Nickel dihydroxide

Endpoint summary

Additional information

The environmental toxicology of Nickel has been subject of numerous reviews/ assessments. For example:

-         Canadian Environmental Protection Act, Priority Substances List Assessment Report, Nickel and its Compounds (1994)

-         U.S.EPA (1980). Ambient Water Quality Criteria for Nickel. EPA 440 /5-80-060

-         WHO (1991). EHC 108. Nickel.

-         ECB (2008). EU-Risk Assessment Nickel and Nickel compounds. EU 3rd priority substance list.

-         OECD (2008). SIAP. Nickel and Nickel compounds.  

 

In OECD SIAP (2008) and EU-Risk Assessment (2008) the hazard of Nickel has been assessed extensively, taking bioavailability correction into account.Within this risk assessment, the risk of nickel to aquatic organisms at the regional scale was characterized by applying semi-probabilistic risk assessment concepts to the ecoregion approach. A series of seven scenarios have been identified to represent frequently occurring existing river/lake types of typical surface waters with characteristics covering a wide range of physico-chemical conditions occurring in the EU surface waters, e.g. oligotrophic, acidic, alluvial aquatic systems. PNECs were calculated using the Ni BLMs from the mean pH, hardness, and DOC values calculated for each of the typical systems.

Freshwater compartment 

A total risk approach was performed focussing on the toxicity of free Ni2+ ions.Ni2+ partitioning coefficient for solid-water in suspended matter (Kp susp) was determined as 26303(log Kp susp = 4.42).

The range of PNEC values ranged from a low of 3.6 ug Ni/L for the Lake Monate scenario to a high of 21.8 ug Ni/L for the Dutch Ditch scenario. These scenarios are based on measured abiotic parameters for specific systems, but the results are considered to be representative for the generic type of systems as defined by the combination of pH, hardness, and DOC. In other words, the PNEC for the River Otter would be representative of other fresh surface water systems with similar abiotic parameter combinations (High pH (i.e pH of 8.1), medium hardness (i.e. 165 mg/L), and low DOC (i.e 3.2 mg/L)).

 

Because the observed variability in abiotic parameters in these existing river/lake types results in major differences in PNEC values, it is relevant to define the regional PNEC on a “water basin-type” basis. This is consistent with the water basin-specific approach recommended for implementing bioavailability for the Water Framework Directive, as it ensures a common protection target for all surface waters in.

 

Because of the variability (both temporal and spatial) related to main abiotic factors (i.e. pH, DOC and hardness) occurring in the different eco-regions, it was decided to perform the risk characterisation based on different relevant combination of percentiles in abiotic factors (based on 10th, 50th and 90th % values). The BLMs have shown that pH and DOC are the mainfactors mitigating the chronic toxicity of Ni towards freshwater organisms. Therefore it was decided to consider at least all relevant combinations between percentiles (10th, 50th and 90^th% values) for pH and DOC. When considering the effect of hardness on the HC5 (50%) values, the relevant worst case combination (low hardness, low DOC and high pH) is always included in the BLM calculations. This means that 9 different HC5 (50%) values, using the full read across approach, have been calculated for each considered eco-region.

 

Risk characterisation ratios varied between 0.07 and 1.38 when an assessment factor of 2 (AF=2) wasused. Thus a potential risks to the aquatic environment was only identified for the eco-region scenario of the river Otter (low DOC/high pH/medium hardness), where the risk ratio varies between 0.49 and 1.38. In generic terms, therefore, potential risks of nickel exposure to aquatic organisms may occur in systems with combinations of high pH (50P = 8.0) and low DOC (50P = 3.4 mg/L).

STP

For an assessment of effects of nickel exposure on microbial activity in STPs there are currently no acceptable data available.

Marine Compartment

A probabilistic analysis of dissolved nickel concentrations was performed for several types of marine waters, including open marine waters, estuarine and estuary-influenced coastal waters, and the. This analysis is presented as Appendix D4 of the Environmental Exposure Assessment. The RWC-ambient PEC (defined as the 90P value) for dissolved nickel concentrations for the different categories are as follows:

 

Estuarine and estuarine-influenced coastal waters:

The global RWC-ambient PEC for dissolved Ni-levels was 2.32 μg/L (range: 0.26 – 3.75μg/L). Based on European data the RWC-ambient PEC for dissolved nickel was 3.34 μg/L(range: 0.26 – 3.75 μg/L).

 

Open marine waters:

The global RWC-ambient PEC for dissolved Ni-levels was 0.27 μg/L (range: 0.12 – 0.33μg/L). Based on European data the RWC-ambient PEC for dissolved nickel was 0.30 μg/L(range: 0.14 – 3.75 μg/L).

 

Baltic Sea:

For this geographic semi-enclosed waterbody with its brackish water properties a RWCambientPEC for dissolved nickel of 0.79 μg/L (range: 0.64 – 0.81 μg/L) was derived.The Marine Effects Assessment reports a PNECmarine value of 8.6 μg Ni/L (SSD approach HC5 -50 = 17.2 µg l-1, AF = 2). RWC-ambientPEC values for all categories of marine waters are well below the PNECmarine value.