Strontium sulphide

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Skin sensitisation

Testing with a corrosive substance is not allowed due to animal welfare and in accordance with section 8.3, column 2, Annex VII of regulation (EC) 1907/2006). Since strontium sulfide was tested to be corrosive to skin with a pH value of 12.6 (1% solution), testing is not justified.

Nevertheless, the sensitisation potential may reasonably be considered by the availability of strontium cations and sulfide anions.

Strontium:Upon dissolution in water and/or physiological media, dissociation of strontium sulfide to release Sr²⁺ions may initially be expected.

However, based on the established fact that strontium ions may form poorly soluble species for example with physiologically present carbonate ions, the bioaccessibility/bioavailability may vary between different physiological conditions. In this context, the water solubility of a substance is used as a first approximation of bioavailability:

-     strontium dichloride is highly water soluble with ca. 538 g/L at 20°C/pH ca. 7 (solubility at pH 1.5; 257.5 g/L at 37°C)

In comparison, the water solubility of strontium sulfide is 120.6 ± 1.9 g/L at 24 ± 1.0 °C pH 12.9.

In conclusion, read across from strontium chlorideto strontium sulfide is considered as justified since the toxicity of these substances may reasonably be considered to be determined by the availability of Sr cations. It is noted that although SrS is a strong base (pH 12.6 for a 1% solution - source: Anonymous, 2009), substantial neutralisation in the gastrointestinal tract at pH-levels of approx. 1.5 – 2 may nevertheless be anticipated.

Sulfides: Sulfides may be seen as ions endogenously occurring under physiological conditions, so that their role in normal human metabolism suggests that a sensitisation potential does not necessarily need to be expected.

In addition it could be stated that long time experience in handling with strontium substances and sulfides does not show any sensitising effects in humans.

Summarising that the LLNA study conducted with strontium dichloride hexahydrate causes no sensitising effects to skin and read across to soluble strontium substances (i. e., strontium dichloride) is justified, a sensitisation potential for strontium sulfide can safely be excluded.

Reference:Anonymous (2009): Solfuro di strontio, ECOL Studio S. R. L., Via Dei Bichi 293, 55100 Lucca, Italia, 2009-12-30

Migrated from Short description of key information:
No data are available on skin sensitisation of strontium sulfide. As strontium sulfide is classified for skin corrosivity and has a pH value 12.6 (1% solution) no testing needs to be initiated. However, testing with strontium dichloride hexahydrate was conducted and study result indicates that the test item is considered not to be skin sensitising.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the outcome of the sensitisation study according OECD 406 conducted with strontium dichloride hexahydrate and under consideration of read-across (see discussion) it can be concluded that strontium sulfide does not have a sensitisation potential and therefore must not be classified and labelled according to Directive 67/548/EEC and Regulation (EC) 1272/2008.