The U.S. Ban on DDT

A Continuing Success Story

Posted: 04-Apr-2005; Updated: 28-Dec-2006

Why was DDT banned originally in the U.S.?  

The pesticide DDT was banned in the United States in 1972 because it contributed to the near extinction of birds, including the bald eagle and the peregrine falcon. DDT is a persistent chemical that becomes concentrated in animal tissues, rising in concentration in animals that are higher in the food chain. It is particularly toxic to fish, aquatic invertebrates and insects (including some that are beneficial). While not immediately toxic to birds, DDT causes long-term reproductive problems by causing eggshells to weaken and crack, threatening the survival of many bird species. Because of its chemical nature, once DDT is applied in a field or other environment, it remains in an active form for decades. People throughout the United States still carry DDT and its metabolites in their bodies, 30 years after the pesticide was banned in this country.  Most other developed countries have also banned DDT, but it is still used in many developing countries.

Did the U.S. ban on DDT do any good?

Since the nationwide ban took effect, there has been a gradual decline in DDT levels in humans and in wildlife.  There has been no resurgence of malaria or any of the other diseases that DDT was used to fight in the United States. Moreover, farmers have found effective alternative means to control insect pests. The DDT ban is one of the very few actions directly responsible for the recovery of species once in danger of extinction, including the peregrine falcon, the bald eagle and the brown pelican. It also has clearly helped other bird species that were not yet endangered but whose populations were declining due to DDT. As Russell Train, chairman emeritus of the World Wildlife Fund put it, "The banning of DDT was one of the most important legal victories ever won for wildlife."

Recent studies have not found an association between DDT exposure in adults and breast cancer. This means DDT isn't toxic to humans, right?

Wrong. Chronic low dose DDT exposure has been shown to be associated with premature birth and low birthweight in babies who were exposed before birth, and with decreased duration of milk supply in nursing mothers. Most of what we know about DDT's toxicity to humans (as with many chemicals) is derived from laboratory-animal studies, which have demonstrated that DDT is likely to cause cancers and other health problems. Although recent studies have not established a link between DDT exposure and breast cancer in adults, they do not address whether prenatal or early childhood exposures to DDT cause breast cancer or other cancers in later life.

Is there truth to the claim that the DDT ban has harmed people?

The resurgence of malaria in certain regions of the developing world has been related to many factors, such as increases in international travel, population growth and ecosystem shifts that bring people more into contact with mosquitoes, and growing resistance of the malaria parasites to medicines. Most important, there have been widespread decreases in funding for the public health measures that had successfully controlled malaria earlier, including tracking and treating malaria cases, educating people on mosquito-avoidance measures and implementing integrated mosquito management plans. 

To attribute the resurgence in malaria to a failure to use one specific pesticide is not only misleading, it's incorrect. Prior to the bans on DDT in the U.S., Europe and other developed countries, mosquitoes were already becoming increasingly resistant to DDT.  As a result, mosquito control experts in those countries were already searching for more effective alternative pesticides and other mosquito-control measures. Recent articles in Science magazine document that mosquitoes throughout the developing world are also now increasingly resistant to DDT. Thus, its effectiveness is limited, and its use will not accomplish public health goals in the absence of a comprehensive pest management program.

What about the new epidemic of West Nile virus? Shouldn't we bring back DDT to get rid of this disease?

No. No pesticide will completely stop West Nile virus. Unlike malaria, whose parasite only lives in mosquitoes and humans, the West Nile virus lives mainly in bird species, which carry the virus with them as they migrate.  For that reason, it is far more complicated to control the West Nile virus, particularly because there is no way to treat the disease in birds. While a public health program involving human diagnosis, case tracking, treatment and mosquito control was able to essentially eradicate malaria in this country, more-aggressive mosquito-control measures (such as use of DDT) will not prove effective for long-term control of West Nile because birds will continue to spread the disease. A vaccine, if it can be developed, will be more effective in preventing human disease, and will avoid widespread ecological damage. Not only would aerial spraying of DDT be ineffective in limiting spread of the West Nile virus, but it would also harm still more birds beyond the massive numbers that have died from the West Nile virus, and would also expose a new generation of humans to this bio-accumulating toxin.

What is Environmental Defense's positon on DDT?

Environmental Defense was founded in 1967 by scientists who were concerned about DDT's role in driving many bird species to the brink of extinction in the U.S. Today, Environmental Defense recognizes the tremendous public health burden of malaria in developing countries. Environmental Defense supports the practical approach taken in the Stockholm Convention on Persistent Organic Pollutants (POPS), which was agreed to by international negotiators in 2001 and which the U.S. has signed but not ratified. 

This treaty allows indoor use of DDT to control disease-spreading insects when "locally safe, effective and affordable alternatives are not available."  The POPS treaty aims to encourage the development of less persistent and toxic alternatives, in order to allow the eventual elimination of DDT. The treaty also provides a system to track DDT usage so that it is not used in widespread, outdoor applications that would harm wildlife and human health. 

Environmental Defense believes that, as cost-effective alternatives become available, all uses of DDT should be phased out.  Due to its relative low price compared to alternative pesticides, DDT use is still prevalent in some developing countries. Special efforts on the part of the developed world should be made either to produce low-cost alternatives and to assist poorer countries in purchasing higher priced alternatives are urgently needed. The long-term answer to control of malaria and other insect-borne diseases lies with adequate investment in public health surveillance, treatment and comprehensive pest management, including the identification of safer and more effective pesticides. We urge the U.S. government to contribute to achieving these goals by ratifying the Stockholm Convention and by providing research, technical and financial assistance to developing countries in all aspects of malaria control.

Letter to U.S. Agency for International Development  (AID) [PDF document] -- April 2004 letter from Environmental Defense to U.S. AID, urging the agency to consider limited indoor use of DDT for malaria control in regions where malaria is spread by indoor-dwelling mosquitoes until better alternatives are developed.