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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
50 mg/L
Based on:
ThOD/L
Initial conc.:
35 mg/L
Based on:
ThOD/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
23
Sampling time:
28 d
Remarks on result:
other: 1st Study
Parameter:
% degradation (O2 consumption)
Value:
6
Sampling time:
28 d
Remarks on result:
other: 2nd Study
Details on results:
In the 1st definitive GLP study the 1st test item replicate reached the 10 % level (beginning of biodegradation) after 1 day. The biodegradation rate was < 10 % from day 3 - 23 and it reached 33 % on day 28. The 2nd test item replicate reached the 10 % level on day 28 with a biodegradation rate of 13 %. The mean biodegradation rate of the test item after 28 days was 23 %.
In the 2nd definitive GLP study the 1st test item replicate reached the 10 % level after 21 days and came to a maximum of 17 % after 25 days. The 2nd test item replicate reached a maximum biodegradation rate of 5 % on day 26. The mean biodegradation rate of the test item after 28 days was 6 %.

BOD5 / COD results

Results with reference substance:
The pass level of a biodegradation > 60 % was reached after 2 days in the 1st GLP study and after 1 day in the 2nd GLP study, respectively. The validity criterion that the degradation should be > 60 % after 14 d was fulfilled.

In the toxicity control of the 1st GLP study, no degradation occurred within 25 days, a biodegradation rate of 4 % was reached on day 28. The degradation of the reference item was inhibited by the test item at the tested concentration.

After a long-lasting adaptation period of 11 days, the biodegradation rate of the toxicity control in the non GLP screening test achieved 49 % after 14 days and came to a maximum of 54 % on day 19. The biodegradation rate after 27 days was 52 % . The degradation of the reference item was inhibited by the test item until day 11, but afterwards a normal course of the biodegradation curve was observed.

In the toxicity control of the 2nd GLP study, containing both test and reference item at the lower concentrations, no degradation occurred within 28 days. The degradation of the reference item was inhibited by the lower test item concentration as well.

Any other information on results incl. tables

A1stdefinitive GLP studywas conducted over a period of 28 days The test item concentration selected as appropriate was 50 mg/L, corresponding to a ThOD of 76.0 mg O2/L per test vessel. The mean oxygen depletion in the inoculum control was 0.0 mg O2/L on day 28. In order to check the activity of the test system, sodium benzoate (45 mg/L) was used as functional control. The functional control reached the pass level > 60 % after 2 days. The 1sttest item replicate reached the 10 % level (beginning of biodegradation) after 1 day. The biodegradation rate was < 10 % from day 3 - 23 and it reached 33 % on day 28. The 2ndtest item replicate reached the 10 % level on day 28 with a biodegradation rate of 13 %. The mean biodegradation rate of the test item after 28 days was 23 %.In the toxicity control containing both test and reference item no degradation occurred within 25 days, a biodegradation rate of 4 % was reached on day 28. The degradation of the reference item was inhibited by the test item at the tested concentration.

In order to verify the results of the 1stdefinitive GLP study, a toxicity control replicate was tested at the same test item and reference item concentrations in a non GLPscreening test over a period of 27 days. After a long-lasting adaptation period of 11 days, the biodegradation rate achieved 49 % after 14 days and came to a maximum of 54 % on day 19. The biodegradation rate after 27 days was 52 %. The degradation of the reference item was inhibited by the test item until day 11, but afterwards a normal course of the biodegradation curve was observed.

A 2nddefinitive GLP study with a lower test item concentration was conducted over a period of 28 days.The test item concentration was 35 mg/L, corresponding to a ThOD of 53.2 mg O2/L per test vessel. Sodium benzoate was tested as functional control at a concentration of 30 mg/L. The functional control reached the pass level > 60 % after 1 day. The mean oxygen depletion in the inoculum control was 16.9 mg O2/L on day 28. The 1sttest item replicate reached the 10 % level after 21 days and came to a maximum of 17 % after 25 days. The 2ndtest item replicate reached a maximum biodegradation rate of 5 % on day 26. The mean biodegradation rate of the test item after 28 days was 6 %. In the toxicity control, containing both test and reference item at the lower concentrations, no degradation occurred within 28 days. The degradation of the reference item was inhibited by the lower test item concentration as well.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Due to inhibitory effects of the test item to the inoculum the test item must be regarded as not readily biodegradable in the 10-d-window and after 28 days.