[(dimethylamino)methyl]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:

2018-08-07 to 2018-11-28

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:

1992-07-17

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

Source Municipal sewage treatment plant, 31137 Hildesheim, Germany

Reasons for the selection Activated sludge from the sewage plant at Hildesheim is well
of the test system suited as it receives predominantly municipal sewage and hardly any industrial chemical waste.

Receipt 2018-08-28

Pre-treatment The activated sludge was washed twice with chlorine free tap water. After the second washing the settled sludge was resuspended in mineral salts medium and was maintained in an aerobic condition by aeration with CO2 free air until test
start (6 days). The amount of inoculum used to initiate inoculation was 4.37 mL/L (25.0 mg/L dw).

Colony forming units Approx. 107 - 108 CFU/L
in the test vessels

Duration of test (contact time):

28 d

Initial conc.:

22 mg/L

Based on:

test mat.

Initial conc.:

51.3 other: mg O2/L

Based on:

other: ThOD in the test vessel

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test Method
Duration 28 days
Application Once at test start
Test vessels Brown glass bottles (volume 500 mL)
Test volume 250 mL
Test medium Mineral salts medium according to OECD 301 F
Temperature Nominal: 20 - 24, ± 1 °C; Actual: 20.9 – 21.7 °C
Dispersion treatment Continuous stirring
Photoperiod Dark, in an incubator


Preparation of Based on the calculated oxygen demand, the test concentration
the test vessels of 22 mg/L, corresponding to an oxygen demand of 51.3 mg O2/L (60.1 mg O2/L with nitrification) in the vessel, was selected.
The test solutions were prepared in measuring flasks and were placed in brown glass bottles as incubation vessels
(inoculum co ntrol, test item and functional control) or were prepared directly in brown glass bottles (toxicity control):
• two for the inoculum control (C1, C2)
• one for the functional control (R1)
• two for the test item (P1, P2)
• one for the toxicity control (T1)

Inoculum control The inoculated test medium, consisting of the required volumes of mineral medium stock solutions, ultrapure water and inoculum, was prepared in a measuring flask. 250 mL of this solution were filled in the brown glass bottles of the inoculum control, using a 2 50 mL measuring flask.
Functional control The reference item was weighed out and transferred into a measuring flask, the required volumes of mineral medium stock solutio ns, ultrapure water and inoculum, were added. 250 mL of this solution were filled in the brown glass bottle of the functional
control, using a 250 mL measuring flask.
Test Item The test item was weighed out and transferred into a measuring flask with ultrapure water. The required volumes of mineral medi um stock solutions, ultrapure water and inoculum were added. 250 mL of this solution were filled in the brown glass bottle of the
test item replicate, using a 250 mL measuring flask.
Toxicity control The reference item was weighed out and directly transferred into the test vessels with 250 mL test item medium (see above),
using a 250 mL measuring flask.
A rubber sleeve with soda lime was hung into the opening of the bottles to absorb evolved CO2. The bottles were closed with
OxiTop measuring heads and the measuring system was activated.

pH-values of the samples were measured at test start and test end (day 28).

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

8

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

80

Sampling time:

28 d

Remarks on result:

other: without correction due to nitrification.

Key result

Parameter:

% degradation (O2 consumption)

Value:

72

Sampling time:

28 d

Remarks on result:

other: after correction due to nitrification.

Results with reference substance:

The pass level for ready biodegradation (≥ 60% degradation) for the reference substance was reached within 3 days. The adaptation phase changed to the degradation phase within 2 days (degradation > 10%), with a maximum of 92% on day 16.

Biodegradation [%] of the Test ItemPhenol, [(dimethylamino)methyl]-inComparison to the Functional Control and Toxicity Control

		Biodegradation [%]				Biodegradation corrected for nitrification [%]
		Study Day [d]				Study Day [d]
	Replicate	7	14	21	28	28
Test Item 22mg/L Test Item	1	9	61	78	83	75
	2	6	58	71	76	68
Functional Control 30 mg/L Reference Item		80	89	90	89	-
Toxicity Control 22mg/L Test Item + 30 mg/L Reference Item		40	72	84	88	-

pH-values at test start and test end.

	pH-Value
	Start	End
Inoculum Control	7.61	1) 7.54
		2) 7.70
Functional Control	7.53	7.70
Test Item	7.68	1) 7.54
		2) 7.48
Toxicity Control	7.62	7.64

Nitrite and nitrate concentrations at test end

	Measured conc. [mg N/L]		corresponding Oxygen consumption	Net BOD corrected for Nitrification [mg O/L]	Biodegradation calculated without nitrification	Biodegradation in relation to ThODNH3 corrected for measured Nitrification
	Nitrite-N	Nitrate-N
	[mg/L]	[mg/L]	[mg/L]		[%]	[%]
C1	0	2.29	10.5	-	-	-
C2	0	2.08	9.5	-	-	-
P1	0.003	3.17	14.5	38.3	83	75
P2	0.004	3.10	14.2	35.0	76	68

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

After a test period of 28 days, the test item is classified as readily biodegradable within the 10-day-window and within the 28 day period of the study.

Executive summary:

The ready biodegradability of the test item was determined with non-adapted activated sludge in the Manometric Respirometry Test for a period of 28 days according to OECD guideline 301 F. The test item concentration selected as appropriate was 22 mg/L, corresponding to a ThOD of 51.3 mg O₂/L (60.1 mg O₂/L with nitrification) per test vessel. The oxygen was depleted by the respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The biodegradation rate is therefore, expressed as the percentage BOD (biological oxygen demand) and was calculated for each study day. The mean oxygen depletion in the inoculum control was 26.3 mg O₂/L on day 28. In order to check the activity of the test system sodium benzoate was used as functional control. The pass level > 60% was reached within 3 days. The biodegradation reached a maximum of 92% degradation on day 16. In the toxicity control containing both test and reference item, 72% degradation occurred within 14 days, with 88% after 28 days. The degradation of the reference item was not inhibited by the test item. The biodegradation of the test item reached the 10% level (beginning of biodegradation) within 8 days and the 60% pass level on day 15. The mean biodegradation on day 28 was 72% after correction for nitrification. The validity criteria of the guideline are fulfilled. The test item is classified as readily biodegradable within the 10-day window and within the 28 day period of the study.

Description of key information

The ready biodegradability of the test item was determined with non-adapted activated sludge in the Manometric Respirometry Test for a period of 28 days according to OECD guideline 301 F. The test item concentration selected as appropriate was 22 mg/L, corresponding to a ThOD of 51.3 mg O₂/L (60.1 mg O₂/L with nitrification) per test vessel. The oxygen was depleted by the respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The biodegradation rate is therefore, expressed as the percentage BOD (biological oxygen demand) and was calculated for each study day. The mean oxygen depletion in the inoculum control was 26.3 mg O₂/L on day 28. In order to check the activity of the test system sodium benzoate was used as functional control. The pass level > 60% was reached within 3 days. The biodegradation reached a maximum of 92% degradation on day 16. In the toxicity control containing both test and reference item, 72% degradation occurred within 14 days, with 88% after 28 days. The degradation of the reference item was not inhibited by the test item. The biodegradation of the test item reached the 10% level (beginning of biodegradation) within 8 days and the 60% pass level on day 15. The mean biodegradation on day 28 was 72% after correction for nitrification. The validity criteria of the guideline are fulfilled. The test item is classified as readily biodegradable within the 10-day window and within the 28 day period of the study.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater