Published today in Cancer Epidemiology, Biomarkers & Prevention, the study found a significant association between DDT in grandmothers' blood during pregnancy, and obesity and early first menstrual periods in their granddaughters—factors known to increase the risk for breast cancer, high blood pressure, diabetes, and heart disease.
"This is the first three-generation study that [shows] it's plausible that an environmental chemical in a grandparent can impact obesity and timing of menarche in the grandchild," Barbara Cohn, a study author and director and senior research scientist at the Public Health Institute's Child Health and Development Studies (CHDS), told EHN.
Transgenerational impacts of DDT
Researchers have established health effects from transgenerational exposure to chemicals in laboratory animals, but never before in humans. Grandchildren's exposure can occur when their mothers are in utero and their mother's egg cells are in development.
DDT compounds are known endocrine-disrupting chemicals that can alter and interfere with natural hormones that are essential for development. DDT exposure has been linked to breast cancer, birth defects, reduced fertility, and an increased risk of diabetes. It was banned in the United States in 1972 but is still used in other countries to kill mosquitoes that carry malaria.
Conducted by researchers at CHDS and the University of California at Davis, the study relied on blood samples collected from pregnant women between 1959 and 1967 as part of the CHDS study that has followed 20,000 pregnant women in California's Bay Area, and their families, for more than 60 years. CHDS investigates how health and disease are passed on between generations. The original cohort of women, the grandmothers, gave blood samples at each trimester during pregnancy and one sample shortly after they gave birth.
The current study is based on a subset of 365 adult granddaughters. The risk of obesity (Body Mass Index greater than 30 kg/m2) in young adult granddaughters was found to be 2 to 3 times greater when their grandmothers had higher levels of o,p'-DDT, a minor compound of DDT, in their blood during or just after pregnancy. Similarly, granddaughters were twice as likely to have earlier first menstrual periods (before age 11) when their grandmothers had higher o,p'-DDT blood levels.
Previous CHDS studies have shown that mothers' DDT exposure during pregnancy or immediately after birth correlates with increased risk of breast cancer and the prevalence of breast cancer risk factors, including obesity, in their adult daughters. While the granddaughters were too young (median age of 26) to measure breast cancer risk, the researchers state that "the impact can't be ruled out."
Timing of toxic exposures
DDT was banned in the U.S. in 1972 but is still used in other countries to kill mosquitoes that carry malaria.(Credit: Tim Lang/flickr)
The study breaks other important ground, according to Julia Brody, executive director at the Silent Spring Institute, who was not involved in the study. First, it shows consistency that o,p'-DDT is the best marker for recent exposure. Most previous studies, conducted after DDT was banned in the U.S., have measured DDT's main breakdown compound (DDE) in women's blood and they largely failed to find a connection to breast cancer.
CHDS researchers focused on o,p'-DDT, a contaminant comprising roughly 15 percent of commercial grade DDT, as a marker for active exposure—that is, exposure during pregnancy many decades ago—because it is more quickly metabolized than DDT's main ingredient (p,p'-DDT) which breaks down to DDE.
Second, Brody told EHN, the study shows, "You can't assume that exposure later in life is the same as exposure early in life." Exposures to DDT at pregnancy appear more impactful than at mid-life, the age that other researchers have focused their investigations into DDT and breast cancer risk.
Cohn agrees. Her research shows that DDT exposure during pregnancy and at puberty is particularly harmful. "The issue of the vulnerability of a pregnant woman should be a major part of the story," she said.
Policies aimed at endocrine disruptors
Researchers further conclude that their results suggest that ancestral DDT exposures may be a contributing factor to the global trend in today's rising obesity rates, and the falling age at first menstrual period.
Though they were not able to account for diet or exposure to other so-called obesogens (chemicals associated with obesity), Cohn pointed to the strong association they found between grandmothers' DDT levels and granddaughters' obesity and said that for other factors to explain granddaughters' obesity, "only the daughters whose grandmothers were exposed to DDT would have to be exposed to current obesogens today," and that's unlikely.
Kelle Moley, deputy director at Reproductive Health Technologies, Bill and Melinda Gates Foundation, thinks the theory has "biological plausibility." She's studied factors in transgenerational obesity in laboratory animals and finds it interesting to see a similar effect in humans. "The study, of course doesn't explain all of it, but it could be some contributing factor to the rise in obesity," she said.
Moving forward, both Cohn and Brody would like policymakers to view the study as proof of concept that exposure to endocrine-disrupting chemicals can impact generations, and to begin looking to animal studies that have documented the impact of endocrine disruptors on future generations to devise policies that reduce human exposure.
"We don't want to wait the next three generations to find out the chemicals that are in use now cause breast cancer," said Brody.
Banner photo: "We're all kind of connected…what you do today has an effect on generations going forward," says Akilah Shahid, pictured here with her mother Dr. Terri Jett and grandmother Beatrice Jett. All three generations participated in the Child Health and Development Studies research program. (Credit: Akilah Shahid)
The series has drawn local, national, and international media coverage, and prompted action from readers, activists, and legislators.
Here's a sampling of the impacts so far, and some additional ways readers can take action to help move the needle on the critical issues covered in the reporting.
Media interviews & stories
- Living on Earth - the NPR podcast interviewed EHN reporter Kristina Marusic
- Philadelphia Inquirer columnist Will Bunch asked, "Will Pa. shrug off new fracking horror stories?"
- NowThis put out a video about Fractured.
- The Independent published a news article about Fractured: "'Cancer-causing' chemicals found in children living near fracking well sites following two-year investigation."
- A TribLive reader wrote a Letter to the Editor: "Nowhere to hide from dangers of fracking."
- Raging Chicken Media interviewed EHN reporter Kristina Marusic for its Out d'Coup podcast.
- Argentinian NGO Observatorio Petrolero Sur cited Fractured in its reporting on communities in northern Patagonia that are experiencing health issues they believe are related to fracking.
- Veronica Coptis, executive director of the Washington County nonprofit The Center for Coalfield Justice, published a moving blog post in response to Fractured.
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I hope that having these test results will empower [these families] to be able to better advocate for their health, for the health of their kids, and for the safety of their communities. And I have seen that start to happen since the series was published." - Kristina Marusic
We should remember this as the year that the great political debate over fracking for oil and natural gas ended—at least here in the critical state of Pennsylvania. On one hand, there's mounting evidence that the frenzy for unconventional gas drilling under the Marcellus Shale has failed to produce any lasting job boom or the tax revenue that its backers promised. On the other hand, scientists have more proof that fracking has polluted the air and water of nearby residents, as worries about the health impacts are spiking. Is it really a debate when both hands are on the same side?
'Skin issues, rashes, breathing issues, … behavioral issues' — These southwestern PA residents spoke out about how living near fracking sites has affected their health.
"This is yet another study showing the harms of what Pennsylvania is surrounded by, whether it's waste or industry with compressor stations or pipelines or frack-pads," Pennsylvania State Senator Katie Muth told The Independent. "Why is this allowed to happen? This is completely preventable."
How much does the average Pennsylvania resident know about the fracking industry and the resulting health detriments it causes? The article "Fractured: Harmful chemicals and unknowns haunt Pennsylvanians surrounded by fracking" in Environmental Health News, about a Washington County family, is a must-read for those who have not been following the issues.
To me, this seems like systemic abuse, because it's like...where can you go?... You can't just leave this abusive relationship with fracking in western Pennsylvania. - Podcast host Kevin Mahoney
Situaciones similares a las descritas por las vecinas de Calle Ciega 10 se han registrado en el estado de Pensilvania, Estados Unidos. Una reciente investigación de Environmental Health News da cuenta de los padecimientos que de quienes viven en una de las áreas más perforadas de ese país.
Rough translation: Situations similar to those described by the neighbors of Calle Ciega 10 have been documented in the state of Pennsylvania, United States. A recent investigation by Environmental Health News accounts for the ailments of those who live in one of the most heavily-fracked areas of that country.
As a mother of two young children living a mile from several oil and gas operations, these articles were challenging to read, and I want to acknowledge that I needed time to move through being consumed by anxiety and fear over the risk my children are being exposed to as I read through them.
Legislative and advocacy action
35 lawmakers wrote a letter to Pennsylvania Governor Tom Wolf urging action in response to Fractured. (Credit: Governor Tom Wolf/flickr)
- 35 lawmakers wrote a letter to Governor Tom Wolf urging action in response to Fractured.
This study adds to an ever-growing mountain of evidence comprising more than ten years of epidemiological studies from across the United States that demonstrate a connection between a person's proximity to shale gas development and a host of negative human health conditions, significant ecological impacts, and dire economic projections for the affected individuals.
- The Better Path Coalition urged Governor Wolf to consider a statewide fracking ban in response to Fractured
The chilling results show that families living near fracking operations have alarming levels of chemicals like xylene, ethylbenzene, styrene, toluene, and others in their bodies, in their air, and in their water...How much more evidence does Governor Wolf need to provide the same protection to Pennsylvanians in the shale fields he was prepared to provide to people in the Delaware River Basin four years ago?
- Concerned Health Professionals of New York issued a statement calling for a comprehensive phase-out of fracking in response to Fractured.
Pennsylvania's children should not be used as laboratory rats in an uncontrolled human experiment involving toxic exposures.
- The Southwest Pennsylvania Environmental Health Project* called for additional research using the same methodology used in Fractured.
The EHN investigation...shows a path forward to definitive biomonitoring approaches when studying the body burden of people living in proximity to shale gas development.
Reader responses
"I've been involved advocating for the Delaware River Basin since before I had my first child, and I am so grateful for the scientific reporting on these outcomes...Let's create a letter-to-the-editor template with talking points to share widely, focusing on Fractured results and the fact that exposures are ongoing and largely undocumented and unknown." - Rachel Dawn Davis
Ohio Valley Environmental Resistance did an action calling out Allegheny County Executive Rich Fitzgerald on his persistent cheerleading for the fracking and petrochemical industries. Held on Pi Day (March 14), it was a science-themed push-back to Fitzgerald's comment that "We believe in science around here," and included literature for surrounding residents with references to this [Fractured] and other studies.
"This is tremendous public health investigation and reporting. Having worked in environmental health previously, I know it was no small feat to design such a study that included air monitoring and urinalysis and looked for correlations between exposures and the metabolites. " -Nina Baird, PhD, MSPH, Assistant Professor at Carnegie Mellon University
How can you push this story forward?
- Contact your elected officials, town council, or county health office, or write a letter to the editor of your local paper to share the investigation and request action.
- Donate to EHN to support continued coverage of this issue and further investigations into issues affecting our health and environment.
- Join local, national, or international networks of people who are interested in and active on this issue. A couple examples: Halt the Harm*, Physicians for Social Responsibility
* Editor's note: Southwest Pennsylvania Environmental Health Project and EHN.org both receive funding from the Heinz Endowments, but their work remains independent from the foundation. Halt the Harm Network's president serves on the advisory board of Environmental Health Sciences, publisher of EHN.org.
Banner photo: Children involved in EHN's Fractured study participate in a 2019 youth climate change protest in downtown Pittsburgh. (Credit: Connor Mulvaney for Environmental Health News)
The study, published in Applied Geochemistry, found that almost every groundwater sample across 32 U.S. aquifers had detectable strontium levels, while 2.3 percent exceeded 4 milligrams per liter (mg/L), the maximum amount that people should consume routinely, according to the Environmental Protection Agency. The public and private wells extending from these aquifers provide drinking water for 2.3 million people.
While low amounts of natural strontium are safe and even beneficial for the human body, these high concentrations can stunt bone growth in children who lack adequate calcium intake. Strontium can replace calcium in bones, weakening them and limiting development, according to Sarah Yang, the Wisconsin Department of Health Services' groundwater toxicologist.
"We're more worried about infants and children because their bones are actively growing," Yang told EHN. "Generally infants and children can absorb more strontium in their intestines, and adults can't."
High strontium in drinking water is linked to rickets in children, an extremely rare skeletal condition causing soft, sometimes deformed, bones.
Strontium, a soft metal that originates from minerals like celestine, makes its way into drinking water naturally. Aquifers with high strontium concentrations are often surrounded by carbonate rock containing limestone and dolomite.
In the USGS study, author MaryLynn Musgrove, a research physical scientist, found that 86 percent of people exposed to high strontium levels drink water supplied by carbonate rock aquifers. More than half of them are using Florida's underground reservoirs, where some freshwater has been blending with limestone and dolomite for 26,000 years.
Texas' carbonate aquifers also stood out.The Edwards-Trinity aquifer system, a sandstone and carbonate formation spanning from Oklahoma to western Texas, had the most frequent occurence of high strontium concentrations in its corresponding wells.
Dolomite is abundant in the bedrock of eastern Wisconsin, where strontium levels are among the highest of U.S. drinking water supplies.
While the USGS study mainly looked at areas exceeding 4 mg/L of strontium in samples, some communities living atop these dolomite layers drink water with more than 25 mg/L, the one-day health advisory limit for children.
"We have a lot of communities that have values above 20, 30, 50 mg/L," John Luczaj, a professor of geosciences at University of Wisconsin, Green Bay, told EHN.
Removal of strontium from drinking water
Credit: USGS
While its radioactive sibling, strontium-90, is regulated, natural strontium contamination is unregulated by the Environmental Protection Agency.
The major dilemma, according to Victor Rivera-Diaz, a writer and researcher for Save the Water, is that it is still a "public health mystery." While some research has conclusively linked strontium to bone degradation, a lack of data has kept the EPA from regulating it under the Safe Drinking Water Act.
"It is a problem," Rivera-Diaz told EHN. "It definitely requires more attention, even more so in the areas that are prone to high contamination."
But this is easier said than done, Rivera-Diaz explained.
Strontium cannot be removed with conventional water treatment technology. Thus, communities would have to look to other systems, such as point-of-entry reverse osmosis.
"Some of these technologies can be quite costly, so that might be a barrier for lower-income communities," Rivera-Diaz said.
Reverse osmosis systems and water softeners are incredibly effective in removing strontium concentrations.
"If it was up to me, I would, in the short term, figure out a way to subsidize technologies that are proven to filter out strontium, especially in those communities where those levels are well above 4 mg/L," Rivera-Diaz said.
Banner photo: Bluewater Globe/Unsplash