2-[4-(4-Alkoxyphenyl)-(pyridin-2-yl)-heteromonocyclyl]phenol

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:

Experiment start date - 04 December 2020; Experiment completion date - 09 January 2021; Study completion date - 29 April 2021.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test Item: FAT 75637/B
Physical Appearance: Light yellow powder
Purity: 99.4 % all organic constituents; 95.0 % main constituent
Batch No: AT-0063765400
Manufactured Date: 21st April 2020
Expiry Date: May 27th, 2025

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Details on inoculum:

The inoculum was secondary effluent, sourced from a treatment plant receiving predominantly domestic sewage. This effluent was used as test system as it is recommended in the guideline. A fresh sample of secondary effluent was collected from the treatment plant and was kept aerobic during transport. This effluent was allowed to settle for one hour, decanted and the decanted effluent was used in the test.

Duration of test (contact time):

28 d

Initial conc.:

22 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock Solution Chemical Quantity (g)
A Potassium dihydrogen orthophosphate, KH2PO4 (AR) 4.2512
Dipotassium hydrogen orthophosphate, K2HPO4 (AR) 10.8734
Disodium hydrogen orthophosphate dihydrate, Na2HPO4.2H2O (AR) 16.7072
Ammonium chloride, NH4Cl (AR) 0.2502
These four constituents were dissolved in and made up to 500 mL using Milli-Q water. The pH of the solution was 7.51.

B Calcium chloride, dihydrate, CaCb.2H2O (AR) 18.2013
This was dissolved in and made up to 500 mL using Milli-Q water.

C Magnesium sulphate heptahydrate, MgSO4.7H2O (ExcelaR) 11.2510
This was dissolved in and made up to 500 mL using Milli-Q water.

D Iron (III) chloride hexahydrate, FeCb.6H2O (AR) 0.1251
This was dissolved in and made up to 500 mL using Milli-Q water.

The test medium for test flasks 1 to 6, was prepared by mixing 24 mL of stock solution A with 1920 mL of Milli-Q water, then 2.4 mL each of stock solutions B, C and D was added and finally the volume was made up to 2400 mL using Milli-Q water in each flask. Similarly, for Flask 7, 3000 mL of test medium was prepared by mixing 30 mL of stock solution A with 2400 mL of Milli-Q water, then 3 mL each of stock solutions B, C and D was added and finally the volume was made up to 3000 mL with Milli-Q water.

- Test temperature: 22.4 to 23.6 ºC
- pH: 7.51 to 7.55
- Aeration of dilution water: Yes
- Continuous darkness: yes

TEST SYSTEM
To each 5 L flask, 2400 mL of mineral medium was added and mixed with 300 mL of the pre-conditioned inoculum. A separate 3000 mL of mineral medium was also prepared in a flask to use it for further dilutions. A sample of the mineral medium was checked for the inorganic carbon content. These flasks were aerated with CO2 free air at 100 mL/minute, overnight to purge the system of carbon dioxide.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Toxicity control: Yes

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

17.06

Sampling time:

28 d

Results with reference substance:

The percent degradation of reference item was 92.51 % and the toxicity control was 43.88 % at the end of the test.

Test Item Solubility: The test item formed a suspended particle and found settled at bottom  in mineral medium at 220 mg/L.

Bacterial Population in the Inoculum: The bacterial population in the inoculum was 7.0 x 10E7 CFU/L.

Degradation of Test Item and Reference Item

Day	Degradation (%)
	Test Item			Reference Item	Test Item+ Reference Item
	Flask 1	Flask 2	Mean
2	0.80	0.29	0.55	16.53	17.42
4	1.60	1.21	1.41	27.99	13.55
7	8.00	7.94	7.97	43.70	19.13
9	10.85	11.81	11.33	59.44	29.74
12	11.49	15.65	13.57	58.52	23.90
14	11.49	15.20	13.35	72.33	31.68
18	12.70	16 .93	14.82	85.60	37.00
22	14.43	18.72	16.58	90.60	40.90
26	15.39	18.72	17.06	92.51	43.88
29	15.39	18.72	17.06	92.51	43.88

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Based on the results, the test item was concluded as non-biodegradable since only 17.06 % mean degradation was achieved within the 28-day period of the test.

Executive summary:

The ready biodegradability of FAT 75637/B was tested using the CO2 Evolution Test. This study was conducted according to OECD test guideline 301C in a GLP-certified laboratory. The test item was added to two test vessels at the concentration of 22.0 mg/L (equivalent to 15.6 mg of Total Organic Carbon/L). Two flasks as controls containing only the inoculum, one flask as procedure control containing reference item and one flask as toxicity control containing the test item and the reference item were included in the test. All the treatments were added with equal volume of inoculum which was collected from the secondary effluent treatment plant receiving predominantly domestic sewage and volume made with mineral media. Treatment mixtures were aerated for 29 days with carbon dioxide (CO2) free air. The CO2 released was trapped in a series of bottles containing barium hydroxide, which were connected to the outlet of each test vessel. The residual barium hydroxide was measured on days 2, 4, 7, 9, 12, 14, 18, 22, 26 and 29 after the initiation of the test. The mean percent degradation of test item was 17.06 % at the end of test while, the percent degradation of reference item was 92.51 % and the toxicity control was 43.88 % at the end of the test. The test fulfilled all the validity criteria. Based on the results, the test item was concluded as non-biodegradable since only 17.06 % mean degradation was achieved within the 28-day period of the test.

Description of key information

FAT 75637/B was concluded as non-biodegradable since only 17.06 % mean degradation was achieved within the 28-day period of the test.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

The ready biodegradability of FAT 75637/B was tested using the CO2 Evolution Test. This study was conducted according to OECD test guideline 301C in a GLP-certified laboratory. The test item was added to two test vessels at the concentration of 22.0 mg/L (equivalent to 15.6 mg of Total Organic Carbon/L). Two flasks as controls containing only the inoculum, one flask as procedure control containing reference item and one flask as toxicity control containing the test item and the reference item were included in the test. All the treatments were added with equal volume of inoculum which was collected from the secondary effluent treatment plant receiving predominantly domestic sewage and volume made with mineral media. Treatment mixtures were aerated for 29 days with carbon dioxide (CO2) free air. The CO2 released was trapped in a series of bottles containing barium hydroxide, which were connected to the outlet of each test vessel. The residual barium hydroxide was measured on days 2, 4, 7, 9, 12, 14, 18, 22, 26 and 29 after the initiation of the test. The mean percent degradation of test item was 17.06 % at the end of test while, the percent degradation of reference item was 92.51 % and the toxicity control was 43.88 % at the end of the test. The test fulfilled all the validity criteria. Based on the results, the test item was concluded as non-biodegradable since only 17.06 % mean degradation was achieved within the 28-day period of the test.