Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test item name: PC-2015-597
Trade name: REWOPOL V 10033
Batch: S015310400 (CoA), date of analytical report: 21.05.2015
Stable under normal conditions (SDS)
Yellowish turbid liquid, characteristic odour
Storage conditions: AT 15-30°C, in a well ventilated room

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Standard OECD 301 test medium was inoculated with 29.6 mg dry mass/L non-adapted microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater (STP: Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany).
Duration of test (contact time):
> 28 d
Initial test substance concentrationopen allclose all
Initial conc.:
140 mg/L
Based on:
ThOD
Initial conc.:
58 mg/L
Based on:
ThOD
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The test solutions were stirred in closed flasks at 22 °C ± 1 °C for 28 days (in duplicate at 2 test concentrations). The rate of degradation was monitored by measuring the quantity of oxygen required to maintain a constant gas volume in the respirometer flasks over a 28-d period. In order to check the procedure, sodium benzoate (in duplicate) was used as a degradable reference item at a concentration of 100 mg/L. Furthermore, an abiotic control in duplicate was used. The pH values was 7.4 °C ± 2 throughout the study.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
80
St. dev.:
12.1
Sampling time:
28 d
Remarks on result:
other: The criteria for the 10-day windows was met (72% between days 2 and 12).
Parameter:
% degradation (O2 consumption)
Value:
94
St. dev.:
1.2
Sampling time:
28 d
Remarks on result:
other: The criteria for the 10-day windows was met (72% between days 2 and 12).

BOD5 / COD results

Results with reference substance:
The degradation of the reference substance sodium benzoate had reached average 88 % within the first 14 days

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
In conclusion, the substance is readily biodegradable. Average biodegradation of 80% based on O2 consumption is above the guideline trigger value of 60% on day 28. The criteria for the 10-day windows was met (72% between days 2 and 12).
Executive summary:

At the Fraunhofer Institute for Molecular Biology and Applied Ecology the biodegradation of PC-2015 -597 was investigated during a 28-day period in a Manometric Respirometry Test according to EC method C.4-D (440/2008/EEC) and OECD guideline 301 F (1992). Standard OECD 301 test medium was inoculated with 29.6 mg dry mass/L non-adapted microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater (STP: Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany). The test solutions were stirred in closed flasks at 22 °C ± 1 °C for 28 days. The rate of degradation was monitored by measuring the quantity of oxygen required to maintain a constant gas volume in the respirometer flasks over a 28-d period. For that purpose a SAPROMAT respirometer (VOITH Inc.) was used. The amount of oxygen taken up by the microbial population during biodegradation of the test item was expressed as a percentage of the ThOD (Theoretical Oxygen Demand). The following test concentrations were used: (1) 272 mg/L (ThOD = 140 mg/L, in duplicate) and (2) 112 mg/L (ThOD = 58 mg/L, in duplicate), respectively, corrected for uptake by the blank inoculum run in duplicate. The second concentration was chosen for the following reason: Some substances with high ThOD’s have gently inclined degradation curves, even when they are completely degradable. However, for these substances it is hard to reach the threshold value within the 10 -day window. Therefore, an additional assay with 112 mg test item (58 mg ThOD) was added. This concentration meets the required concentration of 50 - 100 mg ThOD/L acc. to OECD 301 F. In order to check the procedure, sodium benzoate (in duplicate) was used as a degradable reference item at a concentration of 100 mg/L. Furthermore, an abiotic control in duplicate was used. The pH values was 7.4 °C ± 2 throughout the study.

 

The oxygen uptake of the inoculum blank was average 22 mg/L in 28 days and the pH value was inside the range of 6.8 - 8.1. The degradation of the reference substance sodium benzoate had reached average 88 % (SD= 2.1) within the first 14 days, i.e. the pass level of 60%. With 2 and 17 %, the difference of extremes of replicate values for the removal of test item was less than 20 % for both concentrations, respectively. Hence, the test is valid according to the validity criteria of the guideline. The biodegradation of 272 mg test item per litre (140 mg/L ThOD, concentration [1]) in the static test was found to be at average 80.5 % (71.9 and 89.1% in replicate vessels). A plateau was not yet reached on day 28. On day 28, concentration (2) (112 mg/L test substance, 58 mg/L ThOD) showed higher biodegradation values, average 93.8% (92.9 and 94,7% in replicate vessels). A plateau was not yet reached after 28 days. The 10% generic trigger value for biodegradation initiation was reached within latest 2 days after test initiation. Within the day 10 -window, average 72% and 77% biodegradation occurred, respectively. No inhibitory effects of the test item were observed in the toxicity control where more than 25 % degradation occurred within 14 days. In conclusion, the substance is readily biodegradable..