Nickel difluoride

Endpoint summary

Description of key information

Extensive chronic soil toxicity data sets exist for soil microbial processes, plants, and invertebrates. Many individual NOEC/EC₁₀values were screened for quality and relevancy, which resulted in a data set of high quality data that covered many different species. The selected data set covers different families, different trophic levels and feeding patterns for invertebrates, and microbial activities. Chronic toxicity data for individual species were generated in many different soils, enabling a toxicity comparison between soils and the establishment of toxicity soil-type models.

For PNEC derivation, data for the most sensitive endpoint for a given species were aggregated to derive a species mean ecotoxicity value. Species mean values were used to establish a species sensitivity distribution (SSD), from which an HC5 was derived. The PNEC was derived as a function of the HC5 and an assessment factor (PNEC = HC5/Assessment Factor).

Because clear toxicity differences between various soils were observed, bioavailability dorrection models were established in order to reduce soil-type related impact on the determination of the HC5 (and subsequently the PNEC). Additionally, an ecoregion approach was developped based on 6 reference soil scenarios that represent typical soil conditions, and an HC5 value was determined for each ecoregion scenario.

 

For toxicity to birds, several sub-chronic and chronic feeding studies in which the diet was spiked with a Ni salt were identified. From these studies, generic NOEC values of 150 and 200 mg Ni/kg were determined in a tier I approach. In a tier II approach, refined NOEC values of 12.3 mg Ni/kg and 8.5 mg Ni/kg were determined for the aquatic foodchain and earthworm-eating birds respectively.

Additional information

Soil Effect data sets

Terrestrial microorganisms:

Data for different microbial processes are available, with NOEC/EC₁₀values range from 28 mg Ni/kg for nitrification to 2491 mg Ni/kg for respiration. Additional data are available for enzyme activity measured in soil, with NOEC/EC₁₀values ranging from 7.9 mg Ni/kg for dehydrogenase to 7084 mg Ni/kg for arylsulfatase activity. Data also exist for the growth of different microbial species, with EC₁₀values ranging from 13 mg Ni/kg forAspergillus clavatusto 530 mg Ni/kg forTrichoderma viride.

Terrestrial plants:

NOEC/EC₁₀values are available for different plant species, ranging from 10 mg Ni/kg forSpinacea oleraceato 1303.2 mg Ni/kg for Zea mays. 

Terrestrial arthropods:

Chronic data are available for different species of arthropod soil invertebrates. NOEC/EC₁₀values range from 31 mg Ni/kg for reproduction by the springtailFolsomia candida (Liuet al., 2015) to 1,783 mg Ni/kg for reproduction by F. candida(Liuet al., 2015). 

Soil macroorganisms:

Acute toxicity LC₅₀values for soil macroinvertebrates range from 52 mg Ni/kg dw for Lumbicis terrestris(mortality) to 2,500 mg Ni/kg dw for Caenorhabditis elegans(mortality).  The acute EC₅₀(4 d) values for terrestrial plants range from ≥54.5 mg/kg soil d.w. to ≤1928.2 mg/kg for root elongation forHordeum vulgare.