Registration Dossier

Administrative data

Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: official guideline method, GLP with certificate, good documentation, identity of substance clear but no details on its purity.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001

Materials and methods

Principles of method if other than guideline:
Method followed that described in the German Water Hazard Classification Scheme (Bewertung Wassergefährdenter Stoffe, LTWS - Nr. 10) and ISO 10712 "Determination of the inhibitory effect of water constituents on bacteria ( Pseudomonas cell multiplication inhibition test)"
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test material as stated in study report ("Sponsor's identification"): MEC
Description: clear colourless liquid
Batch number: 009141
Date received: 10.23.2002
Storage conditions: approxiamtely 4 °C in the dark

Remark of the author of this IUCLID dossier concerning the substance identity:
Every page of the copy of the study report contains an annotation referring to the data sharing agreement in place between the licensee that uses this study report and the data owner. In this data sharing agreement the identity of the chemical substance is specified with "Ethyl Methyl Carbonate - EC No. 433-480-9, CAS Nr. 623-53-0".

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
The test material concentration in the test samples was determined by gas chromatography (GC) using an external standard. A volume of test sample was diluted with acetone to give a final concentration of between 0.98 mg/L and 63 mg/L. Standard solutions of test material were prepared in acetone at a nominal concentration of 50 mg/L.

Test organisms

Test organisms (species):
Pseudomonas putida
Details on inoculum:
Freezed dried cultures of Pseudomonas putida were obtained from The National Collections of Industrial and Marine Bacteria, Aberdeen, Scotland. Strain NCIMB 8248

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
16 h

Test conditions

Test temperature:
23 +/- 1 °C
Details on test conditions:
Pseudomonas putida was exposed to an aqueous dispersion of the test material at concentrations of 4.9, 9.8, 19.5, 39, 78, 156, 313, 625, 1250, 2500, 5000 and 10000 mg/L (three replicate flasks per concentration) for approximately 16 hours, at a temperature of 23 +/- 1 °C.

Results and discussion

Effect concentrations
Duration:
16 h
Dose descriptor:
EC50
Effect conc.:
760 mg/L
Basis for effect:
growth inhibition
Details on results:
There were no statistically significant differences between the control and 4.9, 9.8, 19.5, 39, 78 and 156 mg/L test concentrations (P>= 0.05), however all other test concentrations had significantly lower total viable counts than the control (P< 0.05) and, therefore the "No Observed Effect Concentration" (NOEC) was 156 mg/L

Any other information on results incl. tables

Range-finding test: The results show no significant effect on growth at the test concentrations of 1.0 and 10 mg/L. However, growth was observed to be reduced at 100, 1000 and 10000 mg/L. Based on this information test concentrations of 4.9, 9.8, 19.5, 39, 78, 156, 313, 625, 1250, 2500, 5000 and 10000 mg/L were selected for the definitve test.

Definitive test: The growth of Pseudomonas putida (NCIMB 8248) was affected by the presence of the test material over the 16 -Hour exposure period. Accordingly the following results were determined from the date:

EC10 (16h): 100 mg/L

EC50 (16h): 760 mg/L

Evaluation number: 4.0

Chemical analysis of the test preparations at 0 and 16 hours showed the measured concentrations to be near nominal. It was therefore considered appropriate to calculate the results of the test in terms of the nominal test concentrations alone.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
EC10 (16h): 100 mg/L, EC50 (16h): 760 mg/L. It can furthermore be remarked that no data is required for this endpoint if a substance is found to be ready biodegradable (9.1.4 Activated sludge respiration inhibition testing, ANNEX VIII, REGULATION (EC) No 1907/2006). As the substance was found to be ready biodegradable in a study of good quality the delivery of data for this endpoint appears to be optional.

The results of this test do not point to toxicity of the substance towards bacteria under the applied test conditions.