Microplastics found in NZ fish: How safe is our seafood?

Source: 1News

A new study has found microplastics present in a sample of 75% of commercially caught fish in southern New Zealand waters.

 Plastic fibres through a microscope.

The year-long study, published in Marine Pollution Bulletin, examined 155 fish from 10 species, including Red Cod and Tarakihi, caught off the Otago coast.

It's the first study to examine microplastic ingestion in commercial wild fish from southern New Zealand.

“The abundance of microplastics found could pose a risk to human health through consumption of plastic contaminated fish, but more research is needed in this area,” says lead author of the University of Otago study, Isabella Clere.

The Department of Marine Science was behind the study which was co-authored by Bridie Allan discovered, of the microplastics found in 75% of fish, an overwhelming amount were fibres. Of the 391 microplastic pieces retrieved, 98% were less than 3mm.

“We looked at a range of benthic (bottom dwelling) and pelagic (surface dwelling) fish and found microplastics in the guts of all species, suggesting the ubiquity of microplastics throughout all ocean layers," Allan said.

“A random selection of fish guts were analysed to identify the plastic type, with the majority found to be polyethylene, viscose, polypropylene and plastic additives. Polyethylene is the most widely used plastic and also the most prevalent found in the oceans globally."

The study found evidence of microplastic ingestion in 75 % of fish, with an average of 2.5 individual particles per fish.

Clere says the findings highlight how microplastics are not just a localised issue, but a global one.

“Even in rather remote, low populated areas there are signs of plastic contamination within fish. Due to their unique nature being a lightweight and durable material, they are transported across oceans by the wind, currents and through marine organisms.”

She encourages Kiwis to have greater understanding and awareness of our plastic use and misuse.

Isabella Clere.

“We need to take individual responsibility for the products we use, to ensure they do not find their way into any natural environment.

“The durable, strong nature of plastic which makes it such a useful material in society, also makes it not only a local but a global environmental issue," Clere says.

How safe is store-bought fish?

Fish on sale at a food market.

Clere says when microplastic is ingested by fish, it moves through their gastrointestinal tract and stomach.

"Fish we buy from the supermarket is usually filleted, and therefore the gastrointestinal tract and stomach are removed. However, there is still potential that nano-plastics (0.001–0.1 μm) and plastic chemicals are transferred through to the fish muscle tissue which is what humans eat."

She says there's a greater risk of secondary transfer of plastics when seafoods such as sardines and shellfish are eaten whole.

Research into microplastics' risk to humans is still in its early stages, Clere says.

"Working with human subjects is difficult for a multitude of reasons. There have been studies which have found microplastics in human blood and placenta, so we do know that they are present. However, the implications of this we do not know yet, as this research is still in its very early stages.

"Across the world, scientists are looking at microplastics effect on the whole food chain, and how microplastics may be effecting human health, for example cell functioning and reproduction."

New Zealand Food Safety (NZFS) deputy director general Vincent Arbuckle told 1News there is currently no evidence to support microplastics as a concern for our health through food in New Zealand but says more research is needed.

"NZFS is working closely with international colleagues to address data gaps, to determine the occurrence of microplastics in food, and to determine whether or not microplastics in food are actually a risk.

"To this end, NZFS has published a risk profile on microplastics in the diet and, in conjunction with the University of Canterbury and ESR, is currently conducting research into the impact of microplastics in the New Zealand diet on human health.

"We appreciate any other research being undertaken into the issue and carefully review the results of these studies to see what we can take from it," Arbuckle says.