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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted under GLP conditions according to test guidelines
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
not required
Vehicle:
no
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Total suspended solids in the settled sludge were adjusted to a nominal concentration of approximately 4000 mg/L by dilution with municipal water. Fifty mL of synthetic sewage was added to each liter of adjusted sludge. The sludge was maintained at a temperature of 20 ± 2°C and continuously aerated overnight. The pH and total suspended solids concentration of the activated sludge were determined on the day of use in the study.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
None
Test temperature:
19.8 - 20.3
pH:
8.0
Nominal and measured concentrations:
Nominal concentrations: 10, 100 and 1000 mg/L
Details on test conditions:
Temperatures measured throughout the period of sludge maintenance and during the test ranged from 19.8 – 20.3°C. The initial total suspended solids (TSS) concentration of the activated sludge after removal of the supernatant layer measured 21,333 mg/L. The measured TSS concentration of the sludge on the day of testing was 4267 mg/L. The measured pH of the sludge on the day of testing was 8.0.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
888.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
An inhibitory dose response effect was observed for the treatment group. The EC50 value for BADGE MXDA (#42) is 888.9 mg/L, obtained by nonlinear interpolation between 100 and 1000 mg/L. The abiotic treatment mixture dosed with 1000 mg/L of BADGE MXDA (#42) had a respiration rate of
-2.4 mg O2/L/hr showing there was no chemical uptake of oxygen by the test substance.
Results with reference substance (positive control):
The validity of the test was further supported by the results from the 3,5-dichlorophenol reference group, which resulted in an EC50 value of 12.2 mg/L, with 95 percent confidence limits of 3 mg/L and 15 mg/L. The EC50 for the reference substance was within the 2 to 25 mg/L range considered acceptable for the test.
Validity criteria fulfilled:
yes
Conclusions:
The respiration rates in the two controls were 85.1 and 75.0 mg O2/L/hr. Both controls had respiration rates above 34.1 mg O2/L/hr, which is the low limit based on the validity criteria for mixtures with 1.71 g dry weight of suspended solids per liter. The coefficient of variation of the two controlrespiration rates was 8.9%, and was within the 30% limit established for the test. The validity of the test was further supported by the results from the 3,5-dichlorophenol reference group, which resulted in an EC50 value of 12.2 mg/L, with 95 percent confidence limits of 3 mg/L and 15 mg/L. The EC50 for the reference substance was within the 2 to 25 mg/L range considered acceptable for the test.
Executive summary:

The effect of BADGE MXDA (#42) Reaction product of m-phenylenebis(methylamine) with oligomerisation products of 4,4’-propane-2,2-diyldiphenol with 2-(chloromethyl)oxirane (IUPAC name, ECnr. 500-302-7) (from here on referred to as BADGE MXDA (#42) in the report) on activated sludge microorganisms maintained in an aerobic environment was assessed by the Activated Sludge Respiration Inhibition Test Method (OECD Guideline 209). The test contained control, reference and treatment groups. The control replicates were used to determine the background respiration rate of the sludge and were not dosed with the test or reference substance. The reference group was dosed with 3,5-dichlorophenol, a known inhibitor of respiration, at concentrations of 3, 15 and 50 mg/L. The treatment group was dosed with BADGE MXDA (#42) at concentrations of 10, 100, and 1000 mg/L. The

1000 mg/Ltreatment was tested in triplicate. An abiotic control was dosed with the test substance at a concentration of 1000 mg/L to discriminate between abiotic uptake by the test substance and microbial respiration.The respiration rates in the two controls were 85.1 and 75.0 mg O2/L/hr. Both controls had respiration rates above 34.1 mg O2/L/hr, which is the low limit based on the validity criteria for mixtures with 1.71 g dry weight of suspended solids per liter. The coefficient of variation of the two controlrespiration rates was 8.9%, and was within the 30% limit established for the test. The validity of the test was further supported by the results from the 3,5-dichlorophenol reference group, which resulted in an EC50 value of 12.2 mg/L, with 95 percent confidence limits of 3 mg/L and 15 mg/L. The EC50 for the reference substance was within the 2 to 25 mg/L range considered acceptable for the test.

An inhibitory dose response effect was observed for the treatment group. The EC50 value for BADGE MXDA (#42) is 888.9 mg/L, obtained by nonlinear interpolation between 100 and 1000 mg/L. The abiotic treatment mixture dosed with 1000 mg/L of BADGE MXDA (#42) had a respiration rate of -2.4 mg O2/L/hr showing there was no chemical uptake of oxygen by the test substance.

Description of key information

The effect of BADGE MXDA (#42) on activated sludge microorganisms maintained in an aerobic environment was assessed by the Activated Sludge Respiration Inhibition Test Method (OECD Guideline 209).

Key value for chemical safety assessment

Additional information

The effect of BADGE MXDA (#42) on activated sludge microorganisms maintained in an aerobic environment was assessed by the Activated Sludge Respiration Inhibition Test Method (OECD Guideline 209). The test contained control, reference and treatment groups. The control replicates were used to determine the background respiration rate of the sludge and were not dosed with the test or reference substance. The reference group was dosed with 3,5-dichlorophenol, a known inhibitor of respiration, at concentrations of 3, 15 and 50 mg/L. The treatment group was dosed with BADGE MXDA (#42) at concentrations of 10, 100, and 1000 mg/L. The 1000 mg/L treatment was tested in triplicate. An abiotic control was dosed with the test substance at a concentration of 1000 mg/L to discriminate between abiotic uptake by the test substance and microbial respiration.The respiration rates in the two controls were 85.1 and 75.0 mg O2/L/hr. Both controls had respiration rates above 34.1 mg O2/L/hr, which is the low limit based on the validity criteria for mixtures with 1.71 g dry weight of suspended solids per liter. The coefficient of variation of the two control respiration rates was 8.9%, and was within the 30% limit established for the test. The validity of the test was further supported by the results from the 3,5-dichlorophenol reference group, which resulted in an EC50 value of 12.2 mg/L, with 95 percent confidence limits of 3 mg/L and 15 mg/L. The EC50 for the reference substance was within the 2 to 25 mg/L range considered acceptable for the test.

An inhibitory dose response effect was observed for the treatment group. The EC50 value for BADGE MXDA (#42) is 888.9 mg/L, obtained by nonlinear interpolation between 100 and 1000 mg/L. The abiotic treatment mixture dosed with 1000 mg/L of BADGE MXDA (#42) had a respiration rate of -2.4 mg O2/L/hr showing there was no chemical uptake of oxygen by the test substance.