most hydrocarbons are excreted in urine as metabolites; exhalation of unchanged parent compounds and biliary excretion are other potential routes of elimination. 3 The risk and extent of adverse effects are related to the types and amounts of chemicals involved and the duration of the exposure. 3 Toxicosis resulting from exposure …