Biochemistry. The series of chemical alterations of a compound (for example, a drug) which occur within the body, as by enzymatic activity. This entry appears with permission from the Dictionary of Cell and Molecular Biology. Biotransformation is the chemical modification (or modifications) made by an organism on a chemical compound. If this modification ends in mineral compounds like CO2, NH4+, or H2O, the biotransformation is called mineralisation. Biotransformation means chemical alteration of chemicals such as (but not limited to) nutrients, amino acids, toxins, and drugs in the body. It is also needed to render nonpolar compounds polar so that they are not reabsorbed in renal tubules and are excreted. Biotransformation of xenobiotics can dominate toxicokinetics and the metabolites may reach higher concentrations in organisms than their parent compounds. An OSH glossary used in safety and health at work which is, adopted by ILO