Mikroplast. Foto: Oegon State University.

The issue of microplastics is currently high on the maritime policy agenda world wide. But discussions about concrete measures to reduce the plastic pollution in the sea also tend to reveal the obvious dilemma when it comes to microplastics: the lack of knowledge.

– Researchers have warned for plastic in the oceans and in marine animals for almost 50 years, but we still know relatively little about the amount of microplastics found in the ocean, how much is supplied, where the largest amounts of plastic particles come from and what damage they do marine life, says Marie Löf, ecotoxicologist at Stockholm University's Baltic Sea Centre.

But in recent years, intensive research has been conducted in the area. For example, a report from Swedish Örebro University present a series of new findings from various parts of the world that clearly show that microplastics can damage marine animals.

– Some of the injuries are impaired reproduction and reduced nutritional uptake, says Marie Löf.

The zooplankton Daphnia with ingested microplastics. Photo: Zandra Gerdes.

Cause damage to aquatic animals

To pinpoint the harmful effects is a recurring stumbling block in the political discussions about microplastics. The more plastic used in society, the greater the risk of emissions to the sea. At the same time, plastic is now an integral part of people's everyday lives. An average Western European person expend about 100 kilos of plastics per year, making plastic an important production and commodity product. Therefore, critics argue that it is economically unreasonable to introduce rules and prohibitions before knowing precisely what damage the plastic particles cause.

– Previous studies have observed negative effects of microplastics, but at very high concentrations. Now we have new studies showing that microplastics, and the even smaller nanoplastics, can cause damage to aquatic animals even in concentrations which are similar to those we actually find in the marine environment, says Marie Löf.

"The uncertainty should not be used as a reason not to act"

In a new policy brief from the Baltic Sea Centre, based on the report from Örebro University, the current scientific knowledge is coupled with ongoing political processes related to microplastics. And the message is clear: The pollution of both large and small plastic waste to the sea must be greatly reduced – and today's scientific knowledge of harmful effects is sufficient to allow the precautionary principle to govern policy decisions in that direction.

– Microplastics pose a potentially serious risk to marine animals. There are still knowledge gaps, such as the difficulty to determine exactly what effects are due to microplastics and those that may be due to other stress factors in the marine environment. But the uncertainty should not be used as a reason not to act to reduce the input of a pollutant that remains in the marine environment for a very long time, says Marie Löf.

"Thousands of tons of microplastics end up in the Baltic Sea each year"

She recalls that plastics in the sea is not a new phenomenon. Plastics began to pollute our marine environments more than 50 years ago. And since then, production and supply have steadily increased.

– Most plastics that end up in the sea are not biodegradable, which means that they remain in the water for hundreds of years, or even longer. Personally, I think that is the most worrying aspect of this issue. Thousands of tons of microplastics end up in the Baltic Sea each year. And once it is in the sea, we have no way of taking it out again, says Marie Löf.

Text: Henrik Hamrén

Read the Baltic Eye policy brief