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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to EEC Method C.4-E and O.E.C.D. Testing Guideline No. 301D Closed Bottle Test with GLP compliance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
not specified
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
As per IUCLID5 Sections 1.1. - 1.4.

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
The activated sludge was collected on the day of the test from Thorndon Sewage Treatment Works (Suffolk, UK), a trickling-filter plant which treats predominantly domestic waste. It was maintained under aerobic conditions in the laboratory and immediately before use the sludge sample filtered through glass wool and the filtrate used as the inoculum for the test (1 mL filtrate/litre test medium).

Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Two groups of eighteen Biological Oxygen Demand (BOD) bottles (standard bottles, 227 mL) were filled with inoculated
Mineral Salts Medium alone, and with inoculated Mineral Salts Medium and sodium benzoate (2 mg/L) the positive control. Care was taken to avoid the introduction of air bubbles during filling. A third group of BOD bottles (modified with an injection port) were filled with inoculated Mineral Salts Medium and were sealed before the test substance was injected directly into the bottles. A fourth group of four modified bottles was included to determine whether the test substance was inhibitory to the microbial activity of the inoculum during seven days of incubation, contained inoculated Mineral Salts Medium, sodium benzoate and the test substance. The concentrations of dissolved oxygen (DO), temperatures and pH of the contents of duplicate vessels from each group were measured, using a YSI dissolved oxygen meter fitted with a self-stirring DO/temperature bottle probe and a pH meter, at the start of the test after 5, 7, 11, 14, 18, 21, 25 and 28 days at 22 ± 2°C.

Results and discussion

Preliminary study:
In a preliminary solubility trial, Crude 1,3-Dichloropropene was not found to be sufficiently soluble in ultrapure water to allow the preparation of an aqueous stock solution. Test concentrations (nominally 2 mg/L) were established by injecting the test substance (0.6 μl based on density) directly to sealed vessels pre-filled with inoculated media.
Test performance:
The temperatures of the contents of the BOD bottles and incubator ranged from 21.1 to 22.9°C and 21.2 to 22.6°C, respectively during the test, and the pH of the mixtures ranged from 7.3 to 8.1.
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
2
Sampling time:
28 d
Details on results:
Oxygen consumption in bottles containing Crude 1,3-Dichloropropene alone was negligible (at most, 0.09 mgO2/mg or 2% of its COD). Sodium benzoate the positive control had been degraded to 70% of its ThOD (1.67 mgO2/mg) after 14 days of incubation. In the presence of Crude 1,3-Dichloropropene, sodium benzoate had been degraded by 32% after seven days of contact.

BOD5 / COD results

Results with reference substance:
Sodium benzoate had been degraded by approximately 70% after 14 days of contact.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Crude 1,3-Dichloropropene was not considered to be readily degradable under the conditions of this test. However, Crude 1,3-dichloropropene at 2 mg/L reduced the biodegradation of the positive control, sodium benzoate approximately 2-fold during seven days of contact suggesting a potential for the inhibition of sludge mediated biodegradation.
Executive summary:

Crude 1,3 -dichloropropene was evaluated biodegradation potential in an EEC Method C.4 -e and O.E.C.D. Testing Guideline 301D Closed Bottle Test with GLP compliance. Crude 1,3-Dichloropropene was not considered to be readily degradable under the conditions of this test. However, Crude 1,3-dichloropropene at 2 mg/L reduced the biodegradation of the positive control, sodium benzoate approximately 2-fold during seven days of contact suggesting a potential for the inhibition of sludge mediated biodegradation.