Plastic baby bottles are lightweight and convenient-no wonder they account for more than 80% of the global baby bottle market.

But a recent study published in "Nature Foods" found that babies may be exposed to thousands or even millions of microplastic particles every day, which is higher than previously thought.

The biggest question is whether—or how—will affect the health of the baby.

Research co-author, Dr. Jing Jing Wang, a scientist at the AMBER Research Center and Adaptive Nanostructures and Nanodevices Research Center of Trinity College Dublin, Ireland, said that the simple answer is that the researchers don’t know.

"I don't think anyone expected the level we found to be very high," Wang told Today in an email.

"Our goal is not to worry parents. We have communicated as strongly as possible that we do not know the potential health risks of infants ingesting microplastics... Human health has not yet been well developed."

But based on the known effects on the health of animals such as mice and fish, including digestive disorders and brain damage, Wang pointed out that these findings indicate that "we should take measures to remedy the release of microplastics."

According to the US National Oceanic and Atmospheric Administration, microplastics are plastic particles smaller than sesame. They may be harmful to marine and aquatic life and have been detected in human feces.

New research has found that baby bottles made of polypropylene-the typical type of plastic used in such products-release microplastics when heated or shaken. The researchers followed the cleaning, disinfection and mixing techniques recommended by the World Health Organization, imitating the steps taken by parents to prepare infant formula. Then they measured the number of microplastic particles in the internal liquid.

The results were shocking: polypropylene baby bottles leaked an average of 4 million microplastic particles per liter, or about one quart of liquid. Exposure to high temperature water will significantly increase the release of plastic fragments.

The study estimates that the average microplastic exposure level of bottle-fed babies exceeds 1.5 million pellets per day, which is 2,600 times that of adults. Based on the preference for plastic baby bottles in these regions, babies in North America and Europe consume more plastic fragments.

The plastics industry said that reports of such small particles sound shocking, but the detection of something does not mean that it poses a health risk.

The Department of Plastics of the American Chemistry Council said in a statement that with the help of expert scientists, the safety of plastics in contact with food (including baby bottles) is under "very strict supervision" in the United States and Canada. It pointed out that the US Food and Drug Administration considers temperature changes (such as heating) as part of its food contact regulatory approach.

But the pediatrician said that parents were right to be shocked by the results of the study.

"Science is still only scratching the surface of the concerns there. But when you see microplastics, you know that plastics are breaking down, and deeper concerns are actually less obvious concerns," NYU Grossman School of Medicine Said Dr. Leonardo Trasander, professor of pediatrics and director of the Environmental Investigation Center. The dangers of NYU Langone in New York City.

"It's a chemical molecule broken down from a polymer."

Chemicals that are absorbed from plastics into food and are particularly worrying include phthalates, which disrupt metabolism and lower the male sex hormone testosterone; Trasander, lead author of the American Academy of Pediatrics Food Additives and Child Health Policy Statement That said, bisphenols such as BPA is essentially a synthetic estrogen that can make fat cells larger.

He pointed out that researchers know very little about microplastics, and they may not be directly absorbed by the body like these chemicals.

"I do think parents should worry about this," added Dr. Claire McCarthy, a pediatrician at Boston Children's Hospital and an assistant professor of pediatrics at Harvard Medical School.

"The problem is that we don’t know how much they should worry about... We don’t know exactly how much exposure will cause harm, or what factors may increase or decrease harm. But to be fair, we should all use less plastic, especially when feeding babies. And children."

To reduce the amount of plastic fragments consumed by babies, the authors of this new study recommend shaking and heating plastic bottles as little as possible. Wang said that the four main steps to do this are:

Trasande says the simpler solution is to switch to glass. Most of the containers in his house are made of glass. When his two children were babies, he used glass.

Both Trasande and McCarthy recommend that parents generally avoid using plastic baby bottles, or use them sparingly. In addition to glass, stainless steel is also an option.

McCarthy suggested that if you insist on using plastic, parents should wash the bottles by hand instead of putting them in the dishwasher. Machine washing with harsh chemicals at high temperatures will cause abrasion and tearing and help break down plastic polymers.

"As for heating formula or breast milk, parents should not use any plastic products for heating," she said.

"They can be heated in a pan-preferably not a non-stick pan, because those also have chemicals-or in glass. Babies don't necessarily need formula or breast milk to keep warm; this may be to get them used to cool or room temperature A good reason to drink."

A. Pawlowski is the Senior Contributing Editor of Today, focusing on health news and special reports. Prior to this, she was a writer, producer and editor for CNN.