The plastics we breathe (2024)

For years, scientists on the hunt for microplastics have found them almost everywhere. First, they spotted tiny pieces of plastic in the ocean, in the bodies of fish and mussels. Then they found them in soft drinks, in tap water, in vegetables and fruits, in burgers.

Now researchers are discovering that microplastics are floating around us.

They are suspended in the air on city streets and inside homes. One study found that people inhale or ingest on average 74,000 to 121,000 microplastic particles per year through breathing, eating and drinking.

“There’s just so much plastic around us,” said Sherri Mason, researcher and sustainability coordinator at Pennsylvania State University at Erie. “We wear synthetic clothes, and those are shedding microplastics. We work on synthetic carpets. We buy food wrapped in plastic.”

Scientists don’t yet know the exact health effects of all those plastic particles — but their concerns are rising. In recent years, research has shown for the first time that humans are breathing, eating and drinking microplastics in much larger quantities than previously thought. And that plastic is burrowing its way into almost every major organ.

Not only can those tiny particles infiltrate many parts of the body, causing inflammation, but plastics also have a laundry list of chemical additives: flame retardants, lubricants, solvents. These chemicals, in turn, can leach out of particles that have reached some of our most vulnerable organs.

“I call it the spaghetti and the sauce,” said Heather Leslie, an independent scientist who was part of the team that first discovered microplastics in human blood. “The spaghetti noodles are the polymer backbones and the sauce is the additives.”

Of the more than 10,000 chemicals used in the manufacture of plastic, scientists have identified over 2,400 as potentially toxic.

As plastic production increases, so do the risks to human health. In 1950, the world produced 2 million metric tons of plastic every year; last year, it was over 400 million metric tons.

Plastics, unlike other substances, don’t break down — they simply break up into smaller and smaller pieces. Of the roughly 8 billion tons of plastic that have been produced since 1950, less than 10 percent has been recycled. The rest accumulate in landfills, in the oceans or on beaches, slowly sloughing off into microplastics or even tinier nanoplastics.

Some of those particles enter our body when we breathe. Here’s how plastics move through our respiratory system and become entrenched in cells, threatening our health.

When inhaled, the largest pieces are trapped in our airways’ mucus and moved along by hair-like structures called cilia until they are expelled through sneezing. But smaller pieces can penetrate the body’s defenses. If the pieces are small enough – less than 10 micrometers – they can reach the terminal part of the lungs, the alveoli, where oxygen reaches the blood. They can linger in the alveoli for long periods, causing inflammation and potentially other chronic conditions. Small microplastics, probably the ones below 2.5 micrometers, might take the same path as oxygen and enter the bloodstream. Once they are in the bloodstream, they can spread to virtually any place in the body. Microplastics have been found in the placenta, the liver and breast milk. Smaller microplastics can be attacked by some of the body’s defense cells, known as macrophages. But these cells, unable to break down the microplastic, eventually die. The plastic is then swallowed again by another defense cell, which repeats the process, stressing the body’s immune system.

For researchers, tracing the impact of microplastics on human health is a daunting task. Each chemical added to plastics, along with each microplastic shape and size, could have a different impact on the body.

“They all have their own little toxic personalities,” Leslie said. “It’s an analytical nightmare.”

But scientists have found some links. In one study in Italy, people with microplastics in the lining of their arteries were more likely to suffer heart attack, stroke or death from any cause. Another report found that people with inflammatory bowel disease had higher concentrations of microplastics in their feces.

In laboratory tests on human cells, microplastics can cause tissue damage, allergic reactions and even cell death. The chemicals in plastics — like phthalates or bisphenol A — have also been shown to cause hormonal imbalances and disrupt the reproductive system. In mice, microplastics can cause behavioral changes and reproductive problems and can inhibit learning and memory. Researchers also recently discovered that certain cancer cells spread at an accelerated rate after exposure to microplastics; they are now looking into whether microplastics could help trigger early-onset cancer.

Kimberly Wise White, vice president of regulatory and scientific affairs for the American Chemistry Council, said in an email that the plastics industry has committed $15 million to research into microplastics. The group is currently investigating inhalation of microplastics and possible toxicities, she added.

Researchers warn that there aren’t yet studies showing a strong causal link between microplastics and a particular disease. People are exposed to myriad chemicals and toxins every day, making it difficult to identify what specific impacts microplastics have on the body. Scientists also still have yet to understand how long microplastics linger in certain organs and the concentration of the chemicals that they carry with them.

Scientists are most concerned about nanoplastics — tiny microplastics that are less than half the size of PM2.5, a form of air pollution that has been shown to cause lung problems, heart disease and premature death.

Until recently, those nanoplastic pieces were invisible with even the most advanced scientific tools. But now, scientists have developed new methods to identify them, which could upend what we know about the amount of particles inhaled or consumed by humans. A recent study found that because of nanoplastics, there are 100 to 1,000 times as many pieces of plastic in a bottle of water as previously thought.

For now, there is little protection against microplastics or nanoplastics. While countries are working to hammer out a global treaty to reduce plastic waste in the environment, they have yet to come to an agreement.

And scientists worry that in the meantime, microplastics are infiltrating our bodies with untold effects. There are no U.S. laws or regulations governing microplastics in the air or in food.

“We’re really looking at the Wild West,” Leslie said.

Experts say individuals can avoid some microplastics by steering clear of single-use plastic cups and bottles and avoiding plastic takeout containers. But those actions pale in comparison to the massive quantity of plastics added to the environment every year.

And waiting for certainty on the health effects of microplastics could be dangerous. “By the time we have that full answer, we’ll have already impacted human health,” Mason said. “It’ll be too little, too late.”