How much PLASTIC are you INGESTING?

Researchers have found the equivalent of a spoonful of micro- and nanoplastics in autopsied human brains, and suggested links to cancer, cardiovascular disease and dementia. How worried should we be?

- By Glynis Horning

The first synthetic plastic was launched at the London International Exhibition in 1862, but the plastics industry took off only with World War II – first for helmets and parachutes, then to provide eager postwar consumers with lightweight, versatile, durable, inexpensive, colourful alternatives to wood, stone, metal and glass.

Some 75 years later, microparticles of plastic have been found on the summit of Everest, 8.9km above sea level; in the depths of the Mariana Trench, 11 km below the surface of the Pacific; at the North and South poles; and on remote islands believed to be the last remaining pristine places on Earth, free from human activity.

What is more, microparticles are being found inside us – recent studies have detected them throughout the human body, including in blood, saliva, kidneys, liver and brain, suggesting they may move through cell membranes and the blood-brain barrier. Although a 2022 World Health Organization report on the potential human health effects of exposure to microplastics (<5 mm, or a grain of rice) and nanoplastics (<0.001 mm wide) found a lack of conclusive evidence for 'severe adverse effects in humans', it emphasised that 'measures should be taken to mitigate exposure'.

The report highlighted that technologies were not yet able to accurately measure microplastic exposure across populations or determine how many of these particles accumulate in our bodies. A 2019 WWF-funded analysis that estimated the average person consumed a credit card's worth of plastic a week (about 5 g), primarily through drinking water and eating shellfish, was challenged in the journal Environmental Science & Technology (March 2021) as not representing 'the intake of the average person', and for being five or six orders of magnitude too high.