Ethyl 3,4-dihydroxybenzoate

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:

29 August 2016 to 29 September 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl 3,4-dihydroxybenzoate

EC Number:

223-529-0

EC Name:

Ethyl 3,4-dihydroxybenzoate

Cas Number:

3943-89-3

Molecular formula:

C9H10O4

IUPAC Name:

ethyl 3,4-dihydroxybenzoate

Test material form:

solid: particulate/powder

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands
- Storage conditions: preconditioned to experimental conditions by continuous aeration in the climate controlled room
- Storage length: approximately 26 hours
- Preparation of inoculum for exposure: pre-conditioned to expermental conditions
- Pretreatment: allowed to settle, the supernatant is used as inoculum
- Concentration of sludge: 10 mL/L medium
- suspended solids: 3.7 g/L

Duration of test (contact time):

29 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

20.5 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

12 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium according to the guideline
- Test temperature: 21.7 - 22.4°C.
- pH: 7.5-7.6
- pH adjusted: no
- Aeration of dilution water: yes but interrupted on day 13 (<1 day)
- Suspended solids concentration: 3.7 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2 litre brown glass vessels
- Number of culture flasks/concentration: 2 for inoculum controls, 2 for test substance, 1 for reference substance, 1 for toxicity control
- Method used to create aerobic conditions: Synthetic air was sparged through the solutions
- Measuring equipment: A mixture of oxygen (ca. 20%) and nitrogen (ca. 80%) was passed through a bottle, containing 0.5 - 1 litre 0.0125 M Ba(OH)2 solution to trap CO2 which might be present in small amounts. The synthetic air was sparged through the scrubbing solutions at a rate of approximately 1-2 bubbles per second (ca. 30-100 mL/min).
- Test performed in closed vessels due to significant volatility of test substance: NA
- Details of trap for CO2: 3 BaOH traps in serie

SAMPLING: day 2, 5, 7, 9, 12, 13, 14, 19, 23, 27, 29 (+after elution with HCl)

STATISTICAL METHODS: none applied

Reference substance

Reference substance:

acetic acid, sodium salt

Remarks:

40 mg/L, 12 mg/L as TOC

Results and discussion

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 8 - <= 9

Sampling time:

7 d

% Degradation 2

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 61 - <= 68

Sampling time:

14 d

% Degradation 3

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 65 - <= 94

Sampling time:

29 d

Details on results:

Both test bottles reach >60% biodegradation within the 10 day window. Therefore, it was concluded that the >20% difference in duplicates does not interfere with the validity of this test.

Any other information on results incl. tables

CO₂production and percentage biodegradation

Day	HCl (0.05 N) titrated (mL)			Cumulative CO2 (mg) Bottle A	Cumulative CO2 (mg) Bottle B	Biodegradation^1) (%) Bottle A	Biodegradation^1) (%) Bottle B
	Blank (mean)	Bottle A	Bottle B
2	47.07	45.80	46.10	1.4	1.1	2	1
5	47.08	44.55	44.96	4.2	3.4	5	4
7	46.71	44.26	42.61	6.9	7.9	8	9
9	47.02	40.23	24.61	14.3	32.5	16	37
12	47.11	15.75	33.27	48.8	47.8	55	54
13	48.41	41.56	44.18	56.4	52.4	63	59
14	49.10	45.28	47.82	60.5	53.8	68	61
19	47.76	37.46	46.97	71.9	54.7	81	62
23	46.70	41.74	45.68	77.3	55.8	87	63
27	44.37	40.86	43.31	81.2	57.0	91	64
29	46.99	45.13	46.85	83.2	57.1	93	64
29	49.45	48.88	49.67	83.8	57.1	94	64
29	51.26	51.57	51.11	83.8	57.3	94	65

 

Applicant's summary and conclusion

Validity criteria fulfilled:

no

Remarks:

the deviation between the 2 replicates exposed to the test substance was > 20%, as both replicates showed ready biodegradation, this finding is considered not to interfere with the validity of the test.

Interpretation of results:

readily biodegradable

Conclusions:

The substance is considered readily biodegradable under the conditions of the test

Executive summary:

In a CO2 -evolution test, the substance degraded for > 60% (actually 94 and 65% per replicate) during the 29 day test period. As both of the replicates fulfilled the 10-day window criterion, the results are sufficient valid to conclude that the substance is readily biodegradable.