Fish dishes may be safe from microplastics

Majority of tiny particles will pass through certain seafood and not reach our plates, scientists say

MICROPLASTICS may not make their way on to our plates through seafood, as studies on sea bass and shrimp have concluded that most of the tiny particles completely pass through them.

Microplastics, defined as anything less than 5mm in diameter, have been found across the globe. They spread via our waterways and on the air from plastic rubbish, car tyres and fibres.

But researchers in Germany have found almost none in the muscle tissue of sea bass, the part of the fish that makes up a fillet, despite a steady diet.

The fish were fed an average of 163 million bits of microplastic measuring one to five micrometres (thousandths of a millimetre) each over four months – much more than they are normally exposed to. The scientists tracked the microplastics by dyeing them, and found only one or two particles for every five grams of muscle tissue.

“This, along with the fact that the fish grew very well and were in perfect health, tells us that the fish can apparently isolate and excrete these particles before they have a chance to penetrate their tissues,” said Dr Matthew Slater, of the Helmholtz Centre for Polar and Marine Research.

“For everyone who enjoys eating sea bass, that’s very good news.”

Dr Slater believes that the evidence from the sea bass can be extrapolated to other similar species of fish, though more research is needed.

In Spain, researchers found microplastics in the digestive tract of 75 per cent of the shrimp they inspected at three coastal fishing locations along the Mediterranean, a hotspot for microplastic pollution.

More than half of those had balls of the fibres tangled in their stomach, according to the study from the Autonomous University of Barcelona. But they concluded that most of the microplastics are shed with the crustacean’s exoskeleton every three to eight weeks.

Of the 22 or so microplastics fibres they did find in each shrimp, 90 per cent were limited to the stomach, which is rarely eaten by humans.

The research was published in the journal Environmental Pollution.

Both studies are part of emerging research into the implications of the spread of microplastics, which has been hampered by the difficulty of tracking something that can be imperceptibly small.

“It’s abundantly clear that humans and other organisms readily ingest plastic particles. But there’s been a lot of different views about the effects,” said Dr Theodore Henry, an environmental toxicologist at Edinburgh’s Heriot-Watt University.

He led an earlier study which concluded that levels of microplastics found on mussels are a fraction compared to the number ingested from dust and air during a mealtime.

“There’s been speculation that there is harm, but there’s very little evidence,” he said. “These studies are further evidence that consuming seafood products that might be contaminated with plastics is not really an issue.”