Pregnant women and babies face risk from unregulated chemicals

In brief:

• Of 40,000 chemicals registered for use in the U.S., fewer than 30 have undergone an EPA risk assessment.
• New research found pregnant women are exposed to dozens of chemicals and many of them are associated with adverse birth outcomes.
• Stanford will launch a program to close data gaps on chemical health hazards and exposures, and advance policy solutions.

Add untested chemicals to the list of concerns for expectant parents. A new study coauthored by Stanford environmental health scientist Tracey Woodruff finds that most of the pregnant women it analyzed were exposed to dozens of chemicals found in a range of products and industrial applications — leading to preterm birth and reduced birthweight, among other adverse outcomes.

A former senior scientist and policy advisor at the U.S. Environmental Protection Agency, Woodruff joined Stanford earlier this year after leading the Program on Reproductive Health and the Environment at the University of California, San Francisco. She is working to establish a program at Stanford that will focus on improving understanding of the relationship between health effects and chemical exposures, analyzing the effectiveness of interventions like public policies, and identifying how science can better inform decision-making to improve health. 

Below, Woodruff, a professor of epidemiology and population health at the Stanford School of Medicine and a senior fellow at the Stanford Woods Institute for the Environment, discusses findings from the study, what's driving a surge in non-communicable diseases like cancer and cardiovascular disease, and her vision for a new Stanford program to advance science-based policy solutions to reduce toxic chemical exposures.

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Your study found that pregnant women were exposed to dozens of chemicals at once. What does that tell us about the scale of the problem?

Woodruff: We’re only scratching the tip of the iceberg. There are 40,000 chemicals registered for use in the United States that are under EPA's purview. Just over 20 have gone through the full risk assessment process under the Toxics Substances Control Act, the primary law governing chemicals. The chemical industry has been effectively allowed to produce and use chemicals however they want, with very little oversight. The mismatch between the problem and the solution is enormous.

Your study measured chemicals that haven't been widely studied before. How did you decide which ones to focus on?

Woodruff: We prioritized chemicals that haven't been frequently measured in pregnant women before, ones we know have potential for exposures based on other databases, and ones we know have potential for health harms based on other types of health hazard data. 

Your study highlights "replacement chemicals" — substances introduced as supposedly safer alternatives to older chemicals. Why do we keep finding ourselves in this cycle?

Woodruff: Government agencies typically evaluate health risks for chemicals one at a time. This means that when a single chemical is identified as harmful and regulated, a chemical similar in structure, that can have similar health effects but hasn’t been evaluated yet, is still allowed on the market. That is why we and authoritative bodies, like the National Academies of Sciences, Engineering, and Medicine, recommend that agencies regulate entire classes of harmful chemicals, not just one at a time. 

Pregnancy can already feel overwhelming. How do you talk about these risks without making people feel powerless?

Woodruff: The first thing to say is, this is not your fault. Don't blame yourself. The good news is that studies show that some individual actions can reduce exposures. For example, dietary changes that focus on eating nutritious organic foods, like fresh fruits and vegetables, and foods prepared inside the home can reduce exposures to pesticides and plastic-related chemicals. But, it will only solve part of the problem, because there are many exposures beyond our control. That is why we need systematic changes to reduce toxic chemical exposure.

You've pointed to a dramatic rise in non-communicable diseases over the past few decades. What's driving that?

Woodruff: In the '90s, communicable diseases were the biggest share of the global burden of death — disease like tuberculosis, HIV/AIDS, and malaria. Over the past three decades, we’ve seen a dramatic shift to noncommunicable disease as the leading contributor to global mortality. Diseases like cancer, cardiovascular disease, Parkinson’s disease, and diabetes have risen by more than 100% in the U.S. over the past 30 years, a rise so rapid that it cannot be explained by genetics. It is being driven by external factors, like environmental exposures and health-harming products. There are new studies showing that about 30% of global deaths are from health-harming products like fossil fuels, tobacco, ultraprocessed foods, alcohol, and chemicals.

If you could change three things that would most reduce harmful chemical exposures during pregnancy, what would they be? 

Woodruff: First, enact a regulatory system that requires the industry to prove chemicals are safe before they are on the market, this means for both chemicals already on the market and those that are to be introduced. Second, end chemical industry influence on the scientific and regulatory processes. Lastly, reduce plastic production and ban single-use plastics and toxic chemical additives. And these goals are popular with the public. Public opinion polling has consistently shown that across political affiliations, Americans want the government to better regulate chemicals and show that products are safe before allowing them on the market, even if it means those products may cost more.