Are you eating and drinking plastic?

AN ALARMING STUDY published in Toxicological Sciences on Feb. 17 reported the presence of micro­plastics in samples of human placenta, reviving questions about tiny plastic pollutants less than 5 millimeters in size. Scientists have detected microplastics seemingly everywhere—in soil, air, and food; in oceans, lakes, and waterways; from the depths of the Mariana Trench to the top of Mount Everest. While the ubiquity of microplastics is well documented, their health effects are more difficult to quantify.

Where do microplastics come from? There are two different sources. Primary microplastics are particles found in products like exfoliating face washes, toothpaste, and sunscreen. Secondary microplastics are formed in the environment when larger plastic materials (like bottles, bags, and containers) break down, through wind or sun exposure.

Are we consuming microplastics? A 2019 study commissioned by the World Wide Fund for Nature reported that the average person ingests up to 5 grams of microplastics per week, the equivalent of a credit card. Microplastics enter the food chain when animals inadvertently eat them. Researchers have detected microplastics in a variety of seafood, including oysters, prawns, squid, crabs, and sardines. Plastic packaging also contributes to the presence of microplastics in foods. A 2020 study found that opening plastic items such as bottles, bags, and packaging film generates microplastics. This year, a January study in PNAS showed that 1 liter of bottled water contains approximately 240,000 tiny plastic particles, 10-100 times more than previously estimated. And a February study reported on microplastic contamination in 16 commonly consumed proteins, including chicken nuggets and breaded shrimp.

Do these plastics pose a health risk? No research has documented what happens to microplastics when they enter the human body, making it difficult to define their health risks. But some recent studies suggest potential harmful effects. A 2021 Florida State University study showed that exposing lung cells to small amounts of the plastic polystyrene inhibited the cells’ metabolic processes. A 2021 University of Hull toxicology review suggested that the levels of microplastics humans ingest are enough to harm cells. (A February 2024 study in The Lancet Planetary Health also estimated 56,600 premature births in the United States in 2018 were associated with pregnant mothers’ exposure to chemicals found in plastics.)

Can I just avoid consuming this stuff? You can’t entirely, but there are ways to lower intake. Tap water has half the concentration of microplastics as bottled water. Heating food in glass containers is better than using plastic, which can degrade and leach microplastics into your food. Limiting consumption of seafood may also lower your exposure.