Cobalt(2+) hydrogen citrate

PBT assessment

PBT assessment: overall result

PBT status:

PBT assessment does not apply

Justification:

Cobalt hydrogen citrate is a metal-organic salt and composes of cobalt (Co²⁺) and hydrogen citrate (HC6H5O7²⁻) ions. Thus, a PBT assessment based on the criteria set out in the "Guidance on information requirements and chemical safety assessment, Chapter R.11. PBT Assessment (ECHA 2012)” is not fully applicable to the substance. The PBT and vPvB criteria of Annex XIII to REACH Regulation (EC) No 1907/2006 shall not be applied to inorganic substances. Nevertheless for persistence, bioaccumulation, and toxicity the following conclusions can be drawn:

Persistence Assessment

The persistence criterion can only be applied to organic substances determining the lack of degradability of a substance which remains bioavailable. Inorganic metal compounds tend to be present in non-bioavailable forms so the key criterion for classifying inorganic metal compounds should be their capacity to transform in a bioavailable form.

For the inorganic cobalt ion the approach of persistence assessment is not applicable. The organic molecular (citrate) group is readily biodegradable, and also cobalt citrate has been shown to be readily biodegradable according to OECD 301C. Therefore, the test substance does not have potential of persistence according to the screening criteria of P and vP.

Bioaccumulation Assessment

Similarly, the bioaccumulation criterion can only be applied to organic substances, based on lipid partitioning of the substances. In contrast, uptake of inorganic metals is not based on lipid partitioning. Furthermore, organisms have internal mechanisms to regulate the uptake of essential metals and to control the presence of other metals.

For the inorganic cobalt ion, the approach of bioaccumulation assessment is not applicable. Cobalt is essential for regular operation of human vascular and metabolic systems. For this case, removal and sequestration processes that minimize toxicity are complemented by an ability to regulate concentrations for essentiality. As the result that concentrations of essential mineral nutrients in organisms tend to be highly regulated, such essential metals do not need to be classified as “bioaccumulative”.

The citrate group is the only organic molecule present in the test substance. As it is readily biodegradable and easily metabolised in organisms, the test substance is not considered to have potential of bioaccumulation in accordance with the screening criteria for B and vB.

Toxicity Assessment

Only the toxicity criterion can be applied to inorganic metal compounds taking into account that the amount of soluble metal salts can be reduced by different media (by reducing the bioavaliable fraction of the metal). The toxicity criterion will not be fulfilled for ecotoxicity with no ecologically relevant NOECs less than 0.01 mg/L. However, the substance is classified as carcinogenic (cat. 1 or 2), mutagenic (cat. 1 or 2), or toxic for reproduction (cat. 1, 2 or 3) according to Directive 67/548/EEC or carcinogenic (cat. 1A or 1B), germ cell mutagenic (cat. 1A or 1B), or toxic for reproduction (cat. 1A, 1B or 2) according to Regulation (EC) No. 1272/2008 according to Regulation (EC) No. 1272/2008. Thus, the criterion set out in Annex XIII of Regulation (EC) No. 1907/2006 is met and the substance is considered to meet the T criterion.