'Eco-friendly' bioplastics can harm the fetuses of mice. Should we be worried?
Nanoplastics from the breakdown of the “eco-friendly” bioplastic known as polylactic acid (PLA) can build up in the fetuses of pregnant mice, according to a recent international study in PLOS Biology, and the researchers say these nanoplastics have the potential to interfere with the mouse pups' growth.
Marketed as a biodegradable alternative to conventional plastics, and made from corn starch and sugarcane, PLA has become widely used. When PLA breaks down, it produces a nanoplastic called oligomeric lactic acid (OLA).
The study was able to show that OLA could cross the placenta and accumulate in various organs of a mouse fetus.
Associate Professor Alex Polyakov from the University of Melbourne told the AusSMC that the study should give regulators and the public serious pause.
“The researchers not only show an association, but they also identified a plausible biological mechanism, which substantially strengthens the findings,” he said.
“The finding that these particles crossed the placental barrier and accumulated in fetal brains, livers and kidneys is deeply concerning.”
“The placenta is the baby’s primary shield against environmental contaminants. When that barrier is compromised, the consequences for fetal development can be far-reaching and life-long.”
However, Assoc Prof Polyakov suggested using caution when interpreting what the results of this study mean for humans.
“This is an animal study, and mouse placentation is not identical to human placentation simply because humans are not mice! The transport mechanisms by which OLA crosses the placenta remain incompletely understood.”
Professor Oliver Jones from RMIT University also pointed out that there are some other issues to keep in mind when considering the implications of the study.
He told the AusSMC that, although the authors claim the amount of plastic used in the experiment was proportional to what a human would typically consume, they based this information on only one previous study which has since been shown to have overestimated the amount of plastic we might typically be exposed to.
And as many toxicologists will tell you, it is the ‘dose that makes the poison’.
According to Prof Jones, the dose used in the study would translate to 8 milligrams of plastic per day for an 80kg human.
“A recent independent review suggests that a more realistic dose is only 0.0006 milligrams of plastic per day,” he said.
“Therefore, the dose used in the current study is not realistic.”
In addition, Prof Jones points out that the mice were force-fed this dose for 18 consecutive days, but this does not mean the same effect would be seen in people.
“Even if the dose was correct, mice are not mini humans, and we can’t assume the results would be the same.”
Both Prof Jones and Assoc Prof Polyakov suggest that further studies are required to answer the questions raised by this study.
You can see the full AusSMC Expert Reaction here.
This article originally appeared in Science Deadline, a weekly newsletter from the AusSMC. You are free to republish this story, in full, with appropriate credit.
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