Microplastics databaseExplainerChecked 2026-10-01
Where in the body have microplastics been found? Studies of blood, placenta, brain and arteries, and their critics
Studies organ by organ, and the criticism that some methods count fat as plastic
The answer
There are reports of findings in blood, placenta, breast milk, lungs, stool, arteries, brain and more. But a 2026 study that checked 101 studies of the human body against quality criteria found that none met all of the essential criteria.
In particular, it has been pointed out that the method of heating fatty tissue and measuring the breakdown products (Py-GC/MS) may count fat as polyethylene. Whether the amounts found affect health is not known.
Studies by body part
| Part | Study | Method | Result | Caution |
|---|---|---|---|---|
| Blood | Leslie et al. (2022) 22 people | Py-GC/MS (0.0007 mm or larger) | Average 1.6 μg per mL. PET, polyethylene, and styrenics were common | In a study using the same method with fat interference suppressed (Rauert 2025, 8 people), everything other than polyethylene was below the limit of detection |
| Placenta | Ragusa et al. (2021) 6 people | Raman | 12 particles (0.005 to 0.01 mm) from 4 people | Only 3 particles were identified as plastic (colored polypropylene). For the rest, only the pigment was identified |
| Placenta | Garcia et al. (2024) 62 people | Py-GC/MS | 6.5 to 685 μg per g from everyone (average 126.8 μg). Polyethylene was 54% by weight | The main components are polyethylene and PVC, which are said to be hard to distinguish by Py-GC/MS |
| Breast milk | Ragusa et al. (2022) 34 people | Raman | From 26 people (0.002 to 0.012 mm). Polyethylene, PVC, polypropylene | No association with age, seafood, or packaged food |
| Lung | Jenner et al. (2022) 13 samples (surgery) | μFTIR (0.003 mm or larger) | From 11 samples. After subtracting the blank (procedural blank), 0.69 particles per g. Polypropylene 23%, PET 18% | More in the lower part of the lung |
| Stool | Schwabl et al. (2019) 8 people | FTIR (0.05 to 0.5 mm) | From everyone. Median 20 particles per 10 g | Small number of people |
| Stool (Japan) | Tsuji et al. (2026) 22 Japanese people | FT-IR (larger than 0.02 mm) | Median 7.20 particles per g | The tendency to be higher in people who eat seafood often was not significant after correction for multiple comparisons |
| Neck artery plaque | Marfella et al. (2024, NEJM) 257 people | Py-GC/MS and electron microscopy | Polyethylene in 150 people (58.4%) (average 21.7 μg per mg of plaque). Heart attack, stroke, or death over about 3 years: 20.0% vs. 7.5% | Observational study. The authors state that it does not show causation and that laboratory contamination cannot be ruled out |
| Brain | Nihart et al. (2025) Autopsy, 20 to 28 people per time point | Py-GC/MS | Median in 2024: 4,917 μg per g (3,345 μg in 2016). 26,076 μg in the 12 people with dementia | The authors state that they do not assume causation. Germany's BfR called the values “implausibly high,” and other researchers pointed to insufficient contamination control and validation |
| Testis | Hu et al. (2024) 23 people (47 dogs) | Py-GC/MS | Average 328 μg per g, mainly polyethylene | Criticized for not reporting blanks or limits of detection (the criticism was funded by the American Chemistry Council) |
| Liver | Horvatits et al. (2022) 6 with cirrhosis, 5 controls | Raman (0.004 to 0.03 mm) | Not found in the liver, kidney, or spleen of people without liver disease; found only in cirrhotic livers | Even for the liver, a Py-GC/MS study (Nihart) reported a median of 433 μg per g |
There are also reports on semen (found in 34 of 45 people; sperm motility was lower in those with more PET, but not statistically significant; 2025), kidney and urine, bone marrow, and joints.
Criticism of the methods
- Fat and polyethylene: When fat breaks down under heat it releases the same substances as polyethylene, so polyethylene may be overestimated. Substances used to identify PVC are also released from fatty acids. Researchers in Australia concluded that “Py-GC/MS is currently not suitable for measuring polyethylene and PVC in biological samples.” When they measured the blood of 8 people with the effect of fat suppressed, everything except polyethylene was below the limit of detection (Rauert et al. 2025).
- Orders of magnitude apart in the same organ: In the liver, Raman (which counts particles of 0.004 to 0.03 mm) found none in people without disease, while Py-GC/MS found a median of 433 μg per gram.
- The brain study (2025): A researcher who criticized it points out that “the brain is about 60% fat” (news report). The researchers say that contamination controls were limited and there was no verification procedure (Nat Med 2025), and Germany’s BfR called the amounts measured “implausibly high.” The authors reply that most of the criticism is not based on actual data (news report).
- The neck artery study (NEJM 2024): The authors themselves write that they cannot completely rule out contamination in the laboratory.
- The first placenta study (2021): Of the 12 particles found, the type of plastic could be identified for only 3.
- Small particles, conversely, are missed: Particles under 0.001 mm weigh too little to reach the limit of detection of Py-GC/MS, and they slip through filtering methods. When the placenta was examined with a new method, 73% of the particles were under 0.001 mm (Wouters et al. 2026).
Who funded the critics
- The criticism of the testis study (2025) is a paper by an expert panel funded by the American Chemistry Council (stated in the paper).
- The authors of the criticism of the blood study (2024) are employees of the chemical companies INEOS Styrolution and Borealis, and one is paid by the European plastics industry association (stated in the paper).
- On the other hand, Rauert 2025, which showed the fat problem, declared no conflict of interest. What the criticism says has to be checked against the data, separately from who paid.
Research in Japan
A study of the stool of 22 Japanese people (2026; particles over 0.02 mm identified by FT-IR) found a median of 7.20 particles per gram (funded by KAKENHI and the Environment Research and Technology Development Fund). We could not find any document in which the Food Safety Commission of Japan, the MHLW or the Ministry of the Environment gave a view on microplastics inside the body.
Sources
- Leslie et al. (2022) (Blood)
- Ragusa et al. (2021) (Placenta)
- Garcia et al. (2024) (Placenta)
- Ragusa et al. (2022) (Breast milk)
- Jenner et al. (2022) (Lung)
- Schwabl et al. (2019) (Stool)
- Tsuji et al. (2026) (Stool (Japan))
- Marfella et al. (2024, NEJM) (Neck artery plaque)
- Nihart et al. (2025) (Brain)
- Hu et al. (2024) (Testis)
- Horvatits et al. (2022) (Liver)
- Rauert C, et al. Environ Sci Technol 2025;59(4):1984-1994
- Lane, et al. Environ Int 2026;214:110429
- Monikh FA, Materić D, et al. Nat Med 2025;31:4034 (criticism of the brain study)
- Uppu RM, et al. Toxicol Sci 2025 (criticism of the testis study)
- Wilhelmus, et al. Microplastics and Nanoplastics 2024;4:28 (criticism of the blood study)
- BfR, “Microplastics in the brain,” 2025
- Wouters, et al. ACS Nano 2026 (placenta particles under 1 μm)
- Guo, et al. 2025 (semen)
- The Guardian, “‘A bombshell’: doubt cast on discovery of microplastics throughout human body,” Jan. 13, 2026 (news report)
Last checked 2026-10-01. Research and regulations change over time. This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.
This page lists facts from public agencies' documents, laws and peer-reviewed papers. Methods for measuring microplastics differ between studies, so numbers often cannot be compared directly. Public bodies such as WHO, FAO and EFSA do not currently recommend that individuals avoid any particular food because of microplastics.