Can The Plastic Particles in Bottled Water Harm Your Health?

A liter of bottled water contains nearly a quarter of a million pieces of nanoplastic on average, according to new research published this week in the Proceedings of the National Academy of Sciences.

Measuring less than a micron, these nanoplastics are often a tiny fraction of the size of a speck of household dust. In the new study, scientists developed a novel imaging technique which showed that the number of nanoplastic particles in bottled water was between 10 and 100 times higher than previously estimated, said Wei Min, a biophysicist at Columbia University and a co-author of the study.

“Millions of tons of plastic are produced around the world each year,” said Douglas Walker, an analytical chemist at Emory University who was not involved in the new research. Microscopic particles from those plastics can end up in food and beverages in the manufacturing process — they might be introduced through plastic tubing used in machinery, for example — or leach in from packaging such as plastic bottles.

“If you think about the potential for their presence as environmental contaminants, it’s huge,” he said.

But while nanoplastics and slightly larger particles, known as microplastics, are increasingly being found in our food, drinks and even our bodies, their effects on our health are still unclear.

Here’s what we know so far, and what you can do to reduce your exposure.

Can nanoplastics in water harm your health?

Researchers don’t have strong evidence yet for how these particles affect our health. A handful of small studies have found that they can cross the blood-brain barrier, enter the placenta and show up in our urine.

“But if a particular microplastic or nanoplastic is present in a tissue, that doesn’t necessarily mean that it causes damage,” said Dr. Konstantinos Lazaridis, a gastroenterologist who studies the role of environmental factors in liver disease at Mayo Clinic.

It’s possible that tiny plastic pieces simply pass through most people’s bodies without causing much harm, Dr. Lazaridis said. Or it might be that these environmental particles only have an impact in people who already have genetic predispositions to disease, he said.

Some researchers have theorized that microplastics may be behind disease patterns that haven’t yet been explained by other causes, such as the increase in colorectal cancers among young people, or the uptick in Crohn’s disease and ulcerative colitis. But studies are far from conclusive.

Scientists who study microplastics and nanoplastics believe that “the smaller the particle size, the more dangerous it may be,” Dr. Min said. In other words, nanoplastics may have a greater impact on health than microplastics because there are more of them, and because they may be able to more easily enter cells.

A growing body of literature suggests that at least some additives and chemicals found in and alongside plastics can harm our health, Dr. Walker said. This includes chemicals like bisphenol A, or BPA, which has been linked to increased blood pressure and type 2 diabetes; per- and polyfluoroalkyl substances, or PFAS, which may affect fertility; and phthalates, which may interfere with hormones.

But many other chemicals used in plastic manufacturing haven’t been studied for toxicity in humans. One study identified more than 10,000 unique compounds used in plastic manufacturing and found that only a very small fraction had been evaluated for their potential health effects, Dr. Walker said.

Experts also need to better understand exactly how quickly various plastic particles and additives get into our systems, how much may need to accumulate to cause an effect and how long they linger.

How can you minimize your exposure?

You may not be able to avoid nanoplastics or microplastics entirely, but if you want to err on the side of caution, you can take steps to reduce your exposure, Dr. Walker said.

Drink filtered tap water whenever possible. A filter that has a pore size of 1 micron or less can help reduce microplastics in your water; smaller micron pores will be better at filtering out smaller particles. But you should make sure your filter is not made out of plastic itself, Dr. Walker said. Instead, use ceramic or carbon filters certified by NSF International or the Water Quality Association.

When you’re on the go, consider using a bottle made of glass or stainless steel. But if you need to hydrate and all you can access is a plastic water bottle, that’s OK, Dr. Walker said. You can minimize plastic degradation by keeping your bottle away from sunlight and heat.

If you want to reduce your exposure further, Dr. Walker said, try limiting your use of other plastic products, such as food containers and single-use grocery bags.