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Toxicity to microorganisms

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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:
REPORTING FORMAT FOR THE ANALOGUE APPROACH : Please see attached Read Across supporting document in Section 13 which includes the following:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
3. ANALOGUE APPROACH JUSTIFICATION
4. DATA MATRIX
Reason / purpose:
read-across source
Key result
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
Conclusions:
Based on read across to an analogue substance, the EC50 was predicted to be >1000 mg/L.
Executive summary:

The influence of an analogue substance Solvent Red 19E, on the respiration rate of activated sludge was investigated after a contact time of 3 hours under GLP conditions.

The test was performed according to Method C.11 - Activated Sludge Respiration Inhibition Test, Council Regulation (EC) No. 440/2008, published in O.J. L 142, 2008.

Following a preliminary test using 5 concentrations of the test substance in the range 46 to 1000 mg/L, in the main test, 5 concentrations of the test substance in geometric progression with factor of 1.8 were used to investigate the effects of the test substance. Concentrations were 100, 180, 320, 580 and 1000 mg/L. Activated sludge from a municipal sewage treatment plant was exposed to the test material along with two control experiments (one at the beginning and one at the end of the test) an abiotic control and 3,5-dichlorophenol as a reference substance.

In the main test, the test substance caused no inhibition of respiration. Abiotic decomposition was not detected even at the highest concentration of the test substance.

The test met all the validity criteria as the respiration rate of the controls did not differ too greatly and the EC50 of the reference substance was in the appropriate range.

Under the conditions of this study, the EC50 was determined to be >1000 mg/L. Given the structural similarity, The target substance Solvent Red 19T would be expected to have similar properties.

Description of key information

The EC50 was determined to be >1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

The influence of an analogue substance Solvent Red 19E, on the respiration rate of activated sludge was investigated after a contact time of 3 hours under GLP conditions.

The test was performed according to Method C.11 - Activated Sludge Respiration Inhibition Test, Council Regulation (EC) No. 440/2008, published in O.J. L 142, 2008.

Following a preliminary test using 5 concentrations of the test substance in the range 46 to 1000 mg/L, in the main test, 5 concentrations of the test substance in geometric progression with factor of 1.8 were used to investigate the effects of the test substance. Concentrations were 100, 180, 320, 580 and 1000 mg/L. Activated sludge from a municipal sewage treatment plant was exposed to the test material along with two control experiments (one at the beginning and one at the end of the test) an abiotic control and 3,5-dichlorophenol as a reference substance.

In the main test, the test substance caused no inhibition of respiration. Abiotic decomposition was not detected even at the highest concentration of the test substance.

The test met all the validity criteria as the respiration rate of the controls did not differ too greatly and the EC50 of the reference substance was in the appropriate range.

Under the conditions of this study, the EC50 was determined to be >1000 mg/L. Given the structural similarity, The target substance Solvent Red 19T would be expected to have similar properties.