DDT

DDT leaves behind a legacy of long-lasting contamination and harm to both humans and ecosystems. Banned in the U.S. nearly 40 years ago, DDT and its breadown products were found in the blood of 99% of people recently tested by the CDC. USDA found DDT breakdown products in 60% of heavy cream samples, 42% of kale greens, 28% of carrots and lower percentages of many other foods.

Human Health Harms

The science on DDT's human health impacts has continued to mount over the years, with recent studies showing harm at very low levels of exposure. Studies show a range of human health effects linked to DDT and its breakdown product, DDE:

  • Cancer: Girls exposed to DDT before puberty are 5 times more likely to develop breast cancer in middle age, according to the President’s Cancer Panel.  DDT has also been associated with liver and pancreatic cancer. The International Agency for Research on Cancer classifies DDT as "possible carcinogenic to humans."
  • Reproductive Effects: DDT is linked to male infertility, impaired semen quality, miscarriages, early menopuase, birth defects, and low birth weight.

[Text Box: Childhood Exposure & Body Burden: Research shows that childhood exposure to DDT begins before birth.

  • Pregnant women pass DDT to their unborn baby through the placenta, while nursing infants receive doses of DDT though their mother's breastmilk.
  • Children are exposed to higher levels of DDT than adults due to their smaller body size. Studies show infants consume 4 times as much DDT as the average adult.]

DDT & Ecotoxicity

DDT's toxic effects on ecosystems are well known. DDT concentrates up the food chain, reaching high levels in fish and marine mammals. DDT can travel long distances in the atmosphere, which is why it is found on almost every corner of the earth and in places where it has never been used. In the Arctic and Antarctic regions, research shows DDT and its breakdown products in the atmosphere, snow, and wildlife.

[Text Box: Environmental Persistence: Despite bans, DDT can persist in the environment for decades:

  • Concentrations of DDT near a former manufacturing facility at McIntosh, Alabama still represent a significant risk to fish and piscivorous birds in the area--- even though the plant ceased production over 40 years ago, says a recent study.
  • Despite dropping DDT levels in the Arctic's birds, whales, and seals, Adélie penguins in the Antarctic continue to have the same levels of DDT in their bodies as they did 30 years ago. Heidi Geisz of the Virginia Institute of Marine Science and her colleagues found that the birds were being exposed to DDT that was previously locked up in glaciers. See also: Antarctic Melt Releasing DDT, Tainting Penguins]

Experience tells us that eliminating DDT generally improves the health of ecosystems. Since DDT was banned in the U.S., bald eagles have made a dramatic recovery, along with a several other bird species. An Environmental Defense Fund article summarizes:

  • Since 1963 the bald eagle population has rebounded, increasing from less than 500 pairs to over 5,000 nationwide.
  • Peregrene falcons totaled only 39 breeding pairs in 1975. By 1996 however, their population multiplied to 993 pairs.
  • Ospreys have also made a comeback---increasing from less than 8,000 breeding pairs  to 14,246 pairs.

Malaria Control and Mosquito Resistance

Wiping out malaria with DDT is an unrealistic goal. Mosquito resistance among malaria carrying mosquitos forced governments years ago to adopt a more diverse, integrated approach to malaria control.

Long before the United States banned DDT, mosquito populations evolved defenses to DDT's toxins. Mosquitos showed signs of resistance to DDT as early as 1947---only one year after the insecticide was introduced for mosquito control (See: Insecticide Resistance in Insect Vectors of Human Disease). By 1972, nineteen species of mosquitos were resistant to DDT in Africa alone.

[Text Box: Malaria Eradication in the United States:

Once endemic in the United States, malaria decreased rapidly in the first half of the 20th century, without the insecticidal powers of DDT. According to the CDC, from 1920 to 1946, malaria cases decreased from 400 out of 100,000 inhabitants to only 30 cases per 100,000. Malaria deaths likewise decreased from 60 deaths per million to only 2 deaths per million. In 1947 the U.S. commenced the National Malaria Eradication Program which included drainage, removal of mosquito breeding grounds, and some DDT in areas where malaria was still prevelant. ]

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Additional Health Research: Reproductive Harm:

Addition Health Research: Infants and Breastmilk