Environmental hazards from plastic materials

Engineering polymers to make plastic on a mass scale began in the 1950s as a byproduct of the petrochemical industry. In the 1950s the world made about 2m tonnes of plastic a year. In 2018 that figure is 330m tonnes a year – and it is set to treble again by 2050. Plastic manufacture now uses about 6% of all the oil extracted each year and has spread to myriad processes from clothing to packaging to consumer products. Plastic is ubiquitous, insidious and impossible to avoid.

Plastic is virtually indestructible: it resists dissolution by water, air or sunlight, is unpalatable to the microorganisms that break down natural materials and burning it gives off noxious gases. Although we have known for years that some of the additives used to make plastics flexible, transparent or durable are chemically dangerous, few have been tested on humans. Some countries have banned some chemicals – but there is no consistency, and the chemical companies have found it easy to avoid regulation, finding substitutes that are potentially just as dangerous.

When exposed to sunlight, oxygen or the action of waves, plastic does not biodegrade but simply fragments into smaller and smaller bits, until microscopic or nano-sized particles enter the food chain, the air, the soil and the water we drink. If we breathe in or ingest these micro- and nano-sized particles and fibres, they are likely to get into the human bloodstream, lung tissue and breast milk. While some microparticles may pass through the body without causing harm, others may lodge there dangerously. We don’t know how much we are ingesting or breathing, or what effect exposure to hazardous plastic particles may have over years. We don’t know the concentrations that are safe for adults, let alone infants. There is mounting concern that under-studied microplastic particles threaten health by presenting a potentially major source of toxic chemicals to the human body.

Bisphenol-A is a breakdown product of polycarbonate plastics (hard plastics used to make, for example, water jugs). It is a mimic of the female hormone oestrogen and may be causing biological contamination which affects mammalian sexual functioning. It is also a known carcinogen. In one study, 95% of all adults tested in the US had bisphenol-A in their urine.

Minute microplastics and fibres, measuring the width of a human hair or far less, have been found in an extraordinary range of products, such as honey and sugar, shellfish, bottled and tap water, beer, processed foods, table salt and soft drinks. Plastic microfibers found in the dust in our homes and the air we breathe can come from car tyres, carpets and soft furnishings, as well as clothes such as fleece jackets. These are regularly shedding tiny bits of plastic into the environment as they are worn away, For example, 83% of samples of tap water tested in seven countries were found to contain plastic microfibres. A study published in 2018 revealed plastics contamination in more than 90% of bottled-water samples, which were from 11 different brands. Also in 2018, the River Tame in Manchester was found to have 517,000 particles of plastic per cubic metre of sediment – nearly double the highest concentration ever measured across the world. A single wash of manmade textiles may release thousands of microfibres into the air and drain water.