Cobalt(2+) C3/C10 carboxylates salts

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Salt reaction of cobalt(2+) and C3/C10 carboxylates will be classified as skin sensitiser according to section 3.4, annex I of Regulation (EC) 1272/2008 based on animal data from the read-across substance cobalt(II) 4-oxopent-2-en-2-olate with similar bioaccessibility in artificial perspiration (Group 1: High release of cobalt ion in artificial sweat – marked skin sensitisation - Source substances: Co acetyl acetonate, Co dichloride with similar bioavailability - worst case approach with reference to Cobalt propionate).

Read-across entails the use of relevant information from analogous substances (the ‘source’ information) to predict properties for the ‘target’ substance(s) under consideration. Substances whose physicochemical or toxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a category of substances. Structural similarity is a pre-requisite for any read-across approach under REACH (ECHA Read-Across Assessment Framework, 2015).

In accordance with Annex XI, 1.5 of the REACH regulation and the ECHA Guidance Read-Across Assessment Framework (ECHA, 2017), the similarities may be based on:

1) A common functional group (i.e. chemical similarity within the group);

2) Common precursors and/or likelihood of same breakdown products through physical and/or biological processes which result in structurally-similar degradation products (i.e. similarity through (bio) transformation); or

3) A constant pattern in the changing of the potency of the properties across the group (i.e. of physical-chemical and/or biological properties).

Due to the absence of substance specific information for the majority of substances within the cobalt category, the approach will read-across data from representative source substances to all other members of the read-across group.

Due to the route-specific toxicological properties of the cobalt category substances, several read-across groups are formed. For the endpoint skin sensitisation, the following read-across groups are formed:

Group 1: High release of cobalt ion in artificial sweat – marked skin sensitisation

Source substances: Co acetyl acetonate, Co dichloride

Group 2: Moderate release of cobalt ion in artificial sweat – moderate skin sensitisation

Source substances: Co metal powder

Group 3: Moderate release of cobalt ion in artificial sweat – mild skin sensitisation

              Source substances: Co monoxide

Group 4: Low release of cobalt ion in artificial sweat – no skin sensitisation

Source substances: Tricobalt tetraoxide, Co lithium oxide

Group 5: Variable release of cobalt ion in artificial sweat, moderate skin sensitisation (Cobalt substances with long-chain (>C10) ligands)

              Source substances: Co stearate, Co naphthenate

Group 6: Variable release of cobalt ion in artificial sweat, marked skin sensitisation (Cobalt substances with long-chain (>C10) ligands)

              Source substances: Co resinate

Further details on the read-across approach for skin sensitisation and discussion of the underlying hazard data are given in the read-across report attached in IUCLID section 13.2.

Justification for selection of skin sensitisation endpoint:  Key study

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There is no known direct experience or epidemiological information implicating this substance as occupational respiratory sensitizer.

Justification for classification or non-classification

Skin Sensitisation

Salt reaction of cobalt(2 +) and carboxylates C3/C10 will be classified as skin sensitiser, category 1A (H317) according to section 3.4, annex I of regulation (EC) 1272/2008 based on animal data from the read-across substance cobalt(II) 4-oxopent-2-en-2-olate with similar bioaccessibility in artificial perspiration (Group 1: High release of cobalt ion in artificial sweat – marked skin sensitisation - Source substances: Co acetyl acetonate, Co dichloride - worst case approach with reference to Cobalt propionate).

 

Respiratory sensitisation

There is no known direct experience or information implicating this substance as occupational respiratory sensitiser. Thus classification criteria according to regulation (EC) 1272/2008 as respiratory sensitiser are not met.