Microplastics are small particles of plastics under 5mm in size. Some are tiny (less than 0.1 of a micrometre) and are often referred to as nanoplastics. In general, the smaller the particle, the more worried experts tend to be because that’s when they can be absorbed into the bloodstream and potentially enter organs like the lungs, heart and brain. You might also have heard of nurdles. They’re plastic pellets used in manufacturing processes. Microbeads are plastic particles used in exfoliants and abrasives. Then there are microfibres of plastic often shed from synthetic fabrics. What you hear about most though are microplastic particles from packaging, bottles and containers, which can pollute the environment when they break down, especially at sea and one way or other get into the water supply or food chain.
Are we really consuming a credit card a week?
The uncomfortable reality is that we’re all exposed to microplastics and have them to a varying extent in our bodies. However, sometimes the headlines have been misleading. One study which is often quoted, estimated that we consume one credit card equivalent of plastics every week. The problem with that study is they made a major miscalculation. It turns out to be a credit card every 23 thousand years. That doesn’t mean though that you can relax about whether microplastics are doing you harm. For that you need to take into account the shape and size of particles and what they’re made of.
Having absorbed microplastics can we get rid of them?
Nanoparticles are more likely to be filtered from the blood by the kidneys and expelled in your urine. Studies have shown that our urine can contain microplastics. Larger particles while still tiny, may be trapped in our bodies.
So here are the concerns about the microplastics that hang around. One is that as foreign material, they trigger our immune system and cause inflammation in the blood or wherever they land. Inflammation is best described as like a poorly targeted artillery barrage by the immune system and because of that there can be collateral damage to our arteries, brain tissues and other organs, speeding up the ageing process and perhaps accelerating problems like atherosclerosis which is the process which can eventually block arteries. The other process that’s thought to be triggered is oxidative stress – also related to organ damage and accelerated ageing.
Harms?
The research into the human effects of microplastics has focussed on fertility, the digestive system, the lungs, heart and brain.
Fertility
The theoretical concern is what’s called endocrine disruption – the potential to affect how our hormones control egg and sperm production. The evidence that this actually happens is current not strong despite microplastics being found in the fluids carrying eggs and sperm.
Heart and arteries
The way atherosclerosis blocks arteries is by the accumulation of what’s called plaque which ruptures causing a blood clot and sudden blockage and then a heart attack or stroke. There have been studies which have found higher than average levels of microplastics in the artery plaque of people who’ve had a stroke or heart attack. Whether that’s a reflection of diet and lifestyle or a real risk in itself isn’t known.
Brain
The evidence is solid that brains today have more microplastics in them than previous generations and it looks as though people with dementia have higher than average levels. Again, it’s not known whether the particles play any role in cause.
So what should we do?
Bottom line is that we all have microplastics in our bodies. The research isn’t conclusive about the harms, but the potential is real. What some researchers in the field are doing in their own lives is minimising their exposure by trying to avoid plastic containers, packaging and exposure in cooking from non stick surfaces and plastic chopping boards. That’s not easy. Glass containers are more expensive and they break and are hard to use in kids’ lunchboxes. Cast iron cookware can also be pricey. But I must say that’s what I’m doing even though it’s impossible to avoid microplastics.
What’s needed is environmental control and ways of minimising their use in manufacturing.
Further information
Ingested microplastics: Do humans eat one credit card per week? ScienceDirect
