When Rachel Carson published her classic "Silent Spring," she kicked off the modern environmental movement.
Carson was particularly concerned about large scale pesticide spraying, and its impact on plants, animals and birds in its path that were not its intended target. Her research and well presented argument on how chemicals, particularly the use of DDT as a pesticide on American farms, destroyed ecosystems and the beauty of nature, began a crusade that resulted in the ban of DDT in the United States. Carson herself never pushed for a ban, but soon thereafter, agricultural use of DDT was banned worldwide. In the United States, the ban on DDT along with the establishment of the Endangered Species Act, is credited with the comeback of the American Eagle.
DDT, Dichloro-Diphenyl-Trichloroethane, has been so impacted by Carson's work and the uproar that followed "Silent Spring" in 1962 that it is infamous within popular culture and nearly synonymous with poison itself. DDT was first synthesized in the mid-1870s, but wasn't used to kill pests until World War II, when its insecticidal uses were first discovered. The synthetic was used widely during the war to control the spread of malaria and typhus to protect Allied troops.
Today, DDT is manufactured only in China and North Korea. Yet in some ways, the synthetic has returned to its earlier and most successful uses. DDT is one of few substances that has been successful in lowering rates of malaria. It is credited with helping the Allies win the war in the Pacific by protecting the troops from bouts of the illness. With the disease prevalent again in African nations, production may be on the rise. Currently, India is the world's largest consumer of DDT.
In the 1950s, the World Health Organization began a program to eradicate malaria world wide, largely dependent on DDT. Initially, there was great success in slowing malaria in many sections of the world, including North Africa, the Caribbean and the Balkans. But widespread agricultural use led to immunity in some insect groups, reversing gains in some areas.
Today, use of DDT is restricted to vector control, which makes current treatments to eradicate malaria more effective. Environmental groups agree that to ban DDT outright would be impractical, perhaps disastrous, in areas of the world where there is simply no other feasible alternative for fighting mosquitoes and malaria.
Even modern methods for using DDT in malaria control are more environmentally friendly. Instead of wide spraying that can harm ecosystems, homes are now treated indoors with DDT to repel insects attempting to enter structures. This method discourages resistance from insects and uses a fraction of the chemical used previously in outdoor applications. It also discourages soil pollution from DDT, which is hydrophobic and can be heavily absorbed by soils.
Malaria is a major health concern, resulting in more than 1 million deaths a year, according to the WHO. The overwhelming majority of deaths occur in Africa, primarily to children under the age of five. Currently, only 13 countries are using DDT in their anti-malarial programs, but that number is expected to rise, as DDT remains one of the most successful deterrents to the disease. Use of DDT dropped over the years in favors of other anti-malarials and programs to distribute bed netting in areas heavily impacted by the disease.
While the WHO recognizes the success of DDT in fighting malaria, it looks to phase it out if possible. In areas where DDT is used as an anti-malarial for indoor treatment, exposure rates for adults are higher than acceptable, and it is also found in the breast milk of pregnant women. Additionally, Africans themselves do not like the lingering smell, the stains it leaves behind, or the fact that DDT seems to make other insects like cockroaches more active.
Like so many environmental challenges of our day, the use of DDT illustrates the scientific principal that every action has a reaction. While the ban of DDT for agricultural use has likely led to the rebound of many ecosystems and fauna, it may also have resulted in an openness to using the synthetic to fight malaria once more, as resistance to the chemical among insects has now disappeared. Yet in protecting children from malaria, we may in fact be inflicting greater harm on their families and villages.