Carboxylic acids, di-, C5-9

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:

05 Sep - 03 Oct 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Carboxylic acids, di-, C5-9

EC Number:

701-329-9

Molecular formula:

C5di: C5H8O4 C6di: C6H10O4 C7di: C7H12O4 C8di: C8H14O4 C9di: C9H16O4

IUPAC Name:

Carboxylic acids, di-, C5-9

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: from a domestic waste water treatment plant in Rossdorf, Germany
- Preparation of inoculum for exposure: deposited for 15 minutes, washed by centrifugation and liquid phase was decanted; 3 x procedure: re-suspension of solid material in test water and centrifuging; weighing, drying and determination of wet sludge/dry weight ratio of sludge suspension
- Pretreatment: overnight aeration
- Concentration of sludge: 3.5 g dry material/L
- Water filtered: no

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

102.5 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

164.5 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: according to OECD 301 A
- Test temperature: 22 ± 1°C
- pH: 7.1 - 7.6
- Suspended solids concentration: 3.5 g/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: manometric test system with flasks containing approx. 500 mL
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: overnight aeration of sludge suspension
- Measuring equipment: BSB/BOD sensor system (O2 consumption calculated from pressure decrease in reaction vessel)
- Test performed in closed vessels due to significant volatility of test substance: gas-tight closed by a measuring head
- Details of trap for CO2 and volatile organics if used: Potassium hydroxide solution

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: 1
- Toxicity control: 1
- Other: procedure control: 1

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

87

Sampling time:

28 d

Details on results:

Mean pass level of > 60% reached after on test day 9

BOD5 / COD results

Results with reference substance:

75% degradation after 14 days and 78% degradation after 28 days

Any other information on results incl. tables

Table 1: Cumulative Biochemical Oxygen Demand (mg O2/L) in Test Flasks during the Test Period of 28 days.

Time (days)	Test substance		Inoculum control		Procedure control	Abiotic control	Toxicity control
1	15	15	0	0	30	0	55
2	30	25	0	0	70	0	85
9	115	95	0	5	125	0	170
28	150	140	0	5	135	0	245

Table 2: % Degradation in Test Flasks during the Test Period of 28 days.

Time (days)	Test substance		Procedure control	Toxicity control
1	9	9	18	16
2	18	15	41	25
9	68	56	72	50
11	71	63	72	57
28	89	84	78	72

Table 3: Validity criteria for OECD 301 F.

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%.	Difference of duplicate values at day 28 differed by 5%	yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	> 60% after 4 days	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.	64% at day 14	yes
The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg/L in 28 days.	2.5 mg O2/L after 28 days	yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Interpretation of results:

readily biodegradable