Dimanganese trioxide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details on the read across justification refer to the read across statement in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test material on the respiration of activated sewage sludge micro-organisms gave a 3-hour EC50 of greater than 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000 mg/L.

Executive summary:

A study was performed to assess the effect of the test material on the respiration of activated sewage sludge. The method followed that described in the OECD Guidelines for Testing of Chemicals (1984) No 209 "Activated Sludge, Respiration Inhibition Test", Method C.11 of Commission Regulation (EC) No. 440/2008 and US EPA Draft Ecological Effects Test Guidelines OPPTS 850.6800.

During the study activated sewage sludge was exposed to an aqueous dispersion of the test material at concentrations of 10, 32, 100, 320 and 1000 mg/L for a period of 3 hours at a temperature of approximately 21°C with the addition of a synthetic sewage as a respiratory substrate. The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item, 3,5-dichlorophenol.

The effect of the test material on the respiration of activated sewage sludge gave a 3 hour EC₅₀ of greater than 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000mg/L. It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/L.

This information is used in a read-across approach in the assessment of the target substance. Therefore, the molar ratio to convert from manganese dioxide by weight to dimanganese trioxide by weight is 1.82 resulting in an estimated NOEC for dimanganese trioxide of 1000 x 1.82= 1820 mg/L.

Description of key information

The EC50 for respiration inhibition of sewage sludge by manganese dioxide was determined to be above 1000 mg/L (Youngs 2010, OECD 202). ln conclusion, under the conditions of the test by Youngs (2007), manganese dioxide was not toxic to waste water (activated sludge) bacteria at a concentration of 1000 mg/L. This indicates that no hazard has been identified.

This information is used in a read-across approach in the assessment of the target substance. Therefore, the molar ratio to convert from manganese dioxide by weight to dimanganese trioxide by weight is 1.82 resulting in an estimated NOEC for dimanganese trioxide of 1000 x 1.82= 1820 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 820 mg/L

Additional information

The information on manganese dioxide is used in a read-across approach in the assessment of dimanganese trioxide.

For details on the read across justification refer to the read across statement in IUCLID section 13.