Microplastics in the human body: what's been found so far.
In the last few years, researchers have gone looking for plastic inside us — and found it. Blood. Placenta. Lungs. The findings are real and published; their health meaning is still being worked out. Here's the honest state of the science, and why the mouth deserves a place in the conversation.
The landmark detections
In 2022, researchers in the Netherlands reported the first quantifiable detection of plastic particles in human blood (Environment International, Leslie et al.), finding polymers including PET and polyethylene in a majority of donors sampled. A year earlier, an Italian team had reported microplastic fragments in human placenta (Environment International, Ragusa et al., 2021). Subsequent studies have reported particles in lung tissue and, more recently, in reproductive tissues. Detection methods and contamination controls vary between studies — a genuine limitation the field acknowledges — but the direction of evidence is consistent: plastic particles small enough to travel do, and some end up in us.
What science honestly doesn't know yet
Finding particles is not the same as proving harm. Dose–response in humans, long-term persistence, and which particle sizes and polymer types matter most are all open research questions. Laboratory and animal studies give reasons for attention — inflammatory responses, endocrine-active additives hitching a ride on particles — but translating that to human health outcomes is exactly what the current wave of research is trying to do. Anyone telling you the science is settled, in either direction, is ahead of the evidence. Our own position is simply that uncertainty is a reason for transparency, not complacency.
Where the mouth fits
Most public attention has gone to bottled water, food packaging and seafood. Dentistry has been a quieter contributor to the question — odd, because few plastics spend longer in more intimate contact with the body. A 2025 review in the Journal of Hazardous Materials documented micro- and nanoplastic release from resin composites, clear aligners and denture materials through wear and degradation, and a 2025 review in Materials mapped the same territory while noting how sparse real-world exposure data remain. A retainer is worn ~8 hours a night for years; an aligner 22 hours a day for months; a filling is chewed on for a decade. Whatever the eventual health verdict, the mouth is a route of exposure that deserves measurement.
Measurement is the point
This is why bio. exists the way it does. We can't settle the epidemiology — nobody can yet — but we can refuse to add unmeasured plastic to the equation. Our retainers are bio-derived rather than petroleum plastic; our aligners are the only UK aligner made from a plant-based, BPA-free material; and every lot is independently tested with results published at the bio. Standard. Not because the science is finished — because it isn't.
Related reading: Microplastics and BPA in fillings · Microplastics and clear aligners
Cut the exposure where contact is longest.
You can't control every plastic you meet — but the device worn in your mouth eight hours a night is a choice. bio.retainers are bio-derived, not petroleum plastic, and every lot is independently tested with results published in full.