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:
28-May 2003-28 June 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was conducted in 2003 according to OECD Method # 301B and EU method C.4-C and in accordance with GLP. The study material is well characterized.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Buff coloured powder; stored at room temperature in the dark; received at testing laboratory on 22 April 2003. Test material was dissolved directly in culture medium. Final concentration in the test vessel was 16.1 mg/L equivalent to 10mg carbon/L.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Standard material used was sodium benzoate dissolved in culture medium with a final concentration in the test vessel of 16.1 mg/L equivalent to 10 mg carbon per liter.

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Upon receipt sample of activated sludge is maintained on continuous aeration. Excessive amounts of dissolved organic carbon are removed from the activated sewage sludge sample by washing 3 times by settlement and resuspension in culture medium. The suspended solids level of the sludge was determined to be 3.2 g/L prior to use.
Duration of test (contact time):
0 - 28 d
Initial test substance concentration
Initial conc.:
10 mg/L
Based on:
other: test material (48.3 g) used to equal 10 mg carbon per liter
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
The test material at a concentration of 10 mg carbon per liter was exposed to activated sewage sludge micro-organisms with culture medium in sealed culture vessels in the dark at 21 C for 28 days. The degradation of the test material was assessed by determination of carbon dioxide produced. The following test and control solutions were prepared in duplicate and inoculated into 5 liter glass vessels each contained 3 liters solution; 1) inoculated culture medium ( control), 2). the standard material (sodium benzoate) in inoculated culture medium at a final concentration of 10 mg carbon /liter 3) the test material in inoculated culture medium at a final concentration of 10 mg carbon /liter and 4) test material plus standard material in inoculated culture medium at a final concentration of 20 mg carbon/L to act as a toxicity control. The culture vessels are sealed and CO2 free air bubbled through the solution at 40 ml/minute. CO2 produced by the degradation is collected in two 500mL bottles containing 350 ml of 0.05M sodium hydroxide as absorbing solution
Reference substance
Reference substance:
other: Sodium benzoate

Results and discussion

Test performance:
The test validation criteria were acceptable for total CO2 evolution in control vessels, the IC/TC ratio at the start , the test material 's (sodium benzoate) degradation % and the difference in CO2 production at the end of the test for the replicate vessels. The toxicity control attained 56% and was considered not toxic to sewage sludge and no carry over was noted in the second absorber vessel. The pH values ranged from 7.3 to 7.5 and the observations throughout the test period showed the contents of vessels for test material, control, standard material and toxicity control to be "light brown dispersions with no undissolved material present". For inorganic carbon analysis on day 29 there was an increases in all but 2 replicate vessels due to the CO2 in solution being driven off upon addition of the hydrochloric acid on day 28 and resulted in slight increases in percentage degradation value from day 28 to day 29.
% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
2
Sampling time:
2 d
Parameter:
% degradation (CO2 evolution)
Value:
10
Sampling time:
13 d
Parameter:
% degradation (CO2 evolution)
Value:
19
Sampling time:
21 d
Parameter:
% degradation (CO2 evolution)
Value:
30
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
Points of degradation plot (reference substance):
51 % degradation after 2 d
64 % degradation after 13 d
76 % degradation after 21 d
78 % degradation after 28 d

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
The test material attained 30% degradation after 28 days and therefore cannot be considered readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.
Executive summary:

The test material attained 30% degradation after 28 days and therefore cannot be considered readily biodegradable under the strict terms and conditions of OECD Guideline No 301B. This study was assigned reliability rating of 1 (reliable without restriction) and the results are considered valid.