Reaction products of 1,4-Benzenedimethanol and 1-naphthol

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:

10 October 2019 to 05 December 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

See any other information for details

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

yes

Remarks:

See any other information for details

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

yes

Remarks:

See any other inforamtion for details

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

No further details provided in the study

Oxygen conditions:

anaerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

The inoculum: Secondary effluent, microorganisms from a domestic waste water treatment plant.
Origin: The secondary effluent was supplied from the sewage plant for domestic sewage in Veszprém county, Hungary.
Conditioning: The secondary effluent used for this study was allowed to settle approximately for an hour, then the decanted effluent was aerated until use (not later than an hour).

Duration of test (contact time):

28 d

Initial conc.:

1.85 mg/L

Based on:

test mat.

Initial conc.:

3.26 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST UNITS
Type and Size: BOD bottles (300 mL) with special neck and glass stoppers.
Identification: Each test flask was uniquely identified with study code, test group, days of measurement and replicate number.

3.6. TEST CONDITIONS
The test was carried out in an incubator and controlled environment room (during the formulation and oxygen measuring) at a temperature of 22 ± 2°C according to guideline. The test flasks were placed into an incubator and kept at 21.6 - 23.8°C, in the dark. The temperature was measured on weekdays during the experiment.
The oxygen concentration of test water was 8.7 mg/L at the start of the test.
The pH value of the test water was checked prior start of the experiment. The pH of the test water was 7.24.
The test conditions were measured with suitable instruments and documented in the raw data.

3.7. PREPARATION OF THE TEST SOLUTIONS
The respective amount of test item was weighed in directly to reach the required test item concentration of 1.85 mg/L.
The chosen test item concentration was based on the measured chemical oxygen demand (COD): 3.26 ±0.176 mg test item and on the performed 14-d preliminary test. During the preparation of the test solutions they were mixed by mechanical stirring using ultrasonic bath for 10 minutes.
Note: The test item floated on the top of the stock solution. After that the stock solution was applied into the test flasks, remaining amount of test item was observed visually at the bottom of the measuring flasks.
The components were applied in the amounts/volumes in the test flasks:
1.) Test Item (flasks 1a and 1b)
Based on the measured chemical oxygen demand (COD) of 3.26 mg O2/mg test item, (6.30 mg of test item) was thoroughly mixed into 3.40 litres of aqueous test medium (corresponding to 1.85 mg/L test item, wich corresponds to 6.031 mg O2/L).
2.) Procedure Control: Sodium benzoate (flasks 2a and 2b)
Based on the theoretical oxygen demand (ThOD) of Sodium benzoate (1.67 mg O2 per mg; details on calculation are given in the guidelines), stock solution* corresponding to 12.168 mg of Sodium benzoate was mixed into 3.38 litres of aqueous test medium (corresponding to 3.6 mg/L reference item, respectively a ThOD of about 6.012 mg O2/L).
* The concentration of the stock solution was: 360 mg/L.
3.) Inoculum Control (flasks 3a and 3b)
Only filtered inoculum was added to 3.38 litres of aqueous test medium.
4.) Toxicity Control (flasks 4a and 4b)
The test item (6.30 mg) and the reference item stock solution* (34.0 mL) were mixed into 3.40 litres of aqueous test medium corresponding to 1.85 mg/L test item (corresponds to 6.031 mg O2/L) and 3.6 mg/L reference item (ThOD of 6.012 mg O2/L).
* The concentration of the reference item stock solution was: 360 mg/L.
Microbial inoculum (0.5 mL per litre) was added to each preparation bottle.

3.8. COURSE OF THE TEST

3.8.1. Preparation of Test Flasks
Sufficient number of BOD flasks was cleaned with 5 - 10 mL of a wash liquid (2.5 g iodine and 12.5 g potassium iodide per litre of 1% w/v sulphuric acid) by shaking well to coat the bottle walls. After allowing to stand for 15 minutes, the wash liquid was poured off, and the bottles were thoroughly rinsed with tap water and deionised water. Then, the previously described test solutions were filled into the bottles bubble-free until the bottles were completely filled. Then they were tightly closed with glass stoppers.
Test item (flasks 1a and 1b) and procedure control (flasks 4a and 4b) test solutions were agitated on each working day during the experiment.

3.8.2. The Test Bottles
The number of test bottles was the follow:
 10 bottles containing the test item and inoculum
 10 bottles containing the reference item and inoculum (procedure control)
 10 bottles containing only inoculum (inoculum control)
 10 bottles containing the test item, reference item and inoculum (toxicity control)
The reference item and inoculum (procedure control) were also part of a concurrent studies (Charles River Laboratories Hungary Kft. study codes: 19/090-322AN and 19/117-322AN) performed in the same experimental period using the same batch of chemicals and solutions. Raw data sheets are clearly associate data with the appropriate study numbers. Copies of all raw data of positive and negative controls run in parallel were placed in the study file.

3.9. MEASUREMENTS
3.9.1. COD Measurement
The COD (chemical oxygen demand) of the test item was determined in the analytical department of the test facility using Lovibond® COD Measuring System.

3.9.2. Measurement of Oxygen
The incubation period of the closed bottle test was 28 days.
The oxygen concentrations were measured with an oxygen meter with a stirring O2 electrode. Oxygen measurements were performed in duplicate on days 0, 7, 14, 21 and 28.

3.9.3. Measurement of Temperature
Temperature was measured continuously and registered on weekdays.

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Not specified.

Test performance:

The study met the criteria

Key result

Parameter:

% degradation (O2 consumption)

Value:

3.3

Sampling time:

28 d

Key result

Parameter:

BOD5

Value:

0.11 mg O2/g test mat.

Results with reference substance:

The reference item Sodium benzoate was sufficiently degraded to a mean of 69.2% 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.

Dissolved Oxygen Concentrations at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.	mg O2/L after n days of exposure
			0	7	14	21	28
Test item	1.85	1a	8.2	7.9	7.3	7.1	7.1
		1b	8.2	7.9	7.4	7.2	7.1
		mean	8.20	7.90	7.35	7.15	7.10
Reference item	3.6	2a	8.3	4.3	3.9	3.2	3.0
		2b	8.4	4.3	3.9	3.4	3.0
		mean	8.35	4.30	3.90	3.30	3.00
Inoculum control	-	3a	8.2	8.0	8.0	7.7	7.4
		3b	8.3	8.1	7.9	7.6	7.3
		mean	8.25	8.05	7.95	7.65	7.35
Toxicity control	Test item: 1.85 Reference item: 3.6	4a	8.2	3.9	3.2	2.6	2.3
		4b	8.1	3.7	3.5	2.9	2.4
		mean	8.15	3.80	3.35	2.75	2.35

Oxygen Depletion at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.	mg O2/L after n days of exposure
			7	14	21	28
Test item	1.85	1a	0.1	0.6	0.5	0.2
		1b	0.1	0.5	0.4	0.2
Reference item	3.6	2a	3.8	4.1	4.5	4.4
		2b	3.9	4.2	4.4	4.5
Toxicity control	Test item: 1.85 Reference item: 3.6	4a	4.2	4.5	4.8	4.9
		4b	4.2	4.3	4.6	4.8

 

oxygen depletion: (mt0 - mtx) - (mb0 - mbx), where:

mt0: oxygen concentration (mg/L) of test group on day 0 (1a, 2a, 4a and 1b, 2b, 4b from Table 2)

mtx: oxygen concentration (mg/L) of test group on day x (1a, 2a, 4a and 1b, 2b, 4b from Table 2)

mb0: oxygen concentration (mg/L) of inoculum blank on day 0 (mean of 3a and 3b from Table 2)

mbx: oxygen concentration (mg/L) of inoculum blank on day x (mean of 3a and 3b from Table 2)

BOD at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.	BOD after n days of exposure
			7	14	21	28
Test item	1.85	1a	0.05	0.32	0.27	0.11
		1b	0.05	0.27	0.22	0.11
Reference item	3.6	2a	1.06	1.14	1.25	1.22
		2b	1.08	1.17	1.22	1.25
Toxicity control	Test item: 1.85 Reference item: 3.6	4a	0.76	0.83	0.88	0.90
		4b	0.77	0.79	0.84	0.88

BOD=   mgO₂/L of T.i. and/or R.i. – mg O₂/L of 1. Control = mg O₂/mg T.i. and/or R.i.

                       Mg T.i. and/or R.i/L in flask

 

Where:

T.i.                 = test item

R.i.                 = reference item

i. control        = inoculum control

Percentage Biodegradation at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.	BOD after n days of exposure
			7	14	21	28
Test item	1.85	1a	1.7	9.9	8.3	3.3
		1b	1.7	8.3	6.6	3.3
		mean	1.7	9.1	7.5	3.3
Reference item	3.6	2a	63.3	68.3	75.0	73.3
		2b	65.0	70.0	73.3	75.0
		mean	64.2	69.2	74.2	74.2
Toxicity control	Test item: 1.85 Reference item: 3.6	4a	30.9	33.5	35.8	36.5
		4b	31.3	32.0	34.3	35.8
		mean	31.1	32.8	35.0	36.1

Biodegradation %=        BOD ( mg O₂/ mg of T.i. and/or R.i.             X 100

                           COD (mg O₂/ mg T.i. or ThOD (mg O₂/ mg R.i.)

 

Where:

T.i.                 = test item

R.i.                 = reference item

i. control        = inoculum control

 

COD of test item = 3.26 ±0.176 mg O2/mg test item

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

 

 

The biodegradation in the toxicity control was calculated according to the following formula:

 

                  BOD ( mg O₂/ mg of T.i. and/or R.i.             X 100

COD (mg O₂/ mg T.i. or ThOD (mg O₂/ mg R.i.)*½

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

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 under the test conditions used in this study.

Executive summary:

The test item 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 CAS 113601-85-7 reached a mean of 3.3% after 28 days based on the COD of the test item. According to the test guidelines the pass level for ready biodegradability is removal of 60% COD/ThOD.Therefore, the test item is considered not readily biodegradable.

The reference item Sodium benzoate was sufficiently degraded to a mean of 69.2% 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 32.8% biodegradation was noted within 14 days and 36.1% biodegradation after 28 days of incubation.

According to the test guidelinesthe test item can be assumed to be not inhibitory at the applied concentration level of 1.85 mg/L on the secondary effluent microorganismsbecause 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 under the test conditions used in this study.

Description of key information

The test item 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. The test item is considered not readily biodegradable.

The study met the validity criteria.

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

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater