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 freshwater organisms.

Database Development

An overview of all accepted individual high quality chronic eco-toxicity 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 river Rhine using the bioavailability models as explained in the Fact Sheet 4. The river Rhine is characterized by a pH of 7.8, a hardness of 217 mg/L CaCO3, and a DOC of 2.8 mg/L.

Data Aggregation

The selected normalized individual high quality chronic ecotoxicity data of nickel to freshwater organisms are aggregated according to the criteria mentioned in Guidance: Data Aggregation.  An overview of the normalized species mean NOEC/L(E)C10 value for the most sensitive endpoint is provided in Table 2.

SSD Construction and Median HC5 Derivation

The normalized 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 HC5 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 river Rhine for nickel are presented in Figure 3.

PNEC Derivation

An AF of 2 is applied to the median HC5 value calculated for the river Rhine results in a freshwater PNEC = median HC5 / 2 = 10.8 µg/L / 2 = 5.4 µg/L.

The example of the SSD construction and PNEC derivation for nickel as shown here above only applies for the water chemistry prevailing in the river Rhine. However, other water chemistries are encountered in EU surface waters (freshwater rivers and lakes) 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 6.67 and 8.2; hardness between 27.8 and 260 mg/L CaCO3, DOC between 2.5 and 27.5 mg/L) occurring in EU surface waters. Therefore, PNEC values for typical eco-regions in EU surface waters vary, depending on the water chemistry, between 3.6 and 21.8 µg Ni/L. The water chemistry and median HC5/PNEC values calculated for the different selected eco-regions in EU surface waters are summarized in Table 3.

Figure 3

 

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

Taxonomic Group   Species Most Sensitive Endpoint  

Species Mean
NOEC/L(E)C10
Value (µg/L)

Algae Scenedesmus accuminatus Growth rate 35.9
  Desmodesmus spinosus Growth rate 61.8
  Pediastrum duplex Growth rate 62.0
  Chlamydomonas sp Growth rate 77.3
  Ankistodesmus falcatus Growth rate 78.8
Chlorella sp Growth rate 115.3
Coelastrum microporum Growth rate 114.1
Pseudokirchneriella subcapitata Growth rate 98.5
Higher plants Lemna minor Growth 41.7
Lemna gibba Growth rate 23.3
Rotifer Brachionus calyciflorus Intrinsic rate of growth 670.6
Molluscs Lymnaea stagnalis Growth 6.7
Juga plicifera Mortality 109.7
Cladocerans Ceriodaphnia dubia Reproduction 7.5
Ceriodaphnia quadragula Mortality 20.4
Peracantha truncata Reproduction 26.1
Simocephalus vetulus Reproduction & mortality 35.9
Ceriodaphnia pulchella Reproduction & mortality 35.8
Alona affinis Mortality 41.5
Daphnia longispina Mortality 56.6
Daphnia magna Reproduction 50.7
Insects Clistoronia magnifica Mortality 62.2
Chironomus tentans Biomass 481.7
Hydrozoans Hydra littoralis Growth 369.0
Amphipods Hyalella azteca Mortality 94.3
Fish Brachydanio rerio Hatchability 99.2
Pimephales promelas Growth 108.7
Oncorhynchus mykiss Growth 324.5

Amphibians

Xenopus laevis Malformation 293.3
Gastrophryne carolensis Mortality 384.3
Bufo terrestris Growth 1265.9

   

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

Eco-Region Water Chemistry  Median HC5 (µg/L)  PNEC (µg/L)ii
Ditch in The Netherlands pH 6.9, H 260 mg/L, DOC 12.0 mg/L 43.6 21.8
River Otter in the United Kingdom pH 8.1, H 165 mg/L, DOC 3.2 mg/L 8.1 4.1
River Teme in the United Kingdom  pH 7.6, H 159 mg/L, DOC 8.0 mg/L 19.0 9.5
River Rhine in The Netherlands pH 7.8, H 217 mg/L, DOC 2.8 mg/L 10.8 5.4
River Ebro in Spain pH 8.2, H 273 mg/L, DOC 3.7 mg/L 8.7 4.4
Lake Monate in Italy pH 7.7, H 48.3 mg/L, DOC 2.5 mg/L 7.1 3.6
Neutral-acidic lake in Sweden pH 6.7, H 27.8 mg/L, DOC 3.8 mg/L 12.1 6.1

 ii  PNEC is calculated using an assessment factor of 2.