3,3,5-trimethylcyclohexyl methacrylate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

other information

Reason / purpose for cross-reference:

read-across source

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-08-29 to 2017-

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

The inoculum was obtained on 30 August 2016 from the activated sludge of the biological wastewater treatment plant from Mourenx (France, 64) which handles predominantly domestic sewage.

On arrival at the laboratory, the sludge (around 800 mL) was centrifuged at room temperature for 12 min at 1000 g; the solid sewage inoculant portion was re-suspended in dilution water in order to keep the concentration unchanged with respect to the sample. The inoculum was preconditioned 48 hours (aeration) at around 22°C until the flasks were inoculated.

Sub-samples of the homogenised sludge were dried in an oven at approximately 105°C and the suspended solids content determined to be 4.005 g/L.

The inoculum was not adapted to the test item before the biodegradation test.

Duration of test (contact time):

56 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

A total of 9 bioreactors were used:
- 2 each for test item, blank control, reference item control, emulsifying agent control and
- one for toxicity control.

pH was measured in all flasks at the start and the end of the test period.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

16.8

Sampling time:

28 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

47.5

Sampling time:

56 d

Details on results:

THEORETICAL OXYGEN DEMAND
The theoretical oxygen demand of the test item is ThOD = 2.586 mg O2/mg (based on the molecular formula of the different components provided by the Sponsor). This calculation does not take into account any other constituents/impurities within the substance as supplied and is calculated by assuming formation of ammonium, water and carbon dioxide (no nitrification).
The theoretical oxygen demand of sodium benzoate is 1.666 mg O2/mg.

OXYGEN CONSUMPTION AND PERCENTAGE OF BIODEGRADATION
With regard to the oxygen consummation, the emulsifying agent could be considered as not toxic to bacteria and not biodegradable under test conditions. As a consequence, oxygen consummation measured with the emulsifying agent controls was used for final calculations. In addition, as a plateau of the oxygen consummation was not reached at Day 28 for the test item bioreactors, the test duration was extended up to 56 days.
The maximum degradation level of the test item was 16.8% at day 28, and 47.5% at day 56.
The test item did not inhibit the micro-organisms as shown by the toxicity control flask where biodegradation percentage is already 40.1%, higher than 25% after 14 days.
The reference item was readily biodegradable under the conditions of the test as >60% biodegradation was achieved by Day 14; this demonstrates the acceptable viability of the inoculum.

pH was measured in all flasks at the start and the end of the test period (i.e. at day 56), values are comprised between 7.3 and 7.7. 

 Recorded test temperatures where between 21.0 and 22.1°C (mean: 21.7°C).

Validation criteria

The definitive test met the validity criteria of the test guideline detailed as follows:

- the difference of extremes of replicate values of the removal of the test item at the end of the test was less than 20%

- the percentage degradation of the reference compound has reached the pass levels by day 14: 92.8%

- the biodegradation observed in the toxicity control bioreactor was not less than 25% occurred within 14 days: 40.1%

- the oxygen uptake of the inoculum blank was not greater than 60 mg/l in 56 days: 25.4 mg/L

- the pH value was not outside the range 6-8.5: min 7.3, max 7.7

 

The test is thus considered as valid.

Validity criteria fulfilled:

yes

Remarks:

See above.

Interpretation of results:

not readily biodegradable

Conclusions:

The test item 3.3.5-trimethylcyclohexyl acrylate was not readily biodegradable under the conditions of the test. A mean total of 16.8% biodegradation was achieved by Day 28 and 47.5% by day 56.

Executive summary:

The study was conducted in accordance with procedures outlined in OECD Guideline 301F (1992). The ready biodegradability of 3.3.5-trimethylcyclohexyl acrylate was assessed over a 28 days period with an extended period up to 56 days.

 

As test item is known to be difficult to dissolve in water, its dispersion in the medium was improved by using an emulsifying agent (Symperonic P103) as described in ISO 10634 standard.

 

A total of 9 bioreactors were used:

 

- 2 each for test item, blank control, reference item control, emulsifying agent control and

- 1 for toxicity control.

 

The results of the test were as follows:

 

% biodegradation	Test item (mean of replicates)	Reference item (mean of replicates)	Toxicity Control
By day 28	16.8	98.9	52.1
By day 56	47.5	103.5	77.6

 

The test item was not readily biodegradable under the conditions of the test as it failed to achieve a transition from 10% to 60% degradation in a 10-day window during the 28 days test.

 

The test item was not considered to be inhibitory to the microbial inoculum since the biodegradation observed in the toxicity control bioreactor was not less than 25% occurred within 14 days.

 

The definitive test met the validity criteria of the test guideline detailed as follows:

- the difference of extremes of replicate values of the removal of the test item at the end of the test was less than 20%

- the percentage degradation of the reference compound has reached the pass levels by day 14: 92.8%

- the biodegradation observed in the toxicity control bioreactor was not less than 25% occurred within 14 days: 40.1%

- the oxygen uptake of the inoculum blank was not greater than 60 mg/l in 56 days: 25.4 mg/L

- the pH value was not outside the range 6-8.5: min 7.3, max 7.7

Description of key information

A manometric respirometry study assessing the ready biodegradability of the analogue 3,3,5-TRIMETHYLCYCLOHEXYL ACRYLATE (CAS 86178-38-3) was conducted in accordance with the OECD 301 F Test Guideline and GLP requirements.

The test item was not readily biodegradable under the conditions of the test. A mean total of 16.8% biodegradation was achieved by Day 28 and 47.5% by day 56.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, not fulfilling specific criteria

Additional information

The study was conducted in accordance with procedures outlined in OECD Guideline 301F (1992). The ready biodegradability of the analogue 3.3.5-trimethylcyclohexyl acrylate was assessed over a 28 days period with an extended period up to 56 days.

 

As test item is known to be difficult to dissolve in water, its dispersion in the medium was improved by using an emulsifying agent (Symperonic P103) as described in ISO 10634 standard.

 

A total of 9 bioreactors were used:

 

- 2 each for test item, blank control, reference item control, emulsifying agent control and

- 1 for toxicity control.

 

The results of the test were as follows:

 

% biodegradation	Test item (mean of replicates)	Reference item (mean of replicates)	Toxicity Control
By day 28	16.8	98.9	52.1
By day 56	47.5	103.5	77.6

 

The test item was not readily biodegradable under the conditions of the test as it failed to achieve a transition from 10% to 60% degradation in a 10-day window during the 28 days test.

 

The test item was not considered to be inhibitory to the microbial inoculum since the biodegradation observed in the toxicity control bioreactor was not less than 25% occurred within 14 days.