Last month's groundbreaking DDT study — linking exposure in the womb to increased risk of breast cancer — represents more than an interesting footnote in the story of this legacy pesticide.
Not only is DDT still in our environment more than 40 years after it was banned in the U.S., it also continues to be sprayed inside homes in many African countries as part of malaria control programs — a practice that could be quadrupling the risk, it turns out, of breast cancer among daughters of women exposed to the chemical during pregnancy.
The study, published in the Journal of Clinical Endocrinology & Metabolism, looked at breast cancer incidence among daughters of women who were exposed to DDT in the 1960s, when use in the U.S. was widespread. Researchers found that when mothers had higher levels of DDT in their blood, their daughters' risk increased by nearly four times — regardless of family breast cancer history.
Dr. Barbara Cohn, PhD, Director of Child Health and Development Studies at the Public Health Institute in Berkeley, CA — and one of the study's authors — describes the significance of the findings:
"This 54-year study is the first to provide direct evidence that chemical exposures for pregnant women may have lifelong consequences for their daughters' breast cancer risk. Environmental chemicals have long been suspected causes of breast cancer, but until now, there have been few human studies to support this idea."
DDT was "safe"
The study is also significant as a cautionary tale. In the U.S., we have a long and storied history of approving widespread use of pesticides before we fully understand the risk they pose to our health. DDT is the first example in a series of "safer" pesticides that includes organophosphates like chlorpyrifos ("they don't last long in the environment, must be better"), pyrethroids ("the original version was made from flowers!") and neonicotinoids.
In every case, dramatic health or environmental harms came to light many, many years after millions of pounds of the chemicals were applied in fields and communities across the country.
The most recent example is Monsanto's flagship herbicide, RoundUp. Earlier this year, the World Health Organization announced that glyphosate, the main ingredient in the most popular pesticide products on the planet, probably causes cancer. Since its introduction, Monsanto marketed RoundUp as the "safer" alternative to more toxic herbicides like atrazine or 2,4-D.
The lesson? Chemicals designed to kill weeds or insects are not likely to be healthy for humans. It's time to find a better way to manage pests.
Even when they carry diseases like malaria, insects are better managed without reliance on health-harming pesticides. Malaria is a deadly disease that remains a serious challenge in many countries in Africa. Experience around the world shows that the most effective malaria control programs directly involve the community in addressing the challenge with "integrated vector management" approaches, and tackle the underlying issues — like poverty and lack of access to health care.
Relying on "silver bullet" solutions like spraying DDT inside people's homes is not only less effective, but it also needlessly threatens the health of future generations. My colleague Dr. Abou Thiam of PAN Africa shared his perspective on World Malaria Day this year:
"Significant progress is being made in many African countries in the fight against malaria, without the need to use DDT. It’s high time for a full-fledged transition toward safe, sustainable malaria control. Our children deserve nothing less."
Dr. Cohn's recent study underscores the importance of making this transition sooner than later, for the health of both this generation and those to come.