Microplastics have been detected in the human placenta and meconium samples (FPF reported and here) and three studies published in September 2022, continued research on the topic by also looking at the location of microplastics within the placenta, potential sources, and health implications.
In an article published on September 14, 2022, in the journal Environmental Research and Public Health, Antonio Ragusa from Università Campus Bio Medico di Roma, Italy, and co-authors, investigated which placental compartment microplastics localize and whether their presence is associated with the alteration of cell organelles in the respective tissue. For the analysis, the scientists collected placenta samples from ten women with low-risk pregnancies. The women were also asked to fill in a questionnaire to monitor their potential plastic consumption (via cosmetics, hygiene products, diet), lifestyle, and pathophysiological conditions. Using scanning and transmission electron microscopy, the researchers analyzed the different regions of the sampled placenta for microplastic presence and modification of cellular microstructures.
Ragusa and co-authors detected microplastics in all examined samples. They found “particles compatible with microplastics” on the surface of placental villi, in the extracellular environment, as well as inside cells of different placenta cellular layers. The authors hypothesized an association of microplastics with ultrastructural alterations of intracytoplasmic organelles. Specifically, they observed morphological changes of the endoplasmic reticulum and mitochondria “that had never been reported in normal healthy at term pregnancies until today. These alterations are instead characteristic only of pathological states.”
Ragusa et al. further emphasized that the alterations of these organelles may influence the progression of human non-transmissible disease. Moreover, they concluded that microplastics present “in term human placenta could contribute to the activation of pathological traits, such as oxidative stress, apoptosis, and inflammation, characteristic of metabolic disorders underlying obesity, diabetes, and metabolic syndrome and partially accounting for the recent epidemic of non-communicable disease.”
Ragusa et al. previously analyzed human breastmilk for the presence of microplastics and detected the small particles in 26 out of the 34 samples (FPF reported). Shaojie Liu from Fudan University, Shanghai, China, and co-authors investigated placenta as well as breastmilk samples for microplastic presence but also looked at meconium, infant feces, and infant formula. The aim of their research published on September 13, 2022, in the journal of Science of the Total Environment was to evaluate microplastic exposure in pregnant women, fetuses, and infants and identify potential sources. For their analysis, the scientists recruited 18 mothers and their infants and collected placenta and meconium samples during childbirth and breast milk, infant feces, and infant formula samples six months later. To identify plastic particle sources, 14 mothers also provided information on their plastic use and dietary habits through questionnaires.
Liu and co-authors detected microplastics made of 16 polymer types over all samples with polyamide and polyurethane accounting for more than 65% of the total. The majority of the particles, over 74%, had a size between 20 and 50 µm. The highest median abundance of particles was found in meconium (51 particles/g sample), followed by feces (26), breastmilk (20), placenta (18), and infant milk (17). A comparison of microplastic levels with the data collected in the questionnaires led the authors to assume that pregnant women are potentially exposed to microplastics through the usage of toothpaste and scrub cleansers and water intake. On the other hand, lactating infants were assumed to be exposed to microplastics by feeding bottles, plastic toys, and breastmilk consumption. Underpinning the latter, the study results showed that microplastic abundance was higher in infants consuming more than 600 mL of breast milk per day compared to the children who did not. The researchers emphasized that their findings call for “investigating the contribution of plastic products to the microplastic exposure during the lactational period.”
Microplastic presence in the placenta may contribute to pregnancy complications. In an article published on September 13, 2022, in the journal Environmental Pollution, Fatemeh Amereh from Beheshti University of Medical Sciences, Tehran, Iran, and co-authors, explored whether an association exists between microplastics in the human placenta and fetal growth in neonates by performing regression analysis. They compared microplastic levels in placentas from 30 women with normal pregnancies with those in 13 women with intrauterine growth restriction (IUGR) pregnancies using digital microscopy and Raman microspectroscopy.
The amounts of microplastic particles detected in the placentas from IUGR pregnancies were between two and 38 particles/placenta. Particles were detected in all placentas of IUGR pregnancies but only in four out of 30 placentas from normal pregnancies. Characterizing the detected particles, the authors reported that the majority of microplastics were made of polyethylene and polystyrene. In normal pregnancies fragments were the dominant particle shape while IUGR placentas had both fragments and fibers dominating.
In contrast to Liu et al., Amareh and colleagues reported particles smaller than 10 µm were the most abundant size over all analyzed placentas. Furthermore, they found that body lenghts and weight of the foetus decreased with increasing microplastic counts. According to the authors, this preliminary findins suggest that plastic particles might limit placental nutrient exchange. They emphasized that further research is needed to confirm these findings and to generally better understand the toxicological effects of microplastics during critical periods of life such as pregnancy in utero and early life.
Five Horizon 2020 projects are working to better understand the impacts of microplastic exposure to humans with one of the projects, AURORA, focusing on the effects of micro- and nanoplastics on early life health (FPF reported).
References
Amereh, F. et al. (2022). “Placental plastics in young women from general population correlate with reduced foetal growth in IUGR pregnancies.” Science of the Total Environment. DOI: 10.1016/j.scitotenv.2022.158699
Liu, S. et al. (2022). “Detection of various microplastics in placentas, meconium, infant feces, breastmilk and infant formula: A pilot prospective study.” Science of the Total Environment. DOI: 10.1016/j.scitotenv.2022.158699
Ragusa, A. et al. (2022). “Deeply in Plasticenta: Presence of Microplastics in the Intracellular Compartment of Human Placentas.” Environmental Research and Public Health. DOI: 10.3390/ijerph191811593
