Science for Environment Policy | Sixteen-year reduction in levels of toxic PAHs in the Elbe River

Polycyclic aromatic hydrocarbons (PAHs) are a large group of toxic molecules produced by forest fires, industrial processes and the incomplete combustion of fossil fuels. The airborne particles containing these molecules are often washed into watercourses, where they can persist. This study uses long-term monitoring data from the Elbe river, Saxony, Germany, to show how changes in PAH sources affect both the concentrations of these chemicals and the corresponding environmental risks. The researchers suggest that controlling PAHs is the best prevention of harm to aquatic and human health.

Some PAHs are linked to cancer, birth defects and DNA mutations in humans. In the aquatic environment, PAH exposure has adverse influences on invertebrates and vertebrates. In addition, the related breakdown products of PAHs (daughter molecules) can be even more toxic. As PAHs and daughter molecules are known to cause environmental harm1 , listed as priority substances2 by the European Water Framework Directive3 .

Research regarding toxic PAHs to date has not focused on the long-term trends of PAH exposure risk, in response to changes in sources of pollutants; largely because data has been lacking. This study, however, used extensive long-term monitoring data (2001–2016) for the Elbe River in Saxony, Germany. Saxony has undergone significant urbanisation and industrialisation, and the River Elbe has been exposed to pollution from, for example, municipal and industrial effluents. The researchers note that changes in sources of PAHs affect the concentrations of the pollutants in the river and have an effect on the corresponding environmental risks.

Link to the Science for Environment Policy | Sixteen-year reduction in levels of toxic PAHs in the Elbe River