A ticking bomb?

A recent investigation carried out by the University of New Mexico Health Sciences has revealed an alarming finding regarding the presence of microplastics in all the human placentas they investigated. The research findings, published in the journal Toxicological Sciences in February 2024, emphasised the widespread presence of microplastics in human placentas.

It is important to note that the placenta is a temporary organ that links the mother and the foetus through the umbilical cord. It delivers nutrients and oxygen to the developing foetus and acts as a shield to keep infections or viruses from reaching it. As a result, the presence of any contaminant or xenobiotics (substances of foreign origin) in the placenta could be really dangerous for it.

The study further reported the presence of rayon, polystyrene, polyethene and unclassified plastic particles. The researchers analysed 62 placenta samples and found microplastics in all of them. The concentrations of tiny plastic particles typically termed nano- and microplastics (NMP), varied widely — ranging from 6.5 to 685 micrograms of NMP per gram of placental tissue. On average, the amount was 126.8 ± 147.5 micrograms of NMP per gram.

Polyethylene was the most prevalent polymer, accounting for 54 per cent of total NMPs and was consistently found in nearly all samples. Polyvinyl chloride (PVC) and nylon each made up about 10 per cent of the NMPs by weight. The remaining 26 per cent consisted of nine other types of polymers, according to the study.

This is not the first time that microplastics have been reported in important tissues of the human body, particularly the placenta. In another recent study conducted in China in January 2023, researchers examined 17 placentas to examine the presence and characteristics of microplastics. They found microplastics in all placenta samples, with an average of around 2.7 particles per gram and a range of 0.28 to 9.55 particles per gram.

The study identified 11 types of polymers in these microplastics, with PVC making up 43.27 per cent, polypropylene (PP) 14.55 per cent and polybutylene succinate 10.90 per cent. The sizes of the microplastics varied from 20.34 to 307.29 micrometres (μm), with 80.29 per cent being smaller than 100 μm. Smaller microplastics were mostly fragments, while fibres dominated the larger ones (200-307.29 μm).

It’s important to note that most PVC and PP particles were smaller than 200 μm.

Indeed, the initial detection of microplastics in the human placenta was documented in 2021 by a team of researchers from the Department of Pathological Anatomy at San Giovanni Calibita Fatebenefratelli Hospital in Italy. In this investigation, six human placentas obtained from women with uncomplicated pregnancies were subjected to analysis.

Among these placentas, four were found to contain a total of 12 microplastic fragments, varying in size from 5 to 10 μm, which were either spherical or irregularly shaped. All identified microplastics were pigmented, with three of them recognised as stained polypropylene, a thermoplastic polymer.

For the remaining nine fragments, only the pigments could be identified and these pigments were traced back to substances commonly used in man-made coatings, paints, adhesives, plasters, finger paints, polymers, cosmetics and personal care products.

The studies reporting the presence of microplastics in the human placenta raise significant questions, such as the possibility of these particles entering the foetus and the potential long-term consequences. Additionally, understanding the sources of microplastics infiltrating the placenta and whether pregnant women are more susceptible to such exposure is crucial.

Addressing these questions, a 2021 study conducted in Germany not only confirmed the presence of microplastics in the human placenta but also detected them in meconium samples — the first faecal matter of newborns. The samples tested positive for polyethene, polypropylene, polystyrene and polyurethane. This suggested that microplastics are also present in the fetus' body.

However, the study also highlighted the need for a thorough assessment of potential sources of contamination during the sampling and analyses. This critical evaluation is essential for guiding future clinical studies to enhance the accurate detection of microplastics in organ tissues.

The study is an indicator that there is a likelihood that microplastics are entering the fetus' body from the mother’s placenta, pointing towards the importance of further research in this area to understand the implications for both maternal and foetus health.

Concerning the health impact and long-term consequences, scientific studies have found that exposure to microplastics can cause particle toxicity, resulting in oxidative stress and inflammation. The immune system’s inability to eliminate these foreign particles from the body may contribute to persistent inflammation, elevating the risk of neoplasia, which is the uncontrolled, abnormal growth of cells or tissues in the body such as cancer.

In addition, microplastics have the potential to release their components, adsorbed contaminants and pathogenic organisms.

However, our understanding of microplastic toxicity remains constrained and is heavily dependent on factors such as exposure concentration, particle characteristics, adsorbed contaminants, the tissues affected and individual susceptibility. Further research is extremely important to expand knowledge in this field.

While plastics are found everywhere, it's crucial to understand the growing concern around exposure to NMPs. This concern is even more amplified because their presence is reported in the human body, including the placenta, raising alarms for newborns, who are more vulnerable due to their underdeveloped immune systems.

If these tiny plastic particles are not fully eliminated from their bodies, they could become an integral part of their bodies, leading to potential long-term health issues. The increasing prevalence of microplastics poses a threat to our well-being. Although the full extent of the long-term health effects of ingesting and inhaling these small plastic particles is not completely understood, it is unrealistic to assume that they pose no risk whatsoever. DTE

Views expressed are personal