bad science

You (Probably) Don’t Need to Worry About the Chemicals in Your Macaroni and Cheese

“Fear not my creamy goodness.”

It is a confusing time for anyone concerned with eating healthy. While there is more information available than ever before about nutrition, it can be difficult to sift reliable sources of information online from questionable ones. And public-health researchers have shown that inaccurate information has a tendency to win out and to spread far and wide — especially when it tells a scary story about a jargony subject.

Vani Hari, a.k.a. the Food Babe, is a prime example. She has built an impressive media career peddling potentially harmful misunderstandings of — and fears about — chemicals, despite the fact that she doesn’t seem to have any real knowledge about the subject. In one instance, she used her sizable platform to raise fears about the possibility that some beers could contain propylene glycol, which is used in antifreeze. She didn’t know what she was talking about. As NPR reported in 2014, drawing on the work of cancer surgeon and blogger David Gorski, she had confused propylene glycol, which is a component of antifreeze, with propylene glycol alginate, a foam-stabilizing ingredient in beer that is derived from kelp. “It is not the same chemical as propylene glycol, not even close,” wrote Gorski on his blog. “It is not antifreeze.”

Last week provided another unfortunate example of what can happen when chemistry-related public-health fears run ahead of the available evidence, in the form of an article headlined “The Chemicals in Your Mac and Cheese” published on the New York Times health blog, Well. With a viral-ready headline like that, it’s no wonder the article spread and far and wide, quickly garnering aggregated writeups on sites like Time, Fox News, and others.

But neither the article nor the study it summarizes offers solid evidence that there’s any cause for alarm about the quantities of phthalates — the chemicals in question — found in boxed mac ‘n’ cheese. Moreover, the piece didn’t tell the full story, leaving out key information that would have likely rendered the study’s results a bit less scary-seeming.

As the story’s author, Roni Caryn Rabin, points out in her article, phthalates “are industrial chemicals used to soften plastics and are used as solvents, in adhesives and in ink on packaging.” Because they have so many practical uses, they tend to show up just about everywhere. Public-health researchers have generated a body of research showing that in some circumstances these chemicals might be dangerous. Rabin notes in her article, for example, that phthalates “can disrupt male hormones like testosterone and have been linked to genital birth defects in infant boys and learning and behavior problems in older children.” Because of these worries, they “were banned from children’s teething rings and rubber duck toys a decade ago.”

Concerned about the potential presence of these chemicals in commonly eaten foods, the groups behind the study sent a bunch of cheese products to a lab to be tested for phthalates, she writes, and that lab detected them “in all but one of the samples tested, with the highest concentrations found in the highly processed cheese powder in boxed mac and cheese mixes.” Rabin notes that the study was “paid for by environmental advocacy groups, [and] has not been published in a peer-reviewed journal,” and her story includes a number of quotes and paraphrases from concerned-sounding experts and activists. “Although the concentration of phthalates in food may be quite low, measured in parts per billion, they are still present at higher levels than the natural hormones in the body,” Heather B. Patisaul, a biology professor at North Carolina State University, told Rabin. The clear takeaway from the article is that readers should be very concerned about this finding.

So what’s the problem? There are two big, related ones. The first is that if you were looking for reasons not to eat boxed mac ‘n’ cheese, there are plenty right there on the nutrition label. “It is kind of like worrying that Doritos dust isn’t real cheese or that Oreos stuffing isn’t made with organic milk,” said Tim Caulfield, Canada Research Chair in Health Law and Policy at the University of Alberta. “Those worried about the ridiculously low levels of ‘chemicals’ in this product should spend their energy encouraging people to eat more fruits and veggies.” Joe Schwarcz, a chemist at McGill University who heads the university’s Office for Science and Society, echoed this concern. “If you want to scare them about the mac ‘n’ cheese you can scare them about the amount of fat and salt it contains,” he said. “That’s much more meaningful than the phthalates.”

Which brings us to the second point: The mere presence in food of a chemical, even a potentially harmful one, isn’t necessarily a big deal — the amount of that chemical is really important. We eat trace amounts of all sorts of different substances all the time that, were we to eat a hundred or a thousand times more of them, might land us in the hospital. The Times article more or less ignored this very important bit of context, which should accompany any claim about a potentially toxic substance in food.

Other than that one mention of “parts per billion,” the article doesn’t tell readers how much of the substances were found in the mac ‘n’ cheese products. The study itself shows that the average levels of phthalates ranged from 0.6 parts per billion to 295 ppb, depending on the phthalate in question. The most common phthalate — di(2-ethylhexyl) phthalate, or DEHP — was found in the products at an average concentration of 295 parts per billion. Then there was a steep drop-off to the next most common one, diethyl phthalate, which was found at 64 ppb. In other words, the substance found the most in the mac ‘n’ cheese products existed in a concentration of significantly under one part per million. A concentration that low might not matter at all. “We can detect these things in infinitesimal quantities, but the presence of a chemical does not necessarily equate to the presence of risk,” said Schwarcz.

Because mac ‘n’ cheese is, notwithstanding some surely interesting exceptions, generally eaten rather than smoked or injected, there are some intermediate steps between eating something and having its constituent parts end up in your bloodstream, where those parts can potentially do harm. Some chemicals are easily absorbed into the bloodstream; others, not so much. DEHP, for example, mostly passes right through your body, at least according to a 2002 CDC public-health statement on the chemical: “After [it] is ingested, most of it is rapidly broken down in the gut to [another chemical called] MEHP and 2-ethylhexanol … MEHP is poorly absorbed, so that much of ingested DEHP leaves the body in the feces. The compounds that do enter the blood travel through the bloodstream to your liver, kidneys, testes, and other tissues, and small amounts might become stored in your fat and could possibly be secreted in breast milk. Most of the DEHP, MEHP, and 2- ethylhexanol leaves your body within 24 hours in the urine and feces [emphasis added].” This important fact did not find its way into the article, which lumped all the different phthalates together and didn’t address the question of how likely they are to stick around in the human body for any length of time post-ingestion.

To be sure, some substances can be harmful even when ingested at low concentrations. The Environmental Protection Agency, for example, says that public water supplies shouldn’t have arsenic exceeding ten parts per billion. But arsenic is one of the more toxic substances to which humans are regularly exposed. Are ingested phthalates anywhere near this category? The research is somewhat murky. For example, a 2014 report to the Consumer Product Safety Commission cited by Rabin notes that the various studies examining the effects of phthalates on humans (particularly fetuses) and animals don’t yield a fully coherent story about which phthalates are harmful and why, with different studies pointing in different directions. A 2009 review of the literature conducted by Michael Kamrin, an emeritus toxicologist at the University of Michigan who has worked for various state and local governments and who was a science adviser to the Michigan legislature, presented a more skeptical summary of the research. Published in the Journal of Toxicology and Environmental Health, Part B: Critical Reviews, its abstract read, in part, “Analysis of all of the available data leads to the conclusion that the risks are low, even lower than originally thought, and that there is no convincing evidence of adverse effects on humans.” Of the Times article, Kamrin told me in an email, “Unfortunately I do not think it is a positive contribution to public health.”

And yet this doesn’t necessarily mean the presence of phthalates in foods at parts-per-billion concentrations isn’t harmful. But that’s an argument that needs to be made carefully, especially in light of how much false information is floating around about public health. I did reach out to a couple phthalate experts. Robin Whyatt of Columbia University, who has studied maternal and fetal phthalate exposure, said she didn’t want to comment on the study since she hadn’t read it. She referred me to Antonia Calafat, a CDC researcher, who replied through a spokeswoman that she couldn’t comment on the study itself, but that “the detection of phthalates in processed foods at levels higher than those in people is consistent with previous research because of the ubiquity of phthalates in the environment, including materials used for food production (e.g., some plastics).”

To Schwarcz, the Times article was part of a broader, unfortunate trend in how many outlets talk about these sorts of substances. “It’s not unique,” he said. “These days we see so many articles about chemicals in our food with the word chemical being used as a synonym for toxin or poisonous, which is already really disturbing to any of us who practice science. Because chemicals are just the building blocks of the universe.”

Don’t Worry About the Chemicals in Your Mac ’n’ Cheese