The environment in which human beings live is complex and we may encounter many different potentially toxic chemical substances during the course of our lives. These xenobiotic agents may invade the living system in the form of environmental pollutants, in the diet, as pharamaceutically administered compounds or even as chemical weapons and it is becoming widely recognised that free radicals are often involved in this toxicity. This book begins with the principle methods for the detection of free radicals-namely spin-trapping combined with ESR spectroscopy. The specific application of spin trapping to real biological systems is discussed, including how to avoid artefacts of the biological media, and to maximise sensitivity in detection. There follows a section on nitroxides, which are relatively stable free radicals and can be used as probes of cellular metabolism, and to measure the oxygen concentration in cells. The potential toxic effects of nitroxides in skin, when used clinically, is also covered. The toxic action of specific agents is discussed in the next section. These include: airborne particles such as asbestos, coal dust, cigarette smoke, diesel fumes and dusts found in the workplace; alcohol; chemical weapons such as 'mustard gas'; thiols; ionising radiation in its role in damaging DNA and causing cancer; and halogenated compounds, such as organic solvents and refrigerants (CFCs) which are not only damaging to the environment, but are harmful to humans. The toxic influence of free radicals arising from the diet is then convered more generally, how 'antioxidants' protect against cancer, cardiovascular and respiratory disease. Finally, the role of free radicals in the sensitisation and activation of drugs, specifically ketoporfen and anti-tumour agents, and structure-activity relationship (QSAR) approaches to predict the toxicity of free radicals in biological systems are considered. Final year undergraduates and postgraduates studing toxicology, biochemsitry, cell biology or environmental science will find this book valuable reading, whilst researchers in academia, in the pharmaceutical industry and in public health laboratories will appreciate it as a comprehensive and convenient reference. Rhodes; Chris J Liverpool John Moores University,