Liver has a crucial protective role against toxic chemical insults, which is attributed to its potential to convert lipophiles into more water-soluble metabolites by effectively removing it from the body through urine. This process of elimination of toxins is mediated by the expression of a wide spectrum of xenobiotic biotransforming enzymes with their ability to catalyse the oxidation, reduction and hydrolysis and/or conjugation of functional groups on drug and chemical molecules. In addition, the broad substrate specificity, isoenzyme multiplicity and inducibility of many of these enzyme systems are the common characteristics that enables them to manage different chemical structures in the environment to which an individual is exposed daily. 

On the contrary, certain chemicals may also be converted to more toxic metabolites via the help of these xenobiotic biotransforming enzymes, suggestive of the fact that alterations in the behaviour of these enzymes can also result in toxicity. Pharmacogenetic defects of xenobiotic biotransformation enzymes, a subclass of inborn errors of metabolism has produced significant alterations into human populations for the pharmacokinetics and pharmacodynamics of therapeutic and toxic agents, and in turn, may have significant clinical outcomes regarding drug efficacy and toxicity.

Source: Grant DM. Detoxification Pathways in the Liver. Journal of Inherited Metabolic Disease pp 421-430. Available at: https://link.springer.com/chapter/10.1007/978-94-011-9749-6_2