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

Endpoint summary

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.

The transformation and dissolution study (OECD guidance 29) results indicated that the release at pH 6 was higher for all studied elements compared to release at pH 8. Therefore the following 7 and 28 day studies were conducted at pH 6. Based on the screening test results (loading rate 100 mg/L), the most critical components for the assessment were lead and zinc, with releases of 8282 µg/L and 75.4 µg/L, respectively. The other minor leachable metals were silver (34.7 µg/L), cadmium (0.48 µg/L) and copper (17.2 µg/L). Results from the 7 day T/D test (loading rate 100 mg/L, pH 6) showed similar trend in release rates: 12333 µg/L (Pb), 91.4 µg/L (Zn), 15.6 µg/L (Cu), 31.4 µg/L (Ag) and 0.056 µg/L (Cd). In the 28 day test with lower loading rate (1 mg/L, pH 6), only concentrations of Pb (362.4 µg/L) and Zn (3.2 µg/L) were over the detection limits or blank sample values.

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. Conclusions for relevant endpoints are based on read-across data from zinc and lead compounds.

Aquatic toxicitykey values for CSA:

Short-term effects on fish

Key value for CSA:

Freshwater

Lead: 40.8 µg/L value: (EC50 96-h, Pimephales promelas (mortality), 95 % CI: 32.1- 48.3, US EPA 2002)

Zinc: 0.169 mg Zn/l (EC50 96-h, Oncorhynchus mykiss (mortality), 95% CI 118-243, ASTM E-729-88)

Long-term effects on fish

Key value for CSA:

Freshwater:

Lead: 18.9 µg/l (NOEC 570-d, Oncorhynchus mykiss (abnormalitites (scoliosis)), CI 18.2-19.6 µg/L, no guideline)

Zinc: 0.039 mg/l (NOEC 30-d, Oncorhynchus mykiss (mortality), OECD 215)

Marine:

Lead: 229.6 µg/l (NOEC 28-d Cyprinodon variegate (dry weight), s, CI 155.1 - 339.9 µg/L, ASTM Method E1241 2003)

Zinc: 0.025 mg (NOEC 27-d, Clupea harengus (development), no guideline)

Short-term toxicity to aquatic invertebrates

Key value for CSA:

Freshwater:

Lead 26.4 µg/L (EC10 48-h, Ceriodaphnia dubia (mortality), EPA-823-B-94-001)

Zinc: 0.413 mg Zn/l (EC50 48-h, Ceriodapnia dubia (mobility), IC 388-437 µg/l, US EPA EPA 821-R-02-012)

Marine:

Lead: 9.2 µg (EC10 48-h, Mytilus trossolus (abnormal development in embryos), CI 2 - 19 µg, EPA 2006)

No saltwater results from zinc.

Long-term effects on aquatic invertebrates

Key value for CSA:

Freshwater:

Lead: 1.7 µg Pb/L (30-d EC10, Lymnaea stagnalis (reproduction), 95 % IC 0.8-3.7 µg/L, EPA 2002)

Zinc: 0.037 mg/L (NOEC 3-wk, Daphnia magna (growth), no guideline)

Marine:

Zinc: 0.0056 mg/L (NOEC 24-d, Holmesimysis costata, (mortality), EPA/600/R-95-136)

Lead: 95.9 µg (126-d EC10, Neanthes arenaceodentata, (juvenile emergence), 95 % IC 40.8-225.3 µg, ASTM Method E1562)

Algae and aquatic plants

Key value for CSA:

Freshwater:

Lead: 21.7 µg/L (48-h EC50, Pseudokirchneriella subcapitata (growth rate), 95 % CI 20.1-23.5 µg/L, OECD 201)

Zinc: 0.136mg/L (72-h IC50, Pseudokirchnerella subcapitata (growth rate), OECD 201)

Marine

Lead: 52.9 µg/l (96-h EC10, Skeletonema costatum (average specific growth rate), 95% CI 42.3 - 66.3 µg, ASTM E1218 2006)

Zinc: 7.2 mg/kg (EC10 7-d, Ceramium tenuicore, (length), according to author the test will become an international standard within ISO).

Effects on aquatic plants other than algae

Key value for CSA:

Freshwater:

Lead: 29.5 µg/L (7-d IC50, Lemna minor (root length), 95% IC18.9-45.9 µg/L, OECD 221)

Zinc: 60 µg/L (3-d NOEC, Cladophora glomerata (growth rate), no guideline)

Toxicity to microorganisms

Key value for CSA:

Zinc: 0.1 mg/L (4-h NOEC (nitrification rate), ISO DIS 9509)

Lead: 1 mg/L (24-h IC10, (mortality (visually derived)), no guideline)

Sediment organisms

Key value for CSA:

Freshwater

Zinc: 201 mg/kg (NOEC 35-d, Gammarus pulex (growth), Culturing conditions similar to OECD (2005))

Lead: 573 mg/kg (28-d EC10, Tubifex tubifex (reproduction), 95% CL: 392-629 µg/kg, ASTM E1383-94)

Marine:

Zinc: 250 mg/kg (30-wk NOEC, Avicennia marina (growth and survival), OECD 208)

Lead: 680 mg/kg (28-d EC10, Neanthes arenaceodentata (growth rate), conducted following the WES chronic sublethal test method)

Other aquatic organism:

Value used for CSA:

Zinc: 14 mg/L (14-wk NOEC, Chlorophyta (chlorophyta eveness), no standard guideline)

No results from lead.