Methyl 2,4-dihydroxy-3,6-dimethylbenzoate

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:

31 August 1994 - 30 September 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(1992)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aire, Switzerland)
- Preparation of inoculum for exposure: sludge was collected in the morning, washed three times in mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium); kept aerobic until being used on the same day
- Concentration of sludge (dry weight of suspended solids): 3.169 g/L

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
- Composition of medium: According to Guideline 301 F. Deionised water used to prepare the medium contained less than 10 mg/L of dissolved organic carbon.
- Test temperature: 22°C
- pH: inital (t=0): 7.36-7.51, at test end (t= 28 d): 7.37-8.24
- Suspended solids concentration: 30 mg/L (dry weight)
- Continuous darkness: not reported

TEST SYSTEM
- Culturing apparatus: Water bath of the SAPROMAT D 12 respirometer
- Number of culture flasks/concentration: 2
- Measuring equipment: SAPROMAT D 12 (J.M. VOITH GmbH, D-7920, Heidenheim, Germany)
- Test performed in closed vessels: yes
- Details of trap for CO2: Soda lime (approx. 2g) was placed in an attachment of the stopper

SAMPLING
- Sampling frequency: Oxygen consumption of each flask was measured daily
- pH was measured at test initiation (in mineral medium) and at test end (after 28 days, in each flask)

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes

STATISTICAL METHODS: not applicable

Reference substance:

aniline

Remarks:

purity: min. 99.5%

Parameter:

% degradation (O2 consumption)

Value:

16

Sampling time:

2 d

Parameter:

% degradation (O2 consumption)

Value:

59

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

61

Sampling time:

12 d

Parameter:

% degradation (O2 consumption)

Value:

63

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

64

Sampling time:

21 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

63

Sampling time:

28 d

Remarks on result:

other: repl. 1 - 68% degradation, repl. 2 - 57% degradation

Details on results:

Based on the percent degradation of aniline when tested in combination with the test item (toxicity control), it is concluded that the test item is not toxic to microorganisms at a concentration of 100 mg/L (>25% degradation based on ThOD).

- Validity criteria:
1. Not more than 20% difference between replicates of the flasks containing the test substance was reported (i.e. 2. The percentage degradation of the reference substance was 85% after 14 days.
3. In the toxicity control, >25% degradation occurred within 14 days, thus the test substance was not toxic to microorganisms at a test concentration of 100 mg/L.
4. Oxygen consumption of the inoculum blank was not greater than 60 mg/L in 28 days (17.5 mg O2/L).

Results with reference substance:

Aniline (ThOD is 2.41 mg O2/mg): 75% degradation after 5 days and 85% after 14 days was achieved. Therefore, validity criterion was met.

Veramoss (in the report EVERNYL) undergoes 63% biodegradation after 28 days under the test conditions of the OECD 301F test. The biodegradation rate at the end of the 10 -day window (days 2 to 12) is 61%.

Thus, the test item can be regarded as readily biodegradable.

In the toxicity control, after 14 days the consumed oxygen level (of the combined test item and reference substance) was approximately at the level of the sum of consumed oxygen for the test item and the reference substance, indicating that the test item does not inhibit microbial activity.

Validity criteria fulfilled:

yes

Remarks:

yes: 85% biodegradation of reference substance after 14 days; oxygen uptake of incoulum blank is <60 mg/L in 28 days; not more than 20% difference between replicates of the flasks containing the test item

Interpretation of results:

readily biodegradable

Conclusions:

The substance showed 63% biodegradation after 28 days in an OECD TG 301F test.

Executive summary:

The ready biodegradability of the substance was investigated in a study conducted in accordance with OECD TG 301F ( 1992, Manometric Respirometry) and GLP. The substance concentration tested was 100 mg/L, with an activated sludge concentration of 30 mg/L. Under the conditions of the test, the reference substance aniline was biodegraded for 85% after 14 days. In the toxicity control the substance was not toxic to the inoculum. The substance showed 63% biodegradation after 28 days, of which 61% are within the 10 day window. Therefore the substance is regarded as readily biodegradable.

Description of key information

Key study: OECD TG 301F

The ready biodegradability of the substance was investigated in a study conducted in accordance with OECD TG 301F ( 1992, Manometric Respirometry) and GLP. The substance concentration tested was 100 mg/L, with an activated sludge concentration of 30 mg/L. Under the conditions of the test, the reference substance aniline was biodegraded for 85% after 14 days. In the toxicity control the substance was not toxic to the inoculum. The substance showed 63% biodegradation after 28 days, of which 61% are within the 10 day window. Therefore the substance is regarded as readily biodegradable.

Additional information: OECD TG 301D

In another study, performed according to OECD TG 301 D, the substance showed less biodegradation: 21% biodegradation after 28 days, at a test concentration of 4 mg/L.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable