They are found in water, in the air, on our plates, and now in human blood and the placenta. Microplastics are a legitimate concern. But what do they do once inside the body? Several reviews published in October 2026 point to a favoured target: the mitochondrion.
Particles everywhere, even in our tissues
Microplastics are plastic fragments smaller than five millimetres; nanoplastics, a thousand times smaller still, fall below one micrometre. They come from the breakdown of packaging, synthetic textiles, tyres and some everyday products. We swallow them, we breathe them in, and some pass through the skin.
A review published in October 2026 in the Journal of Advanced Research takes stock: these particles have been detected in many human tissues and fluids. The authors stress one essential point: finding them in the body does not, on its own, prove that they make us ill. That is precisely what research is trying to establish.
The power plant on the front line
A meta-analysis published on 9 October 2026 in Cardiovascular Toxicology pooled thirteen studies in rodents exposed to polyethylene, the most widespread plastic in the world. The result is consistent from one organ to the next, kidney, heart, lung, brain, reproductive organs: the enzymes that allow mitochondria to produce energy work much less well, oxidising molecules increase, and the cell's antioxidant defences run out.
In other words, the mitochondrion produces less and "leaks" more, which damages the cell from within. The heart, a heavy energy consumer, appears particularly exposed. The authors remain cautious: these are animal studies, often at high doses, and the level of certainty is rated low.
During pregnancy, the placenta under watch
Another review, published in Reproductive Toxicology, looks at the placenta, the organ that feeds the baby and also uses a lot of energy. In animals, exposure to plastics disrupts its mitochondria and the way it handles fats, which could slow the growth of the foetus. In pregnant women, evidence of a cause-and-effect link is still lacking, and large follow-up studies are awaited.
Key takeaways
- Microplastics are present in the human body, but their real effect on health remains to be demonstrated.
- In animals, they slow mitochondrial energy production and promote oxidative stress, in several organs at once.
- The heart and the placenta, both big energy consumers, are receiving particular attention.
- Reducing everyday exposure remains a common-sense approach while human studies are awaited.
Sources
- Kehinde SA et al. Polyethylene microplastics and cardiometabolic mitochondrial-redox dysfunction in preclinical rodent models: a systematic review and meta-analysis. Cardiovascular Toxicology, 2026. https://doi.org/10.1007/s12012-026-10203-x
- Wu W et al. Micro- and nanoplastic exposure and human health. Journal of Advanced Research, 2026. https://doi.org/10.1016/j.jare.2026.10.009
- Gong W et al. Maternal exposure to microplastics and nanoplastics: placental lipid metabolic dysregulation as a potential link to fetal growth restriction. Reproductive Toxicology, 2026. https://doi.org/10.1016/j.reprotox.2026.109375
