DDT is a synthetic pesticide with a unique and controversial history. During the Second World War, many soldiers became ill with malaria, spread by mosquitoes, and typhus, spread by lice. Pyrethrum was in short supply, so the pesticide DDT came to the rescue and dramatically reduced the spread of both diseases. Typhus was virtually eliminated in many areas in Europe, and DDT sprayed in many areas in the South Pacific virtually eliminated malaria in the region. In fact, chemist Paul Hermann Muller received the Nobel Prize in medicine for discovering how effective and efficient DDT was in dispatching these problematic pests.
In addition, after the war, DDT was made available as an insecticide for public agricultural use. Production increased, and DDT’s use skyrocketed.
Ten years later, the World Health Organization relied largely on DDT in their program to eliminate malaria worldwide. Mortality from the disease was greatly reduced, and the disease was eliminated from Taiwan, much of the South Pacific, northern Australia, northern Africa, the Balkans and most of the Caribbean. And while the disease wasn’t eliminated in Sri Lanka and India, deaths did decrease.
DDT’s success, however, was short lived, as many insect populations quickly developed resistance to the compound. In tropical areas, there was no break in the life cycle of the mosquito – there were always new mosquitoes being born to spread the disease, and the administrative and financial infrastructure to pursue an organized and ongoing program was largely lacking. Malaria remains a deadly disease in Africa today, and current efforts focus on controlling the spread of the disease and treating it, rather than attempting to eradicate it.
Fast forward to 1962, when the book Silent Spring was published. This book, by U.S. biologist Rachel Carson, suggested that DDT, along with other pesticides, could cause cancer. Carson contended that the widespread use of DDT was releasing numerous chemicals into the environment, an activity that should be curtailed until more was known about the way these chemicals could affect humans and our environment. In addition, she claimed that birds were especially vulnerable to DDT and, in fact, the ban on DDT – together with the Endangered Species Act – are said to be the two factors instrumental in the resurgence of the bald eagle in the U.S.
Publication of this book helped mark the beginning of the environmental movement and the birth of a new awareness of how human actions affect the world around us. In 1963, then U.S. President Kennedy ordered a Science Advisory Committee to investigate the claims made by Carson. The Committee concurred with Carson’s ideas and recommended that many pesticides be phased out. “Ban DDT” became the rallying cry for the burgeoning ecological movement.
In response to this book and the environment created, DDT was banned in the U.S. in 1972, and the Stockholm Convention went on to ban its use in agriculture worldwide.
However, use of DDT is permitted under an exemption for public health. In 1979, for example, it was used to suppress vectors of the bubonic plague in California. This continued occasional use of DDT is controversial, but used as it is now – only against specific disease vectors or for indoor residual spraying – DDT can still play a crucial role in modern disease management.