Example

Data Compilation

See Guidance: Data Compilation

Data Quality Screening

The quality screening criteria as defined in Guidance: Data Quality Screening were applied to select the high quality chronic ecotoxicity data of nickel to soil organisms.

Database Development

An overview of all accepted individual high quality chronic ecotoxicity data is presented in the Environmental Risk Assessment of Nickel and Nickel Compounds (see EU Risk Assessments).

Data Normalization

In this example, the data were normalized to the physico-chemical conditions prevailing in the Danish soils using the ageing and bioavailability models as explained in Fact Sheet 5.  The soils in Denmark are characterized by a pH of 6.3, a CEC of 10.4 cmol/kg, a clay content of 8.9%, and organic matter (OM) content of 0.6%.

Table 2: Selected Species Mean Ecotoxicity Data to Nickel for the Most Sensitive Endpoint

Taxonomic Group/Process

Species

Most Sensitive
Endpoint 

Species Mean
NOEC/L(E)C10 Value (mg/kg)

Higher plants

Lycopersicon esculentum

Shoot yield 182
Hordeum vulgare Root yield 293
Spinacia oleracea Total yield 75
Avena sativa Yield grain 82
Medicago sativa Yield total plant 105
Raphanus sativus Yield 170
Allium cepa Yield 277
Trigonella poenumgraceum Yield 497
Lolium perenne Yield 46
Lactuca sativa Yield leaves 139
Zea mays Not reported  209
Invertebrates  Folsomia candida           Reproduction  398
Folsomia fimetaria Reproduction 277
Eisenia fetida Reproduction 281
Enchytraeus albidus Reproduction 164
Eisenia veneta Reproduction 132
Lumbricus rubellus Mortality 918
Microbial process/species Nitrification NO3 production 160
N-mineralisation NO3 production 253
Glucose respiration CO2 release 168
Maize respiration CO2 release 255
Aspergillus flavipes Hyphal growth 492
Aspergillus flavus Hyphal growth 554
Aspergillus clavatus Hyphal growth 43
Aspergillus niger Hyphal growth 563
Penicillium vermiculatum Hyphal growth 163
Rhizopus stolonifer Hyphal growth 412
Trichoderma viride Hyphal growth 738
Gliocladium sp. Hyphal growth 294
Serratia marcescens Colony count 234
Proteus vulgaris Colony count  46
Bacillus cereus Colony count 408
Nocardia rhodochrous Colony count 263
Rhodotorula rubra Colony count 357
Respiration CO2 release 137
Glutamate respiration CO2 release  51
ATP content / 87
Enzymatic activity  Urease / 293
Phosphatase / 639
Arylsulfatase / 1164
Dehydrogenase / 28
Saccharase / 87
  Protease / 87

Data Aggregation

The selected normalized individual high quality chronic ecotoxicity data of nickel to soil organisms are aggregated according to the criteria mentioned in Guidance: Data Aggregation. An overview of the aged normalized (to the conditions prevailing in the Danish soils) spe-cies mean NOEC/L(E)C10 values for the most sensitive endpoint is provided in Table 2.

SSD Construction and Median HC5 Derivation

The species mean NOEC/L(E)C10 values in Table 2 were further ranked from low to high. Subsequently, a log-normal distribution was fitted through the ranked species mean toxicity data. From this SSD the median 5th percentile was calculated using the ETx model. The SSD and the median HC5 value for the normalized ecotoxicity data to the physico-chemical conditions prevailing in the soils in Denmark are presented in Figure 3.

PNEC Derivation

An AF of 2 is applied to the median HC5 value resulting in a soil PNEC = median HC5 / 2 = 47.0 mg Ni/kg / 2 = 23.5 mg Ni/kg.

The example of the SSD construction and PNEC derivation for nickel, as shown above, only applies for the soil chemistry prevailing in the Danish soils. However, other soil chemistries are encountered in the EU soils resulting, therefore, in the setting of different PNEC values for Ni. These different eco-regions, as shown in Table 3, have been selected in the EU Risk Assessment to provide examples of typical conditions covering a wide range of physico-chemical conditions (pH between 3.0 and 7.5, CEC between 2.4 and 36 cmol/kg, clay between 7 and 46%) occurring in EU soils. Therefore, PNEC values for typical eco-regions in EU soils vary, depending on the soil chemistry, between 4.3 and 96.2 mg Ni/kg. The soil chemistry and median HC5/PNEC values calculated for the different selected eco-regions in EU soils are summarized in Table 3.

Figure 3

 

Table 3: Overview of the Soil Chemistry and Median
HC5/PNEC Values for the Different Selected EU Eco-Regions

Eco-Region Soil Use Soil Chemistry L/A
Factorii
Median HC5 (µg/L) PNEC (µg/L)iii
Acid sandy soil in Sweden Arable land pH 4.8, OM 2.8%, clay 7%, CEC 2.4 cmol/kg 1.05 8.5 4.3
Loamy soil in The Netherlands Arable land pH 7.5, OM 2.2%, clay 26%, CEC 20 cmol/kg 3.01 99.2 49.6
Peaty soil in The Netherlands Grassland pH 4.7, OM 40%, clay 24%, CEC 35 cmol/kg 1.04 186.3 93.2
Acid sandy soil in Germany Forest land pH 3.0, OM 9%, clay 7%, CEC 6 cmol/kg 1.0 25.0 12.5
Clay soil in Greece Woodland pH 7.4, OM 4.5%, clay 46%, CEC 36 cmol/kg 2.75 192.3 96.2
Soils of different types in Denmark Arable & forest land pH 6.3, OM 0.6%, clay 8.9%, CEC 10.4 cmol/kg 1.38 47.1 23.6

 

ii  The term leaching-ageing factor (L/A actor) refers to the combined effect of leaching (due to changing ionic strength) and ageing (due to long-term reactions) on nickel bioavailability and toxicity in soil.

iii  PNEC is calculated using an AF of 2.