Trimanganese tetraoxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no hazard identified

Marine water

Hazard assessment conclusion:

no hazard identified

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

no hazard identified

Sediment (marine water)

Hazard assessment conclusion:

no hazard identified

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no hazard identified

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Aquatic

A standard acute toxicity study with Daphnia was conducted as a limit test, with Mn3O4 at 100% v/v saturated solution (equivalent to 0.022 mg/L) and showed no effects. Therefore the 48-hour EC50 was greater than 0.022 mg/L, and the NOEC was 0.022 mg/L. A standard acute toxicity study with fish was conducted with Mn3O4 as a limit test at 100% v/v saturated solution and showed no effects. Therefore the 96-hour LC50 was greater than 100 % v/v and the NOEC was 100 % v/v (equivalent to 0.022 mg/L – assuming that the manganese concentrations in the 100% saturated solutions of the acute daphnia and fish tests were equivalent). Similar results were obtained in a standard test study on Algae, resulting in 72h EC50 > 100% v/v saturated solution, and NOEC = 100% v/v saturated solution. A 21-day chronic study on Daphnia gave a NOEC of 100 mg/L (based on nominal loading). It should be noted that the levels of manganese measured in the test solutions were much lower than the background concentration of manganese in European environments (15.9 µg Mn/L in surface water; “Probabilistic Distribution of Manganese in European Surface Water, Sediment and Soil and Derivation of Predicted Environmental Concentrations (PEC)”, Parametrix, 2009 and supported by GEMAS data) and hence have very limited relevance for assessment of any potential risk from Mn3O4 to the aquatic environment.

Sediment

No experimental data on sediment toxicity exist. The data are not required as the substance has been shown to have a high potential to adsorb to sediment. Any ionic metal leaching out into the sediment compartment is predicted to bind strongly to soil and sediments. On this basis the bioavailable concentration of manganese to sediment organisms is predicted to be much less than the background concentration of manganese in European soils (452 mg Mn/kg in sediment according to “Probabilistic Distribution of Manganese in European Surface Water, Sediment and Soil and Derivation of Predicted Environmental Concentrations (PEC)”, Parametrix, 2009 and supported by GEMAS data)and hence has little relevance for assessment of any potential risk from Mn3O4.PNEC sediment was calculated by the equilibrium partitioning method.

Terrestrial

No experimental data on soil toxicity exist. The data are not required as the substance has been shown to have a high potential to adsorb to soil.

Any ionic metal leaching out into the soil compartment is predicted to bind strongly to soil. On this basis the bioavailable concentration of manganese to sediment organisms is predicted to be much less than the background concentration of manganese in European soils (452 mg Mn/kg in sediment according to “Probabilistic Distribution of Manganese in European Surface Water, Sediment and Soil and Derivation of Predicted Environmental Concentrations (PEC)”, Parametrix, 2009 and supported by GEMAS data)and hence has little relevance for assessment of any potential risk from Mn3O4.PNEC soil was calculated by the equilibrium partitioning method.

STP

No effects on sewage sludge were observed in a standard 3hr study on Mn₃O₄. Hence the NOEC for Mn₃O₄ is 1000mg/L.

Conclusion on classification

According to the 2nd ATP to the CLP Regulation (EU) No 286/2011, the methodology for determining the environmental classification of metal compounds that have limited solubility, is based on the assumption that the ecotoxicological effects are determined by the fraction of dissolved metal. On this basis, relevant ecotoxicological information generated with a soluble metal compound expressed in terms of mg metal ion per litre) are compared with the level of metal ion released from the sparingly

soluble metalcompound under investigation (as determined during transformation/dissolution protocol testing).

The relevant ecotoxicological values (environmental reference values, ERV) for manganese were established by considering the database of available studies conducted with soluble manganese compounds (i.e. manganese dichloride, manganese sulphate, and manganese nitrate). The database was refined through application of suitable relevance and reliability criteria. From the resulting studies, the short term toxicity study with the lowest L(E)C50 was selected as the acute ERV for manganese (3.2 mg Mn/L; Davies & Brinkman, 1998 - Rainbow trout study with MnSO4), and the long term toxicity study with the lowest NOEC was selected as the chronic ERV for manganese (0.55 mg Mn/L; Davies & Brinkman, 1998 - Brook trout study with MnSO4). Both studies were conducted on standard species, and were assessed to be of adequate relevance and reliability for use in hazard determination of manganese. Summaries of these studies are included in this dataset.

The acute and chronic ERV values were compared to the levels of Mn release, as determined through transformation/dissolution protocol testing with Trimanganese tetraoxide (Rodriguez, 2010). During the transformation/dissolution protocol test with Trimanganese tetraoxide at initial test substance loading rates of 1, 10 and 100 mg/L, the level of manganese measured in the pH 6 media, following a 7 day exposure period, were 87.0, 338.2 and 1221.1 µg Mn/L, respectively. The level of manganese measured in the pH 6 media following 28 days exposure, at the 1 mg/L test material loading rate, was 219.5 µg Mn /L.

Since the level of Mn release following a 7 day exposure of Trimanganese tetraoxide to environmentally relevant water, at all three loading rates, was lower than the acute ERV, Trimanganese tetraoxide does not require classification in terms of acute aquatic toxicity. Since the level of Mn release following a 28 day exposure of Trimanganese tetraoxide to environmentally relevant water, at a loading rate of 1 mg/L, was lower than the chronic ERV, Trimanganese tetraoxide does not require classification in terms of chronic aquatic toxicity.