The Symposium on the Global Effects of Environmental Pollution has performed an important task; it has helped to determine the world-wide impact of certain types of local pollution and has uncovered certain unsuspected effects that might hold dan­ gerous implications for the future. This Symposium should help to make the world aware of a crisis that is becoming more ominous and that involves the developing as well as the developed countries - the crisis of the human environment. The causes of this crisis are not difficult to discern. There has been an unprecedented increase in the world's population, an ever-increasing rate of urbanization, and in many countries, a continuous process of industrialization. Essentially, advancing technology has made it possible for a minority of mankind to achieve affluence and holds out hope for improving the well-being of the great majority. But, because it has not been integrated into the natural environment, this very technology - in industry, in agriculture or in transport - is having many undesir­ able and potentially catastrophic consequences. Our air, our water and our soil are in grave danger. Many species of animal and plant life have become extinct or are facing extinction. The loss to mankind is grave and even the future oflife on earth may be in danger. The challenge is to find ways of repairing the harm already done and to prevent further harm.