Federal science panel takes deep dive on microplastics

When it comes to research on microplastics, some doctors and scientists see concerning evidence of health risks to people, while others question what the science is really showing.

Now, a work group at the National Academies of Sciences, Engineering and Medicine is taking a hard look at what we know — and don't know — about health risks to people from environmental exposure to microplastics.

The panel plans to produce a series of short, peer-reviewed summaries of its work.

On an April 10 NASEM webinar, some experts called for stepped up regulation, treating chemicals used in making plastics with the same tighter scientific review given to chemicals used in pharmaceuticals.

Philip Landrigan, a pediatrician and director of the Program for Global Public Health and the Common Good at Boston College, said that while there are gaps in the research and results from different studies are not standardized, there's enough information to be very concerned.

Microplastics, he said, have been detected in "basically any organ in which it's been sought."

As one example, he pointed to a 2024 New England Journal of Medicine study that found heart patients with microplastics in arteries had a 4.5-fold increase in heart attacks, stroke or death over three years compared with patients without such microplastics.

He noted a study that linked microplastics to aggregation of proteins linked to Parkinson's disease, as well as other research connecting plastics to health problems.

"Microplastics have been linked to gut inflammation. They're linked to preterm birth by way of placental accumulation," Landrigan said. "They've been found in the testis.

"These are early data, they're mostly small sample sizes, the methods are not yet standardized," he said. "But all that said, these data can't be ignored. We can't just say, oh, the methods are imperfect or the data don't count."

Landrigan urged the NASEM group to support a pharmaceutical-style regulatory system for chemicals in plastics, requiring much more evidence that chemicals are safe before they're allowed on the market.

"I would argue, as a physician who cares for children, that we need a similar regulatory regime for chemicals in general and chemicals that go into plastic," Landrigan said. "There's no rational basis for strictly regulating chemicals that go into children in the form of a pill and not equally strictly regulating chemicals that go into children because they come from a toy or a baby bottle."

Landrigan also called for a global cap on plastic production, a point being debated in the United Nations plastics treaty, to limit impacts from "reckless" growth in production.

But others on the webinar questioned what the science was showing.

Todd Gouin, a scientist specializing in environmental chemistry and a consultant with TG Environmental Research, pointed to significant uncertainty in studies based on the testing and measurement methods.

He said a widely discussed February study in Nature Medicine on microplastics in the brain, for example, may not have been measuring plastics at all, but rather fatty acid lipids in the brain, because of limits in the measuring equipment.

"The brain of course has a very high level of fatty acids as lipid content," he said. "It's perhaps not surprising that there is a potential, or very high probability, that what they're reporting in that study is not plastic at all.

"That's not to say that we don't take these things seriously, I think it's important to take it very seriously, but also to reflect on the plausibility of what you're seeing," he said.

Gouin, who previously worked as a scientist for consumer goods maker Unilever plc, also questioned studies that he said don't measure real-world exposures to microplastics.

"For instance, we have a large number of studies reporting results for polystyrene spheres of say, 10 nanometers," he said. "This is not something we are typically exposed to on a day-to-day basis, so there is a need for us to avoid an apples-to-oranges comparison in terms of microplastics research.

"At the moment there is a lot of apples-to-oranges comparisons going on, which of course makes it very difficult to do a risk assessment," Gouin said.

Landrigan, however, said he was referring to studies that measured microplastics in people.

"Those are studies based on real people exposed to microplastics in their everyday life," he said. "They're clinical studies and they observed effects at levels at which people are exposed.

"Now of course one can argue that maybe these studies aren't very meaningful because the strategies used for evaluating the particles were not standardized, which is true," Landrigan said. "But the studies are still very provocative."

The U.S. state farthest along in regulating microplastics, California, is both taking a precautionary approach and recognizing the need for better science, said Valerie Hanley, a senior toxicologist with the Department of Toxic Substances Control within the California Environmental Protection Agency.

Starting with two state laws in 2018, California has been measuring microplastics in drinking water with an eye toward developing standards, she said.

As well, in 2023, the state's Safer Consumer Products Program launched a rulemaking to add microplastics to its list of potentially regulated chemicals, she said.

"Once microplastics have been officially added to the candidate chemical list, we can start naming chemical product combinations," Hanley said. "In advance of that, we are scoping several different product categories that contain or generate microplastics. That's one of our priority products that we're focusing on in SCP at this time."

She said it's a very complex topic for regulators to address, pointing to both rising levels of microplastics in the environment, along with more studies of their health impacts.

As well, she said there's a huge variety of chemicals with vastly different properties in the large category that's labeled microplastics.

"That makes it very challenging in the risk assessment point of view to try to take this huge group of chemicals … and have one criteria that comes out from that that is health protective," she said. "That is one of the huge challenges, and again, why the precautionary approach of trying to reduce while the science catches up is so critical."

The panel plans a fourth and final webinar in its series in May.