Rachel Carson Was Right: World Health Organization on Pesticides and Cancer

pesticide sprayer

In 1962, Rachel Carson published a groundbreaking book, Silent Spring, that rang the alarm about the health and environmental impacts of rampant pesticide use – on our crops, lawns, and gardens. Two of those toxic chemicals – DDT and lindane – were the subject of a recent World Health Organization review. The agency found that they pose cancer risks to humans, highlighting the need for more effective public protections against dangerous pesticides.

At the time of Silent Spring's release, the chemical industry launched vicious personal attacks against Carson. Criticism continued long after her death from breast cancer in 1964, with industry apologists claiming that Carson's DDT claims were based on "sentimental fanaticism" and a selective reading of science. Other critics blamed her for the spread and persistence of malaria, saying that the DDT bans she inspired have hampered efforts to wipe out mosquitoes that carry the disease.

Rachel Carson was right to worry about DDT.

But the recent World Health Organization assessment underscores Carson's concerns about DDT. The review found that DDT "probably" causes cancer and could raise the risk of non-Hodgkin lymphoma (a cancer of the immune system's lymph nodes), testicular cancer, and liver cancer. Liver cancer is especially deadly, with a five-year survival rate of only 17 percent.

The World Health Organization's International Agency for Research on Cancer was even more pointed about the risks of lindane, finding that it definitively causes cancer in people. Lindane was heavily used in agriculture but has been severely restricted due to its toxicity, though it is still found in some prescription lice and scabies treatments used primarily on children. According to the cancer research agency, exposure to lindane could increase the risk of non-Hodgkin lymphoma by 60 percent.

The weed killer Roundup, widely used in the U.S., probably causes cancer.

The June review comes on the heels of another World Health Organization finding that glyphosate, a weed killer better known as Roundup, probably causes cancer in humans. Manufactured and marketed by Monsanto, the chemical is widely used by the agricultural industry and has also been implicated in the rapidly shrinking population of monarch butterflies because it kills off milkweed, the monarch caterpillar's only food source. Monarchs are a key indicator species in the United States, meaning that if they are disappearing, there is something wrong in our environment. They also help plants reproduce; like bees, bats, and hummingbirds, they are important pollinators.

Click the map above to view an animation showing Roundup usage in the United States from 1992-2012. Created by Environmental Working Group based on U.S. Geological Survey data.

Our national pesticide law is supposed to prevent harmful products from reaching the market, but the chemical industry is masterful at exploiting loopholes.

The U.S. Environmental Protection Agency (EPA) is supposed to carefully oversee pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act. The law is often held up as a model because it directs chemical companies to prove the safety of pesticides before EPA allows them on the market.

But the law doesn't work the way it's supposed to: because of intense chemical industry influence, EPA often grants "conditional" pesticide registrations, which means companies don't have to submit all the rigorous scientific studies normally needed to sell these products in American stores. When government relies only on industry studies to assess safety, even when companies submit a full set of materials, that evidence can be slanted in the industry's favor and rarely includes information on potential damage to our immune and hormone systems or the potential to cause learning problems in children.

Another shortcoming of our current national pesticide policy is that new scientific evidence, like that released by the World Health Organization, is frequently ignored, and dangerous pesticides remain on the market despite the risks they pose.

We need stronger government oversight and enforcement to keep these harmful products off our lands and out of the food supply.

In Silent Spring, Rachel Carson wrote, "[T]he chemical barrage has been hurled against the fabric of life." We can all play an important role in pushing back on this onslaught by decreasing or eliminating our own pesticide use on our lawns and gardens, but we can't take on the powerful chemical industry by ourselves.

To protect our families and communities, we need strong, comprehensive oversight and enforcement from our government to keep risky poisons off store shelves and away from our croplands. A good first step would be to ensure our national pesticide law actually works as intended – making pesticide companies prove their products are truly safe for people and our natural resources before they can be sold and used.

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It seems from what I can gather that among the pesticides developing in the 1940's that DDT is the safest. There's been no record of anyone getting cancer or dying from DDT. When parathion began to be used as a substitute there were reports of deaths among the farm workers spraying it. Also Dieldrin was originally developed in the 1940s as an alternative to DDT. It was very widely used during the 1950s to early 1970s. A study by the Journal of Clinical Epidemiology in the year 2000 indicates that Dieldrin is a estrogenic mimic shown to interact with the estrogen receptor. The study tracked 7712 women participants for 17 years and concluded that Dieldrin was associated with a significant increase in the risk of breast cancer. There’s also some other data available that shows that polychlorinated biphenyls, or PCBs are linked to higher risk of breast cancer. PCB’s were dumped into the environment from the 1930’s right up to 1979 and DDT became the scapegoat from numerous health problems in animals and humans caused by PCB’s.

New science is emerging on the risks of DDT. For example, the authoritative World Health Organization review is one piece of evidence (see the press release at http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr236_E.pdf). Another study, published in June in The Journal of Clinical Endocrinology & Metabolism, is another piece of evidence (see the brief Science write-up of the study at http://news.sciencemag.org/biology/2015/06/ddt-may-quadruple-breast-cancer-risk).