Presence in mother and fetal tissues
In an article published on November 6, 2024, in the journal Ecotoxicology and Environmental Safety, Hanxiang Sun from Tongji University, China, and co-authors investigated microplastics in six types of tissues, maternal blood, placenta, amniotic fluid, umbilical vein blood, umbilical cord, and fetal membrane. The samples were obtained from 12 pregnant women undergoing a cesarean section. Upon sample pretreatment, the scientists analyzed plastic particles between 10 and 500 µm by laser direct infrared (LDIR). To account for potential contamination during sample treatment and measurement, controls were run in parallel, and no microplastics were detected.
The researchers reported a median of 10 particles/g in the umbilical cord, 8 in maternal blood, 7 in fetal membrane, 5 in amniotic fluid as well as in placenta, and 3 particles/g in umbilical vein blood. The microplastics were made of 16 different polymer types with polyamide being the most prominent. Particles in the smaller size range were more abundant; 90% had a size between 20 and 100 µm.
While the authors found microplastic levels in amniotic fluid to increase with maternal age and body mass index of the mother, no further association between microplastic levels and lifestyle factors was identified. Total microplastics in maternal blood did not correlate with levels in fetal appendages or umbilical vein blood. Importantly, the sample size for this study was very small, which is also why the authors call for replication with a larger sample size.
Previously, microplastics have been detected in human breastmilk, placenta, and meconium samples, but Sun and co-authors were the first to detect microplastics in fetal appendages and umbilical cord blood and explore an association of microplastic levels in maternal blood, fetal appendages, and umbilical vein blood.
Effects on placental explants
In an article published on November 20, 2024, in the journal Frontiers in Endocrinology, Ashelley Kettyllem Alves de Sousa from the Federal University of Alagoas, Maceio, Brazil, and co-authors studied microplastic effects on placental cells ex vivo. The scientists collected placentas from 40 healthy pregnant women and performed a battery of in vitro bioassays with them using smaller size tissue explants. For their tests, they incubated the cells for 25 hours with different concentrations of 5 µm diameter polystyrene (PS) microplastics functionalized with carboxylic surface groups.
Microplastics induced effects in several of the assays. 100 µg/mL were cytotoxic with toxicity increasing over time as assessed with lactate dehydrogenase (LDH) release assay. Results of several biochemical assays demonstrated that particles induced oxidative stress. For instance, microplastics’ exposure increased glutathione peroxidase activity and markers of oxidative damage including malondialdehyde and carbonylated proteins. Kettyllem Alves de Sousa and co-authors also performed metabolomic profiling with proton nuclear magnetic resonance. Here, they reported reduced levels of alanine, formate, glutaric acid, and maltotriose in microplastic-exposed compared to unexposed samples.
The researchers emphasize that their findings indicate potential risks for maternal and fetal health “highlighting an urgent need for targeted resources and strategic initiatives to address plastic pollution at the environmental level.” At the same time, they call for research to expand the knowledge on MP effects on pregnancy and fetal development, also including other polymer types.
Microplastic effects beyond the placenta
Zhang et al. systematically reviewed and integrated the current understanding of microplastic impacts on reproductive and developmental health. Other studies published between October and November 2024 explored microplastics’ effects on bodily processes outside the reproductive system.
Deng et al. reviewed the potential role of microplastics in the transition from chronic inflammation to carcinogenesis. Schnee et al. found PS nano- and microplastics to be internalized into human breast epithelial and breast cancer cells, with a possible association with cancer progression. Microplastic exposure has previously been associated with several cancers, e.g., liver and ovarian cancer development, colorectal cancer, and breast cancer metastasis.
In a narrative review, Zheng et al. explore the association between small plastic particles and cardiovascular disease; also providing recommendations for future research. In another review, Bora et al. discuss the potential association between microplastic exposure and changes in the gut microbiome as well as with cardiometabolic and inflammatory diseases, and disorders related to the Gut-Brain Axis.
References
Alves de Sousa, A. K. et al. (2024). “Polystyrene microplastics exposition on human placental explants induces timedependent cytotoxicity, oxidative stress and metabolic alterations.” Frontiers in Endocrinology. DOI: 10.3389/fendo.2024.1481014
Bora, S. S. et al. (2024). “Microplastics and human health: unveiling the gut microbiome disruption and chronic disease risks.” Frontiers in Cellular and Infection Microbiology. DOI: 10.3389/fcimb.2024.1492759
Deng, Y. et al. (2024). “Microplastics: an often-overlooked issue in the transition from chronic inflammation to cancer.” Journal of Translational Medicine. DOI: 10.1186/s12967-024-05731-5
Schnee, M. et al. (2024). “Effects of polystyrene nano- and microplastics on human breast epithelial cells and human breast cancer cells.” Heliyon. DOI: DOI: 10.1016/j.heliyon.2024.e38686
Sun, H. et al. (2024). “Microplastics in maternal blood, fetal appendages, and umbilical vein blood.” Ecotoxicology and Environmental Safety. DOI: 10.1016/j.ecoenv.2024.117300
Zhang, Z. et al. (2024). “Reproductive and developmental implications of micro- and nanoplastic internalization: Recent advances and perspectives.” Ecotoxicology and Environmental Safety. DOI: 10.1016/j.ecoenv.2024.117245
Zheng, H. et al. (2024). “Microplastics and nanoplastics in cardiovascular disease—a narrative review with worrying links.” Frontiers in Toxicology. DOI: 10.3389/ftox.2024.1479292
This article was originally published by Lisa Zimmermann at the Food Packaging Forum.
