A report recently published in The Lancet Diabetes & Endocrinology garnered a lot of attention by claiming that endocrine-disrupting chemicals cost the U.S. $340 billion in healthcare and lost productivity.
Certain chemicals are theorized to cause health problems by interfering with the endocrine system, which regulates a number of bodily functions through hormone action. Despite the media attention which may imply otherwise, it’s not just synthetic chemicals which are capable of endocrine action. Certainly, the media’s favorite endocrine supervillain, Bisphenol A (BPA), can show weak interaction under some circumstances. But soy, Vitamin D, and even caffeine interact naturally with our hormone receptors as well.
The claim that the U.S. is throwing away billions due to low-level exposure to chemicals in everyday items is enough to give anyone pause. Unfortunately, the “groundbreaking” economic analysis relied upon the findings of previous studies suffering from small sample sizes, flawed methodology, illogical leaps, and assumptions
In pegging the cost of endocrine disruptors at $340 billion, the researchers first had to assume each chemical it examined was, in fact, an endocrine disruptor, despite such allegations being unsupported by science. That is to say, they took the illogical leap that endocrine interaction compelled particular health problems. And that’s a major assumption, considering most studies show weak correlations at dosages mirroring exposure in the general population.
Additionally, the authors neglected to detail how they selected the literature fueling their endocrine-disrupting allegations. While a simple omission may not raise a red flag for the average reader, it can mask bias. We can’t know which studies the authors decided to include in their evaluation of chemical-fueled health consequences. Were only papers which upheld the authors’ hypothesis considered? Were those revealing no link between chemicals and negative health effects excluded from the authors’ review entirely?
As a consequence, independent scientists won’t be able to replicate their paper, which is a shame. Science thrives on replication and review, and anything less detracts from public knowledge.
Consider the paper’s treatment of BPA. Extensive governmental reviews have confirmed BPA’s safety at its current usage level. And that’s not to say BPA is understudied, or that science hasn’t yet found it’s “Aha!” moment. A vast library of studies have examined its impact, with over 10,000 citations listed on PubMed alone.
With research universities and federal health agencies under constant pressure to impress their donors (or Congressional Appropriations Committees) with results, it’s not unworldly to speculate that data may be “cherry-picked” to fit a researcher’s hypothesis.
But given the uncertainty of correlation, should we still worry about chemicals generally affecting the human endocrine system? It’s worth noting that most studies of endocrine disruption examine chemicals in concentrations orders of magnitude higher than what the average American would be exposed to. Literature reviews have found even “low dose” evaluations employ exposure rates up to 500 times what a typical person would be exposed to. While this evaluation is useful in determining hazard – evaluating whether a substance feasibly could cause harm at some level – it does nothing to communicate whether or not a chemical should be of legitimate concern to the average person.
Mercury offers a useful analogy. While swimming in a bath of the metal would likely kill you, the amount of mercury the average male would consume in tuna is so low, he could safely eat several pounds of the fish each week without giving mercury a second thought. (And the health benefits of consuming tuna far outweigh the tiny risk of mercury exposure.)
Negating risk assessment causes this report to build its analysis on the back of feeble data, because a statistical analysis can only be as good as the data it evaluates.
Truthfully, health science is a game of incremental understanding. Wild claims that endocrine disruptors cost our economy billions do more to set back public understanding than to advance it—along with creating unnecessary fear about trace chemicals we encounter in our everyday lives.
Dr. Joseph Perrone is chief science officer at the Center for Accountability in Science.