The three approaches that have been advocated for carcinogenic risk assessment of PAHs are toxicity equivalency factors (TEFs), comparative potency of mixtures and the use of B[a]P as a surrogate (WHO, 1998). A summary of the key aspects of each approach is presented in Table 1. In this paper, we will be using the term potency equivalency factors (PEFs) rather than TEFs. The term PEF was suggested by Collins et al. (1998) and is deemed more appropriate for carcinogenic risk assessment of PAHs, as it does not infer an evalu-ation of other toxicological effects of PAHs. A critique of the three approaches is given below.
Table 1
Advantages and disadvantages of the three approaches used for inhalation carcinogenic risk assessment for mixtures containing PAHs