ICPR – International Commission for the Protection of the Rhine

ICPR Priority Substances

In its Rhine Action Programme (RAP) and in the EU Water Framework Directive (WFD), substances, which pose a risk to man and its environment to an extent that priority action must be taken to reduce their occurrence, have been classified as so-called priority substances.

The Rhine Action Programme 1985-1995 fixed targets for the reduction of some 60 priority substances by 50 per cent, for some heavy metals even by 70 per cent. For most substances and groups of substances the reductions planned were achieved, in some cases they have even been exceeded. The positive effects on the waters are evident when comparing monitoring results with the ICPR target values.

Comparison of environmental quality standards and target values with measured values  
Report time frame Report no
2021 to 2023 in preparation
2019 to 2020 293
2017 to 2018 281
2015 to 2016 251
2013 to 2014 239
2009 to 2012 220
1990 to 2008 193
1990 to 2006 180
1990 to 2004 159
1990 to 2001 143
1990 to 2000 123


Examples of priority substances

Pesticides of agricultural origin, e.g. herbicides, insecticides and fungicides are washed out of or off the soil by rainwater or reach waters via drains after spills when rinsing and filling spray guns. Biocides applied in agriculture may drift off with the wind. Some pesticides are applied to sealed surfaces and washed off by rainwater.

The concentrations of many chemicals used for fighting weeds, fungi and insects have decreased in Rhine water. However, 3 substances fail to meet the target values.

Today, different ICPR member states have banned several priority pesticides. For some authorized substances uses have been restricted Only some of the pesticide agents used in agriculture and other areas and reaching waters were included in the original list of priority substances. 

Diuron is a persistent herbicide that is no longer authorised as a plant protection product but is still authorised as a biocide in ICPR member states. After application as weed destruction agent on sealed surfaces, such as yards and parking areas it is washed into the sewer with the rainwater, flows through wastewater treatment plants and finally into the rivers.

Fenitrothion is an insecticide which also flowed into the Rhine with the fire fighting water during the warehouse fire in Schweizerhalle in 1986. It is poisonous for many water organisms. Organophosphates such as fenitrothion are neurotoxins. Even low concentrations of this substance in water change the search for food and the learning behaviour of salmon.

Lindan is an insecticide which was above all used in agriculture and forestry. It damages functions in the nerve tracts of insects. This substance is persistent and, due to deposits in fatty tissue, it accumulates via the food chain. In 2000, the annual charge of this substance in the Rhine was estimated to 120 kg.