Reaction mass of copper oxide and manganese dioxide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

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 endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “assessment report”.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

assessment report

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 429 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

inhibition of total respiration

Remarks on result:

other: value recalculated based on the ratio of MnO2 and CuO in the reaction mass

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 429 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

inhibition of total respiration

Remarks on result:

other: value recalculated based on the ratio of MnO2 and CuO in the reaction mass

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 > 1429 mg/L. The NOEC after 3 hours exposure was >= 1429 mg/L.

Executive summary:

The study used as source investigated the respiration of activated sewage sludge acc. to OECD 209. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross reference “assessment report”.

Reference 2

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 endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “read-across: supporting information”.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

14 mg/L

Nominal / measured:

nominal

Conc. based on:

element (dissolved fraction)

Remarks:

copper

Basis for effect:

inhibition of heterotrophic respiration

Remarks on result:

other: converted concentration: CuSO4 pentahydrate to proportional Cu

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

580 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

inhibition of heterotrophic respiration

Remarks on result:

other: value recalculated based on the dissolved copper fraction acc. to OECD 29, i.e. 2.42%

Validity criteria fulfilled:

yes

Conclusions:

The 3h-EC50 (activated sludge, respiration inhibition) was 14 mg Cu/L (dissolved), corresponding to 580 mg/L submission substance (nominal).

Executive summary:

The study used as key source reference was performed according to OECD 209. The EC50 value (activated sludge, respiration inhibition) of the source copound was determined for every batch of activated sludge during the years 1991-2004. The lower EC50 value of the valid range was used protectively as key value. The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (structural analogue) is outlined in the attached document (see section 13 or find a link in cross reference).

Description of key information

3h-EC50 (activated sludge, respiration inhibition) = 14 mg Cu/L (dissolved), corresponding to 580 mg/L (nominal, total fraction, submission substance) (OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:

14 mg/L

Additional information

Two reliable key studies and one supporting study were available for the hazard assessment of toxicity to microorganisms for the submission substance reaction mass of copper oxide and manganese dioxide.

 

The key study used to assess the effect of the constituent manganese dioxide on the respiration of activated sewage sludge followed OECD 209 and was performed in compliance with GLP (RL 1, 2010). 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. The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item. The effect of the test material on the respiration of activated sewage sludge gave a 3h-EC50 > 1429 mg/L (value recalculated based on the ratio of MnO2 and CuO in the reaction mass). The NOEC after 3 hours exposure was >= 1429 mg/L (value recalculated based on the ratio of MnO2 and CuO in the reaction mass). Therefore, no hazard was anticipated for the constituent manganese dioxide well above the maximum water solubility.

The key study used to assess the adverse effect of dissolved copper to microorganisms was performed according to OECD 209 (RL2, 2004). The 3h-EC50 of copper-(II)-sulphate pentahydrate was determined for every batch of activated sludge in NOACK-Laboratories, Germany during the years 1991-2004. Copper-(II)-sulphate pentahydrate was used as soluble copper salt. The present study was cited by the OECD 209 for valid EC50 values of proposed reference substance copper-(II)-sulfate pentahydrate. Therefore, it was considered reliable. The derived lower EC50 value of the valid range was used as key value for the environmental hazard assessment for the submission substance, i.e. 14 mg Cu/L (dissolved), corresponding to 580 mg/L submission substance (value recalculated based on the dissolved copper fraction acc. to OECD 29, i.e. 2.42%, see section 4.8).

In a supporting study, rapid toxicity of water-soluble copper (copper sulfate) was investigated using a fed-batch reactor technique (RL2, 1996). The inhibition of oxygen consumption of microorganisms was studied. Synthetic sewage sludge consisted of six bacterial colony types obtained from domestic sewage sludge and was used as inoculum. Four test concentrations and controls were used to obtain a dose-response curve in order to derive the EC50 value. The 4h-EC50 was 6.5 mg/L (dissolved), corresponding to 269 mg/L submission substance ( alue recalculated based on the dissolved copper fraction acc. to OECD 29, i.e. 2.42%, see section 4.8). As the study was performed with synthetic sewage sludge consisting of six bacterial colony types only, the derived effect concentration was considered not representative for realistic environmental conditions and too sensitive with respect to the limited number of bacterial types. The derived effect concentration of the presented key study (acc. to OECD 209, RL2, 2004) was performed with domestic sewage sludge. Therefore, the respective 3h-EC50 value was considered to represent more realistic environmental conditions and preferred to the effect concentration of the supporting study. 

As copper was the toxic element of the submission substance, the key value for the environmental hazard assessment of the reaction mass of copper oxide and manganese dioxide was based on the derived effect concentration of copper.