Microplastics in the Placenta: The 2024 UNM Study Explained

MicroPlastics Research DeskEditorial team

December 8, 2025

11 min read

Last reviewed: May 25, 2026 by the MicroPlastics Research Desk. Submit a correction or see our editorial standards.

Quick Answer

A landmark 2024 University of New Mexico study (Garcia et al., Toxicological Sciences) detected microplastics in 100% of 62 human placentas tested, averaging ~127 micrograms per gram of placental tissue. The dominant polymer was polyethylene (54%), followed by PVC and nylon. This is the first study to quantify microplastic mass in the placenta, earlier 2020 work only confirmed their presence. For pregnant women, the takeaway is not panic but priority: filter drinking water, eliminate plastic food storage and reheating, reduce synthetic cosmetics, and ventilate the home.

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Microplastics in the human placenta. UNM 2024 study explained

Last updated: May 25, 2026

Key Takeaways

The 2024 UNM study found microplastics in every single placenta tested (n=62, 100% positive).
Average concentration: ~127 µg/g of placental tissue, orders of magnitude higher than detected in blood or other tissues.
Polyethylene was the most common polymer found (54%), the plastic used in bags, bottles, and food wrap.
The placenta acts as a filter, particles small enough to cross can reach the developing fetus directly.
The 2021 Ragusa study previously detected microplastics in the placenta but did not quantify mass.
Highest-leverage actions: water filtration, no plastic in microwave, no plastic-stored hot foods, ventilated home.

UNM 2024 placenta study, what they found

placentas tested positive: 62 / 62placentas tested positive100% detection rate, n=62
Garcia et al. 2024 (Toxicological Sciences)
mean microplastic mass per gram of tissue: ~127 μg/gmean microplastic mass per gram of tissuehighest concentration measured in any human organ to date
Garcia et al. 2024
of detected polymer was polyethylene: 54%of detected polymer was polyethylenethe plastic in bags, bottles, and food wrap
Garcia et al. 2024
identified across the 62 samples: 12 polymersidentified across the 62 samplesPE, PVC, nylon, polypropylene, polyurethane, others
Garcia et al. 2024
analytical method (pyrolysis GC/MS): Py-GC/MSanalytical method (pyrolysis GC/MS)first study to quantify microplastic mass in placental tissue
Garcia et al. 2024
first detection in placenta (Ragusa et al.): 2021first detection in placenta (Ragusa et al.)qualitative only. 2024 UNM is the first quantitative mass study
Ragusa et al. 2021 (Environment International)

What the 2024 UNM placenta study found

Researchers at the University of New Mexico Health Sciences Center analyzed 62 human placentas donated after birth. Using a new pyrolysis gas chromatography–mass spectrometry (Py-GC/MS) method, they could measure not just the presence of microplastics but their actual mass per gram of tissue.

UNM 2024 placenta study, headline numbers
Metric	Result
Placentas with detectable microplastics	62 of 62 (100%)
Average concentration	~127 µg/g of tissue
Range across samples	6.5 to 685 µg/g
Most common polymer	Polyethylene (54%)
Second most common	PVC (10%)
Other polymers detected	Nylon, PET, polystyrene, polypropylene
Detection threshold	~7 ng/g

Why this is different from the 2021 Ragusa study

The 2021 Italian study by Antonio Ragusa (Environment International) was the first to detect microplastics in human placentas, finding particles in 4 of 6 samples. That study used Raman spectroscopy and could identify the polymer type but not quantify the mass.

The UNM 2024 study advanced this in three ways:

Larger sample. 62 placentas vs 6.
100% detection, not 67%, every single one.
Mass quantification, we now know roughly how much, not just whether.

How microplastics reach the placenta

The placenta is the organ that connects the developing fetus to the mother. Maternal blood flows through it, and small particles can cross from the mother into placental tissue (and in some cases further, into the fetus). The microplastics found in placental tissue likely arrive through:

Inhalation, indoor air has 3–15× the microplastic load of outdoor air. Inhaled particles cross into blood.
Ingestion, bottled water, plastic-packaged food, plastic-reheated meals.
Skin absorption of chemicals, phthalates, BPA, parabens from cosmetics, then transferred via blood.
Maternal blood, the 2022 Leslie study confirmed microplastics in 77% of healthy human blood samples.

What this means for pregnancy

The UNM authors and other reproductive toxicologists emphasize that placental microplastics are a marker of exposure, not yet proof of harm in humans. But the biological pathways for concern are well-established in animal and cell-culture work:

Placental dysfunction, animal studies show MP exposure reduces placental weight, alters nutrient transport, and increases inflammation.
Fetal growth restriction, phthalates and BPA (often carried on microplastics) are linked to lower birth weight in human cohort studies.
Endocrine disruption. BPA, BPS, and phthalates interfere with thyroid and sex hormones critical for fetal development.
Neurodevelopmental impact, prenatal phthalate exposure is associated with altered cognitive outcomes in children.

Practical reduction strategy during pregnancy

See our dedicated trimester-by-trimester guide for week-by-week steps. The top six interventions:

Filter drinking water. A NSF-certified pitcher (Clearly Filtered) or under-sink reverse osmosis removes 99%+ of microplastics.
Never microwave plastic. A 2023 study found microwaving plastic food containers releases up to 4.22 million microplastic particles per cm² in 3 minutes.
Switch to glass food storage. Pyrex, Anchor Hocking, or Weck jars. Stainless or silicone for travel.
Drink from glass or stainless, not single-use plastic bottles. The 2024 Naixin Qian study found bottled water has 240,000 plastic particles per liter.
Audit cosmetics. Avoid synthetic fragrance, BHA, BHT, oxybenzone, parabens. See cosmetics guide.
Ventilate the home. Open windows; HEPA-filter bedroom and main living area; vacuum twice weekly.

What we still don't know

Whether the polyethylene found is from food packaging, water, or air, likely a mix.
Whether particles cross into fetal tissues at meaningful concentrations in humans.
The specific dose-response relationship between placental microplastic load and birth outcomes.
Whether removing exposure during pregnancy reduces placental load by birth (likely partial, given particle persistence).

The 2024 UNM study makes it clear: by the time pregnancy is in progress, the placenta is already being exposed. The most useful framing is risk reduction, not elimination, every gram of plastic avoided is a gram less in the system.

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Frequently Asked Questions

Have microplastics really been found in the placenta?

Yes. A 2024 University of New Mexico study published in Toxicological Sciences detected microplastics in 100% of 62 human placentas tested, averaging about 127 micrograms per gram of tissue. An earlier 2021 study by Ragusa et al. first confirmed their presence in a smaller sample of 6 placentas.

What kind of plastic is most often found in the placenta?

In the UNM 2024 study, polyethylene was the dominant polymer (about 54% of samples), the same plastic used in shopping bags, food wrap, and squeezable bottles. PVC, nylon, PET, polystyrene, and polypropylene were also detected.

Can microplastics cross from the placenta to the baby?

Animal studies show that particles smaller than about 100 nanometers can cross the placental barrier into fetal tissues, and some particles up to a few micrometers may also cross under inflammatory conditions. In humans, this has been less directly studied, but the placenta is known to be permeable to many plasticiser chemicals (BPA, phthalates) that travel into fetal blood.

Does microplastic exposure during pregnancy harm the baby?

No human study has yet proven direct harm from microplastic particles themselves during pregnancy. However, the chemicals carried by them (BPA, phthalates, PFAS, parabens) have been linked in human cohorts to lower birth weight, altered thyroid function, and neurodevelopmental changes. Animal studies show clearer effects: reduced placental weight, altered nutrient transport, inflammation, fetal growth restriction.

What is the most important thing a pregnant woman can do to reduce exposure?

In order of impact: (1) filter drinking water, (2) never microwave food in plastic, (3) switch food storage to glass, (4) avoid bottled water, (5) audit cosmetics for synthetic fragrance and parabens, (6) ventilate the home and HEPA-filter the bedroom.

Is it too late to reduce exposure if I am already pregnant?

No. Microplastic and chemical loads turn over partially, reducing exposure during pregnancy reduces what is delivered across the placenta from that point forward. Every reduction matters, especially for the higher-risk second and third trimesters when fetal organ systems are still developing.

Sources

Garcia MA, Liu R, Nihart A, et al. (2024). Quantitation and identification of microplastics accumulation in human placental specimens using pyrolysis gas chromatography mass spectrometry. Toxicological Sciences.
Ragusa A, Svelato A, Santacroce C, et al. (2021). Plasticenta: First evidence of microplastics in human placenta. Environment International.
Leslie HA, van Velzen MJM, Brandsma SH, et al. (2022). Discovery and quantification of plastic particle pollution in human blood. Environment International.
Qian N, Gao X, Lang X, et al. (2024). Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. PNAS.
Hussain N, Jaitley V, Florence AT (2001). Recent advances in the understanding of uptake of microparticulates across the gastrointestinal lymphatics. Advanced Drug Delivery Reviews.

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