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Diesel Exhaust
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HEALTH EFFECTS OF DIESEL EXHAUST Diesel engines are used in automobiles, generators, light-duty and heavy-duty vehicles as well as railroad locomotives. When diesel fuel burns in an engine, the resulting exhaust is made up of soot and gases representing thousands of different chemical substances. 90% of the soot consists of <1u diameter particles that can be inhaled and deposited in the lungs. Diesel exhaust contains 20-100 times more particles than gasoline exhaust. These particles carry absorbed cancer causing substances known as polynuclear aromatic hydrocarbons (PAH)’s. The gases in diesel exhaust can also create health problems. The top eight are listed here:
Those most likely to be occupationally exposed to diesel exhaust include bridge, tunnel and loading dock workers, auto mechanics, toll booth collectors, truck and forklift drivers and people who work near areas where diesel powered vehicles are used, stored and maintained.
The chronic effects of exposure to diesel exhaust include those shown below. Few studies have been done, however, to establish chronic effects. In terms of cancer risk, no consistent evidence suggests that diesel emissions induce cancer in rats at sites other than the lung. Prolonged exposure to diesel emissions does not produce lung tumors in hamsters, and the results in mice are equivocal, which suggests that species-specific factors play a critical role in the induction of lung tumors by diesel emissions. In addition, few epidemiologic studies have considered the effects of confounding by nondiesel particulates, cigarette smoke, asbestos exposure, diet and socioeconomic factors. However, those studies that have been done, consistently show a weak association of 1.2 - 1.5 relative risk increase in lung cancer. Thus the EPA, the ACGIH, NIOSH and IARC agree that diesel exhaust is a human carcinogen. Other respiratory disorders caused or exacerbated by diesel exhaust include asthma and chronic bronchitis.
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