1,2-dihydro-2-oxoquinoline-4-carboxylic acid

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:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1,2-dihydro-2-oxoquinoline-4-carboxylic acid

EC Number:

239-827-9

EC Name:

1,2-dihydro-2-oxoquinoline-4-carboxylic acid

Cas Number:

15733-89-8

Molecular formula:

C10H7NO3

IUPAC Name:

1,2-dihydro-2-oxoquinoline-4-carboxylic acid

Test material form:

solid: particulate/powder

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Secondary effluent, microorganisms from a domestic waste water treatment plant.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

31 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation 1

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation 2

Parameter followed for biodegradation estimation:

other: Total Oxidised N, Nitrite and Nitrate

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

Conditions for the validity of the test :
 Oxygen depletion in the inoculum control did not exceed 1.5 mg O2/L after 28 days.
 The residual oxygen concentration in the test flasks did not drop below 0.5 mg O2/L at any time.
 The difference of extremes of replicate values of the removal of the test substance at the plateau, (at the end of the test or at the end of the 10 or 14-d window) would not have been greater than 20 %.
 The percentage degradation of the reference item reached the level for ready biodegradability (> 60 %) within 14 days.
 The percentage degradation in the toxicity control containing both the test item and the reference item reached the level for ready biodegradability (> 25 %) by exposure day 14.

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

51.4

Sampling time:

28 d

BOD5 / COD results

BOD5 / COD

Key result

Parameter:

ThOD

Value:

1.95 g O2/g test mat.

Results with reference substance:

ThOD of reference item = 1.67 mg O2/mg reference item

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 3.1 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.
The study met the validity criteria.
The test item was not considered to have significant inhibitory effects on the secondary effluent microorganisms.
Based on the results of this study, the test item is considered not readily biodegradable.

Executive summary:

The test item ACIDE HYDROXY was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

The test system was a microbial inoculum of good quality, collected from a sewage plant for domestic sewage. The sludge was allowed to settle and then aerated until use.

Under the test conditions the percentage biodegradation of ACIDE HYDROXY reached a mean of 51.4 % after 28 days based on the ThOD of the test item. According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD. Therefore the test item is considered not readily biodegradable.

The reference item Sodium benzoate was sufficiently degraded to a mean of 66.7 % after 14 days, and to a mean of 74.2 % after 28 days of incubation, based on ThOD, thus confirming the suitability of the used inoculum.

In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 37.2 % biodegradation was noted within 14 days and 50.0% biodegradation after 28 days of incubation.

According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 3.1 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.

The study met the validity criteria.

The test item was not considered to have significant inhibitory effects on the secondary effluent microorganisms.

Based on the results of this study, the test item is considered not readily biodegradable.