Nanogirl Michelle Dickinson: How to avoid eating your clothes

Washing breaks off microfibres from clothing that can end up flowing through our waterways as microplastics. Photo / Getty Images

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We all know that plastics in our oceans are a danger not only to marine life but also to our food supply. Banning single-use plastic bags from our supermarkets and microbeads from our body wash has got New Zealand started in addressing some of the problems, but for a bigger impact, it might pay to read the label on your clothing.

Polyester, Lycra, and nylon are all cheap and versatile materials that give you the comfortable, breathable stretch in your activewear and the warm, long-lasting durability in your outerwear. These materials are also synthetic or man-made fibres created from plastic and making up about 60 per cent of all clothing globally.

With the rise of fast fashion, where high-street brands produce cheap, low-quality clothing to meet consumer demands for on-trend clothing, the amount of clothing dumped into landfills each year is steadily rising.

This over-consumption of clothing, however, is only one part of the challenge when it comes to what we wear. Scientists are now looking into the contribution that synthetic fabric clothing could be making to ocean plastic pollution from a simple act that most of us do every week.

Throwing your clothes into the washing machine is part of the process of owning and maintaining them. The machine along with water and detergent cleans your clothes through a process of agitation in the drum.

This agitation not only gets the dirt out of your clothing but, according to a study published in the journal Environmental Science and Technology, also breaks off small pieces of loose fibre from your clothing.

These tiny fibres, known as microfibres are so small that they easily pass through the filtration system in the washing machine as well as the sewage filters in the waste water facility and can end up flowing out through our waterways as microplastics.

The researchers set up a series of experiments where they washed new and old clothing that was made from either polyester fleece or nylon shell material. Alarmingly, they found that on average one synthetic fleece jacket released 1.7g of plastic microfibres with each wash.

They also found that older clothing shed almost twice as much than new jackets. When they compared types of washing machines they found that the mass of microfibre produced from top-load washing machines was approximately seven times more than was produced by a front-loading machine.

Microfibres are typically less than 5mm in length with a diameter of a few micrometres - thinner than a human hair. They are easily consumed by fish and other wildlife, where they accumulate in the stomach of the animal.

The shape of the fibres creates another problem too – specifically their high surface area to volume ratio. The surface of plastic is charged in a way that means it strongly attracts and absorbs chemicals known as "persistent organic pollutants" or POPs, which include polychlorinated biphenyls and dioxins.

POPs have been found in the human body and are linked to adverse reproductive, developmental, behavioural, neurological and immunologic health effects. In the ocean these absorbed POPs can accumulate with the plastics in the animals, leading to high concentrations in their tissues, which further magnify as they move up through the food chain.

So, if you don't want to inadvertently eat plastic from your clothing, natural fibres like cotton and wool are more friendly as they biodegrade more easily. However, if you still love your fleece – and the planet - you might want to consider wearing it one more time before throwing it in for a wash.