Chapter 23 Toxicological and Environmental Aspects of Polycyclic Aromatic Hydrocarbons (PAHs) and Related Compounds

Abstract

Publisher Summary This chapter discusses the toxicological and environmental aspects of polycyclic aromatic hydrocarbons (PAHs) and related compounds. The model compound in PAHS with two condensed cycles is naphthalene. Similar to polycyclic aromatic hydrocarbons (PAHs) with a larger number of aromatic cycles, naphthalene is considered a possible human carcinogen. Besides carcinogenicity, toxic effects are induced by high levels of naphthalene. In humans, these include hemolytic anemia, manifested by symptoms such as fatigue, lack of appetite, restlessness, and paleness. High levels of oral exposure to naphthalene also can cause nausea, vomiting, diarrhea, blood in the urine, and yellow skin. High-level exposures to naphthalene also can lead to cataract formation in laboratory animals and humans. There are no differences regarding the toxicological effects between naphthalene and methylnaphthalenes. For most PAHs, the main health-related concern is carcinogenicity. The chapter describes the classification of PAHs regarding carcinogenicity, and the mechanism of PAH carcinogenicity. The presence of PAHs in the environment can be natural or can be caused by human activities. PAHs occur naturally in fossil fuels such as coal, crude oil, coal-tar pitch, creosote, and asphalt. They are further transferred to numerous products made from these materials such as gasoline and other types of combustibles. Simple hydrocarbon PAHs are frequently associated with two other groups of polycyclic aromatic compounds. One group consists of PAHs that have functional groups attached to the aromatic rings. The most common compounds from this group are the nitro-PAHs and the hydroxy-PAHs.