Are there toxins in water bodies?

Small concentrations of environmental toxins can be found in Finnish lakes and rivers. Where do they come from, and do they put human health or the environment at risk?

Harmful and hazardous substances ended up in water bodies especially in the second half of the 20th century. Some of these substances came from industrial plants, including the chemical, forest and metal industries. Other toxins originate from pesticides or consumer products.

Things changed in the late 20th century as governments began to pay more attention to environmental toxins. The most hazardous substances were banned, or their use was restricted. Industrial processes were developed, and wastewater treatment improved. For example, this meant that chlorine emissions from pulp bleaching could be reduced to about one tenth of their previous level over a short period of time. Emissions of mercury and other heavy metals were also reduced sharply, as were PCB emissions to water.

As the emissions were reduced, water bodies started to gradually recover from toxins. However, toxin residues can still be found in sediments, water and aquatic organisms. Their concentrations in fish rarely exceed the limits set to protect human health. On the other hand, no limit values for food use have been set for many harmful substances. As fish is a healthy food, you should eat it following recommendations. The benefits are greater than the risks!

Minor quantities of harmful substances still end up in water bodies, for example from old products. Long-range transboundary pollution adds to this loading and is the main reason behind the fact that the maximum levels for certain flame retardants are commonly exceeded in water bodies, both in Finland and elsewhere in Europe. The general chemicalisation of the environment is also a cause for concern.