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Microplastics Are Everywhere, Including in Our Bodies. Here's What We Know — and Don't Know — About the Impacts

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Someone's hand showing multicolored microplastics.
A researcher holds microplastic pollution washed up on a beach. (Alistair Berg/Getty Images)

Microplastics are everywhere.

In our water, our food, even the air we breathe.

The tiny fragments, fibers and films, less than 5 millimeters long, are often made of what’s known as “forever chemicals,” which can take thousands of years to break down.

They've been found in human organs — even placentas — as well as plants and animals.

And their effect on human health is still largely unknown, according to Matt Simon, a science journalist at Wired and author of the book A Poison Like No Other: How Microplastics Corrupted Our Planet and Our Bodies.

In an interview last fall with KQED Forum host Mina Kim, Simon explained how microplastics literally rain down on us, much like acid rain once did before strict regulations were put in place to limit sulfur dioxide emissions from power plants.

Microplastics are “the pernicious glitter that has bastardized the whole earth,” Simon said. And they're hardly confined to outdoor environments.

More on microplastics

“One of the first places as far as microplastic pollution is concerned is indoor environments. There have been a number of studies that have quantified just how much of this stuff is in the air, and that's coming in large part from the clothes that we're wearing,” Simon said, noting that some plastic fibers inevitably flake off and fall on the ground as they degrade over time. “Some two-thirds of clothing is now made out of synthetic fibers. That's plastic.”

Simon added that, compared to adults, infants and toddlers likely have a higher concentration of microplastics in their bodies.

“This is largely due to plastic bottles for formula,” he said. “If you are preparing infant formula in a plastic bottle, there's a calculation that something on the order of a million particles are coming off per day. And that's ingested per baby.” He also cautioned against freezing or microwaving plastic containers, and suggested using glass products whenever possible.

Given the dearth of research and data on the issue, Simon said, it will likely take as long as another decade to find clear evidence of impacts to human health. But early studies don’t look promising, he added, particularly because many plastics contain endocrine-disrupting chemicals like bisphenol A (BPA).

A major part of the problem, Simon said, is a lack of information about the specific chemicals that make up various types of plastics. “The industry won’t tell us. They don't put an ingredient list on their products," he said, leaving researchers to try to reverse-engineer them to figure out what they're made of.

“What we know from the studies is that the dust inside people's homes is likely to be the greatest exposure for microplastics. We're just breathing it in,” said Scott Coffin, research scientist at the California State Water Resources Control Board. He recommended buying a good air filter to reduce the amount of contaminated dust indoors, and trying to get rid of as much plastic fiber as possible.

Coffin's agency is the first in the country to create a road map for monitoring microplastics in many of California's major drinking water sources, and to establish a preliminary health-based threshold and testing methods.

“It will be the world’s first health-based guidance value of any sort for microplastics formally recommended by a working group or government agency,” Coffin told CalMatters in 2021, at the onset of the project. “This will carry a lot of authority, even if it is just a preliminary guidance level.”

By next year, he said, consumers in large water districts across the state, including those serving San Francisco and the East Bay, could start receiving notifications about the level of microplastics in their pretreated water sources, including supplies in Hetch Hetchy reservoir and other major Sierra Nevada reservoirs feeding the Bay Area.

The state Water Resources Control Board also posted a report last month detailing the potential effects of microplastics on the health of the San Francisco Bay.

“Our tentative conclusion at this point is that we have enough evidence to suggest that there is potential harm to the ecosystem,” Coffin said.

Those findings are in line with Simon's research, who also noted that plastics in general, and microplastics in particular, emit potent greenhouse gases like carbon and methane as they degrade — not to mention the extremely carbon-intensive process of producing them in the first place.

At the end of the day, Simon said, individual responsibility can only go so far to mitigate the potential risks. He noted how the plastics industry largely sidestepped stricter regulations in the 1980s and 1990s by promoting recycling “as this thing that was our responsibility as consumers” — even though less than 10% of plastics worldwide are actually recycled today. A similar situation is now playing out with microplastics, he said.

“We can take steps to lessen our emissions of microplastics and lessen the amount of plastic that we're buying in general,” he said. But that only goes so far: What's really needed, he added, are stricter production controls and increased government oversight of a very loosely regulated industry.

“We need our government and we need to elect politicians that take this seriously,” he said.


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