Catabolism of PAHS

Abstract

Polycyclic aromatic hydrocarbons (PAHs) refer to hydrocarbons containing two or more fused benzene rings in a linear, angular, and cluster arrangement (Figure 1). PAHs are mainly formed as products from the combustion of fossil fuels, as by-products of industrial processing and during the cooking of foods91. PAHs enter the environment from a multiplicity of sources which include direct aerial fallout, chronic leakage of industrial or sewage effluent, accidental discharge during transport, use and disposal of petroleum products, and from natural sources such as oil seepage and surface water run-off from forest and prairie fire sites. More specifically, industrial effluent from coal gasification and liquefaction processes, waste incineration, coke, carbon black, and other petroleum-derived products releases high quantities of PAHs into the environment. PAH contamination, particularly from the high-molecular-weight types, in soil and aquifers is a cause of great environmental concern because of their toxic, mutagenic, and carcinogenic effects on experimental animals and their potential health risk to humans19, 38, 95. Some PAHs are classified as priority pollutants to be monitored in aquatic and terrestrial ecosystems by the U.S.