Biodegradable Plastic Byproducts Impair Fetal Growth in Mouse Study

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. Yichao Huang and De-Xiang Xu of Anhui Medical University, China, and Mingliang Fang of Fudan University, China, report these findings in a new study published March 26^th in the open-access journal PLOS Biology.

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.

In the new study, 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. Furthermore, they 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. 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. The researchers 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.

The authors add, "One of our co-authors Dr. Mengjing Wang had previously discovered that the widely merchandized 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, aka OLA, pose developmental threat particularly during the susceptible stage in utero?"

"What we have found was quite astonishing to us. 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."