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Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP and appropriate guidelines
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Principles of method if other than guideline:
not relevant
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
E-AF098T (Batch No. T# 176-3), a white powder. Stored at room temp, dry, closed container.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not relevant

Sampling and analysis

Analytical monitoring:
not required
Details on sampling:
not applicable

Test solutions

Vehicle:
no
Details on test solutions:
The test substance and 3,5-dichlorophenol (positive control) were added to the incubation vessels using stock solutions of 1.0 and 0.5 g/L respectively. Since the test substance is poorly water soluble, it was dissolved in dichloromethane and subsequently added to the test flasks.
The stock solution of 3,5-dichlorophenol was prepared by dissolving 0.05 g of this material in 1 mL of 1 M NaOH. Then diluting this to approximately 30 mL with deionized water, adding under stirring 0.5 M H2SO4 to the point of incipient precipitation and finally diluting the mixure to 100 mL with deionized water. The E-AF098T stock solution was prepared by dissolving 0.1 g of the test substance in 100 mL dichloromethane.

The synthetic sewage feed contained the following amounts of substances in 1 liter of deionized water: 16g peptone, 11 g meat extract, 3 g urea, 0.7 g NaCl, 0.4 g CaCl2.2H2O, 0.2 g MgSO4.7H2O, 2.8 g K2HPO4.
The dry weight of the inoculum was determined by filtrating 50 mL of the activated sludge over a preweighed 12 um filter.




Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Secondary activated sludge, WWTP Nieuwgraaf, Duiven, The Netherlands.

Study design

Test type:
other: aerobic
Water media type:
freshwater
Limit test:
no
Total exposure duration:
0.5 h
Remarks on exposure duration:
no remarks
Post exposure observation period:
No observations done

Test conditions

Hardness:
Deionized water were used.
Test temperature:
20.3-20.6
pH:
Beginning of the test: 7.1-7.3
End of the test: 7.3-7.4
Dissolved oxygen:
0.3
Salinity:
Deionized water were used.
Nominal and measured concentrations:
The test was performed in the presence of various concentrations of the test substance.
The nominal concentrations (in mg/L) are: 0, 25.85, 51.7, 103.4, 206.8, 413.6.
Details on test conditions:
The toxicity of E-AF098T to activated sludge was determined by measuring the respoiration rate after a contact time of 30 min at various concentration of test substance (as mentioned above).
Since the test substance is poorly water soluble, it was dissolved in dichloromethane and subsequently added to the test flasks. The solvent then was allowed to evaporate by placing the test flasks in a ventilated hood.
Control flasks of the test substance received only the solvent dichloromethane which was then also allowed to evaporate.

The test was performed in 300 mL Erlenmeyers. The homogenized activated sludge was incubated in a shaking water bath (100 rpm, 20oC) with various concentrations of the test compound and synthetic sewage.
The inhibitory effect of the test item at a particular concentration was expressed as a percentage of the mean respiration rates of the controls.
The respiration rates of the activated sludge were measured in Biological Oxygen Monitor instrument.

Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
Duration:
30 min
Dose descriptor:
IC50
Effect conc.:
> 414 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
30 min
Dose descriptor:
NOEC
Effect conc.:
>= 414 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
The calculated respiration rates and inhibition percantages of E-AF098T are attached (see attached file "Results", Table II; Figure 2).
No inhibition of the respiration of the activated sludge was measured at the highest concentration tested of 414 mg/L of the test substance.
Results with reference substance (positive control):
The calculated respiration rates and inhibition percantages of the positive control are attached (see attached file "Results", Table I; Figure 1).
EC50 = 7.4 mg/L.
Reported statistics and error estimates:
The EC values were computed from the best-fitted line (least square method) through the points given by the probit of the percentage inhibition and the logarithm of the concentration of the substance. All computations were performed with the program TOXCALC on a personal computer.

Any other information on results incl. tables

No futher information

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
No inhibition of the respiration of the activated sludge was measured at the highest concentration tested of 414 mg/L of the test substance.
E-AF098T is therefore considered harmless to activated sludge.
Executive summary:

The toxicity of E-AF098T to activated sludge was determined by measuring the respiration rate after a contact time of 30 minutes at various concentrations of the test substance. The inhibitory effect of the test item at a particular concentration is expressed as a percentage of the two controls.

No inhibition of the respiration of the activated sludge was measured at the highest concentration tested of 414 mg/L of the test substance. E-AF098T is therefore considered harmless to activated sludge.