One of the most difficult decisions facing those responsible for the enforcement of environmental regulations and laws is how much clean-up is necessary. A decision to do too little may cause irreversible damage to the environment, while a decision to do more than is necessary may waste resources better spent elsewhere. Using an approach similar to clinical biochemistry in human medicine, this book is a critical examination of the use of biomarkers (the physiological or biochemical changes caused by chemicals) to indicate the state of health of wildlife in the environment. Because of the increasing concern over the effects of toxic chemicals on the biosphere, the choice of reliable indicators to measure the effect of them in animals is therefore absolutely crucial. David Peakall has been involved in researching biomarkers for many years and has been active in a number of international advisory bodies dealing with pollution problems. His book looks at the range of biomarkers, their usefulness in monitoring pollution and the prediction of the biotoxic effects of the release of toxic chemicals. He concludes that basing decisions on the physiological function of organisms, using the biomarkers and the concept of "exclusion zones", is a more rational and successful approach to pollution problems compared with the classical toxicological approach of setting pollution "levels".