DDT - A Brief History and Status
Development of DDT
DDT (dichloro-diphenyl-trichloroethane) was developed as the first of the modern synthetic insecticides in the 1940s. It was initially used with great effect to combat malaria, typhus, and the other insect-borne human diseases among both military and civilian populations. It also was effective for insect control in crop and livestock production, institutions, homes, and gardens. DDT's quick success as a pesticide and broad use in the United States and other countries led to the development of resistance by many insect pest species.
Regulation Due to Health and Environmental Effects
The U.S. Department of Agriculture, the federal agency with responsibility for regulating pesticides before the formation of the U.S. Environmental Protection Agency in 1970, began regulatory actions in the late 1950s and 1960s to prohibit many of DDT's uses because of mounting evidence of the pesticide's declining benefits and environmental and toxicological effects. The publication in 1962 of Rachel Carson's Silent Spring stimulated widespread public concern over the dangers of improper pesticide use and the need for better pesticide controls.
In 1972, EPA issued a cancellation order for DDT based on its adverse environmental effects, such as those to wildlife, as well as its potential human health risks. Since then, studies have continued, and a relationship between DDT exposure and reproductive effects in humans is suspected, based on studies in animals. In addition, some animals exposed to DDT in studies developed liver tumors. As a result, today, DDT is classified as a probable human carcinogen by U.S. and international authorities.
- known to be very persistent in the environment,
- will accumulate in fatty tissues, and
- can travel long distances in the upper atmosphere.
After the use of DDT was discontinued in the United States, its concentration in the environment and animals has decreased, but because of its persistence, residues of concern from historical use still remain.
Since 1996, EPA has been participating in international negotiations to control the use of DDT and other persistent organic pollutants used around the world. Under the auspices of the United Nations Environment Programme, countries joined together and negotiated a treaty to enact global bans or restrictions on persistent organic pollutants (POPs), a group that includes DDT. This treaty is known as the Stockholm Convention on POPs. The Convention includes a limited exemption for the use of DDT to control mosquitoes that transmit the microbe that causes malaria - a disease that still kills millions of people worldwide.
In September 2006, the World Health Organization (WHO) declared its support for the indoor use of DDT in African countries where malaria remains a major health problem, citing that benefits of the pesticide outweigh the health and environmental risks. The WHO position is consistent with the Stockholm Convention on POPs, which bans DDT for all uses except for malaria control.
DDT is one of 12 pesticides recommended by the WHO for indoor residual spray programs. It is up to individual countries to decide whether or not to use DDT. EPA works with other agencies and countries to advise them on how DDT programs are developed and monitored, with the goal that DDT be used only within the context of programs referred to as Integrated Vector Management. IVM is a decision-making process for use of resources to yield the best possible results in vector control, and that it be kept out of agricultural sectors.
Additional information on DDT:
- EPA History: DDT (dichloro-diphenyl-trichloroethane)
- National Pesticide Information Center (NPIC) DDT Factsheets
- Stockholm Convention on POPs
- The World Health Organization press release promoting the indoor spraying of DDT in fighting malaria