Nanoplastics Released by ‘Eco-Friendly’ Bioplastics May Slow Fetal Development in Mice

The results of a study headed by teams at Anhui Medical University and Fudan University has found that when the “eco-friendly” bioplastic, polylactic acid (PLA), biodegrades, the resulting nanoplastics can accumulate in the fetuses of pregnant mice and interfere with fetal growth.

The murine study discovered that exposure to environmentally relevant doses of oligomeric lactic acid (OLA) nanoplastics released by PLA damages placental vascular development, leading to intrauterine growth restriction (IUGR) in the pups.

Co-senior authors Yichao Huang, PhD, De-Xiang Xu, PhD, of Anhui Medical University, and Mingliang Fang, PhD, at Fudan University, reported on their findings in PLOS Biology, in a paper titled “Oligomeric lactic acid nanoplastics induce intrauterine growth restriction in mice by disrupting GATA2-mediated placental vascular development.” In their paper the scientists concluded, “Our study found that even exposure to environmentally relevant doses of OLA disrupts placental vascular development by inhibiting the VEGF signaling pathway that regulates angiogenesis. This further indicates that OLA bioplastics may be more toxic to the placenta than conventional microplastics.”

“Humans are increasingly exposed to ‘eco-friendly’ biodegradable microplastic pollution, whose usage in packaging and medical applications is growing exponentially,” the authors wrote. PLA, which is made from corn starch and sugarcane, came onto the market as a biodegradable alternative to conventional plastics around two decades ago and has since become one of the most widely used bioplastics. Due to exponential growth in the production of PLA for packaging and medical applications, humans are increasingly exposed to its main breakdown product, oligomeric lactic acid (OLA) nanoplastics, which have recently been shown to have negative health effects, the team continued.

“Our previous research, together with other reports, suggests that OLA released from PLA upon digestion could be taken up from the gut and hence reach and accumulate in other organs through circulation, resulting in intestinal inflammation and microbiome dysbiosis. However, it is yet to be further elucidated the biodistribution of OLA, particularly the in utero environment for both the pregnant women, the fetus and the placenta.” In a release, the authors noted, “One of our co-authors Dr. Mengjing Wang had previously discovered that the widely merchandised PLA microplastics undergo gut enzyme–mediated hydrolysis into oligomeric products that are toxic to the intestinal tract and can trigger enteritis … To follow up on this work, as toxicologists, we went on to ask an additional question: do these oligomeric products, a.k.a. OLA, pose developmental threat particularly during the susceptible stage in utero?”

For their newly reported study the researchers exposed pregnant mice to OLA at doses proportional to what a human typically consumes and looked for impacts on the mouse pups. They demonstrated that OLA crosses the placenta and accumulates in various organs in the fetus. The findings also showed that OLA interferes with a signaling pathway that controls the development of blood vessels in the placenta, which leads to slower growth of the fetus. “Mechanistically, dams exposed to OLA may inhibit the VEGF signaling pathway by reducing the nuclear translocation of GATA2, thereby impairing placental vascular development and limiting the growth potential of the fetus,” the team stated. This is a concern, because in humans, low birth weight is associated with an increased risk of stillbirth, as well as a higher risk of developing multiple other health problems later in life.

This work is the first animal study to evaluate the developmental health effects from the breakdown products of a supposedly eco-friendly plastic in pregnant mammals. “To the best of our knowledge, this is the first animal study evaluating the developmental toxicology of OLA, breakdown product of an environmentally friendly alternative to classic polymer plastics, at environmentally relevant dose in terrestrial mammals during pregnancy,” the investigators commented. They propose that future work should focus on evaluating the exposure levels and health risks associated with eco-friendly plastics in humans, and a rethinking of our approach to plastic alternatives. Our work provides key data for the developmental toxicity of OLA and its broader implications for the substantial health threat posed by PLA bioplastics,” they wrote.

“What we have found was quite astonishing to us,” the researchers further noted in their release. “Even under realistic exposure dose scenario during pregnancy, OLA nanoplastics can penetrate the placenta and even reach the fetus, in a mouse model. Such exposure would then cause placental vascular dysplasia and further lead to compromised fetal development … “While biodegradable plastics present a viable path to mitigate traditional plastic pollution, their potential health hazards necessitate a recognition in responsibility toward informed consumer intentions and conscientious usage.”