Hazard classification of manganese metal and inorganic manganese compounds

The publication of the Assessment of Regulatory Needs Report (ARN) by the ECHA (2020) and the Restriction Road Map Report by the Commission (2022)highlighting concerns related to environmental toxicity from the exposure of simply inorganic manganese substances triggered a review of available ecotoxicity data vis-à-vis the now available guidance documents and updated CLP regulation.

According to the ECHA Guidance on the application of the CLP criteria (2024) 1 , theenvironmental hazard classification of metals and metal compounds is limited to the acute andlong-term hazard posed by metals and metal compounds when they are available (i.e. exist asdissolved metal ions). The Transformation/Dissolution protocol study (TDp), as outlined instandardised guideline - OECD 29 (2002), is recognised as the most appropriate means ofdetermining the rate and extent of metal and metal compound transformation into soluble forms(i.e. dissolved metal ions).

To determine the environmental hazard classification of metals and metal compounds,ecotoxicity data from studies conducted with soluble metal compounds are utilised. The resultsfrom such studies are reported in terms of the soluble metal ion concentration (μg Me/L)causing the ecotoxicity effect this is used to generate a relevant ecotoxicity reference value(ERV) for both short-term and long-term hazard should be derived. This is the level at whichthe metal ion will be assumed to cause toxicity and is expressed as L(E)C50 (acute ERV) andNOEC/ECx or an HC5 for extensive data sets (chronic ERV). The effect level is transcribed for the metal or metal compound underinvestigation.

Ecotoxicity Reference Values

Acute: The acute ERV is taken as the lowest available L(E)C50 value from the available dataset ofrelevant and reliable short-term ecotoxicity studies on soluble manganese compounds.

Chronic:A chronic ERV can be considered as the lowest available NOEC/ECx or, when extensivedataset is available, an HC5 value can be calculated. Since the dataset for chronic effects of Mnon freshwater species was considered sufficiently large, an HC5 value was derived from aspecies sensitivity distribution (SSD)– this is the first time this approached is used for simple manganese substances. The results emanating from this robust SSD evaluation concluded that, no inorganic Mn substance registered under the support of the manganese consortium will be considered as hazardous to the aquatic environment.

Conclusion: NOT CLASSIFIED ASHAZARDOUS TO THE AQUATICENVIRONMENT for acute of chronic exposure

For a detail report contact reach@manganese.org