Angela Merkel confirms that traditionally lightly salted herring can be eaten without fear
Under the influence of sun, ultraviolet rays, wind and sea waves, plastic entering the water gradually breaks down into tiny particles and forms a thin layer of foreign matter floating on the surface of oceans and seas. These microscopic-sized wastes become particularly dangerous over time, turning into peculiar accumulators of toxic substances.
Fragments of plastic waste end up in the stomachs of birds and inhabitants of the deep sea. The fish that ends up on our plates feed on the same. But not all fish species consume plastic equally. This conclusion was reached by scientists at the Alfred Wegener Institute for Polar and Marine Research (AWI) in Bremerhaven, part of the Helmholtz Association.
The focus of the current study by biologists was on species such as mackerel, flounder, herring, Atlantic cod, and rough dab. In total, about 300 fish were examined. Scientists paid special attention to the stomach contents of fish caught in the North and Baltic Seas.
The champion in plastic absorption turned out to be Atlantic mackerel. Oceanologists found polymer microparticles in the stomachs of 13 out of 30 mackerel. However, herring had no plastic in their stomachs at all, depending on the season. 'Obviously, the reason lies in the feeding habits of certain fish species,' suggests biologist and research project leader Gunnar Gerdts.
Mackerel feeds on needlefish fry and likely mistakes plastic particles floating on the surface for prey. The similarity to fry of the plastic fibers found in mackerel stomachs, according to scientists, confirms this assumption. Fish that prefer to hunt at depth are much less likely to swallow hazardous waste.
As a result of the study, biologists were unable to find any evidence that fish become ill from consuming polymer waste. The search for alleged harmful effects on humans who eat 'undiscriminating' mackerel and other 'dubiously' feeding fish also proved fruitless.
'Most of the microscopic particles settle in the digestive tract,' explains AWI expert Lars Gutow. Before eating, fish are gutted, which helps prevent plastic from ending up on our plates. However, the question remains unanswered whether toxic substances accumulated in polymer microparticles manage to enter the fish's bloodstream and how this might affect the human body.
A second study conducted by scientists confirmed that another group most at risk of absorbing microplastics is invertebrate mollusks. They live in coastal environments and consume large amounts of algae, whose sticky surfaces become covered with a thick layer of polymer particles.
For laboratory studies, biologists chose the periwinkle, which is considered a delicacy. Scientists marked the food for the coastal snail with fluorescent dye and found that harmful substances do not remain in the mollusk's body for long—they are naturally excreted along with undigested food residues.
So, can we not worry about health? Scientists cannot give a 100% guarantee yet. After all, it is still unknown how both animals and humans will feel after long-term and massive consumption of this risky food.