# Microplastics and PFAS

Rating: Early — Mostly animal or cell studies; few or uncontrolled human data
Type: Condition
Updated: 2026-10-18
Canonical: https://heretic.bio/articles/microplastics-and-pfas.html

> Microplastics and PFAS ("forever chemicals") accumulate in human tissue. A 2024 NEJM study found microplastics in the carotid plaque of over half of surgery patients, who then had a higher risk of heart attack, stroke or death, and a 2025 study reported plastic in brain tissue. For PFAS, a randomized trial found that regular blood or plasma donation lowered blood levels in firefighters. But how plastics are measured is disputed: some methods can mistake natural fats for polyethylene.

Microplastics and nanoplastics (MNPs) are fragments of plastic small enough to enter tissue; PFAS ("forever chemicals") are fluorinated compounds used in non-stick, waterproof and firefighting products that persist in the body for years. Both are now measurable in most people. The research has moved fast since 2024, and so has the hype: detox protocols and binders are being sold on the back of studies that show association, not cause. This entry separates what has been measured, what it is linked to, and the one intervention with randomized evidence for lowering body burden.

## What has been found in human tissue

Study| Finding| What it does not show  
---|---|---  
Marfella et al., _NEJM_ 2024| Polyethylene was detected in carotid plaque from 150 of 257 surgery patients (58%); those with plastic in their plaque had 4.53 times the risk of heart attack, stroke or death over about 34 months (95% CI 2.00 to 10.27) (PMID [38446676](https://pubmed.ncbi.nlm.nih.gov/38446676/))| Cause. Plastic in plaque may mark other exposures, diet or poverty; the study was observational and the confidence interval is wide.  
Nihart et al., _Nature Medicine_ 2025| MNPs, mostly polyethylene shards at nanoscale, in decedent liver, kidney and brain; concentrations higher in 2024 than 2016 samples, and higher still in brains of people with dementia (PMID [39901044](https://pubmed.ncbi.nlm.nih.gov/39901044/))| That plastics cause dementia (dementia may impair clearance), or the precise mass in a brain. An Author Correction was published (PMID [40164728](https://pubmed.ncbi.nlm.nih.gov/40164728/)), and lipids are a recognized source of false-positive polyethylene signals in pyrolysis mass spectrometry, which matters for a fat-rich organ like the brain (PMID [41352016](https://pubmed.ncbi.nlm.nih.gov/41352016/)).  
  
The widely shared claim that a human brain holds "a spoon" or about 7 g of plastic comes from extrapolating the brain concentrations in this study. It should be treated as an overstatement of an uncertain measurement, not a fact.

## What lowers body burden: the evidence

Only one intervention has randomized evidence, and it is for PFAS, not microplastics. In 285 Australian firefighters with elevated blood PFOS, donating plasma every 6 weeks for a year cut mean PFOS by 2.9 ng/mL and PFHxS by 1.1 ng/mL; whole-blood donation every 12 weeks cut PFOS by 1.1 ng/mL; the observation group did not change (PMID [35394514](https://pubmed.ncbi.nlm.nih.gov/35394514/)). This works because PFAS bind to blood proteins, so removing plasma removes the chemical. Whether it changes health outcomes was not tested. Therapeutic plasma exchange (see [Therapeutic plasma exchange](therapeutic-plasma-exchange-tpe.html)) uses the same principle at larger scale, but no randomized trial has tested it for plastics.

No randomized trial has shown that any supplement, sauna protocol, binder or chelator lowers microplastic levels in human tissue. Reducing exposure (heated plastic food containers, PFAS-treated textiles and cookware, contaminated water) is plausible but has not been tested against health outcomes either. For heavy metals, where chelation does have a trial record, see [Heavy metal burden and chelation](heavy-metal-burden-and-chelation.html).

## Where it sits on the Heretic scale

**Early.** Body burden is real and rising, and the cardiovascular association in the NEJM study is large, but harm in humans has not been shown to be causal and measurement methods are still maturing. The one bright spot, PFAS reduction by plasma or blood donation, is a single randomized trial with a lab endpoint. What would move it: replication of the plaque finding with exposure measured before disease, and intervention trials that track clinical outcomes.

## Sources

1. Marfella R, et al. (2024). "Microplastics and Nanoplastics in Atheromas and Cardiovascular Events." N Engl J Med 390(10):900-910. PMID 38446676 . DOI 10.1056/NEJMoa2309822 (PubMed 38446676, DOI 10.1056/NEJMoa2309822)
2. Nihart AJ, et al. (2025). "Bioaccumulation of microplastics in decedent human brains." Nat Med 31(4):1114-1119. PMID 39901044 . DOI 10.1038/s41591-024-03453-1 (PubMed 39901044, DOI 10.1038/s41591-024-03453-1)
3. Nihart AJ, et al. (2025). "Author Correction: Bioaccumulation of microplastics in decedent human brains." Nat Med 31(4):1367. PMID 40164728 . DOI 10.1038/s41591-025-03675-x (PubMed 40164728, DOI 10.1038/s41591-025-03675-x)
4. Almeida FN, et al. (2026). "Py-GC-MS/MS quantification of microplastics in vertebrate tissues: Addressing false positives of polyethylene." J Hazard Mater . PMID 41352016 . DOI 10.1016/j.jhazmat.2025.140658 (PubMed 41352016, DOI 10.1016/j.jhazmat.2025.140658)
5. Gasiorowski R, et al. (2022). "Effect of Plasma and Blood Donations on Levels of Perfluoroalkyl and Polyfluoroalkyl Substances in Firefighters in Australia: A Randomized Clinical Trial." JAMA Netw Open 5(4):e226257. PMID 35394514 . DOI 10.1001/jamanetworkopen.2022.6257 (PubMed 35394514, DOI 10.1001/jamanetworkopen.2022.6257)