Donald Trump had been president less than a week when he vowed to slash regulations by 75 percent. Within two weeks of taking office he’d ordered agencies to rescind two regulations for every new rule. This “regulation trading” program forces public health agencies to make impossible choices, argued a top Environmental Protection Agency official who resigned in protest after 30 years on the job: “Should EPA repeal two existing rules protecting infants from neurotoxins in order to promulgate a new rule protecting adults from a newly discovered liver toxin?”

Last week, the White House announced that Trump had “far exceeded” his promise to eliminate regulations. “Agencies have issued 22 deregulatory actions for every one new regulatory action,” the statement declared. Trump’s war on regulations comes on the heels of Congress’ overhaul of the 1976 law that gave the EPA authority to safeguard the country from dangerous chemicals. The EPA’s ability to implement those safeguards, however, withered in the face of industry lawsuits contesting its decisions and the sheer volume of chemicals approved for commerce, at 85,000 and counting. By the time Congress finally reformed the law last year to enhance chemical safety, the agency had restricted or banned just five chemicals despite evidence that entire classes of chemicals endanger public health.

This week PLOS Biology launches a special collection — Challenges in Environmental Health: Closing the Gap between Evidence and Regulation — that examines the failure of U.S. chemical policy to keep pace with advances in environmental health science. We’ve been honored to work with Guest Editor and National Institute of Environmental Health Sciences Director Linda Birnbaum, who advised us on selecting topics and commissioning peer-reviewed commentaries from leading experts in environmental health.

The collection highlights key advances in the science of environmental health as well as barriers to incorporating these advances into public health policy. The articles cover a wide range of issues, including the difficulty of revising outdated concepts in toxicology; regulatory flaws that allow hazardous chemicals to contaminate our air, food, and drinking water; technical challenges in assessing risks from short-lived compounds and from multiple, simultaneous exposures; and the failure to ban chemicals even in the face of overwhelming evidence of harm.

Here’s a roundup of the commentaries we’re publishing this week:

Sheldon Krimsky reviews multiple factors that have hindered rational regulation of industrial chemicals. Most problematic, he says, are standards that place the onus on government to demonstrate “unreasonable risk” rather than requiring manufacturers to demonstrate safety before allowing compounds on the market.

Bruce Lanphear reviews three decades’ worth of research on some of the most extensively studied substances, including lead, asbestos, and benzene, and shows that the amount of toxic chemical linked with disease or death — contrary to the old toxicology saw, the dose makes the poison –is proportionately greater at the lowest doses or exposures. If other widely disseminated chemicals and pollutants follow the same trend, Lanphear says, “we will need to achieve near-zero exposures to protect public health.”

But how do scientists assess risk, and ascertain exposures, when we’re all exposed to multiple chemicals every day? Joseph Braun and Kimberly Gray describe new methods that epidemiologists are developing to assess risks from chemical mixtures, identify periods of heightened vulnerability, and flag chemicals that may be particularly harmful to children’s health.

Among those chemicals that may pose special risks to children are a class of persistent organic pollutants called perfluoroalkyl acids (PFAAs), which have increasingly turned up in drinking water supplies. Gloria Post and her colleagues describe the disconnect between recent research — which indicates that PFAAs concentrate in blood at levels over 100 times greater than those in drinking water — and drinking water guidelines that don’t account for the fact that infants receive much higher exposures than adults, relative to body weight, from the same drinking water source.

Since Congress gave the Food and Drug Administration authority to ensure the safety of chemicals in food in 1958, thousands have entered the food system without adequate safety testing, say Maricel Maffini and her colleagues. Current efforts to roll back health and safety standards and dramatically cut budgets at the already under-resourced FDA, the authors say, threaten to further erode the agency’s ability to safely manage chemicals in the food supply.

Leo Trasande explores the costs and consequences of the Trump administration’s repeal of a ban on the insecticide chlorpyrifos, against the advice of the EPA’s own scientists. “This case study is emblematic of a broader dismissal of scientific evidence and attacks on scientific norms,” Trasande argues. “Scientists have a responsibility to rebut and decry these serious challenges to human health and scientific integrity.”

Concern about limiting exposures to pesticides is a hot issue in California, which grows most of the nation’s fruits and vegetables. In an effort to protect the most vulnerable populations, state officials proposed a quarter kilometer buffer zone around schools and childcare centers. Though buffer zones are a step in the right direction, Robert Gunier and his colleagues say, protecting children and pregnant women requires reducing exposures at home and work, too, which means rethinking agriculture’s heavy reliance on pesticides.

The collection’s discussion of risks posed by ubiquitous chemicals will likely engender controversy. Manufacturers that produce toxic chemicals worth billions of dollars have historically tried to discredit even the most meticulous scientists who’ve raised concerns about the compounds. When Rachel Carson documented pesticides’ potential risks to wildlife, she was labeled a hysterical woman. When Herbert Needleman linked low levels of lead to lower IQ in children, he was accused of scientific misconduct. When Irving Selikoff linked asbestos to high rates of lung cancer and mesothelioma, his scientific integrity was attacked and — a decade after his death — his medical credentials questioned. Today, researchers who study hormone-disrupting chemicals like atrazine and bisphenol A must contend with the same smear tactics.

As the contributors to this special collection make clear, science is not always enough to ensure that regulations keep us safe. Closing the gap between evidence and policy will depend on the resolve of engaged citizens — both scientists and nonscientists — who are willing to weather attacks on their credibility to ensure policymakers follow the best available science to protect public health.