Article 16 of the Water Framework Directive (EC 2000) mandates the European Commission (EC) to select priority substances (PS) and identify priority hazardous substances (PHS) with a provision to review the list of PS at the latest four years after the entry into force of the WFD. Furthermore, the EC has to propose measures to control and reduce point and diffuse sources for the progressive reduction of PS and the cessation of PHS within 20 years after the adoption of the EC proposal. In addition quality standards applicable to the PS concentrations in surface water, sediments and biota have to be developed.
In 2001, a list of PS was adopted (Decision 2455/2001/EC) identifying 33 substances of priority concern at EU level, including a subset of PHS (11 and 14 as ‘PS under review’ for possible classification as PHS) that require the cessation or phase-out of discharges, emissions and losses within 20 years of adopting measures for that purpose.
A proposed Daughter Directive (COM (2006) 397) was developed by the EC and published in July 2006 in order to comply with the requirements of Article 16 of the WFD. The Directive has two objectives:
to ensure a high level of protection of the aquatic environment by setting environmental quality standards (EQS) for the PS and certain other pollutants;
to define good chemical status in surface water bodies through compliance with EQS.
Environmental Quality Standards (EQS) are concentrations of pollutants which should not be exceeded in order to protect human health and the environment (COM (2006) 397). There were already defined EQS at community level, also most Member States had their own EQS. However, all these EQS varied considerably across the EU. Therefore the EC decided to harmonise the EQS values based on toxicity and ecotoxicity data as well as bioaccumulation potential, environmental contamination and human risk. The EQS were derived from aquatic NOEC (No observed effect concentration) data (Lepper, 2005). Finally, the 33 identified substances of priority concern were classified as follows:
Priority substances (PS): Alachlor, atrazine, benzene, chlorofenvinphos, chloropyrifos, 1,2-dichloroethane, dichloromethane, di(2-ethylhexyl)phthalate (DEHP), diuron, fluoranthene, isoproturon, lead and compounds, naphthalene, nickel and compounds, octylphenol, pentachlorophenol, simazine, trichlorobenzenes, trichloromethane and trifluralin.
Priority Hazardous Substances (PHS): Anthracene, brominated diphenylether (PentaDBE), cadmium and compounds, chloroalkanes (C10-13), endosulfan, hexachlorobenzene, hexachlorobutadiene, hexachlorocyclohexane, mercury and compounds, nonylphenols, pentachlorobenzene, polyaromatic hydrocarbons (PAHs)1 and tributylin (TBT) compounds.