MIT’s Undark magazine describes itself as a publication that “will explore science … as a frequently wondrous, sometimes contentious, and occasionally troubling byproduct of human culture.” Its name refers to a “radium-based industrial and consumer product … that was both awe-inspiring and, as scientists would only later prove, toxic and deadly.” In a recent article for the magazine, Michael Schulson offers a tendentious account of what is known about exposure to toxic substances in the environment, and then places his review in the context of the Trump administration’s Make America Healthy Again (MAHA) agenda.

Last July, Schulson contacted me and asked for my perspective on “the growing public attention to some parts of the environmental epidemiology and toxicology research fields—visible in the claims of the MAHA movement, as well as efforts like a new children’s health initiative led by Philip Landrigan, Linda Birnbaum, and others.” In a series of emails, I provided some thoughts on important issues to consider when reading about this topic. I mentioned “endocrine disruption” as a good example of the challenges associated with assessing low-level environmental exposures. And I pointed him to a chapter in my book Getting Risk Right: Understanding the Science of Elusive Health Risks that gives a detailed treatment of this question. I also offered to suggest further articles that might address the issues that interested him.

Here is an excerpt from an email I sent Schulson on 15 July 2025:

There are good examples of exposures that looked important/scary initially but that, as larger and better studies were done, turned out to be nothing. This happened with DDT and breast cancer, with BPA and estrogenic effects, and with glyphosate (Roundup) and non-Hodgkin’s lymphoma, and with other pesticides (atrazine, I believe). A more recent topic of interest is PFAS, and I’m not up on this. But this too appears difficult to get a handle on.

However, when I read the published article, I found that Schulson gives an unsatisfactory account of a complicated story. The article opens by focussing on Linda Birnbaum—head of the National Institute of Environmental Health Sciences (NIEHS) from 2009 to 2019—and then goes on to quote statements from roughly a dozen researchers and others. Unfortunately, the use of personalities to represent different points-of-view is no substitute for a careful exploration of the underlying questions. In addition, Schulson’s apparent bias towards certain informants appears to undermine his objectivity.

Birnbaum is clearly an important figure, but Schulson treats her as a hero and his account verges on hagiography. During her tenure at NIEHS, Birnbaum was instrumental in funding a large number of studies of the chemical bisphenol-A (BPA). BPA was introduced in the 1960s to line food containers to prevent spoilage, and it has since been used in a wide array of consumer products. In the early 2000s, BPA became the focus of health concerns, particularly about its potential to leach out of food containers and baby bottles. Some early studies appeared to show that the compound could have adverse effects, ranging from effects on sexual and neurobehavioural development to cancer. However, in 2010, the US Food and Drug Administration issued a report restating its position that BPA was safe and “posed ‘negligible’ or ‘minimal’ concern for most adults and ‘is not proven to harm children or adults.’”

To cut a long story short, the NIEHS under Birnbaum got caught up in an “availability cascade”—a self-reinforcing process of collective belief-formation in which a claim triggers a chain reaction of repetition that makes the claim seem increasing plausible as its prevalence in public discourse grows. This is known, more colloquially, as a “bandwagon effect.” Whichever term one uses, it describes the view of many academic scientists studying BPA. They came to believe that anomalous findings—often obtained from small studies and tests with ambiguous results—provided serious evidence of adverse effects, even at low doses. These researchers were influenced by the “endocrine disruption hypothesis” pioneered by the toxicologist Theo Colborn in the 1990s and popularised in her bestselling book, Our Stolen Future. Since then, the whole basis of the endocrine disruption hypothesis has been robustly challenged by other researchers.

The steady stream of alarming results prominently reported in the media led to campaigns to eliminate BPA in baby bottles and other consumer products. There were even calls to ban it entirely. At the same time, due to the availability cascade, each new disturbing finding generated increased public concern and calls for further studies, creating a self-perpetuating cycle. Through repetition and the massive publicity that each new finding received, the belief that BPA was causing harm became a conviction in many minds. In response to this apparent crisis, the National Institutes of Health spent US$172.7M on BPA between 2010 and 2014, approximately seventy percent of which was awarded by the NIEHS in Birnbaum’s early years at the institute.