Fact Sheet 8 (January 2017)

Data Comilation, Selection, And Derivation of PNEC Values for the Sediment Compartment

The Existing Substances Risk Assessment of Nickel was completed in 2008. The straightforward explanation of the goals of this exercise was to determine if the ongoing production and use of nickel in the EU caused risks to humans or the environment.  The European Union launched the Existing Substances regulation in 2001 to comply with Council Regulation (EEC) 793/93.  “Existing” substances were defined as chemical substances in use within the European Community before September 1981 and listed in the European Inventory of Existing Commercial Chemical Substances. Council Regulation (EEC) 793/931 provides a systematic framework for the evaluation of the risks of existing substances to human health and the environment.


The conceptual approach to conducting the environment section of the EU risk assessment of nickel included the following steps (Figure 1):

  • Emissions of nickel and nickel compounds to the environment were quantified for the whole life cycle, i.e. from production, use, and disposal;
  • Concentrations of nickel resulting from these emissions were determined in relevant environmental media (water, sediment, soil, tissue) at local and regional scales (PECs);
  • Critical effects concentrations (PNECs) were determined for each of the relevant environmental media;
  • Exposure concentrations were compared to critical effects concentrations for each of the relevant environmental media (risk characterization); and
  • Appropriate corrective actions (also described as risk management) were identified for situations where exposure concentrations were greater than critical effects concentrations.  Where exposure concentrations were below critical effects concentrations, there was no need for concern or action.

The initial EU Risk Assessments for Nickel and Nickel Compounds were developed over the period from 2002 to 2008 but the European Commission identified some remaining data gaps in particular with respect to the sediment compartment (Official Journal of the European Union 2008). Therefore, a multilaboratory, multiphase research project was conducted to provide a scientific basis for a bioavailability based approach for assessing risks of nickel in sediments. The laboratory testing initiative was conducted in three phases to satisfy the following objectives:

  1. evaluate various methods for spiking sediments with nickel to optimize the relevance of sediment nickel exposures;
  2. generate reliable ecotoxicity data by conducting standardized chronic ecotoxicity tests using 10 benthic species in sediments with low and high nickel binding capacity; and
  3. examine sediment bioavailability relationships by conducting chronic ecotoxicity testing in sediments that showed broad ranges of acid volatile sulfides, organic carbon, and iron.

A subset of 6 nickel-spiked sediments was deployed in the field to examine benthic colonization and community effects. The sediment testing program yielded a broad, high quality data set that was used to develop a Species Sensitivity Distribution for benthic organisms in various sediment types, a reasonable worst case predicted no-effect concentration for nickel in sediment (PNECsediment), and predictive models for bioavailability and toxicity of nickel in freshwater sediments (Schlekat et al., 2016).

 Figure 1

Fact Sheet 8

Data Compilation, Selection, and Derivation of PNEC Values for the Sediment Compartment