In 2019, a study by the World Health Organisation estimated that the average adult would consume between 300 and 600 microplastics a day. Three years later, a recent study by the Medical University of Vienna has suggested that on average, people eat five grams of micro and nanoplastics every week. There is growing concern around the levels of harm microplastics can cause as they’ve been found in human blood, lungs and faeces. Here Dr Ashlee Jahnke, Head of Research at biodegradable biopolymer research platform Teysha Technologies, explains how microplastics have impacted human bodies and what steps can be taken to reduce microplastic pollution for the future.
In March 2022, scientists from the Netherlands and the UK analysed blood samples from 22 anonymous donors and found plastic particles in 17 of them. Half of the samples in the study contained PET plastic and a third contained polystyrene. Polyethylene terephthalate (PET) is a clear and lightweight plastic that is widely used for food and beverage packaging. Despite being 100 per cent recyclable and approved as safe for food and beverage contact by organisations like the FDA, it is still prone to fragmenting into microplastics.
Microplastics are tiny plastic particles, that measure less than five millimetres, that can enter the body through food, water and breathing. Primary microplastics, typically known as microbeads, are designed for commercial use and can be found in cosmetics or synthetic textiles. Secondary microplastics are formed unintentionally as a result of the breakdown of larger plastics through exposure to environmental factors like water erosion and ultraviolet radiation from the sun. These microplastics can be transported to remote areas of the world by wind and water.
The impact of microplastics on the human body
Currently, there isn’t sufficient evidence to uncover how plastic particles are retained in the body or the damage they can cause. One study has found that microplastics can latch onto the outer membranes of red blood cells and limit their ability to transport oxygen. In 2022, scientists also discovered that microplastics could breach the blood-brain barrier in mice and negatively impact the microglial cells in the brain. The desire to discover more about the effect of microplastics on the human body has led to charities like Common Seas imploring the UK Government to allocate £15 million of Whitehall R&D funding towards research into human health impacts of plastics.
One previous study found that the number of microplastics found in the faeces of bottle-fed babies was ten times higher compared to adults. This is because the recommended high-temperature process for sterilising baby bottles, which involves sterilising the bottle in 95 degree Celsius water and then shaking the formula powder with 70 degree Celsius water in the bottle, caused them to shed millions of microplastics and nanoplastics.
Most experiments that aim to answer whether microplastics cause harm use animals like mice and rats. In one experiment, mice that were exposed to microplastics saw tissue damage, a decrease in body weight and changes in lymphocyte composition. There was also evidence of intergenerational problems as the offspring of mice exposed to microplastics suffered liver damage and metabolic disorders. However, despite these studies, many argue there is still not enough sufficient evidence to answer whether microplastics cause harm in the human body.
How microplastics show the flaws in solutions to plastic pollution
Despite the strong narrative that plastics and microplastics are dangerous for the environment and for human bodies, the Organisation for Economic Co-operation and Development (OECD) estimates that plastic production will double by 2040 at the current trajectory.
Plastics, like PET, that are used in 70 per cent of soft drink bottles are praised for being 100 per cent recyclable. Two life-cycle studies found that plastic bottles made using PET created fewer greenhouse gas emissions and generated less solid waste than drinks in glass bottles or aluminium cans. These factors make PET a desirable, sustainable choice for food and drink packaging manufacturers.
However, a 2022 study found that the faeces of people with more severe IBD symptoms had 1.5 times more microplastic particles per gram than those from healthy subjects. PET plastic was one of the most common types of plastics found in the faeces, which is similar to the study of microplastics in the bloodstream.
How can the microplastic problem be solved?
Action has been taken to limit the production of some microplastics. In 2018, the UK Government banned the sale of products containing microbeads, small pieces of plastic that are added to products like face scrubs and shower gels. Businesses are also getting involved. In 2021, Teysha Technologies partnered with a major North American multinational additives manufacturer to begin developing alternatives to petroleum-based microplastics. These alternatives, once developed, have the potential to be used in a variety of applications like dyes, paints, exfoliants, emulsions and lubricants.
According to market data collected by European Bioplastics and nova-Institute, global bioplastic production is set to increase from 2.42 million tonnes in 2021 to approximately 7.59 million tonnes in 2026. Bioplastics are seen as a popular alternative to traditional petrochemical plastics as they use less fossil fuel resources and have a smaller carbon footprint. However, for many bioplastics to degrade quickly and less harmfully, they must go through industrial composting.
As interest grows in biopolymers, so does innovation. Teysha Technologies is researching and testing the next generation of environmentally friendly biopolymers, like AggiePol, that offers variable solubilities, thermal transition temperatures and mechanical behaviours. The biopolymer can be tuned to each application requirement to operate and break down in specific environmental conditions. The result is an environmentally-friendly, biodegradable plastic.
Though more research is needed to understand the prevalence of microplastics in the human body and the harm that they can cause, businesses must consider environmentally-friendly alternatives for their products.
Dr Ashlee Jahnke is Head of Research at biodegradable biopolymer research platform Teysha Technologies,