A synthetic compound used as an insecticide and pesticide to fight human illnesses and agricultural pests, until in the seventies it was proven toxic and dangerous.
Despite being prohibited as a pesticide, its medical use continues, especially to control malaria.
Dicloro-Difenil-Tricloroetano (DDT) is a compound soluble in oils and organic solvents, although insoluble in water.
Despite having been synthesized in 1874, its amazing insecticide properties (it was defined as the “miracle compound”, given its effects) weren’t discovered until 1939, coinciding with the beginning of World War II, where it was used successful to combat typhus, malaria and other illnesses transmitted by mosquitos and other insects, among both the troops and the civilian population.
After the war, the efficiency of DDT extended its use as a pesticide and its production increased dramatically. DDT was used in a generalized manner to protect crops from pests worldwide, until the 1970s when the public learned about the environmental effects of using this synthetic compound.
The denouncement by Rachel Carson
In her successful book Silent Spring (1962), Rachel Carson explained the environmental damages derived from the use of DDT. Carson predicted that, if the use of DDT continued, all the birds in the world would disappear.
With the help of other scientific personalities, Rachel Carson alerted the world of the of the danger of irreversible contamination of food, since the compound accumulates in food chains.
Once Carson’s studies were ratified by other biologists and scientists, the U.S. Environmental Protection Agency (EPA) banned the use of DDT in 1972.
Its prohibition extended to other countries (the first to adopt a ban where Norway and Sweden; the U.S., and in the eighties European countries like the United Kingdom). However, in countries like India its use hasn’t been banned.
Despite an order in 1971 from the U.S. District Court of Appeals to begin the de-registration process for DDT, EPA administrator William Ruckelshaus initially rejected an outright ban stating it to be proven safe and non-toxic to humans and animals. Due to public outcry, in the summer of 1972 Ruckelshaus announced a ban on most uses of DDT:
- DDT was excluded from the list of authorized substances for protection of plants and pest control.
- Now, the ban extends to the production, user and sale of all plant protection products that contain DDT.
To prevent malaria without endangering people, animals and plants
In 2006 the World Health Organization announced that it would return to using DDT as an insecticide to eradicate malaria (and to kill the mosquitos that transmit the disease).
Although this international organization considers that its use isn’t harmful to nature and, instead, effective in the prevention of this disease, its use continues to be controversial.
The United Nations Environment Program (UNEP) called for the elimination of 12 compounds that “can kill people, damage the nervous and immune systems, cause cancer and reproductive disorders and interfere with normal infant and child development,” among those was DDT.
Due to its characteristics, according to the Stockholm Convention on Persistent Organic Pollutants (POPs) from May of 2005, DDT was classified as one of these compounds:
- Highly toxic; they are unstable and persistent and last decades before degrading; they evaporate and can spread across vast distances through the air or water, and accumulate in the fatty tissue of humans and wild species.
DDT and malaria
Those in favor of the use of DDT to combat malaria argue that:
- It is an efficient method to eradicate malaria in Europe and and has practically done just that in India.
- They defend the effectiveness of the substance given the low cost of use and the fact that there are no issues with patents.
However, the environmental community and part of the scientific community don’t believe that DDT is benign:
- DDT is noxious to the food chain and animals and possibly carcinogenic for humans.
- Despite not having been banned in India, malaria continues to be present in this country, although it has dropped from 100 million cases in 1935 to isolated cases currently.
The effects of DDT on human health are controversial, although many studies present varying results:
- DDT is catalogued as “moderately toxic” by the U.S. National Toxicology Program.
- Chronic toxicity: DDT has been associated with neurological and psychiatric problems.
- Cancer: The EPA classified DDT in 1987 as a carcinogenic substance.
- Other studies relate the use of DDT with reproductive problems and child development.
DDT and the environment
Among the diverse effects of DDT on the health of animals, many highlight:
- Problems in reproduction and development.
- Possible defects on the immune system and premature death of birds.
- Effects on the liver and kidney.
- Block of sexual development in many animals, during several studies.
- Reduction in the quality and quantity of microscopic animals in phytoplankton, a fundamental pillar of the marine food chain.
- DDT has been detected in animals in the Arctic, clear proof of the action and influence on the development of life on the planet.