Most of our pre-occupations arise from the modern paradox: while our longevity, health and environment have never been better we spend more time than ever before worrying about all three. Numerous health scares, which often develop every week only to be forgotten by next weeks' news, attest to these pre-occupations. One of the key reasons for scares developing is because people forget the old adage: the dose makes the poison. A substance (like radiation, or vitamin A) can be fatal in high doses, but at low does will not cause a problem (radiation) or even be beneficial (vitamin A). But even where the occasional scare turns out to be valid it may be inappropriate for poor countries to be worried too much about it. Indeed, it may be necessary for these countries to allow things to happen which we would sensibly discourage or even prohibit. And it is on this dichotomy, and specifically one example, that this paper focuses. The classic example of this phenomenon is the current attempt by western governments, via the United National Environment Programme (UNEP), to ban globally the pesticide DDT. There is ample evidence that DDT can be environmentally harmful. Much of this evidence comes from the agricultural use of DDT in the 1950s and 1960s, when the amount sprayed ran into millions of tons in America alone. The resultant concentration of DDT led to egg-shell thinning, and allegedly other effects. DDT is not harmful to humans, even in relatively high doses. In fact there is not one study in the scientific literature on DDT, which adequately shows any human health problem from DDT. In short, DDT was harmful to birds at high does when used outdoors. Low dose use of DDT is therefore unlikely to cause any significant irreversible harm to the environment. Spraying of DDT in houses and on mosquito breading grounds was the primary reason that rates of malaria around the world declined dramatically after the Second World War. Nearly one million Indians died from malaria in 1945, but this was reduced, by DDT spraying, to a few thousand by 1960. However, the concerns about the environmental harm of DDT led to a decline n spraying, and a resurgence of malaria. Although deaths are not as high as in 1945, there are once again millions of cases of malaria in India, and over 500 million cases (and two million deaths) worldwide every year – most in sub-Saharan Africa. And the number of cases is accelerating, for example, cases of malaria in South Africa have risen by over 1000% in the past five years. Only those countries that have continued to use DDT (Ecuador and India and a few others) have contained or reduced malaria. Malaria is obviously a human tragedy, but it is also an economic disaster. According to Jeffrey Sachs of Harvard's Center for International Development malaria costs about 1% of Africa's wealth every year. In many countries, malaria halves the growth that would otherwise have occurred. Richard Tren of the group Africa Fighting Malaria estimates that without DDT all growth in at least seven countries would be extinguished. Ye t in 1997 UNEP proposed a treaty to restrict and possibly ban 12 chemical pollutants (including DDT) that were considered particularly damaging to health and environment. None of these chemicals is produced or used in rich countries. It is therefore simple for Western governments to ban them. But the consequence of a DDT ban will be thousands of deaths and economic stagnation in many of Africa's poorest countries. Perhaps worse still, aid agencies from US and Europe are pressuring countries into not using DDT, because of its perceived problems. Belize, Madagascar, Bolivia and other countries have stopped using DDT because they feared the loss of donations to other health programs. In addition to detailing the above distant and contemporary history the monograph will show how developing nations (and in this case their health officials) must be allowed to make decisions given their local knowledge and requirements, and not be dictated to by Geneva-based bureaucrats. The advice that developed nations can give to these countries is often invaluable, but the trade-off that developed country individuals and officials have to make are barely conceivable to westerners.