Technical guidance on normal levels of contaminants in Welsh soil : Benzo[a]pyrene (BaP): January 2013

Benzo[a]pyrene (BaP) is a yellow-coloured organic compound made up of five aromatic rings that contain only C and H atoms (Figure 1). It belongs to a family of compounds called polynuclear aromatic hydrocarbons (PAH) and typically comprises about 5 to 7% by weight of the total PAH content. BaP is widely regarded as the most carcinogenic of the non-substituted (parent) PAH compounds and is consequently used as a benchmark for toxic equivalent factors applied to concentrations of other PAH , the only other parent PAH ranked 1.0 besides BaP is dibenz(a,h)anthracene.