Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:
Reliable, guideline confirm skin sensitisation studies (guinea pig maximisation tests) are available for four molybdenum substances: sodium molybdate, ammonium dimolybdate, molybdenum trioxide and roasted molybdenite concentrate, all showing a clear absence of sensitising properties to the skin. It is considered to be very unlikely that the sodium/ammonium/calcium/iron moieties, as contained in some molybdenum substances add any reasons for concern regarding skin sensitisation based on their ubiquitous physiological presence in biota and/or their essential role in human physiology. The four tested substances cover the range of moderately to very soluble substances. Given that (i) all molybdenum substances have been shown to release molybdate as the only relevant molybdenum species upon contact with aqueous media, and (ii) since uptake into/through skin requires dissolution, these four substances are considered to represent worst case surrogates for all other molybdenum substances, so that unrestricted read-across is considered feasible to all other molybdenum substances.

Migrated from Short description of key information:
Not considered to be a skin sensitiser, based on the clear absence of sensitising properties of several molybdenum substances in reliable guinea pig maximisation studies.

Justification for classification or non-classification

No classification required for sensitisation: a range of moderately to very soluble molybdenum substance did not show any sensitising effects in reliable guinea pig maximisation studies. For the lack of toxicological relevance because of their ubiquitous physiological presence in biota and/or their essential role in human physiology of the sodium/ammonium/calcium/iron moieties (which are contained in some molybdenum substances), there are no reasons for concern regarding skin sensitisation for these substances. Further, since these four substances can be considered to represent worst case surrogates for all other molybdenum substances, read-across from the existing data set to all other molybdenum substances is considered to be justified without restriction.