Plastics nowadays are ubiquitous.

They make up the clothes we wear, contain and wrap the food and beverages we eat and drink, and are in countless consumer products. But what is their impact on human health?

A growing body of research is finding that microplastics, particles of plastic that are sometimes so small they are invisible to the naked eye, are found in human tissue, including the lungs, guts, bloodstream — and placentas.

Researchers from the University of Hawaii John A. Burns School of Medicine have found an increasing accumulation of microplastics in local placentas that provide nourishment to babies in utero.

“We were shocked that these little pieces of plastic were getting across the mom’s gut and landing in the placenta,” said Dr. Men-Jean Lee, a JABSOM researcher and OB-GYN at Kapiolani Medical Center for Women & Children.

In examining placentas donated by Hawaii women over a 15-year period, they found that microplastics in placentas consistently increased as time progressed.

Lee, along with Rodrigo Weingrill and Johann Urschitz from UH Manoa’s Institute for Biogenesis Research, examined 10 placentas from noncomplicated births that took place in 2006, 2013 and 2021.

In 2006, six out of 10 placentas the researchers examined contained microplastics. In 2013, nine out of 10 placentas contained microplastics.

Then in 2021, researchers found 10 out of 10, or 100%, of placentas examined contained microplastics.

The study and results, along with an analysis of what kinds of plastics were found in the placentas, were recently published in Environment International.

How plastics enter the body

Microplastics — particles smaller than 5 millimeters — can accumulate in human body tissue three ways, according to Weingrill: ingestion, inhalation and through the skin.

They can be ingested when a person eats something containing plastic particles, potentially through the consumption of seafood or fish, or, as studies have shown, food microwaved in certain single-use, disposable plastics.

Microplastics also can be breathed in if plastic distintegrates and turns into airborne dust, a concern that many health officials are paying attention to in the aftermath of the Aug. 8 wildfires on Maui.

Another route is through skin contact via microplastics in personal care and cosmetic products — think microbeads, which have since been banned.

They’re basically everywhere, according to Weingrill, in the soil, the ocean and potentially the air after incineration.

Placentas are a unique and transitory organ that work like sponges, he said, absorbing oxygen and nutrients, so it would tend to retain plastic particles, as well.

JABSOM has an archive of donated placentas dating back to 2006 to tap into for research purposes.

But, according to Lee, they were stored in plastic tubes while in deep freeze.

So in 2021 the researchers collected fresh placenta samples, taking extra steps to ensure none were stored in plastic or came into contact with plastics.

They found that not only did the accumulation increase over time, but that the size of the plastic particles grew over time as well, with all the samples in 2021 containing microplastics.

“So they’re not just increasing in size and accumulating more in the tissues, but you have new players,” said Rodrigo. “Some of these players we couldn’t even identify. We don’t know if it’s a byproduct of plastic degradation or if they are new chemicals not present in the database we’re analyzing.”

Maternal health impacts

While the findings are concerning, Lee said they mark the beginning of a research journey.

The next step is to understand the health impacts of these microplastics on mothers and babies.

To that end the team has received a $200,000 grant from the National Institutes of Health to more specifically study the impacts of microplastics in the placenta.

“Usually, we think of the placenta as an organ that is attached between mom and baby so that the oxygen and nutrients can get over from mom to help feed the baby,” said Lee. “But it also protects the baby from getting viruses and bacteria and infection.”

Questions to explore include whether the placenta prevents microplastics from getting to the umbilical cord or baby. Do the plastics pose any threats to the pregnancy? How about chemicals that leach from plastic, such as Bisphenol A and phthalates?

Research has linked these chemicals with endocrine disruption that can lead to health issues such as fibroids and infertility, she said, along with developmental issues like attention deficit hyperactivity disorder and autism.

Lee believes the study shows how placentas can serve as a “plastic pollution monitoring system.”

Global production of plastics, meanwhile, has reached about 400 million tons per year, according to the United Nations Environment Programme, with a shift toward single-use plastics.

Hawaii is challenged not only due to its remote location in the Pacific, but because plastic disintegration here is exacerbated by sunlight, heat and salt.

Down the line, Lee plans to study whether there is a link between lifestyle choices and the accumulation of plastics in placentas.

She acknowledged that plastic is difficult to avoid, even in a hospital, scientific laboratory or operating room.

But understanding how it affects human health can offer insight into how to mitigate its harm through lifestyle changes, particularly in Hawaii.

“What’s going to be interesting is how we manage the plastics going forward,” she said, noting the COP28 climate change conference underway examines the problem of plastics and human health. “We’re a coastal community, and sustainability is really important to us.”