ABSTRACT
S-Transferases ................................................................................... 145 7.4 Miscellaneous Drug-Metabolizing Enzymes................................... 147 7.5 Problem Areas.................................................................................. 148 7.6 Epilogue............................................................................................ 155 References .................................................................................................. 155
Every living cell of the organism is exposed to a variety of substances, some of which are harmful by causing acute, subacute, or chronic functional failure, mutation, or teratogenesis. Although the toxicity of several compounds and natural products have been known for centuries and some, such as arsenic, have been used as poisons, the carcinogenicity of chemicals was first described in 1775 by Sir John Perivall Pott,
who observed scrotal cancer in chimneysweepers in the U.K. Since then, the tumor producing effect of many chemicals was shown primarily in laboratory animals. Tissues, which are mostly affected, include liver, esophagus, lung, nasal mucosa, urinary bladder, tongue, stomach, and pancreas.
A relationship has been found between the dose of the substance, its
