Nickel(III) oxy hydroxide

Sediment toxicity

Description of key information

PNEC sediment: Pending outcome of sediment testing program.

Additional information

PNEC sediment: Pending outcome of sediment testing program

A technical conclusion ii (no further information or testing required) was determined for all compartments of the European Union Risk Assessment for Nickel and Nickel Compounds (2008-2009) except for the sediment compartment, which received a technical conclusion i (further information or testing required). EU Member States and the ECB (European Chemicals Bureau) have accepted a formal testing recommendation for sediments, which was published in the Official Journal of the European Union on May 28th, 2008.

The need for additional testing arose from the conclusion that the ecotoxicity results of the whole sediment toxicity tests conducted under the historic conclusion i) research program (2004-2005) were confounded by technical issues associated with the introduction of Ni into sediments in the laboratory, and the subsequent diffusional loss of Ni into overlying water. Briefly, relatively poor sorption of Ni to sediment particles resulted in the loss of dissolved Ni from the sediments. Furthermore, observed toxicity to the sediment toxicity test organisms was explained by Ni concentrations in overlying water, as opposed to Ni concentrations in the sediments. Interpretation of these ecotoxicity data required that conservative assumptions be applied to the outcome of these tests, which resulted in PNECsed (Predicted No Effects Concentration for nickel in sediments) values that were below ambient and natural background concentrations. These PNECsed values were neither scientifically defensible nor sustainable and their application would have led to the conclusion of risk at 100% of the operational sites within the RA, as well as at the regional scale. As such, the Danish Rapporteur and other Memberstates recommended that further testing should be conducted to generate the data to calculate a scientifically sound PNECsed, based on laboratory approaches aimed at controlling the diffusional loss of Ni from sediments and that could be validated in the field. 

Research has been conducted in order to achieve the following objectives:

1. To evaluate optimal sediment spiking techniques,

2. To generate reliable ecotoxicity data on sediment dwelling organisms providing effect concentrations relating to bulk sediment concentrations;

3. To develop an integrated, equilibrium-partitioning based bioavailability model for normalizing the sediment effect concentrations to bioavailable sediment concentrations under both aerobic and anaerobic conditions

A research program was developed to specifically address these components. Research conducted by the U.S. Geological Survey (USGS) in Columbia, MO. (USA) evaluated multiple spiking methods to determine the distribution of Ni between pore-water and solid-sediment phases over time under laboratory conditions and was compared to the distribution of Ni in naturally Ni contaminated field collected sediments. After the optimal spiking approach was identified, extensive ecotoxicity testing was conducted for nine benthic organisms and for eight sediment types to evaluate the bioavailability of Ni in a wide range of sediments and toxicity to a variety of benthic organisms, in order to determine effect concentrations relating to bulk sediment concentrations. These data were used to generate an integrated bioavailability model for toxicity in sediments. The relationships in the model were also tested in the field in a field study conducted by University of Michigan (USA), which looked at Ni behavior, acute toxicity, and chronic benthic recolonization. Additional supplemental research conducted by Natural Resources Canada/University of Quebec (CA) examined the partitioning of Ni in field sediments from a Ni contaminated lake, which was used in the evaluation of the optimal spiking strategy employed by the USGS. Finally, research that examined the solid phase speciation of the Ni spiked sediments and field sediments was conducted by Northwestern University (USA).  

 A Technical Conclusion i) group was formed to provide technical guidance on the development of a scientifically defensible approach for the Ni sediment toxicity testing program. The Technical Conclusion i) group was composed of sediment experts from academia, consulting, NiPERA, and EU Member States. The research program began in quarter 4 of 2008 and the testing portion of the program was completed in quarter 2 of 2010. Data analysis and compilation were completed in quarter 4 of 2010 and the program is currently in the final reporting stage. According to the guidance and to clarification provided by ECHA, Industry is required to submit the information directly to the Member State Competent Authority (in this case Denmark as the Rapporteur State) for evaluation.

The Technical Conclusion i) Group made a final evaluation of the data generated in the Sediment Testing Program at the end of 2010.  The Nickel Industry delivered final research reports of the University of Michigan, the Northwestern University Solid Phase Speciation Study, the NR CAN/University of Quebec Nickel Partitioning Evaluation, and the Sediment Effects Assessment drafted by the ARCHE Consultancy of Ghent, Belgium to the Danish Environmental Protection Agency (DEPA) in November 2010. In addition, a summary of the Technical Conclusion i) Group’s recommendations, drafted by the group’s chairman, Dr. Colin Janssen was also delivered to DEPA in November, 2010.  Draft reports of the research conducted by the USGS were submitted to DEPA and final USGS reports are anticipated in spring 2011, after a thorough internal and external review process. Representatives from DEPA have indicated receipt of the above cited reports and have stated that the review process will begin upon the delivery of the final USGS reports in mid-2011.