Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Summary of degradation

MnO2 is inorganic and hence the ready biodegradation and hydrolysis tests are not relevant. This is because there is no carbon to be evolved and no chemical bonds to be broken, respectively. The water solubility of MnO2, as determined in the water solubility study (EU Method A.6), is 0.073 mg/L at 20°C; the Mn release from MnO2 as determined in the transformation dissolution study (OECD 29), is 47.1 µg/l after 7 days from 100 mg/L loading (i.e. similar to the water solubility). These limit values are of the same order of magnitude as the background concentration of manganese in European environments (15.9 µg Mn/L in surface water, 452 mg/kg in sediment, 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).

 

Volatilisation

Data on volatilisation are not available for the substance. MnO2 is a solid and hence is not volatile.

 

Distribution modelling

No distribution modelling data exist.

 Summary of environmental distribution

An adsorption / desorption study on Mn2+ has been conducted in 35 soils following the OECD sorption guideline. Data for 100 day incubations show that, as expected, the sorption is pH sensitive. A median Kd value of 1355 mL/g has been determined for all soils (pH range 3.0-8.5). Since Manganese dioxide comprises of Mn4+ this form of the substance can be expected to adsorb to soil to a slightly greater extent than Mn2+

 

 

Summary and discussion of bioaccumulation

No experimental data on bioaccumulation exist. The data are not required as the hazard and risk assessment performed during the chemical safety assessment concludes that the substance is not classified and is of no immediate concern to the environment. Furthermore, manganese is an essential trace nutrient in animals and is required for the photosynthetic process in plants. Hence unacceptable bioaccumulation is highly unlikely to occur in any organism due to their ability to regulate intake and loss from natural sources.

Secondary poisoning

Bioaccumulation of MnO2 is not expected to occur. Hence no secondary poisoning risk exists.

 

Assessment of PBT/vPvB Properties - Comparison with the Criteria of Annex XIII

According to the Guidance on information requirements and chemical safety assessment, Chapter R.11: PBT assessment, “the PBT and vPvB criteria of Annex XIII to the regulation do not apply to inorganic substances”. Therefore MnO2 is not considered to require any further assessment of PBT properties.