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A study published in PLOS Biology looks at gestational exposure to microplastics in mice.
Dr. Ovokeroye Abafe, Assistant Professor in Environmental Sciences, Brunel University of London, said:
“The dose of OLA given to the mice, which they stated as proportional to what a human typically consumes is an overestimation, as the weekly consumption of 0.1 – 5.0 g of PLA by human as reported in the manuscript, is a suggested weekly intake for all microplastics not necessarily PLA alone.
“The work provides further insights into the toxicity of biodegradable plastics. Not much is known about the fate and toxicity of biodegradable alternatives to conventional plastics, thus this work provides some important advancement in understanding the developmental toxicity of polylactic acid oligomers in mice.
“Important confounders were accounted for, with some acknowledged by authors as limitations of the study. The study was carried out using mice, thus should not be directly translated to humans due in part to limitations in allometric scaling of animal data to human. It is important to account for real-life exposure scenario, for instance are OLAs released following the ingestion of PLA, and what levels of OLA are available for systemic circulation?
“The study provides important data to further the understanding of the safety of bioplastics, but it is important to note that these are based on orally dosed mice, which may not necessarily reflect real-life exposure scenarios for human.
“The levels used in the study were derived based on human weekly intake for all microplastics, not necessarily for PLA or OLA alone as stated in the study. This highlights the need to understand the bioavailability of OLA following oral ingestions of PLA by human.”
Dr Vahitha Abdul Salam, Senior Lecturer in Vascular Pharmacology at Queen Mary University of London:
“This is an interesting and technically well-executed study that adds to growing evidence that nanoplastics can cross biological barriers, including the placenta, at least under experimental conditions. The imaging and tracing approaches used appear appropriate, and the findings are broadly consistent with earlier work suggesting that very small plastic particles can distribute systemically in animal models.
“However, an important consideration is how representative the exposure conditions are of real-world human exposure. Studies in mice often use controlled doses and particle types that may not fully reflect the complexity, diversity, and typically lower levels of nanoplastic exposure in humans. This means that while the study demonstrates what is biologically possible, it does not yet establish that the same degree of accumulation occurs in human pregnancy.
“The conclusions are therefore scientifically plausible but should be interpreted with caution. There are still significant gaps in our understanding of how nanoplastics behave in humans, including their sources, exposure levels, and long-term biological effects. In particular, differences in placental structure, exposure routes, and metabolism between mice and humans need to be carefully considered.
“Importantly, this study contributes to an emerging body of research highlighting potential developmental exposure pathways, but it does not provide direct evidence of harm in humans. The real-world implications will depend on future studies that better quantify human exposure and link this to clinically relevant outcomes.
“Overall, this work represents a valuable step forward in the field, but further research, especially in human-relevant models and at realistic exposure levels, is needed before firm conclusions about risk can be drawn.”
Prof Oliver Jones, Professor of Chemistry, RMIT University, said:
“This paper explores the possible toxicity of plastic oligomers. So firstly, what is an oligomer? Plastics are polymers. A polymer (from the Greek meaning many parts) is made of repeating subunits called monomers (one part). Polymer chains can be thousands of monomers long, but if you have only a few, usually between 2 and 40, monomers, the molecule is called an oligomer.
“While the study itself sounds scary, I think there are some methodological issues to keep in mind. Firstly, the authors claim the amount of plastic they used in the experiment was environmentally relevant. However, they are basing this on only one study, which was a) behind the myth that we humans eat a credit card’s worth of plastic each week and b) has since been shown to have severely overestimated the amount of plastic we might be exposed to [1, 2]. For example, their dose of 0.1 mg of plastic per kg of body weight per day would translate to 8 milligrams of plastic per day for an 80 kg human. A recent independent review suggests that a more realistic dose is only 0.0006 milligrams of plastic per day [3]. Therefore, the dose used in the current study is not realistic. In addition, the mice were force-fed this dose for 18 consecutive days; it is no surprise they showed some form of effect, but this does not mean the same effect would be seen in people even if the dose was correct; mice are not mini humans. The plastic used, polylactic acid, is also not very common. So, while the paper raises interesting questions around biodegradable plastics, that are worth exploring, I do not think it is quite the smoking gun it might at first appear to be.”
References
1. Pletz M. Ingested microplastics: Do humans eat one credit card per week? Journal of Hazardous Materials Letters 2022. 3: p.100071.
2. Green H. Are You eating a credit card every week? 2022 Available from: https://youtu.be/2Ntp6BqhSng Accessed 16/05/24.
3. Mohamed Nor N.H. et al. Lifetime accumulation of microplastic in children and adults. Environmental Science & Technology 2021. 55: p.5084-5096.
Dr Ria Devereux, Environmental Research Fellow, University of East London (UEL), said:
“This is a very interesting study on biodegradable plastics and potential toxicity, especially as it is an early-stage toxicological investigation. However, whilst the media coverage will raise awareness, it does have the potential to cause unnecessary panic by linking the findings to human reproductive outcomes such as low birth rates, increased risk of stillbirth or long-term health risks.
“In particular the first line of the press release “Nanoplastics from biodegradable plastics can cross the placenta and accumulate in foetal organs” does not make it clear that this study was conducted on mice. The authors themselves have emphasised this further down the article “OLA nanoplastics can penetrate the placenta and even reach the foetus, in a mouse model.”. This distinction is important as the findings in mice do not directly translate to humans and this study does not explicitly prove that placental transfer of OLA nanoplastics can occur in humans. Further studies are needed to investigate the transportation route across the placenta as well as real world exposure assessments.
“An issue with many of these studies is important to emphasise that under laboratory conditions yes, this may occur in mice, however this does not mean in the real-world similar risks occur. It also does not mean this happens to humans.
“The study does not explain how OLA crosses the placenta in mice and if it may be possible in humans. This study also uses “human relevant” doses however there may be problems with these doses as they are often estimates in themselves.
“Overall, this study highlights that more studies are needed on biodegradable plastics, but it is in its early stages and not definitive proof of being a risk to human health.”
‘Oligomeric lactic acid nanoplastics induce intrauterine growth restriction in mice by disrupting GATA2-mediated placental vascular development’ by Jia Lv et al. was published in PLOS Biology at 18:00 UK time Thursday the 26th of March 2026.
DOI: https://doi.org/10.1371/journal.pbio.3003676
Declared interests
Dr. Ovokeroye Abafe: “I have no competing or conflicting interest to declare”
Dr Vahitha Abdul Salam: “I am an academic researcher working on the health effects of environmental pollutants, including micro- and nanoplastics. I have received research funding from public and charitable sources and collaborate with academic and industry partners on environmental health research. I have no direct financial interest in this specific study.”
Dr Ria Devereux: “no interests to declare.”
Prof Oliver Jones: “I am Professor of Chemistry at RMIT University. I conduct research on environmental pollutants, including microplastics. I have, in the past, received research funding from various water utilities and the Environment Protection Authority Victoria (though not for microplastics research).”