In an article published on October 7, 2021, in the peer-reviewed journal Reproductive Toxicity, Jianing Hu and co-authors from the Institute of Shanghai Key Laboratory of Embryo Original Diseases, China, analyzed microplastics reproductive toxicity using an allogeneic mating murine model.
The scientists exposed nine mice in early pregnancy to 10 µm polystyrene (PS) microplastics (250 µg in 200 µL saline) and collected blood, spleen, and placenta samples for assessing alterations in immune cell surface markers. They also calculated embryo resorption rates and evaluated placenta morphology by histological analysis. The study showed that PS particle exposure increased the embryo resorption rate in mice compared to the control group “suggesting a potential female reproductive toxicity.” The authors also reported that microplastics exposure disturbed the immune balance. For instance, an increased number of helper T cells was observed in the placenta of the microplastic exposure group as well as a reduced percentage of natural killer cells. Hu et al. concluded that PS microplastics have “the potential to cause adverse effects on pregnancy outcomes via immune disturbance, providing new insights into the study of reproductive toxicity of MP particles in the human body.”
The researchers emphasized that they used an intraperitoneal instead of an oral exposure route and microplastic concentrations higher than those measured in the environment. Thus, further studies are considered necessary to assess effects under more realistic conditions. A previous study has reported that environmentally relevant particle concentrations of PS microplastics induced reproductive toxicity in male mice (FPF reported). Small plastic particles have also been detected in the human placenta (FPF reported and here). 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).
In a book chapter published on October 10, 2021, by Springer publishing, Esther Garrido Gamarro and Violetta Costanzo from the Food and Agriculture Organization of the United Nations (FAO), Rome, Italy, confirm that further studies are needed to understand microplastic impacts on human health and also add that effects due to plastic additives and environmental contaminants sorbed to plastics need to be better understood. The authors assessed human exposure to selected plastic-associated chemicals (additives and sorbed) by the uptake of microplastic-contaminated seafood. The authors reported, “exposure to contaminants through seafood indicates the contribution of microplastic contaminants, and additives through fisheries and aquaculture products are negligible compared to other sources.” They further emphasized that “an exposure assessment from the whole diet should be carried out, and the toxicity of some of the most common polymers and plastic additives, as well as their mixtures, needs to be carefully evaluated.“
Hu, J. (2021). “Polystyrene microplastics disturb maternal-fetal immune balance and cause reproductive toxicity in pregnant mice.” Reproductive Toxicity. DOI: 10.1016/j.reprotox.2021.10.002
Garrido Gamarro E., Costanzo V. (2021). “Dietary Exposure to Additives and Sorbed Contaminants from Ingested Microplastic Particles Through the Consumption of Fisheries and Aquaculture Products.” Springer, Cham. DOI: 10.1007/978-3-030-78627-4_8