3. Mechanisms of toxic action

Several mechanisms are involved in xenobiotic toxicity. Some of these mechanisms relate to metabolism; in fact, the organism is capable of forming a compound more toxic than the ingested product, and the metabolite formed may be the cause of alterations, necrosis or cancer. The toxic compound may also interfere with essential proteins such as hemoglobin, inhibiting its normal function of transporting oxygen, or inhibiting a number of enzymes essential to the degradation of endogenous compounds. On the other hand, substances such as alcohol can induce enzymatic reactions, increasing the quantity of toxic compounds formed, as can tobacco compounds. In this section, we describe some of the mechanisms of toxicity.