Sources, distribution, and health effect of carcinogenic polycyclic aromatic hydrocarbons (PAHs) – current knowledge and future directions

Polycyclic aromatic hydrocarbons (PAHs) are chemical compounds containing two or more fused benzene rings in linear, angular or cluster arrangement, consisting of only carbon and hydrogen. Polycyclic aromatic carbons (PACs) include the unsubstituted hydrocarbons (PAHs) and substituted PAHs (e.g. nitro-PAH, oxygenated PAH). PAHs are the most stable form of hydrocarbons having low hydrogen-to-carbon ratio and usually occur in complex mixtures rather than single compounds. They are usually generated under inefficient combustion conditions (e.g. in incomplete supply of oxygen).This paper deals with type carcinogenic PAHs generated in the environment from various sources, environment distribution and health effect.This paper provides a review of current information on the concentrations, burdens and fate of PAHs in the atmosphere, with reference to the historical trends in PAH emissions. The major anthropogenic sources of PAHs and their effect on the concentrations of these compounds in air on a national–inter...