Xenobiotic metabolising enzymes modify most organic compounds into water soluble compounds. Sequence variations of these enzymes can lead to significant interindividual differences in the metabolism of xenobiotics. This review covers important sequence variations of phase I (cytochrome P450) and phase II (glutathion S-transferases, N-acetyltransferases, sulfotransferases, UDP-glucuronosyl transferases) enzymes and elucidates the significance for occupational health. At the present time, the determination of various sequence variations is not suitable for an individual risk assessment in occupational health.
