Introduction The human race is faced with grave environmental problems. Significant parts of the former Soviet Union are seriously contaminated by chemical and radioactive substances, as are parts of the former Eastern bloc. The environmental clean-up bill at United States’ nuclear weapons facilities is estimated to be at least one hundred and thirty billion dollars. Motor vehicles are killing between forty and fifty thousand people every decade in the United Kingdom alone, and that is a state with a relatively modest accident rate. This makes them one of the most lethal technological intrusions into the natural environment. The depletion of the world s ozone layer is continuing and many medical researchers believe that the incidence of potentially lethal skin cancer is likely to keep on increasing as a consequence. Potentially catastrophic changes in climate and sea level are alleged to lie in wait if the world’s industrialised and industrialising states do not cut back drastically on their use of fossil fuels. Species of plants that may contain substances with valuable medical uses are disappearing forever at an alarming rate. Huge tracts of the earth’s surface are threatened with creeping desertification and millions of the world’s people are without sufficient food for a healthy existence.