Nickel sulphide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

7.1 µg/L

Assessment factor:

1

Extrapolation method:

sensitivity distribution

PNEC freshwater (intermittent releases):

0 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

8.6 µg/L

Assessment factor:

2

Extrapolation method:

sensitivity distribution

PNEC marine water (intermittent releases):

0 µg/L

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.33 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

109 mg/kg sediment dw

Assessment factor:

1

Extrapolation method:

sensitivity distribution

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

109 mg/kg sediment dw

Assessment factor:

1

Extrapolation method:

sensitivity distribution

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

29.9 mg/kg soil dw

Assessment factor:

2

Extrapolation method:

sensitivity distribution

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

0.12 mg/kg food

Assessment factor:

10

Additional information

The approach for deriving PNEC values was used in the 2008/2009 European Union Existing Substances Risk Assessment of Nickel (EU RAR) (EEC 793/93). The EU RAR was jointly prepared by the Danish Environmental Protection Agency (DEPA), which served as the Rapporteur of the Existing Substances Risk Assessment of Nickel, and the Nickel Producers Environmental Research Association (NiPERA), which represented the Nickel Industry in this process. The complete Environment section of the EU RAR can be found in the pdf linked to the following URL:

 http://ecb.jrc.ec.europa.eu/DOCUMENTS/Existing-Chemicals/RISK_ASSESSMENT/REPORT/nickelreport311.pdf

 

All of the approaches described were discussed by the Technical Committee for New and Existing Substances (TC NES), and received final approval at the TC NES I meeting in April, 2008.

 

Common effects assessment basis:

 

The ecotoxicity databases on the effects of soluble nickel compounds to aquatic, soil- and sediment-dwelling organisms are extensive. It should be noted that the effects assessments of Nickel sulfide is based on the assumption that adverse effects to aquatic, soil- and sediment-dwelling organisms are a consequence of exposure to the bioavailable Ni-ion, as opposed to the parent substances. The result of this assumption is that the ecotoxicology will be similar for all soluble Ni substances used in the ecotoxicity experiments. Therefore, data from soluble nickel substances are used in the derivation of chronic ecotoxicological NOEC and L(E)C10 values. If both NOEC and L(E)C10 data are available for a given species, the L(E)C10 value was used in the effects assessment.

Conclusion on classification

Ni sulfide is classified as Aquatic Acute I/Chronic I in the 1st ATP to the CLP. Classification was confirmed by results of the Tranformation/Dissolution Screening Test.

The 2^ndATP to the CLP introduced the chronic (long-term) environmental toxicity endpoint as defined by the 3^rdversion of the UN-GHS into the EU hazard classification and labeling scheme. The GHS and EU scheme include the concept of degradation whereby rapid degradation from the water column (greater than 70 % removal in 28 days) results in different classification cut-off values and categories.  For metals and inorganic metal compounds, the rapid and irreversible removal from the water column is equated to the rapid degradation concept for organics.  The current draft guidance on metals includes  a proposal to apply the “rapid degradation principle for organics” measured as a 70 % removal rate in 28 days in a comparable way for metals from laboratory and field experiments or by using a recently developed model.  A Unit World Model (UWM) has recently been developed specifically for metals, building on previous screening-level calculations that have been developed for organic contaminants, and is capable of assessing the fate and effects of chemicals by the simultaneous consideration of chemical partitioning, transport, reactivity, and bioavailability.  With regard to hazard assessment, the UWM is capable of assessing the removal of soluble metals from the water column resulting from sorption to particulate material, settling to the sediment compartment, and subsequent changes in speciation via precipitation by sulfides naturally present in the sediment compartment. 

 

The UWM was used to assess the rapid removal of a group metals (e.g., Ni, Cu, Pb, Zn, As, Al, Co) in a generalized lake environment resulting from metal removal from the water column and sequestration in sediment.  To estimate sorption by particulate matter in the water column, the UWM can use empirical, measured distribution coefficients (Kd), or the speciation module within the UWM (the Windermere Humic Aqueous Model, or WHAM) can calculate Kds. When an empirical Kd of log 4.42 was used, greater than 70% nickel removal was achieved in every loading and pH scenario. WHAM-based Kds tended to be substantially lower than empirical Kds, indicating that refinement of the WHAM approach was needed. To this end, the UWM was refined to accommodate an updated version of WHAM (WHAM 7). Additionally, the inorganic thermodynamic database used by WHAM to perform speciation calculations was updated because the previous version was found to be out of date and inaccurate. Analyses using WHAM7 and the revised inorganic thermodynamic database showed that greater than 70% nickel removal was achieved under the three pH scenarios with metal loadings at the acute and chronic ERVs at 28 days.  At the upper chronic cutoff value of 1 mg/L, rapid removal was achieved for pH 6 and 8 without oxide binding and for all three pH values with oxide binding.  Rapid removal was demonstrated at all pH values when loading was based on acute Ecotoxicity Reference Values (120 µg Ni/L at pH 6 and 68 µg Ni/L at pH 8) and chronic Ecotoxicity Reference Values (2.4 µg Ni/L) using calculated Kd values. Based on these results, nickel sulfide fulfills the criteria for rapid degradation for the environmental classification scheme in the 2^ndATP to the CLP.