Contaminants in the environment. A multidisciplinary Assessment of Risks to Man and Other Organisms

The Summer School' 'Multidisciplinary Assessment of Environmental Risks for Human Health" focused on human health hazards presented by contaminants with the major emphasis on direct effects. However, there are also indirect effects of contaminants that are or may be detrimental to mankind. Contaminants can have damaging effects on aquatic organisms such as fish and small molluscs, which are important sources of food-especially in third-world countries. Also, the injudicious use of insecticides has sometimes led to outbreaks of pest infestation, causing damage to crops, as a consequence of the decimation of natural predators or parasites. Thus, the program of the Summer School has also included certain presentations on ecotoxicological issues that have relevance to the main theme of the course. The School gave attention to disparate aspects of the problem of risk assessment-from the molecular mechanisms that underly toxicity to the practical and administrative issues of environmental management. The basis scientific issues of environmental toxicology apply to all animals. In considering them, no distinction has been made between man and other animals. Indeed, most of the scientific work has involved the use of laboratory animals acting as surrogates for man. Thus the first three sections of the book deal mainly with principles that are relevant to living organisms generally. The fourth section, however, deals specifically with the question of risks for human health. The final section deals with environmental management in a broad way, touching on issues relevant to both the "human environment" and the "natural environment." The individual sections will now be considered in a little more detail. Section I is concerned with the distribution and fate of contaminants. It includes a chapter dealing with models that may be used to predict the distribution of chemicals in the global environment. Two other chapters discuss approaches to the problem of monitoring. A more specialized chapter deals with one of the most serious problems encountered in environmental toxicology - the biomagnification of persistent contaminants in marine food chains. Section II focuses on the relationship between metabolism and toxicity. This is fundamental to an understanding of the scientific basis of selective toxicity. An important practical aspect of this is the suitability of animal models for humans in toxicity testing. A better understanding of the metabolic regulation of toxicity should lead to the employment of better models for predicting toxicity to man. Although metabolism of contaminants is usually associated with detoxification, there are important exceptions to this rule. Some carcinogens and some highly toxic organophosphorus insecticides are activated by metabolism. These issues are brought out by contributors to this section. Section III deals with toxic effects of contaminants. Clearly in the present text, it would not be appropriate to attempt a comprehensive view of the subject. Instead only a few selected examples are given, and emphasis is placed on the question of biomarkers. Until now, much of the work on environmental contamination has been concerned only with the measurement of levels of chemicals. Seldom has it been possible to say anything about the consequent effects. Taken alone, data on residue levels are of little assistance in reaching decisions about the control of environmental chemicals. A major purpose of the development of biomarkers is to overcome this problem-to provide measures of harmful effects of chemicals in the environment, thus giving a firm scientific basis for policy decisions on pollution control. Section IV is concerned with the question of effects of contaminants on human health. With eight chapters, this is the largest section in the book, in keeping with the particular focus of the School. General issues such as environmental epidemiology and fate of inhaled substances are dealt with here, but the main focus is on the human health risks presented by specific compounds. Section V concludes the text by focusing on issues of environmental management. These include valuable contributions on the policy of International Organizations concerned with pollution. Regarding the overall book, it should be stressed that this is a collection of articles by authorities in specific fields. It focuses on specific issues, within a wide framework. It is hoped that this will provide valuable reading to students attending the Summer School at Siena in the future, and also to others following courses in environmental toxicology elsewhere. Finally it may also be of value to interested lay people having a scientific background