Reaction mass of cobalt olivine and crystalline silicon dioxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.62 µg/L

Assessment factor:

3

Extrapolation method:

sensitivity distribution

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

2.36 µg/L

Assessment factor:

3

Extrapolation method:

sensitivity distribution

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.37 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

53.8 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

69.8 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

assessment factor

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

10.9 mg/kg soil dw

Assessment factor:

2

Extrapolation method:

sensitivity distribution

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Reaction mass of cobalt olivine and crystalline silicon dioxide is moderately soluble in environmental media. Based on results of a standard transformation/dissolution test according to OECD Series No 29, the dissolution at a loading of 1 mg/L Reaction mass of cobalt olivine and crystalline silicon dioxide results at pH 6, the pH that maximises dissolution, in dissolved cobalt levels of 101 µg Co/L and 138 µg Co/L after 7 and 28 days, respectively. Thus, the rate and extent to which Reaction mass of cobalt olivine and crystalline silicon dioxide produces soluble (bio)available ionic and other cobalt-bearing species in environmental media is limited. Reaction mass of cobalt olivine and crystalline silicon dioxide contains also silicon, but silicon does not have an ecotoxic potential (see OECD SIDS Silicon dioxide, 2004), as also confirmed by the absence of respective ecotoxicity reference values in the Metals classification tool (MeClas) database (http://www.meclas.eu/ accessed on 18.04.2021).

Further, the limited solubility of Reaction mass of cobalt olivine and crystalline silicon dioxide is expected to determine its behaviour and fate in the environment, and subsequently its bioavailability and potential for bioaccumulation and ecotoxicity. A conservative read-across approach is applied based on all information available for different inorganic cobalt substances and the fate of the released cobalt ions can ultimately be expected to be similar to the common fate of cobalt ions in the environment. For further information on the applied read-across approach, please refer to the RAAF document “Read-across approach for environmental toxicity of the pigments “Reaction mass of cobalt olivine and crystalline silicon dioxide” & “Olivine, cobalt silicate blue", 2021 attached in IUCLID Section 13.

The PNEC and ERV derivations for cobalt ions are explained in section "7.6. PNEC derivation and other hazard conclusions" of the respective CSR of substances in the “Cobalt Category”, including cobalt dichloride (EC # 231-589-4, CAS # 7646-79-9).

Conclusion on classification

Reaction mass of cobalt olivine and crystalline silicon dioxide contains cobalt and silicon, but silicon does not have an ecotoxic potential (see OECD SIDS Silicon dioxide, 2004), as also confirmed by the absence of respective ecotoxicity reference values in the Metals classification tool (MeClas) database (http://www.meclas.eu/ accessed on 18.04.2021). Thus, the aquatic hazard potential of the substance Reaction mass of cobalt olivine and crystalline silicon dioxide is evaluated by comparing the dissolved cobalt levels resulting from the transformation/dissolution test after 7 and 28 days at a loading rate of 1 mg/L at pH 6, the pH that maximises dissolution, with the lowest acute and chronic ecotoxicity reference values (ERVs), respectively, as determined for the (soluble) cobalt ion. The reported ERVs for cobalt ions are as follows:

Acute:             Lemna minor:              52.0 μg/L

Chronic:          Hyalella azteca:           7.6 μg/L

The dissolution of Reaction mass of cobalt olivine and crystalline silicon dioxide results in dissolved cobalt levels of 101 µg Co/L and 138 µg Co/L after 7 and 28 days, respectively (Kopf, 2014).

Regarding the potential for short-term toxicity, the dissolved cobalt concentration of 101 µg Co/L in the T/D test after 7 days at pH 6 is higher than the acute ERV for Lemna minor of 52.0 μg Co/L. Hence, the substance Reaction mass of cobalt olivine and crystalline silicon dioxide may be considered sufficiently soluble to cause short-term toxicity at the level of the acute ERV for cobalt ions.

According to ECHA (2017b), “An ecotoxicity validation step may be important for alloys and complex metal containing materials (e.g. ores, concentrates, slags), where binding of the metal to abiotic and biological binding sites will in many cases be competitive.” Further, according to the T/D protocol (OECD Series No 29), “For hazard classification purposes the results of the dissolution / transformation protocol are compared with existing ecotoxicity data for metals and metal compounds. However, for purposes such as data validation, there might be cases where it may be appropriate to use the aqueous medium from a completed transformation test directly in an OECD202 and 203 daphnia and fish ecotoxicity test. If the CaCl2.2H2O and MgSO4.7H2O concentrations of the transformation medium are reduced to one-fifth of the ISO 6341 medium, the completed transformation medium can also be used (upon the addition of micronutrients) in an OECD 201 algae ecotoxicity test.”

Accordingly, short-term ecotoxicity validation tests were performed with Reaction mass of cobalt olivine and crystalline silicon dioxide for all three trophic levels, i.e. the toxicity of the dissolved fractions of individual loadings after 7 days of dissolution of Reaction mass of cobalt olivine and crystalline silicon dioxide was tested. Respective EC/LC50 values for the short-term toxicity to daphnia and fish are above 1000 mg/L (Schlechtriem, 2013; Teigeler, 2013), respectively, whereas the 72-h EC50 for the effect on growth rate of freshwater alga (Pseudokirchneriella subcapitata) amounts to 89 mg/L (Wenzel, 2013). Altogether, the aquatic toxicity data of Reaction mass of cobalt olivine and crystalline silicon dioxide indicate that its potential for acute toxicity is significantly lower than the acute aquatic toxicity of soluble cobalt salts. The EC/LC50 values of Reaction mass of cobalt olivine and crystalline silicon dioxide for all three trophic levels are above the classification criteria for acute (short-term) aquatic hazard. In accordance with Table 4.1.0 (a) of Regulation (EC) No 1272/2008, the substance Reaction mass of cobalt olivine and crystalline silicon dioxide does not meet classification criteria for acute (short-term) aquatic hazard.

Regarding the potential for long-term toxicity, the dissolved cobalt concentration of 138 µg Co/L in the T/D test after 28 days at pH 6 is higher than the long-term ERV of cobalt ions of 7.6 μg/L for aquatic invertebrates (Hyalella azteca). Hence, the substance Reaction mass of cobalt olivine and crystalline silicon dioxide may be considered sufficiently soluble to cause long-term toxicity at the level of the chronic ERV for cobalt ions. The cobalt ion satisfies the requirements for “rapid environmental transformation, i.e. > 70% removal from the water column in 28 days and limited sediment remobilisation potential under most environmental conditions.

Based on the maximum cobalt content of 50.3 % for Reaction mass of cobalt olivine and crystalline silicon dioxide, the chronic ERV of cobalt ions can be recalculated for Reaction mass of cobalt olivine and crystalline silicon dioxide resulting in an ERV of 15.1 μg/L. In accordance with Table 4.1.0 (b) (ii) of Regulation (EC) No 1272/2008, the substance Reaction mass of cobalt olivine and crystalline silicon dioxide would meet classification criteria for long-term aquatic hazard Category 2.

For a more accurate refinement, the dissolution rate of Reaction mass of cobalt olivine and crystalline silicon dioxide is taken into account, and the ERV for Reaction mass of cobalt olivine and crystalline silicon dioxide is calculated from the chronic ERV of cobalt and the transformation/dissolution data of Reaction mass of cobalt olivine and crystalline silicon dioxide obtained under the same circumstances as follows:

ERV(Pigment) = ERV(Co++) x loading(Pigment) in TD test / dissolved concentration (Co+) measured after 28 days in TD test, resulting in an ERV of 55.07 μg/L. In accordance with Table 4.1.0 (b) (ii) of Regulation (EC) No 1272/2008, the substance Reaction mass of cobalt olivine and crystalline silicon dioxide would also meet classification criteria for long-term aquatic hazard Category 2.

Hence, the substance Reaction mass of cobalt olivine and crystalline silicon dioxide is considered sufficiently soluble to cause long-term toxicity at the level of the chronic ERV for cobalt ions and in accordance with Table 4.1.0 (b) (ii) of Regulation (EC) No 1272/2008 meets classification criteria for long-term aquatic hazard Category 2. These hazard conclusions are in agreement with classification conclusions of the Metals classification tool (MeClas) database (http://www.meclas.eu/ accessed on 18.04.2021).

In sum, the substance Reaction mass of cobalt olivine and crystalline silicon dioxide is of limited solubility and does not meet classification criteria of Regulation (EC) No 1272/2008 for acute (short-term) aquatic hazard but meets criteria for chronic (long-term) aquatic hazard Category 2.