Concentrates of lead and zinc compounds with sulfur resulting from hydrometallurgy (hot acid leaching, super-hot acid leaching and flotation)

Short-term toxicity to aquatic invertebrates

Description of key information

According to transformation/dissolution study (OECD guidance 29) conducted for the substance, the most critical constituents leachable to water from this UVCB substance are lead and zinc compounds. Therefore, the chemical safety assessment focuses on the properties of constituents and the key values for CSA are selected based on the read-across data on the most bioavailable compounds of Pb and Zn.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

26.4 µg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

9.2 µg/L

Additional information

The environmental hazard assessment was conducted based on the most critical constituents of the substance. This substance is an inorganic UVCB substance and can be described as a moist solid powder which is insoluble to water. Therefore, the transformation/dissolution study (OECD guidance 29) was conducted for the substance and the results of this study were used for the chemical safety assessment.

According to the chemical composition analysis, the main phases of the substance are lead sulphate and zinc sulphide. The product consists primarily of sulphur (ca. 35 %), lead (ca. 25 %) and zinc (ca. 17 %) together with minor trace elements such as silver, silicon, aluminium, calcium and iron.

According to T/D study results, the most soluble and critical components of this substance are lead and zinc. Therefore, the studies for this endpoint have been selected as a read-across data for the critical constituents. The read-across justification is presented in CSR annex I. All read-across data for ecotoxicology are based on test data using either soluble Pb or Zn salts or measured (dissolved) Pb or Zn concentrations. The weight of evidence approach was used to make conclusions on the key value for CSA.

Toxicity of lead and its compounds

Freshwater

For invertebrates, 43 individual reliable acute toxicity data points for two different species were put forward for hazard assessment purposes. The acute toxicity values (48h-LC50) for Ceriodaphnia dubia varied between of 26.4 µg dissolved Pb/L (at pH 8.1 and hardness of 25 mg/L) and 3115.8 µg dissolved Pb/L (at pH 8.15 and hardness of 103.2 mg/L). The acute toxicity values (48h-LC50) for Daphnia magna varied between of 107.0 µg dissolved Pb/L (at pH 8.3 and hardness of 152 mg/L) and 108.8 µg dissolved Pb/L (at pH 7.6 and hardness of 54 mg/L).

The lowest freshwater toxicity (EC50 48-h, Ceriodaphnia dubia, (mortality)) value: 26.4 µg/L (EPA-823-B-94-001)

Marine:

Acute marine NOEC/L(E) C10 values are available for 2 echinoderms (Strongylocentrotus purpuratus, Dendraster excentricus), 3 bivalve molluscs (Mytilus galloprovincialis, Mytilus trossolus, Crassostrea gigas) and 1 annelid (Neanthes arenaceodentata). No-effect levels for dissolved lead for marine invertebrates were situated between 9.2 µg Pb/L (Mytilus trossolus; endpoint: abnormalities) and 1409.6 µg Pb/L (Mytilus galloprovincialis; endpoint: mortality).

The lowest marine toxicity (EC10 48-h, Mytilus trossolus (abnormal development in embryos)) value: 9.2 µg (CI 2 - 19 µg, EPA 2006)

Toxicity of zinc and its compounds

Freshwater

Ecotoxicity data is available from 5 standard species is relevant and good quality. Tests were done according to standard protocol or equivalent.

Key data (lowest EC50 values) are for Ceriodapnia dubia: 0.413 mg Zn/l (single value) at low pH and low hardness, for Ceriodapnia dubia: >0.53 mg Zn/l (single value) at low pH and high hardness, for Ceriodapnia dubia: 0.147 mg Zn/l (geometric mean value) at neutral/high pH and low hardness and for Ceriodapnia dubia: 0.228 mg Zn/l (geometric mean value) at neutral/high pH and high hardness.

The lowest freshwater toxicity value (EC50 48-h, Ceriodapnia dubia (mobility)): 0.413 mg Zn/l (CI 388-437 µg/l, US EPA EPA 821-R-02-012)

Marine

No data

Conclusions for CSA:

Toxicity of the test substance is evaluated by using WoE read-across data from the two critical components of the test substance (zinc and lead). From the toxicity data, lead has the lowest key values for short-term toxicity to invertebrates. Therefore, the toxicity values from lead were used as key values for CSA. However, as lead and zinc are both relevant for environmental ES&RC, key values from both constituents were used for PNEC-derivation and taken into account in the exposure assessment (CSR sections 9&10).