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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:

16 May 2002 to 28 June 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

July 1992

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Name used in report: T-71
Batch/Lot number: 10142
Appearance: White powder
Purity: 98.4%

Oxygen conditions:

anaerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Standard activated sludge obtained from Chemical Biotesting Center of the Chemicals Evaluation and Research Institute, Japan, on April 18, 2002 was used.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Details on study design:

Determination of biochemical oxygen demand (BOD) in a closed BOD determination system
BOD was determined under the following conditions:
Apparatus used: Coulometer OM-2000" (I.D. No. 1) (SOP/INS/4.6.1), a closed BOD determination system supplied by Ohkura Electric Co., Ltd.
Test conditions:
Concentration: test substance: 100 mg/L standard activated sludge: 30 mg/L
Temperature: 25±1 °C
Test fluid: 300 mL
Incubation period: May 22- June 19, 2002 (28 days)

Test method: The basal culture fluid was adjusted to pH 7.0.
The following test blocks were set:
Test substance decomposition block (triplicate): Test substance (30.00 mg for No. 1, 30.01 mg for No.2, 30.02 mg for No. 3) + 290 mL of basal culture fluid+ 10 mL of activated sludge (900 mg/L)
Basal respiration block (single): 290 mL of basal culture fluid + 10 mL of activated sludge (900 mg/L*)
Aniline decomposition block (single): 29.5 μL of aniline (30.12 mg) + 290 mL of basal culture fluid + 10 mL of activated sludge (900 mg/L*)
Stable block in water (single): 30.03 mg of the test substance+ 300 mL of purified water
* The sludge was diluted with the basal culture fluid to 900 mg/L based on the concentration of suspended materials in activated sludge cultures.
In order to prepare test fluid, the test substance was weighed into culture bottles as shown above, and designated amounts of the basal culture fluid or purified water were added, followed by the activated sludge solution. The test fluid bottles were incubated for 28 days in an BOD determination system, and BOD was determined over time. During incubation, the presence or absence of leakage from the system, temperature in the system's thermostatic chamber, presence or absence of growth of activated sludge in the culture bottles, the test substance dissolution rate, and presence or absence of coloration due to degradation were monitored and recorded. After incubation for 28 days, culture bottles removed from the system were observed for pH, dissolution of the test substance, and biota, and residual concentrations of the test substance were determined by the direct assay method described below.

Determination of residual concentrations of the test substance in culture bottles by direct assay
Residual concentrations of the test substance were determined.
Pre-analysis treatment: Culture bottles removed from the system on the 28th day of culture were observed for pH, dissolution of the test substance, and biota, and the test fluid in the bottom of the soda lime cup used for sludge observation was washed into the culture bottles with 100 mL of methanol. After stirring for a while, fluid in the culture bottles was transferred to a 1-L volumetric flask using a funnel. Inside the culture bottles and funnel were washed with 580 mL of methanol used in several installments, and washings were added to the separator. After stirring for 30 min until the test substance was dissolved, the stirrer was washed with a small amount of methanol and removed. After further shaking, methanol was added to make 1 L when fluid temperature was equilibrated. Aliquots of the resulting fluid were filtered through Ekicrodisc 13CR, and the filtrate obtained was assayed by HPLC.

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

-1

Sampling time:

28 d

Key result

Parameter:

% degradation (test mat. analysis)

Value:

2

Sampling time:

28 d

Details on results:

For details see attachment "T-71 - degradation and residual rates biodegredation study.pdf".

Results with reference substance:

The aniline degradation rate on the 7th day was 66% and the oxygen consumption curve was normal, indicating that the degradation activity of activated sludge was normal.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Description of key information

Biodegradation in water: screening tests: aerobic biodegradation ≤10% (biological oxygen demand (BOD) and test item decrease) in 28 days (OECD 301B, Modified MITI Study (I)).

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater