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Environmental fate & pathways

Hydrolysis

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Administrative data

Endpoint:
hydrolysis
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Mill scale is mainly and primarily composed of high-purity iron oxides (on average above 65%, i.e. FeO, Fe2O3, Fe3O4). Besides, other metal oxides and spinels, elements, and trace compounds such as oil residues <1% for all the uses except for batteries and Melting charge for which <3% can be found in the mill scale. More information on the justification of read across can be found in the attached document in the endpoint summaries of section 5 and 6.

Data source

Materials and methods

Test material

Constituent 1
Reference substance name:
Iron
EC Number:
231-096-4
EC Name:
Iron
Cas Number:
7439-89-6
IUPAC Name:
iron(2+)

Results and discussion

Applicant's summary and conclusion

Conclusions:
Under REACH (ECHA 2008, Chapter R.7B – Endpoint Specific Guidance), the term ‘Hydrolysis’ refers to the “Decomposition or degradation of a chemical by reaction with water”, and this as a function of pH (i.e., abiotic degradation). The need for testing may be waived if “The substance is highly insoluble in water), or if “The substance is readily biodegradable”. The latter property of a substance assumes a rapid mineralization of the substance and therefore hydrolysis tests will provide little information. In the case of the current substance ([Me-oxide]), the chemical safety assessment will be based on elemental metal concentrations, regardless of their (pH-dependent) speciation in the environment. Hence, as the assessment is based on the element concentration (i.e., [Fe] ), physicochemical processes like decomposition and degradation by reaction with water are not relevant. Formation of different [Fe]-hydroxides may occur, but the chemical assessment will not make any differentiation among the different [Me]-species (pooling of different speciation forms). This elemental-based assessment (pooling all speciation forms together) can be considered as a worst-case assumption for the chemical assessment. In general, (abiotic) degradation is an irrelevant process for inorganic substances that are assessed on an elemental basis.