Doctors find microplastics in the human heart

Microplastics—plastic fragments less than 5 millimeters wide, or about the size of a pencil eraser—are everywhere, even in the human heart and its surrounding tissues.

Fibers, flakes, spheres, foams: every day we eat, drink, and inhale tiny bits of plastic but what happens once they enter our bodies is a question that worries a growing number of scientists and clinicians, and doctors have recently reported that these .

“Microplastics have been detected in human stool, lungs, and placentas, which have direct exposure to the external environment through various body cavities, including the oral/anal cavity and uterine/vaginal cavity,” say the authors of a new study from researchers from Johns Hopkins. “Crucial data on microplastic exposure in completely enclosed human organs are still lacking.”

The report, published on July 13, 2023, said microplastic specimens were collected from 15 cardiac surgery patients, including 6 pericardia, 6 epicardial adipose tissues, 11 pericardial adipose tissues, 3 myocardia, 5 left atrial appendages, and 7 pairs of pre- and postoperative venous blood samples.

“Nine types of microplastics were also detected in pre- and postoperative blood samples with a maximum diameter of 184 microns, and the type and diameter distribution of microplastics in the blood showed alterations following the surgical procedure,” said the study’s authors. “Moreover, the presence of poly(methyl methacrylate) in the left atrial appendage, epicardial adipose tissue, and pericardial adipose tissue cannot be attributed to accidental exposure during surgery, providing direct evidence of microplastics in patients undergoing cardiac surgery.”

Everywhere scientists look for microplastics, they’ve found them — food, water, air and some parts of the human body. But examinations of our innermost organs that aren’t directly exposed to the environment are still limited.

In the pilot study of people who underwent heart surgery, researchers report in ACS’ Environmental Science & Technology that they found microplastics in many heart tissues. They also report evidence suggesting that microplastics were unexpectedly introduced during the procedures.

Microplastics are plastic fragments less than 5 millimeters wide, or about the size of a pencil eraser. Research has shown that they can enter the human body through mouths, noses and other body cavities with connections to the outside world. Yet many organs and tissues are fully enclosed inside a person’s body, and scientists lack information on their potential exposure to, and effects from, microplastics. So, Kun Hua, Xiubin Yang and colleagues wanted to investigate whether these particles have entered people’s cardiovascular systems through indirect and direct exposures.

The researchers collected heart tissue samples from 15 people during cardiac surgeries, as well as pre- and post-operation blood specimens from half of the participants. Then the team analyzed the samples with laser direct infrared imaging and identified 20 to 500 micrometer-wide particles made from eight types of plastic, including polyethylene terephthalate, polyvinyl chloride and poly(methyl methacrylate).

This technique detected tens to thousands of individual microplastic pieces in most tissue samples, though the amounts and materials varied between participants. All of the blood samples also contained plastic particles, but after surgery their average size decreased, and the particles came from more diverse types of plastics.

Although the study had a small number of participants, the researchers say they have provided preliminary evidence that various microplastics can accumulate and persist in the heart and its innermost tissues.

They add that the findings show how invasive medical procedures are an overlooked route of microplastic exposure, providing direct access to the bloodstream and internal tissues.

More studies are needed to fully understand the effects of microplastics on a person’s cardiovascular system and their prognosis after heart surgery, the researchers conclude.

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