Scientists have tracked microplastics from the ocean to the atmosphere to human brain tissue. In the new review, the investigation moves into the skeleton, and the pictures it assembles contain warnings that orthopedic surgeons recognized decades ago.
Biological tissue under stress
Bones are not fixed frames. Living cells destroy and rebuild themselves in a constant cycle, with some cells building new tissue and others removing old tissue.
When this balance tips toward removal, bone density is lost and fractures are more likely. Researchers from Brazil, Canada and France have compiled evidence of how plastic particles can tip the balance in the wrong direction.
Rodrigo Oliveira from the State University of Campinas coordinated the study with colleagues from Laval University and Picardy University Jules Verne.
Laboratory studies collected in the review show that plastic particles inhibit bone cell survival and accelerate their aging. The particles also pushed the system toward cells that lysed the bone.
Old warning from orthopedics
The idea that plastic debris can erode bone is not new. Orthopedic researchers have been doing this work since 1978, when a British team first linked polyethylene fragments to bone loss around prosthetic joints.
When the surfaces of artificial hips and knees wear down, tiny plastic particles are released. These particles collect in nearby tissue, causing a condition surgeons call periprosthetic osteolysis. In this condition, the bone around the implant dissolves and loosens.
This mechanism reads like a preview of new environmental problems. Immune cells engulf the plastic, release inflammatory signals, and recruit bone-resorbing cells to the site.
Orthopedic studies have also mapped dose-response. More wear debris means more bone loss, and particles of a certain size were found to be the most active. Reducing the amount of debris slowed the damage.
Therefore, decades of implant research have already described how one common plastic, polyethylene, causes bone destruction. A new review takes that local, well-mapped process and asks whether environmental particles do something similar throughout the body.
Same plastic covers a wider range
Polyethylene is in the center of both floors. Not only does it wear out joint replacements, but it also ranks as one of the most common polymers in human blood. Polyethylene is also used in everyday life, from grocery bags to bottles to food packaging.
The difference is exposure. While implant debris stays close to the hardware, microplastics in the environment enter through the food we eat, the water we drink, and the air we breathe.
The same particles have already been detected in brain tissue, with levels highest in people with dementia. Researchers have now identified plastic debris in human bone, cartilage, and intervertebral discs.
This detection turns questions about the experimental dish into questions about the population as a whole.
How particles reach the skeleton
Plastic particles enter the body through several routes and travel through the bloodstream. Small fragments can enter tissues that are rich in blood vessels, and bone is one of the most vascular tissues.
Studies have linked plastic to the risk of heart attacks and strokes, but the same circulation that transports plastic to arteries can also direct it to bone marrow and bone surfaces. Once there, the particles meet the very cells that control bone strength.
Animal studies showed the most acute effects. Study co-author Oliveira said the particles caused enough damage that “the growth of the animal’s skeleton was inhibited.”
Why is an aging world important?
Aging and hormonal changes already thin the skeleton, and this process causes conditions such as osteoporosis. New cellular stressors can turn a manageable decline into a more rapid decline.
The stakes are high. The International Osteoporosis Foundation reports that the number of femoral neck fractures worldwide will nearly double between 2018 and 2050.
This prediction holds true even though fracture rates are actually declining in most regions. The aging of the population is driving growth, and the addition of additional risk factors means that the number of vulnerable people continues to grow.
What evidence is still lacking
The strongest arguments are based on solid evidence. Plastic particles reach human bones, and laboratory studies have shown that they interfere with the cells that maintain bone strength.
The open questions are clinical. Scientists need to learn how much exposure matters, which polymers act most aggressively, and who faces the greatest risk.
The authors also call for a standard method to measure particles. Consistent methods align results from different laboratories and build a clearer signal.
Orthopedics offers another lesson here. Researchers have spent decades figuring out how implant fragments damage bone, but there is still no reliable drug that can reverse that damage without surgery.
The environmental version of this problem is newer and far more widespread. This review frames this as a well-founded reason to treat plastic exposure as a bone health problem, rather than a resolved danger.
diary international osteoporosis The full text of the study was published.
—–
Like what you read? Subscribe to our newsletter for fascinating articles, exclusive content and the latest updates.
Check us out on EarthSnap, the free app from Eric Ralls and Earth.com.
—–
