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Potential health effects of microplastics and pathogens

Research that found microplastics in the faeces of people from Europe, Russia, and Japan, has confirmed that we do in fact ingest microplastics. This research also demonstrated that some microplastic particles are egested from our bodies. However, is this true for all ingested microplastics, or does a percentage remain in our bodies? In order to understand this, a wide range of animal studies has been conducted and scientists found that the smallest microplastics can pass the gut barrier and reach the bloodstream. From there, these plastic particles can travel to other parts of the body. For example, in rats, plastics were detected in the stomach, intestines, kidney and heart. Very small plastic particles have even been detected in the foetuses of mice and in the brain of fish.

Based on these type of studies, researchers have hypothesized that human exposure to microplastics could lead to oxidative stress, DNA damage and inflammation, among other health problems. Particularly, when inflammation becomes chronic, this can pave the way to very serious health problems. However, it’s not only the plastic particles themselves that are potentially harmful: the surface of microplastics in the environment are colonised by micro-organisms, some of which have been identified as human pathogens.

Human pathogens have a particularly strong bind to plastic waste, more so than to natural surfaces. Research published in 2016 identified the human pathogen Vibrio cholera, which causes cholera in humans, attached to microplastics sampled from the North and Baltic Seas. Moreover, plastic does not biodegrade and can consequently travel long distances in the aquatic environment. So we have to ask: does plastic litter contribute to the spread of pathogens? Particularly in areas with poor sanitation facilities and high plastic pollution, it is hypothesized that plastic could be contributing to the spread of diseases.

How many microplastics do you ingest per day?
We are not sure yet. Scientists are presented with a huge challenge, as current analytical methods can’t yet detect the smallest microplastics in food or human samples (like blood, for example). As a result, there is still a limited understanding of the extent of our exposure to microplastics, and no understanding of the potential presence of microplastics in our bloodstream and other parts of our bodies. Without understanding exposure, scientists cannot determine risk.

Based on data currently available, scientists attempted to estimate the annual intake of microplastics by an average American citizen in 2019. This was estimated to range between 74,000 and 121,000 particles, depending on age and sex of the citizen, though the researchers believe this is an underestimation because only 15% of food consumed could be assessed. This study designated bottled water as one of the highest sources of plastic particle intake; bottled water contains about 100 microplastics per litre on average. More research has since been conducted, for example, plastic teabags and baby bottles have been found to release millions of micro- and billions of nanoplastics into tea and baby formula. These studies suggest that our exposure has gravely been underestimated, but more research will need to be done to fully understand the extent of how much plastic we ingest and how much remains in our bodies.

Knowledge gaps
Clearly, there is still a lot we do not know. Based on the available scientific information, the World Health Organization (WHO) concluded that microplastics in drinking water pose no risk to human health. The Plastic Health Coalition argues that there are simply too many knowledge gaps to assess the health risks of microplastics. Current available data on human exposure is incomplete and has – due to lacking analytical methods – not taken into account the smallest and most hazardous plastic particles. Moreover, scientific research into the potentially harmful effects of microplastics in humans is still in its infancy worldwide. New scientific research is urgently needed.

Groundbreaking Research Projects
A Dutch organisation that finances health research, ZonMw, initiated a one-of-a-kind research program called Microplastics & Health, in order to provide scientists the opportunity to study the effects of microplastics on human health. In March 2019, 15 short-term research projects started to find answers to the most pressing questions around microplastics and human health. The research projects are divided into four categories: the digestive system, the lungs, the immune system, and the spread of micro-and nanoplastics to other parts of the human body. The Dutch Organisation for Scientific Research (Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO), the Gieskes-Strijbis Fund, and the Ministry of Infrastructure and Water Management pledged a total of for initial research. At the Plastic Health Summit in October 2019, during which researchers presented their preliminary results, ZonMw announced an additional pledge of toward more research. With this program, the Netherlands is one of the global leaders in this field. The Plastic Health Coalition regularly communicates about the various projects and findings. Click on the pictures to find out more about the preliminary results.