Carboxylic acids, di-, C4-6

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Read-Across from glutaric acid, which is a structural analogue and serves well as a representative substance for the carboxylic acid mixture.

Qualifier:

according to guideline

Guideline:

EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material :
PHYSICO-CHEMICAL PROPERTIES
- Melting point: 97°C (Merck-Index)
- Boiling point: 303°C (Merck-Index)
- Vapour pressure: 3,84*10-6 hPa at 25°C (Yaws, 1994)
- Water solubility (under test conditions): 1600 g/L (at 25°C Yalkowsky, 1992)
- log Pow: -0.29 (Hansch&Leo, 1995)
- pKa: pK1 = 4,34; pK2 = 5,22 (Merck-Index)


OTHER PROPERTIES
- Adsorption characteristics: adsorption coefficient (Log Koc) 1.066 (calculated by EPIWIN)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Type: mixed population of aquatic microorganisms
- Origin: effluent of a domestic waste water treatment plant (Wupper area water authority, Germany)
- effluent concentration: 0.5 mL / 900 mL
- pretreatment: none

Duration of test (contact time):

14 d

Initial conc.:

20 mg/L

Based on:

DOC

Reference substance:

aniline

Parameter:

% degradation (DOC removal)

Value:

100

Sampling time:

14 d

Results with reference substance:

Aniline shows 100% degradation within 7 days.

Test ends after 14 days, as 100 % of glutaric acid was degraded.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Glutaric acid is readily biodegradable. After 14 days 100 % of the test substance had been degraded in a Modified OECD Screening Test.

Executive summary:

Glutaric acid is readily biodegradable. After 14 days 100 % of the test substance had been degraded in a Modified OECD Screening Test. (EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)).

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Read-Across from succinic acid, which is a structural analogue and serves well as a representative substance for the carboxylic acid mixture.

Qualifier:

according to guideline

Guideline:

other: other guideline: "Biodegradation test of chemical substance by mircoorganisms etc." stipulated in the order Prescribing the Items of the test relating to the new chemical substance (1974)

Principles of method if other than guideline:

This guideline corresponds to 301C, ready biodegradability: modified MITI Test (I) stipulated in the OECD Guidelines for testing of chemicals (May 12, 1981)

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
PHYSICO-CHEMICAL PROPERTIES
- Melting point: 185-187°C (Merck-Index)
- Boiling point: 235°C (Lide, 2002)
- Vapour pressure: 2.55e-7 hPa at 25°C /Yaws, 1994)
- Water solubility: 83.2 g/L at 25°C (Yalkowsky, 1992)
- log Pow: -0.59 (Hansch & Leo, 1995)
- pKa: 4.21 at 25°C (Lide, 2002)


OTHER PROPERTIES
- Adsorption characteristics: adsorption coefficient (Koc) 6.3 (calculated by EPIWIN)

Oxygen conditions:

aerobic

Inoculum or test system:

other: sludge samplings from different sewage plants, rivers, bays and a lake in Japan

Details on inoculum:

sludge samplings from different sewage plants, rivers, bays and a lakes
sludge conc.: 30 mg/l related to BOD

Duration of test (contact time):

14 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter:

% degradation (O2 consumption)

Value:

78

Sampling time:

14 d

Remarks on result:

other: related to BOD

Parameter:

% degradation (test mat. analysis)

Value:

100

Sampling time:

14 d

Remarks on result:

other: HPLC analysis

Parameter:

% degradation (TOC removal)

Value:

99

Sampling time:

14 d

Remarks on result:

other: TOC analysis

A blank control (sterile mineral medium only), positiv control (aniline as refer-ence compound at 100 mg/l) and succinic acid control (succinic acid in pure water at 100 mg/l) in 300 ml were incubated simultaneously. Oxygen consumption resulting from biodegradation of the compounds was measured over 14-day test period using an Okura Electric Closed System Oxygen Consumption measuring apparatus (Coulometer). Percentage biodegradation was calculated based on BOD, TOC and HPLC analysis.

The test solutions were maintained in a darkened room at a temperature of 25 ±1 °C and continuously stirred by magnetic stir bars over the 14-day test period.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

After 14 days, succinic acid showed 78 % degradation realting to BOD, and 100% degradation relating to the test substance concentration.

Executive summary:

A test on ready biodegradability was conducted according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). After 14 days, succinic acid showed 78 % degradation realting to BOD, and 100% degradation relating to the test substance concentration.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Read-Across from adipic acid, which is a structural analogue and serves well as a representative substance for the carboxylic acid mixture.

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
PHYSICO-CHEMICAL PROPERTIES
- Melting point: 151°C (Rhodia Study, 2008)
- Boiling point: 337.5°C at 1013 hPa (Merck Index)
- Vapour pressure: 0.097 hPa at 18.5°C (Kirk-Othmer)
- Henry's law constant (for volatie substances): 9,656e-9 hPa m³/mol 25°C (Currenta, 2009)
- Water solubility: 23 g/L at 25°C (MITI, 1992)
- Solubility in organic solvents: Adipic acid is not stable in alcohol. The corresponding ester is formed (Beyer, 2004).
- log Pow: 0.093 at pH 3.3 (BASF-Study, 1988)
- pKa: 4.34-5.44 at 18°C; 4.43-5.42 at 20°C; 4.43 at 25°C (Beilstein, 2003)
- Base or acid catalysis of test material:
- UV absorption: t1/2 = 2,9d (Currenta, 2009)

OTHER PROPERTIES
- Adsorption characteristics: adsorption coefficient (Koc) 21.5 (Currenta, 2009)
- Toxicity to microorganisms: Activated sludge, 3-hour EC50 4747 mg/l (Bayer AG, 1988)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Details on inoculum:

1 drop of effluent per liter

Duration of test (contact time):

30 d

Initial conc.:

2 mg/L

Based on:

DOC

Parameter:

% degradation (O2 consumption)

Value:

83

Sampling time:

30 d

related to BOD

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation rate is 83 % after 30 d.

Executive summary:

The ready biodegradability of adipic acid was tested according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test). The biodegradation rate is 83 % after 30 d.

Reference 4

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Guideline study according to OECD guideline 302B.

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, industrial (adaptation not specified)

Details on inoculum:

-Source: BASF sewage plant
-Dry weight of sluge in supply vessel: 6g/L

Duration of test (contact time):

7 d

Initial conc.:

400 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

- pH adjusted: yes (no further information)

Parameter:

% degradation (DOC removal)

Value:

93

Sampling time:

1 d

Parameter:

% degradation (DOC removal)

Value:

99

Sampling time:

7 d

Details on results:

Control of physical and chemical stability of the test substance (without inokulum):
Stocksolution of Test substance: 3g/L, TOC=DOC= 1350 mg/L,
within 10 days the test substance is stabil (calculated initial DOC concentration=400 mg/L, measured DOC 0d=401 mg/L, measured DOC 10d=422 mg/L).

Calculated initial DOC concentration: 400 mg/L

Measured, corrected initial DOC concentration: 417 mg/L

Measured DOC concentration after 3h: 397 mg/L

Measured values:

Date1988	Day	Control DOC (mg/L)	Testsubstance DOC (mg/L)	Size of DOC Elinmination (%)	pH
29.9.	0	---	453/451	-14	4.2
29.9.	3h	13	390/397	5	7.7
30.9.	1	13	43/37	93	8.2
2.10.	2	13	14/12	100	8.1
6.10.	7	13	16/18	99	8.6

Validity criteria fulfilled:

not specified

Interpretation of results:

inherently biodegradable

Conclusions:

The biodegradation rate is 99 % after 7 d.

Executive summary:

The inherent biodegradability of carboxylic acids was tested according to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test). The biodegradation rate is 99 % after 7 d.

Description of key information

Carboxylic acids, di-, C4-6 is readily biodegradable as well as inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Several screening tests on biodegradation in water are available resulting in ready biodegradability of the substance. The test were carried out with the mixture and the single acids.

There is one test available carried out to assess the ready biodegradability of the multi constituent substance “dicarboxylic acids”. The test substance was a residue from adipic acid manufacturing containing the following composition: 60 % adipic acid, 14 % glutaric acid, 6 % succinic acid, 10 % carbon, 6.5 % vanadium pentoxide, 3 % copper nitrate and 5 % copper (Bayer, 1988c). Using this mixture, a Closed Bottle Test was performed resulting in 56 % degradation after 28 days of exposure. It is discussed in the ICCA OECD/HPV-program, that it is not clear how the compounds other than the dicarboxylic acids affect the biodegradation. Therefore, the study should not be used for assessment.

In a test on ready biodegradability of adipic acid conducted according to the OECD guideline 301 D (Determination of the Ready biodegradability: Closed Bottle Test) 83 % degradation was observed after 30 days (Gerike, 1979). Although, no information on the 10-day window criterion is given, and more than 70% of the test substance has been degraded indicating a potential for complete ultimate biodegradation, it is considered that the criteria for ready biodegradability are fulfilled.

Regarding the ready biodegradability of succinic acid, an aerobic ready test, performed according to the national Japanese standard method comparable to the OECD TG 301 C guideline. After a period of 2 weeks more than 90% biodegradation of succinic acid was observed (MITI, 2002).

Concerning ready biodegradability of glutaric acid, 100 % of the test substance had been degraded after 14 days in a Modified OECD Screening Test. (EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)) (Bayer AG, 1993).

Based on this result the substance should be classified as readily biodegradable.

With regard to dicarboxylic acids, only one test for inherent biodegradation of dicarboxylic acids in water exists. The test was performed according to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test). The biodegradation rate was 99 % after 7 d (BASF, 1988).

Based on these results the subtsance is considered to be inherently biodegradable.