The harmful effects of plastic microbeadsby Rebecca Priestley
Tiny pieces of plastic called microbeads are making their way into the ocean and up the food chain.
International concern is increasing over the plastic microbeads contained in some body scrubs and toothpastes. Once used, these tiny pieces of plastic are washed down the shower or basin plughole and into our wastewater pipes. Environmental studies, including one by University of Canterbury PhD student Phil Clunies-Ross, just published in the New Zealand Journal of Marine and Freshwater Research, show that many of these microbeads survive wastewater treatment and find their way into the ocean, along with other forms of microplastic.
Clunies-Ross’ study involved collecting sand samples from the strand line of 10 beaches in and near Christchurch. Back in the lab, Clunies-Ross recovered, examined and counted the plastics. He found microplastics at eight of the 10 sample sites, with up to 45 particles in each kilogram of sand. Most of the offending plastics were polystyrene (55%), polyethylene (21%) and polypropylene (11%).
Microplastics are pieces less than 5mm in diameter. They include pre-manufactured microplastics, such as the microbeads used in cosmetics and industrial abrasives, and the plastic pellets or nurdles used in plastic manufacturing. Secondary microplastics are formed from the degradation of larger plastic objects or from fibres washed off synthetic clothing.
A recent report by the World Economic Forum estimates that by weight, more plastic will be in the ocean than fish by 2050. It’s horrible to think of all that plastic polluting our beaches and oceans, but is it dangerous?
“There’s growing evidence that microplastics are harmful to marine species,” says Clunies-Ross.
British scientists have found that these little plastic particles can damage the digestive systems of smaller marine animals, such as zooplankton, he says. “They’re also finding that some of these particles can transfer pollutants to marine species.”
When they’re out in the ocean, these plastics soak up contaminants such as DDT and other persistent pollutants, so the surface of the microplastics can have pollutant concentrations up to a million times that found in the water.
Zooplankton are eaten by small fish, which are eaten by bigger fish, and so on. “If we’re dosing up the primary level of our food chain with these contaminants, it may end up eventually transferring up to us.”
One thing we could do to address this problem, says Clunies-Ross, is regulate the use of products containing microbeads, in line with recent or pending bans in the US, Canada, Australia and the EU. A spokesperson for the Ministry for the Environment says it is still looking at the issue of microbeads and has yet to decide what approach to take.
But the main source of microplastics in the ocean is the breakdown of larger plastics.
Initiatives such as the Ocean Cleanup and SeaBin are developing innovative new technologies that can remove plastics from the ocean and near-shore environments.
“But these are projects where you’re investing a lot of money to remove relatively small amounts of plastic,” says Clunies-Ross. “It’s been estimated that about 10% of all plastic ends up in the ocean, so reducing the plastics getting into the ocean is our best bet in the long term.”
Even in the absence of any New Zealand regulations, we can all play a part in reducing plastic contamination of our oceans by not buying or using products containing microbeads and by adopting a reduce, reuse, recycle attitude to all plastic products.
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