(A) The chemical structures of DB[a,l]P and B[a]P with definitions of the fjord region and the bay region, respectively. (B) The chemical structures for the 14R-DB[a,l]P-dA, 10R-B[a]P-dA and 14R-DB[a,l]P-dG adducts. The distal aromatic rings highlighted in grey cause steric crowding in the 14R-DB[a,l]P-dG structure.