2. Toxicity of PAHs
Although studies in experimental animals on individual PAHs, mainly on benzo[a]pyrene, have shown various
toxicological effects, such as haematological effects, reproductive and developmental toxicity and
immunotoxicity, it is the carcinogenic and genotoxic (DNA-damaging) potential of these compounds that has
attracted most attention. A number of PAHs have shown carcinogenicity in experimental animals and
genotoxicity and mutagenicity in vitro and in vivo. The International Agency for Research into Cancer (IARC)
in 1987 concluded that benzo[a]pyrene is a probable human carcinogen. Some other PAHs have also been
identified as being carcinogens, with possible genotoxic properties. Although the PAHs are lipophilic
chemicals like the dioxins and PCBs, they are metabolised or broken down faster than the latter chemicals,
both in the human body and in the environment, and thus persistence for long periods is not such a major
problem.