Tin antimony grey cassiterite

Endpoint summary

Description of key information

The rate and extent to which tin antimony grey cassiterite produces soluble (bio)available ionic and other tin, antimony or vanadium bearing species in environmental media is limited. Further, the poor solubility of tin antimony grey cassiterite is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity. Proprietary studies are not available for tin antimony grey cassiterite. However, the fate and toxicity of tin antimony grey cassiterite in the environment is evaluated by assessing the fate of its ecotoxicologically relevant moieties, the tin, antimony and vanadium ions.

 

Regarding the acute (short-term) aquatic toxicity, the poorly soluble substance tin antimony grey cassiterite is evaluated by comparing the dissolved metal ion level resulting from the T/Dp after 7 d at a loading rate of 1 mg/L with the acute ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. Dissolved antimony, tin and vanadium concentrations of 0.40 µg/L, 5.71 µg/L and 0.18 µg/L, respectively, in the T/Dp after 7 days at pH 8 (i.e. the pH that maximizes the dissolution) are significantly lower than the corresponding acute Ecotoxicity reference levels (ERVs) (Sb = > 1770µg/L (EU, 2008), Sn = 9800 µg/L and V = 693 µg/L (MECLAS v 5.2)). Hence, the substance tin antimony grey cassiterite is not sufficiently soluble to cause short-term toxicity at the level of the acute ERV (expressed as the EC50/LC50). Two supporting non-GLP studies on the acute toxicity of the dispersed pigment on zebrafish (OECD TG 203) and Daphnia magna (OECD TG 202) provide further evidence on the low potential for acute aquatic toxicity since effects were not observed at 100 mg/L (nominal, dispersed) and the respective LC/EC50 values are estimated with > 100 mg/L (nominal, dispersed).

 

Regarding the long-term aquatic toxicity, tin antimony grey cassiterite is evaluated by comparing the dissolved tin, antimony and vanadium ion level resulting from the T/Dp at a loading rate of 1 mg/L after 28 d with the lowest chronic ERVs. Dissolved antimony, tin and vanadium concentrations of 0.61 µg/L, 8.89 µg/L and 0.21 µg/L in the T/Dp after 28 days at pH 8 (i.e. the pH that maximizes the dissolution) are significantly lower than respective chronic toxicity levels (Sb = > 1000µg/L (EU, 2008), Sn = 1001 µg/L and V = 76 µg/L (MECLAS v 5.2)). Hence, the substance tin antimony grey cassiterite is not sufficiently soluble to cause chronic toxicity at the level of the chronic ERV (expressed as the NOEC).

Based on the poor solubility of tin antimony grey cassiterite in environmental media, it is concluded that tin antimony grey cassiterite is not acutely and chronically toxic to aquatic freshwater organisms. Thus, tin antimony grey cassiterite is not a classified or non-classified acute and chronic hazard to aquatic organisms.

Additional information

Tin antimony grey cassiterite is poorly soluble in environmental media. Based on ECHA’s Guidance on the Application of the CLP Criteria (Version 5.0, July 2017), “the hazard classification schemes for metals and metal compounds are limited to the acute and long-term hazards posed by metals and metal compounds when they are available (i.e. exist as dissolved metal ions, for example, as M+ when present as M-NO3), and do not take into account exposures to metals and metal compounds that are not dissolved in the water column but may still be bioavailable, such as metals in food…”.

 

For poorly soluble metals and inorganic metal compounds that cannot be easily tested in aquatic toxicity test, the following is stated: ”where the compound is sufficiently poorly soluble that the levels dissolved following normal attempts at solubilisation do not exceed the available L(E)C50, it is the rate and extent of transformation, which must be considered.”

 

According to ECHA’s Guidance on IR & CSA, Appendix R.7.13-2 (2008), “in some cases, the metal compound will be only poorly soluble and sufficiently stable to not rapidly transform to a water soluble form. Under these circumstances, the substance itself should be assessed taking into account its specific partitioning characteristics. For the aquatic environment, it can be assumed as a first estimate that the substance will dissolve up to its water solubility limit, and that this fraction will be the bioavailable form. Refinement of the assessment can be done by taking into account kinetics of the dissolution… In case ecotoxicity data are lacking for a specific metal or metal compound, read-across ecotoxicity data from other inorganic compounds of the same metal could be considered. The basic assumption using this approach is that it is the bioavailable metal fraction that is causing the effects (e.g. free metal ion or other specific metal species complexes (e.g. CuOH+). Ecotoxicity data of simple soluble metal salts can be combined on condition that the metal ion is responsible for the effects observed for the metal salts considered (e.g. CuSO4, CuCl2). Appropriate standard ecotoxicity effects data (acute, chronic) measured for such soluble metal salt are thus combined by expressing the effects data (NOECs and PNEC) as dissolved (bioavailable) metal ion concentration (μg Me/L)”.

 

ECHA’s Guidance on the Application of the CLP Criteria (Version 5.0, July 2017) further states that “A decision on whether or not the substance is classified will be made by comparing aquatic toxicity data and solubility data.”

 

The solubility of tin antimony grey cassiterite in environmental media is low. In a short-term transformation/dissolution test with a loading of 100 mg/L, a dissolved antimony, tin and vanadium concentrations of 2.57 microg/L, 8.26 microg/L, and 4.51 microg/L, respectively, was determined at pH 8 after 7 days. Transformation/dissolution at a loading of 1 mg/L resulted in dissolved antimony, tin and vanadium concentrations of 0.40 µg/L, 5.71 µg/L and 0.18 µg/L, respectively, at pH 8 after 7 days and 0.61 µg/L, 8.89 µg/L and 0.21 µg/L, respectively, at pH8 after 28 days.

 

In sum, tin antimony grey cassiterite can be considered environmentally and biologically inert during short- and long-term exposure.