Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methacrylate

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:

2010-03-01 to 2010-03-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study OECD 310, GLP. The 10-day criterion for ready biodegradability was met. This study was accidently cited with an error (wrong method was cited in the SIDS of IBOMA (Draft version 06 July 2011). The correction of the guideline in the SIDS of IBOMA is important to show that the very low degradation of 6 % is caused by the volatilization in CO2 Evolution test, OECD 301 B.

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

Version / remarks:

(2006), EN ISO 14593 (1999)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

TEST SYSTEM: lnoculum of the aqueous phase of non adapted activated sludge
Reasons for the selection of the test system: Activated sludge from the sewage plant at Hildesheim is well suited as it receives predominantly municipal sewage and hardly any industrial chemical waste.
Source: Municipal sewage treatment plant, D-31137 Hildesheim
Pretreatment: The activated sludge was washed twice with autoclaved tap water. After the second washing the settled sludge was resuspended in mineral salts medium and was maintained in an aerobic condition
by aeration for 4 hours. Thereafter the sludge was homogenized with a blender, filtered through a folded filter and was maintained in an aerobic condition by aeration with COrfree air for 3 days.
10 ml/L were used to initiate inoculation
Colony forming units in the test solution: 10 E5 - 10E8 CFU/L

Duration of test (contact time):

28 d

Initial conc.:

24.5 mg/L

Based on:

test mat.

Initial conc.:

18.4 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TESTITEM lsobornyl methacrylate
Replicates: Triplicates (testend 5 replicates)
TOC: 0.752 mg C/L
Test concentration: 24.5 mg/L (corresponding to 1.96 mg test item / test vessel)
Carbon content in the vessel: 18.4 mg C/L
TOXICITY CONTROL: Test item in test concentration + 30 mg/L reference item
Replicates: Triplicates (testend 5 replicates)
INOCULUM CONTROL: Test medium without test and/or reference item
Replicates: Triplicates (testend 5 replicates)
ABIOTIC CONTROL: Testitem in test concentration without inoculum, poisoned with
10 ml/L HgCb (10 g/L)
Replicates: 10 flasks in total, analysis was not necessary
TEST METHOD
Duration: 28 days
Application: Once at test start, the test item (2 μL/test vessel) was injected
directly into the test solution.
Headspace to liquid ratio: 1 :2
Test vessels / volume: Headspace flasks / 120 ml
Test medium / volume: Mineral salts medium acc. to OECD 310 / 80 ml
Agitation: Shaker (150 - 200 rpm)
Temperature: 20.0 - 21. 5 °c
Photoperiod: Low light conditions

Reference substance:

benzoic acid, sodium salt

Remarks:

as functional control

Key result

Parameter:

% degradation (CO2 evolution)

Value:

70

Sampling time:

28 d

Remarks on result:

other: The 95% confidence interval on day 28 was 66 - 74 %.

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

8 d

Parameter:

% degradation (CO2 evolution)

Value:

43

Sampling time:

10 d

Parameter:

% degradation (CO2 evolution)

Value:

49

Sampling time:

14 d

Parameter:

% degradation (CO2 evolution)

Value:

70

Sampling time:

18 d

Details on results:

The ready biodegradability of the test item lsobornyl methacrylate (batch no.: 1280910350) was determined with a non adapted activated sludge over a test period of 28 days in the Headspace Test. The study was conducted from 2010-03-01 to 2010-03-29 according to OECD 310 and EN ISO 14593 at DR.U.NoACK-LABORATORIEN. The test item was tested at a concentration of 24.5 mg/L in triplicates, corresponding to a carbon content (TOC) of 18.4 mg C/L in the test vessels.
The biodegradation of the test item was followed by TIC analyses of the quantity of C02 produced by the respiration of bacteria. The amount of TIC produced was calculated by correcting the results of the test and reference item for endogenous TIC production of the control groups and the blind value of the sodium hydroxide solution. The biodegradation was calculated for each sampling time. The primary biodegradation was determined by specific test item analysis at test end.
To check the activity of the test system sodium benzoate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % after 2 days and came to a maximum of 95 % on day 21. The biodegradation rate came to 81 % on day 28. The 95 % confidence interval on day 28 was 80 - 82 %.
In the toxicity control containing both test and reference item a biodegradation rate of 57 % occurred within 14 days and it came to a maximum of 74 % after 28 days. The biodegradation of the reference item was not inhibited by the test item in the toxicity control. The 95 % confidence interval on day 28 was 64 - 84 %.
The 10 % level (beginning of biodegradation) was reached after 9 days. The 60 % pass level was reached within the 10-d-window after 17 days. The biodegradation came to 70 % after 28 days. The 95 % confidence interval on day 28 was 66 - 74 %.
The mean primary biodegradation, calculated from the remaining test item concentration at test end, was > 92 %.

Results with reference substance:

82 % after 8d
95 % after 21 d
81 % after 28 d
The functional control reached the pass level of 60% after 2 days and came to the maximum of 95 % on day 21. The biodegradation rate came to 81% on day 28. The 95% confidence interval on day 28 was 80 - 82%.
In the toxicity control containing both test and reference substance a biodegradation rate of 57% occurred within 14 days and came to the maximum of 74 % after 28 days. The biodegradation of the reference substance was not inhibited by the test substance in the toxicity control. The 95%
confidence interval on day 28 was 64 - 84%.

The validity criteria of the test have been met:

- The percentage of degradation of the reference substance in the control series is greater than 60% in 14 days;

- The mean amount of TIC (total inorganic carbon) produced in the inoculum controls at the end of the test was 1.10 mg C/L (validity criterion: TIC < 3 mg C/L).

The Degradation of the reference substance has not been inhibited by the presence of the test substance.

Confidence lnterval for the Test ltem, Functional Control and Toxicity Control Samples on Day 28

Replicate	Degradation[%]					95 %Confidencelnterval [%]
	1	2	3	4	5
Testltem, 24.5mg/L	75	67	68	68	72	66 -74
FunctionalControl,30mg/L	80	82	82	81	80	80 -82
ToxicityControl, 24.5 mg/L Test ltem +30 mg/L Referenceltem	78	63	70	76	83	64 - 84

Validity criteria fulfilled:

yes

Remarks:

according to the guideline

Interpretation of results:

readily biodegradable

Conclusions:

In a valid guideline study according OECD 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)), 70 % (95% confidence interval on day 28 was 66 - 74%) biodegradation was obtained after 28 days. The 10-day criterion for ready biodegradability was achieved. Therefore Isobornyl methacrylate is classified as readily biodegradable.

Executive summary:

Under the conditions of the OECD 310 Headspace test, the percentage of biodegradation of Isobornyl methacrylate was 70 % after 28 days (95% confidence interval on day 28 was 66 - 74%; end of trial). In the time interval of 10-days following the start of the biodegradation phase, it reached about 65 to 70%. The 60% pass level was reached by test substance within the 10-d window after 17 days.

The substance can be regarded as readily biodegradable according to criteria in the guideline OECD 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test). The substance did not show inhibitory effect against micro-organisms.

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Description of key information

Isobornyl methacrylate was readily biodegradable in GLP guideline study (OECD 310).

70 % biodegradation within 28 days fulfilling 10 days windows

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable