Polycyclic aromatic hydrocarbons or polynuclear aromatic
hydrocarbons (PAHs) are chemical compounds made up of more
than two fused aromatic rings in a linear or clustered arrangement,
usually containing only carbon (C) and hydrogen (H) atoms,
although nitrogen (N), sulphur (S) and oxygen (O) atomsmay readily
substitute in the benzene ring to form heterocyclic aromatic
compounds. They are produced through incomplete combustion
and pyrolysis of organic matter. Both natural and anthropogenic
sources such as forest fires, volcanic eruptions, vehicular emissions,
residential wood burning, petroleum catalytic cracking and
industrial combustion of fossil fuels contribute to the release of
PAHs to the environment [1]. Several hundred different combinations
of PAHs exist, but up to 28 compounds as listed in Table 1
have recently been identified as hazardous contaminants in January
2008 by the US Environmental Protection Agency (US EPA)
[2]. The distinguishing feature of these toxic compounds is that
they are highly hydrophobic. As such, PAHs easily adsorb onto the
organic matter of solid particles, forming persistent micropollutants
in the environment. Air, soil, water and vegetation all act as
environmental sinks for PAHs, although a preliminary inventory
of PAHs in the UK environment showed that soil was the major
repository for PAHs [3].
Soils contaminated with PAHs pose potential risks tohumanand
ecological health. The assessment of the actual risk for mutagenic
and carcinogenic effects requires accurate exposure information
which is extremely difficult to assess in practice [4]. Nonetheless,