SUMILIZER GP

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 Apr - 13 May 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks:

standard activated sludge

Details on inoculum:

- Source of inoculum/activated sludge: standard activated sludge purchased from Chemicals Inspection & Testing Institute, Japan, on 22 Jan 1998 (Sludge No.100122)
- Method of cultivation: 24.9 - 25.1 °C, > 5 mg/L dissolved oxygen and pH 6.41 - 7.75
- Concentration of sludge: 3694 ppm
- Water filtered: no

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 24.9 - 25.1 °C
- pH: 7.1 - 8.19
- Suspended solids concentration: 30 mg/L, corresponding to 10^7 - 10^8 cells/L according to OECD 301

TEST SYSTEM
- Culturing apparatus: 300 mL
- Number of culture flasks/concentration: 3
- Measuring equipment: Coulometer (TypeOM-2001A)

SAMPLING
- Sampling frequency: oxygen consumption: measured automatically and continuously for 28 days by coulometer, residual quantity of the test substance: determined by liquid chromatography after pre-treatment of the test solution at the end of exposure

CONTROL AND BLANK SYSTEM
- Inoculum blank: 1
- Abiotic sterile control: 1
- Toxicity control: -

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Remarks on result:

other: -9% degradation

Parameter:

% degradation (test mat. analysis)

Value:

0

Sampling time:

28 d

Remarks on result:

other: -2% degradation

Results with reference substance:

After 7 days: 62%
After 28 days: 72%
(Reported in the test report. The rates were based on ThOD_NO2)

Degradation rate:
After 7 days: 77%
After 14 days: 80%
(Re-evaluated from the test report. The rates are based on ThOD_NH3, which is approved by OECD 301)

Table 1: Degradation rate based on oxygen consumption:

Bottle no	Test bottle	Amount of test substance added (mg)	TOD (mg)	7th day		28th day
				BOD (mg)	Degradation rate (%)	BOD (mg)	Degradation rate (%)
1	Procedure control	30.3	91.1	60.3	62	75.9	72
2	Control blank	-	-	4.0	-	10.0	-
3	Test suspension	30.1	82.3	1.4	-3	3.6	-8
4	Test suspension	30.0	82.1	1.5	-3	3.8	-8
5	Test suspension	30.3	82.9	0.0	-5	1.5	-10
6	Abiotic control	30.1	-	0.0	-	0.0	-
				Average degradation rate of test suspensions: -4		Average degradation rate of test suspensions: -9

Table 2: Degradation rate of the test substance based on determination of residual quantity by liquid chromatography

Bottle no	Test bottle	Amount of test substance added (mg)	Residual amount of test substance	Degradation rate (%)
3	Test suspension	30.1	30.5	-3
4	Test suspension	30.0	30.5	-3
5	Test suspension	30.3	29.6	0
6	Abiotic control	30.1	29.5	-
				Average degradation rate of test suspensions: -4

Table 3: Validity criteria for OECD 301 C

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	< 20%	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	Toxicity control not required	Not applicable
The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg O2/L in 28 days. Values higher than 60 mg/L require critical examination of the data and the experimental technique. If the pH value is outside the range 6-8.5 and the oxygen consumption by the test substance is less than 60%, the test could be repeated with a lower concentration of test substance.	BOD after 28 days in 300 mL = 10 mg, corresponding to 33.3 mg/L	Yes
A test is considered valid if the difference of extremes of replicate values of the removal of the test substance at the plateau or at the end of the test, as appropriate is less than 20% and if the percentage degradation of aniline calculated from the oxygen consumption exceeds 40% after 7 days and 65% after 14 days.	BODr of reference compound by day 7: 60.3 mg BODr of reference compound by day 14: 64.8 mg BODp of procedure control by day 7: 4.0 mg BODp of procedure control by day 14: 6.2 mg Degradation = (BODr – BODp)/TOD ×100 Degradation rate: After 7 days: 77% After 14 days: 80% (Re-evaluated from the test report. The rates are based on ThOD_NH3 [TOD: 72.9 mg], which is approved by OECD TG 301)	yes

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Description of key information

Not readily biodegradable: 0% biodegradation after 28 d (OECD 301 C)

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

One study is available assessing the biodegradability of the test item by activated sludge microorganisms. The test was performed according to OECD 301C and was conducted under GLP standards. 100 mg/L initial test concentration was mixed into 300 mL of an aqueous mineral test medium and inoculated with 30 mg/L sludge. The mixture was incubated for 28 d and the biodegradation of the test material was calculated from the oxygen consumption throughout the study and calculated from direct determination (LC).

- 9% degradation was determined from the oxygen consumption measurement. The residual rate calculated from direct determination of the test item was 100% in the test suspension at test termination. The test results indicate that the substance is not readily biodegradable.