Manganese oxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.008 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.011 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.001 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

100 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

8.18 mg/kg sediment dw

Assessment factor:

500

Extrapolation method:

assessment factor

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.82 mg/kg sediment dw

Assessment factor:

5 000

Extrapolation method:

assessment factor

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

8.15 mg/kg soil dw

Assessment factor:

50

Extrapolation method:

assessment factor

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 at 100% v/v saturated solution (equivalent to 3.2 mg/l) and showed no effects. Therefore the 48 Hour EC50 was greater than 3.2 mg/l, and the NOEC was 3.2 mg/l. A standard acute toxicity study with fish was conducted with MnO 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 3.2 mg/l). A standard chronic study on Algae resulted in 72H ErC50 > 1.3 mg/l, EyC50 = 1.1 mg/l, NOEC = 0.41 mg/l whilst an 8 day chronic study on Daphnia gave EC50 (immobilisation) = 4.1.mg/l, EC50 (reproduction) = 2.5 mg/l and NOEC = 1.3 mg/l.

It should be noted that the aquatic PNEC values are comparable to 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 limited relevance for assessment of any potential risk from MnO.

Sediment

No experimental data on sediment toxicity exist. The data are not required as the hazard assessment performed during the chemical safety assessment concludes that the substance is not classified and is of no immediate concern to the environment. PNEC sediment is calculated by the equilibrium partitioning method.

It should be noted that the PNEC value is considerably lower than the background concentration of manganese in European environments (452 mg/kg in sediment; “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 MnO.

Terrestrial

No experimental data on terrestrial toxicity exist. The data are not required as the hazard assessment performed during the chemical safety assessment concludes that the substance is not classified and is of no immediate concern to the environment. PNEC soil is calculated by the equilibrium partitioning method.

However, MnO is used in fertilizer preparations for crops/soils and hence high localised concentrations in soil would not be expected to have adverse effects in the soil environment. It should also be noted that the PNEC value is considerably lower than the background concentration of manganese in European environments (428.6 mg/kg in soil; “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 MnO.

STP

No effects on sewage sludge were observed in a standard 3hr study on MnO. Hence the NOEC for MnO 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 Manganese oxide (Rodriguez, 2010). During the transformation/dissolution protocol test with Manganese oxide 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 157.9, 1862.7 and 8803.1 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 456.4 µg Mn /L.

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

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