3-(2,2-dimethyl-3-hydroxypropyl)toluene

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2000-07-19 to 2000-09-12

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

no adsorption control

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

Version / remarks:

1992

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Municipal sewage treatment plant, Hildesheim; Germany
- Pretreatment: The activated sludge was filtered.The filtrate was maintained in aerobic condition by aeration until test begin.
- Colony forming units of the inoculum: 3.7 x 10^5 CFU/mL

Duration of test (contact time):

56 d

Initial conc.:

19.9 mg/L

Based on:

other: ThTOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral nutrient solution acc. to OECD 301 E
- Test temperature: 22 +/- 2°C
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2L Erlenmeyer flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The vessels were stirred continuously with magnetic bars.

SAMPLING
- Sampling frequency: samples were taken at regular time intervals (0, 1, 5, 7, 14, 21, 28, 35, 49 and 56 days).

CONTROL AND BLANK SYSTEM
- Inoculum blank: Duplicates
- Reference compound: single replicate
- Control: Nutrient solution and inoculum, duplicates
- Toxicity control: yes, single replicate

Reference substance:

other: Sodium acetate

Key result

Parameter:

% degradation (DOC removal)

Value:

16

Sampling time:

56 d

Parameter:

% degradation (DOC removal)

Value:

7

Sampling time:

28 d

Details on results:

7% degradation after 28 d, 16% degradation after 56 days,70% pass level and 10-day window were not met.
In the toxicity control containing both test (19.9 mgC/L) and reference item (130 mg/L), the biodegradation came to 64 % after 14 days. The test item can be assumed to be not inhibitory in the test.

Results with reference substance:

97% after 14 d, >= 70% pass level was reached.

Biodegradation of the test item in comparison to the functional control and the toxicity control

	Biodegradation [%]
	Study day [d]
	7	14	21	28	35	49	56
Test item (19.9 mgC/L)	0	0	8	7	10	18	16
Funcional control (130 mg/L)	95	97	88	88	-	89	100
Toxicity control (19.9 mgC/L (test item) + 130 mg/L reference item)	64	64	64	64	67	69	69

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

This study indicates that the substance is not readily biodegradable (16% after 56 d (TOC consumption, OECD 301E)).

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1987-10-06 til 1987-11-26

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)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): From a well-operated municipal sewage treatment plant (Hamburg-Neuenfelde). This sewage treatment receives no or minimal effluents from industry.
- Preparation of inoculum for exposure: Upon arrival at the laboratory, the activated sludge was aerated for 4 hours. 500 ml of the mixed liquor was sampled and homogenised for 2 minutes at medium speed in a waring blender. lt was then settled for ca. 30 min. The supernatant was decanted to provide sufficient volume for a 1 per cent inoculum for each CO2 test flask.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: According to guideline
- Test temperature: 20-21°C
- pH: 7.6

TEST SYSTEM
- Culturing apparatus: 5 Litre disposable amber carboys
- Number of culture flasks/concentration: 1 per concentration (10 and 20 mg/L)

SAMPLING
- Sampling frequency: Day 1, 2, 3, 6, 9, 13, 17, 21, 27, 28
- Sampling method: For sampling the CO2 adsorber nearest the carboy was removed for titration. The remaining two adsorbers were each moved one place closer to the carbox, and a new adsorber filled with 100 ml of fresh 0.025 N Ba(OH)2 was made as needed (before any BaCO3 precipitate was evident in the second trap).

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 1 replicate
- Toxicity control: No

Reference substance:

other: sodium-n-dodecylsulfate

Key result

Parameter:

% degradation (CO2 evolution)

Value:

4

Sampling time:

28 d

Details on results:

The amount of CO2 produced by the test sample was found to 3 - 4 % after 10 days and did not increase by the end of the test.

Results with reference substance:

> 60% after 10 days and 86% after 28 days (tested concentration: 20 mg/L)

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

This study indicates that the substance is not readily biodegradable (4% after 28 d (CO2 evolution, OECD 301B)).

Description of key information

Not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

All available experimental studies indicate that the substance is not readily biodegradable.

In an OECD 301E (TOC consumption) test 16% biodegradation was observed after 56 days. In an OECD 301B (CO2 evolution) test 4% biodegradation was observed after 28 days.

In the toxicity control of the OECD 301E test containing both test (19.9 mgC/L) and reference item (130 mg/L), the biodegradation came to 64 % after 14 days. Thus, it can be assumed that the test item was not inhibitory in the test.

Therefore the test substance should be regarded as not readily biodegradable.