DDT
DDT was created as the first synthetic insecticide in the 1940s. It was originally used with great success to fight malaria, typhoid and other insect-borne human diseases, among both military and civilian population.
DDT was effective in reducing morbidity and mortality from malaria during World War II. The World Health Organization anti-malaria campaign (spraying DDT, fast treatment and diagnosis to interrupt the transmission cycle) was also initially successful. For example, in Sri Lanka, the program reduced the number of malaria cases from one million per year before spraying to 18 cases in 1963 and 29 in 1964. The program was then suspended to save money, and malaria morbidity rate increased to 600,000 cases in 1968 and the first quarter of 1969.
As production and use of DDT increased, public reaction became more controversial. Concerns have been expressed about its ability to kill harmless and beneficial insects (especially pollinators), birds, fishes and, ultimately, humans. DDT toxicity problem was complex. One the one hand because the effects of DDT varied for different species, on the other hand because successive low dose exposures could accumulate, causing damage comparable to high doses. Some countries have tried to regulate DDT usage.
In 1957, The New York Times reported an unsuccessful attempt to restrict further use of DDT in Nassau County, New York. That matter attracted attention of naturalist writer Rachel Carson and in 1962 she published her big work on a subject – “Silent Spring”. In this book Carson claims that pesticides, including DDT, poisoning both wildlife and the environment and seriously endangering human health. “Silent Spring” became a bestseller, that was followed with initiation of the modern environmental movement in the United States. A year after its establishment, John F. Kennedy ordered President’s Science Advisory Committee to investigate Carson’s claims. In 1972, DDT was finally banned in the United States.
Along with the adoption of the Endangered Species Act, the United States ban on DDT was a major factor in saving such species as bald eagle and peregrine falcon which were nearly extinct at the time.
Since 1996, EPA has been involved in international negotiations to control the use of DDT and other persistent organic pollutants used around the world. Under The United Nations Environment Programme, countries have cooperated and adopted a treaty on global ban or restriction of persistent organic pollutants (POPs), including DDT.
DDT officially recognized to be able to fivefold increase the future risk of breast cancer among young women. Studies have shown that in low doses it can act as an endocrine disruptor, cause different birth defects, increase the risk of liver cancer etc. But the cause of all these diseases is very complex and therefore there is no clear and direct connection between DDT and such health issues.
Although DDT is no longer used in the United States, human exposure to DDT and its metabolites continues. For example, the primary metabolite of DDT, DDE, is much more persistent than the parent compound and thus is still found in the environment in small amounts. It is also accumulating inside adipose tissue (fat) increasing harmful effects on the body with age. In addition, DDT is still used in many parts of the world, especially where there is a high danger of contracting malaria, which has higher mortality rate than cancer, cardiovascular diseases and HIV/AIDS.
Links:
Stokstad E (June 2007). “Species conservation. Can the bald eagle still soar after it is delisted?”. Science. 316 (5832): 1689–1690. doi:10.1126/science.316.5832.1689
Environmental Health Criteria monograph No. 009, Geneva: World Health Organization, 1979
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2022666/
