A method of screening a hydrocarbon stream for potential toxicological hazards. The method involves providing a hydrocarbon stream; conducting 2-dimensional gas chromatography (2D-GC) analysis to quantify saturates and aromatic distribution in the hydrocarbon stream; identifying 2-8 ring aromatic distribution and weight percentage of 2-8 ring aromatic molecules in the hydrocarbon stream from the 2D-GC analysis; relating the weight percentage of 2-8 ring aromatic molecules in the hydrocarbon stream from the 2D-GC analysis to a mutagenicity index (MI), in which the MI is determined in accordance with ASTM Standard Method E 1687; and assessing a potential toxicological hazard of the hydrocarbon stream based on the weight percentage of 2-8 ring aromatic molecules in the hydrocarbon stream from the 2D-GC analysis and a MI threshold value. The 2-8 ring aromatic distribution preferably includes 3-6 ring aromatics, more preferably 3.5-5.5 ring aromatics. The 2-8 ring aromatic distribution includes mono alkylated and multi alkylated aromatic molecules.