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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011-07-22 to 2011-12-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
yes
Remarks:
The Dissolved Organic Carbon control of Ultra Pure Water used for the test medium was not determined.
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
The inoculum came from the activated sludge of the biological wastewater treatment plant from Abidos (France, 64). The effluent, obtained 3 days before seeding the flasks, was centrifuged at approximately 20°C for 15 min at 1000 g; the base was re-suspended in dilution water in arder to keep the concentration unchanged with respect to the sample. The inoculum was preconditioned (aeration) until the flasks were inoculated. The amount of dry material in the inoculum, determined by desiccation at 105°C until a constant weight is obtained, was 5.55 g/L.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
A 2.6 g/L solution of N,N DIETHYLHYDROXYLAMINE in the dilution water was prepared and used in a proportion of 10 mL per flask (260 mL). Sample of medium (10 mL) being taken at the beginning of the test for NO2 and NO3 analysis, the remaining (25 mg of test item) corresponded to a theoretical 02 mass of 49.36 mg per flask (ThOD 1.9745 mg 02/mg).
A parent solution of sodium benzoate in the dilution water to 2.5 mg/mL, was used in a proportion of 10 mL for 250 mL of dilution water, i.e. 25 mg, corresponding to a theoretical O2 mass of 41.65 mg per flask (ThOD 1.67 mg O2/mg). ln the inhibition monitoring flask, equivalent quantities of test and reference items are introduced. For this flask, the corresponding theoretical mass of O2 was 91.01 mg per flask.
The flasks were installed in the respirometer where the stirring system was started. After a waiting period of approximately 3 hours, which is necessary to reach the thermal equilibrium of the solutions at a temperature of 22 ±2°C, the aerated inoculum, was added ta all the flasks that were then plugged.
Reference substance:
other: sodium benzoate
Preliminary study:
no data
Parameter:
% degradation (CO2 evolution)
Value:
11
Sampling time:
28 d
Details on results:
The maximum degradation level of N,N DIETHYLHYDROXYLAMINE was 11% in 28 days.
As no biodegradation was observed, the latency phase was not determined.
N,N DIETHYLHYDROXYLAMINE did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is already 46 %, higher than 25 % after 14 days.
Results with reference substance:
The percentage degradation of the reference item reached a level of 93% by 14 days which is above the required level of 60 %.
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The study of the "ready" aerobic biodegradability of N,N DIETHYLHYDROXYLAMINE using the OECD method 301 F shows that this item reached a maximum biodegradation level of 11 % in 28 days. The item did not demonstrate any inhibiting effect on the micro-organisms. Based on these criteria, the N,N DIETHYLHYDROXYLAMINE is not readily biodegradable.
Executive summary:

The aerobic degradation of N,N DIETHYLHYDROXYLAMINE has been examinated during 28 days according to OECD guideline 301 F and under GLP requirements. Under the test conditions, the percentage of biodegradation of DEHA reached 11 % of the ThOD at the end of the test. Validity criteria were fulfilled. The test substance did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is 46% higher than 25% within 14 days.

According to OECD guideline 301F, N,N DIETHYLHYDROXYLAMINE is not readily biodegradable.

Description of key information

The aerobic degradation of N,N DIETHYLHYDROXYLAMINE (DEHA) has been evaluated during 28 days according to OECD guideline 301 F and under GLP requirements (Study report, 2011). The inoculum came from the activated sludge of a biological wastewater treatment plant. Under the test conditions, the percentage of biodegradation of DEHA reached 11 % of the ThOD at the end of the test. Validity criteria were fulfilled. The test substance did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is 46% higher than 25% within 14 days. According to this test, DEHA is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information