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

Long-term toxicity to fish

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 fish

Fresh water fish

Effect concentration:

18.9 µg/L

Marine water fish

Marine water fish

Effect concentration:

229.6 µg/L

Additional information

The environmental hazard assessment was conducted based on the most critical constituents of the substance. The critical constituents were selected based on the transformation/dissolution study (OECD guidance 29) was conducted for the substance target substance.

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 compound

Freshwater:

The high quality chronic freshwater database contains toxicity data towards lead for 6 freshwater fish species (Oncorhynchus mykiss, Salvelinus fontinalis, Pimephales promelas, Lepomis macrochirus, Salvelinus namaycush, Ictalurus punctatus, Salmo salar). No-effect levels for dissolved lead for fish were situated between 18.9 µg Pb/L (Oncorhynchus mykiss; endpoint: scoliosis) and 1558.6 µg Pb/L (Pimephales promelas; endpoint: dry weight).

The lowest chronic toxicity (NOEC 570-d Oncorhynchus mykiss (abnormalitites: scoliosis)) value: 18.9 µg/l (CI 18.2-19.6 µg/L, no guideline)

Marine:

The chronic toxicity database for marine fish contains result for 1 marine fish with NOEC 28 -d result of 229.6 µg/l (Cyprinodon variegatus, endpoint: dry weight).

The lowest toxicity (NOEC 28-d, Cyprinodon variegatus (dry weight)) value: 229.6 µg/l (CI 155.1 - 339.9 µg/L, ASTM Method E1241 2003)

Toxicity of zinc and its compounds

Freshwater

Species NOECs have been put into the respective species sensitivity distributions. Extensive high quality chronic data were available on 7 (freshwater) and 1 (marine) fish species. These data were all screened for relevancy to the environment under study.

The freshwater species are part of 4 families: Cyprinodontidae (Jordanella), Cyprinidae (Phoxinus, Pimephales), Salmonidae (Oncorrhynchus, Salvelinus, Salmo trutta) and Cottidae (Cottus). Species NOECs range between 0.044 and 0.530 mg Zn/l (dissolved concentrations). The sensitivity of these species is equally distributed over the species sensitivity distribution. The fish species NOECs are combined with the other freshwater chronic data in the SSD to give the HC5 from which the PNEC is derived. Lowest single NOEC was 0.039 mg/L (NOEC 30-d Oncorhynchus mykiss).

The lowest toxicity (NOEC 30-d, Oncorhynchus mykiss (mortality)) value: 0.039 mg/l (OECD 215)

Marine

The saltwater species comes from the family Clupeidae (Clupea harengus). This species is not among the most sensitive ones in the species sensitivity distribution. The fish species NOEC is combined with the other marine chronic data in the SSD to give the HC5 from which the PNEC saltwater is derived. NOEC = 0.025 mg Zn/l (NOEC 27-d Clupea harengus) (dissolved concentrations)

The lowest toxicity (NOEC 27-d, Clupea harengus (development)) value: 0.025 mg (no guideline)

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 long-term toxicity to fresh water fish. 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 taken into account in the exposure assessment (see section 9&10 of CSR). All relevant fish chronic values for lead and zinc were used as a part of the PNEC derivation (statistical extrapolation method).