Cobalt Nickel Manganese Oxide

Carcinogenicity

Description of key information

It is proposed to classify for carcinogenicity based on properties of some nickel and cobalt salts. Certain salts of nickel and cobalt have harmonised classifications for carcinogenicity via mechanisms which are understood and have thresholds. If exposures to nickel and cobalt from the registered substance are limited to below these thresholds, then carcinogenicity would not arise. Effects that were seen in a 90-day inhalation study that was previously conducted with a comparable substance (NMC; cobalt lithium manganese nickel oxide) included lung epithelial inflammation, metaplasia and regeneration), and these were associated with carcinogenesis with other salts of nickel or cobalt.and classification for carcinogenicity (Cat 1A, inhalation) is proposed on this basis.

Justification for classification or non-classification

Some concerns are expressed towards the carcinogenic potential of pNMC oxide, due to the classification of some of the metals and metal oxides present in the substance as carcinogenic substances. In particular nickel (EC 231-111-4) is classified as a category 2 carcinogen, while nickel monoxide (EC 215-215-7), nickel dioxide (EC 234-823-3), cobalt nickel dioxide (EC261-346-8) and cobalt lithium nickel oxide (EC 442-750-5) are classified as Category 1A carcinogens according to Annex VI of the CLP regulation.

Based on known properties and harmonised classification of other nickel or cobalt containing compounds, and taking into account the outcome of the MeClas calculation, a classification as a category 1A carcinogen is proposed.

 

The registrants, however, would like to point out that the classification of pNMC oxide as a carcinogenic substance is a conservative approach:

• The registered substance, pNMC oxide, is a unique chemical substance and does not contain nickel or cobalt in the specific form of any of the carcinogenic substances referred to above. Therefore reference to these substances and their classification should be carefully considered in conjunction with existing information on the substance itself.
• The existing in vitro data, obtained from multiple studies conducted according to OECD guidelines and under GLP conditions, showed that pNMC oxide does not express any mutagenic effects under the conditions of those tests.
• To date there are insufficient adequate data available to make wholly conclusive statements as to the carcinogenic potential of the substance, although all the existing in vitro mutagenicity data on the substance itself indicate a negative response.