Toxicology Was Built for Poison, Not Your Bathroom Cabinet

If you’ve ever read two headlines in the same week: one telling you a chemical in your shampoo is “perfectly safe at the levels used” and another telling you it’s “going to cause cancer”, and felt genuinely unable to tell who’s right, you’re not alone, and you’re not failing at science literacy.

You’re running into a set of compounding problems that have nothing to do with your intelligence and everything to do with how complicated the field of environmental health is.

The impact of science on toxic chemical pollution—driving dismissal or action— depends on how the science is translated, funded, and how it gets filtered through your phone before it reaches you.

I’ve spent 20 years working on federal chemical safety policy, including helping write the law that governs how states, the EPA and FDA regulate chemicals in commerce. Here’s what I’ve learned about why this topic feels so impossible to parse—and why in order to do the topic justice I had to write a book.

Modern toxicology traces back to a 16th-century Swiss physician named Paracelsus, who coined the principle that still gets repeated today: “the dose makes the poison.” Even water is toxic in a large enough amount (something the chemical industry loves to share at every legislative hearing). Even a poison can be medicine in a small enough amount.

It’s an elegant, useful idea, and for a long time it was the right tool for a singular job—describing how much of a substance we could consume before it hurt us. Early toxicology was mostly built to answer questions about acute exposure. How much arsenic kills you. How much lead in one dose causes organ failure.

But a huge amount of the chemical exposures we face today isn’t like those early problems to solve. The science of toxicology and environmental health (a broad field of science that studies the intersection of our environment and health, everything from lead in toys, PFAS in drinking water, and asthma and air pollution). What constitutes harm is no longer seen as just one big dose—we now know small, chronic, everyday exposure to hormone-disrupting chemicals (EDCs) in plastics, cosmetics, and household products. And for that particularly category of chemicals, “the dose makes the poison” doesn’t reliably hold up.

Researchers studying endocrine-disrupting chemicals have documented what’s called a non-monotonic dose-response since the 1930s—meaning the harm doesn’t rise neatly with the dose. Sometimes a lower dose produces a bigger effect than a higher one, because these chemicals are interacting with your hormone system, not just accumulating like a poison in the classic sense. A major review in Endocrine Reviews laid this out clearly: the field has spent decades documenting effects at low doses that the old framework simply doesn’t predict. The scientific consensus challenging the “dose makes the poison” is widespread, with dozens of scientific consensus statements dating back to the 1990s.

This nuance about the shift from old school toxicology to our modern day understanding matters because when someone—even a credentialed scientist—reaches for “the dose makes the poison” to wave away a concern about PFAS or phthalates, they’re applying 500-year-old acute-toxicity logic to a chronic, hormonal exposure problem it wasn’t built to explain. As I wrote in a recent piece on science communicators getting this wrong, that’s not more scientific. It’s an outdated framework being used with a lot of confidence.

(Note, while I harp on outdated toxicology frameworks and toxicologists who are stating these old phrases in defense of the status quo, there are a growing body of modern toxicologists who understand how to apply new scientific consensus to decide what is worth worrying about.)

Here’s the second problem, and it’s not really about science at all, it’s about incentives. Algorithms are optimized for engagement, and engagement is optimized for emotion, and fear is one of the most reliable emotions there is. A headline that says “This common household chemical could be quietly harming your child“ will always outperform one that says “New study finds an association between chemical exposure and one developmental marker, more research needed.“ The second headline is honest. The first one gets shared.

This cuts in both directions, by the way. It’s not just wellness influencers overstating risk for engagement—it’s also “science communicators” who’ve built large followings by being the confident, condescending voice of “actually, that’s not backed by science,” often in fields like immunology or nutrition that have little training in environmental chemical exposure at all. Both personas are optimized for the algorithm, not for nuance. Neither is optimized for what’s actually true, which tends to be more boring and more conditional than either extreme.

When a new drug goes through the FDA, it goes through controlled human clinical trials, specifically designed to measure safety and effect at defined doses in defined populations. That system exists because we’ve decided, as a matter of ethics, that it’s acceptable to expose consenting, monitored volunteers to a substance whose benefit might outweigh a known, bounded risk in service of treating a disease.

We do not have an equivalent system for industrial and consumer chemicals, and we shouldn’t. It would be unethical to deliberately dose people with a chemical to see what happens to their hormones or their children’s neurodevelopment. (For the history buffs, there was a group of volunteers in the early 1900’s who signed up to be poisoned via a government program called The Poison Squad).

To bridge this gap, environmental health science relies on a patchwork: animal studies, cell studies, and epidemiology, which studies people who are already being exposed involuntarily, through their water, air, food packaging, or workplace. That’s a fundamentally harder, slower, and messier way to build evidence than a clinical trial, and it’s part of why the evidence often looks “associational” rather than airtight.

It’s not weaker science because the researchers are worse. It’s the best ethical science possible for a problem we can’t run controlled experiments on. And under the Toxic Substances Control Act, the law that governs most industrial chemicals, tens of thousands of chemicals already in commerce were simply presumed safe when the law passed in 1976, with no testing required at all—a gap the 2016 reform I helped support, was designed to start closing.

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The researchers publishing in high impact, top tier journals like Endocrine Reviews, Environmental Health Perspectives, and JAMA Network Open—the actual experts on chemical exposure and human health—are not on TikTok explaining their findings in sixty seconds. They’re writing grant applications, most of them funded through a strained federal system, competing for a shrinking pool of NIEHS dollars, and publishing in journals most people will never open.

As I’ve written before, this field is chronically underfunded, underreported, and poorly understood by the public—not because the science is weak, but because almost no one with the platform to reach millions of people has the training to translate it accurately, and almost no one with the training has the platform. (This is also why immunologists, cosmetic chemists, and dermatologists have swept in to try and fill the social media void, although in a wildly unhelpful way.)

That vacuum gets filled by people who are good at social media but aren’t the actual experts, on both the fear-mongering side and the dismissive side.

The people who should be the loudest voices in this conversation are the quietest.

None of this means you should throw up your hands. It means the fix isn’t “do more of your own research” but rather large scale systemic change. Which I’ve had a front row seat in witnessing and recount in my book Cleaning House.

Individual vigilance can’t substitute for a regulatory system that requires chemicals to be proven safe before they reach the market, the way we require it of drugs. We’ve been asked to be our own federal agencies and that’s simply not cool.

That’s the whole premise behind laws like the Frank R. Lautenberg Chemical Safety Act, and it’s exactly what’s being chipped away at right now—there have been nearly 20 rollbacks to major federal chemical safety protections in the last 15 months alone. Contact your members of Congress. Show up for public comment periods. Policy is slow, unglamorous, and it’s the only lever that changes exposure for everyone, not just people with the time and money to shop their way out of it.

Reducing your own exposure is reasonable and worthwhile, but as I discuss in my book let’s not drive yourself crazy. You can’t shop your way to safety. And clean consumption is not a substitute for systemic change; no one should feel like they’ve failed their family because they missed something on an ingredient label.

Look for credible certifications like EWG Verified (beauty), MADE SAFE (cleaners, products, furniture), Clean Label Project (great for supplements & protein powders), and leverage websites like Hilde which evaluate companies for their safety and sustainability programs and Clearya, the only browser extension I like. (Skip Yuka and Think Dirty).

The people living next to manufacturing and incineration facilities—disproportionately low-income communities and communities of color—carry a chemical burden that no amount of careful shopping will fix, because it’s not coming from their bathroom cabinet. Any conversation about toxic chemical exposure that doesn’t include fenceline communities is an incomplete conversation, and often a quietly privileged one.

This science is hard to understand because it was built to answer a different question than the one we’re now asking of it, because the platforms delivering it to you are optimized for outrage, because we’ve made the ethically correct choice not to run human trials on chemicals, and because the people who actually know the answers don’t have megaphones. That’s not a reason to disengage. It’s the reason this fight belongs in Congress, in state legislatures, and in the boardrooms of the companies making these products—not only in your grocery cart.

If this was useful, subscribe to The Environmental Health Brief, and check out my related pieces on why “pseudoscience” call-outs from sci-comm influencers get this wrong and the rollbacks unraveling a generation of chemical safety progress. By subscribing you’ll be the first to receive my non-partisan voting guide ahead of the midterm elections called Cleaning House at the Ballot Box. Paid annual subscribers receive a free copy of my book!

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The nuance around toxic chemicals and environmental health is already disappearing—flattened by social media, distorted by partisan politics, drowned out by wellness noise and bad-faith dismissals in equal measure.

The last thing I want to do is make credible information harder to find.