Are our bodies full of microplastics or not? There’s a way to resolve this debate, and scientists must hurry | Debora MacKenzie

3 hours ago 1

Are we being injured and killed by ubiquitous, teeny-tiny shards of toxic plastic? Or aren’t we? For many months, the Guardian has reported a series of worrying scientific results that our bodies are full of jagged microplastic particles that could be giving us everything from heart attacks to reproductive problems.

But on Tuesday, the Guardian revealed that a significant number of scientists think many of these studies showed no such thing. Or maybe they did. The methods are new and riddled with problems, so we can’t always reliably tell.

If you, like me, have spent the past few decades watching battle after battle over environmental pollutants – from DDT to cigarette smoke, to ozone destroyers to greenhouse gases – it will all look familiar. New problems present new challenges, and science takes a while to work them out. But eventually, it does. Science’s unique and greatest strength is that it is self-correcting. The current battle among researchers of microplastics is the first salvo in that process.

Here is how the disputes arose. Similar to the earlier cases just mentioned, as a new environmental nasty emerged, a community of specialists developed delicate, precise techniques to track the nasties and measure their impact, beyond any reasonable dispute. Scientists are, with good reason, persnickety about exact measurements and experimental controls. The analytical specialists who chase sometimes tiny quantities of pollutants and pinpoint their effects are arguably the most persnickety of the lot.

But as microplastics got more attention, along came a bunch of researchers who often weren’t even analytical specialists, but medical scientists used to dealing with very different complex systems such as blood or brains or hardened arteries. They knew microplastics were everywhere, so they went to the analytical literature for ways to measure them. They then used these methods to measure microplastics in the biological systems they are familiar with. For instance, in one of the disputed papers, an Italian team found nearly five times more heart attacks and strokes in people with jagged microplastics in their hardened arteries than in those apparently without.

But inevitably, the analytical researchers, mainly chemists, wrote horrified letters to journal editors. They contend, for example, that the methods being used can read ordinary bodily fats in a sample as plastics, potentially giving false readings; that there weren’t proper corrections for the amount of background plastic in the laboratory; and that more controls were needed.

The clinical teams have replied that there is a steep learning curve, and that this sort of work hasn’t been done in biological material before. Maybe some more controls would help, but more background plastics wouldn’t account for some things, such as that five-fold difference in heart attacks. And it isn’t at all clear whether any of these methodological shortcomings mean that there aren’t microplastics in humans, or that they aren’t having ill effects. They just raise uncertainties.

Eventually, the analytical experts will start working more closely with the clinical crowd, and they will all learn to measure microplastics robustly in human tissue and investigate possible impacts on health. That is, if the agencies that fund scientific research keep funding them.

That’s why the uncertainties worry both sides. Any dispute over methods “only provides ammunition to deniers”, warns one analyst. And these days, there are plenty of science deniers around.

We have seen this before. Naomi Oreskes and others have abundantly documented how people who make money from some pollutant or other “manufacture” doubt about science, enough to block action. But the example I know best was also the one where scientists learned how to fight back.

The few companies who made the CFC chemicals that destroy stratospheric ozone, allowing more, deadly UV light to hit our planet, pointed for years to methodological disputes among ozone scientists to claim that “the science isn’t certain enough to do anything drastic” – such as banning CFCs. It worked.

But the world eventually banned CFCs, and the ozone layer is healing, because in the 1980s a few scientists, headed, improbably, by a British expat at Nasa, Bob Watson, organised all the other scientists to summarise for governments what they agreed was true, and conduct experiments to resolve their disagreements. It was a specific project meant to resolve the “uncertainty” for the wider world – and unleash action. “It’s important to get everyone, the industry scientists and every country that does research involved,” Watson told me then. It also worked.

Microplastic and nanoplastic research now has to learn that lesson. We know there are problems, wrote one scientist in response to scathing criticism from analytical teams, but we’d be better off spending our limited funding developing better methods, rather than “continually engaging in a dialogue”. Wrong. Dialogue is how you’re going to get the methods.

A group of biomedical researchers want “interlaboratory studies” to compare methods “and learn from each other”, with multidisciplinary teams “ideally including industry scientists”. Others call for “an international and interdisciplinary collaboration of experts” to improve research methods.

That’s more like it. Cynics will roll their eyes at the bit about industry scientists, but I know Watson would say that’s what you need. Everyone. So science can do its thing, creating knowledge on the basis of real, robust data about the world, without disputes that block progress – or discourage funding for the needed research.

And we need that sooner rather than later. Enough skirmishing in letters columns in journals. The plastics industry is more powerful than the CFC-makers were, and it has friends who know how to manufacture doubt. (Researchers I spoke to said that their papers have been denounced to journal editors by chemical industry figures who were not analytical experts.)

This is your ozone moment, microplastics people. Time to see the bigger picture, and find a way to resolve this battle, keep public trust and move forward with this vital research.