Methyl 3-aminocrotonate

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:

November - December 1999

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)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Test item code: LZ937.00
Expiration date: 21 May 2000
Delivery date: 11 October 1999
Test material was stored at ambient temperature in the dark.
Physical state: White crystalline solid
Storage conditions: Stored at ambient temperature in the dark

Oxygen conditions:

anaerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Source: Haddington Sewage Works
A local sewage processing plant which handles predominantly domestic sewage.
Received: 16 November 1999
The activated sludge was well mixed prior to sampling for solids content determination. The solids content of the sludge was determined as 3.7 g solids per litre sludge. The sludge was then allowed to settle for at least 30 minutes prior to a sample of the supernatant being withdrawn for use as the test microbial inoculum.

Duration of test (contact time):

28 d

Initial conc.:

38.4 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

A totally sealed system was constructed supplied on a positive pressure basis by CO2 free air. CO2 was removed by passing through self-indicating soda lime granules contained in a glass trap. The CO2 free air was then passed through the bioreactor set-ups and exited the system through non-return valves. A total of 6 bioreactors (2 litre capacity) were used 2 for LZ937, 2 controls, 1 for the reference material and 1 for the toxicity control.
The test material bioreactors each contained 1930 ml of mineral media, 20 ml of microbial inoculum and 50 ml of test material stock. The reference material bioreactor contained 1910 ml of mineral media, 20 ml of microbial inoculum and 69 ml of reference material stock. The control bioreactors each contained 1980 ml of mineral media and 20 ml of microbial inoculum. The toxicity control bioreactor contained 1860 ml of mineral media, 50 ml test material stock, 69 ml reference material stock and 20 ml of microbial inoculum. Each bioreactor was connected to three traps, each trap containing 100 ml 0.0125M Ba(OH)2. At a trap collection the trap closest to the bioreactor was taken for titration and the two remaining traps were then moved towards the bioreactor. A new trap containing freshly prepared Ba(OH2) was then placed third in line from the bioreactor. Trap changes were conducted on Days 2, 5, 7, 9, 12, 14, 19, 23 and 29. During these trap changes the vacuum system was switched off to allow a trap changeover to be conducted. All sampled traps were then titrated. Each trap sample was titrated against 0.05 M HCI utilising the colour change from pink to colourless with phenolphthalein indicator of which a few drops were added to each trap. The pH was determined (Jenway 3071 pH meter) in each bioreactor at Days 0, 28 and 29. The pH was adjusted on Day 0, to values between 7.2 and 7 .6. On Day 28 concentrated HCI was added to the bioreactors to acidify and drive off residual CO2 overnight.

Reference substance:

benzoic acid, sodium salt

Remarks:

Batch 9746702 197)

Test performance:

In this test LZ937 commenced biodegradation activity after day 2, and had biodegraded by 61.6 % on day 12. As LZ937 had achieved over 60%
biodegradability within the 10 day window it can be concluded that LZ937 is readily biodegradable under the conditions of the test.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

69.7

Sampling time:

28 d

Details on results:

The results of the toxicity control indicated a potential slight reduction (20 % inhibition) of microbial activity in the presence of the LZ937. Titrations during the period of biodegradation activity were within 20% of the mean values. There was a penetration of CO2 into the test system after day 23 of this test, however as the 10 day window for both test and reference materials had been identified, this penetration of CO2 into the system later in the test is not considered to affect the validity of the test. The penetration of CO2 into the system after day 23 resulted in high control CO2 production in day 29 results. However prior to this point the control CO2 production was low. With the exception of exceeding the limit of CO2 production in the controls at day 29, all validity criteria were met. The pH of the bioreactors was measured at the end of the test.

Results with reference substance:

The reference material was readily biodegradable, 75.6 % biodegradability was achieved by day 9 in this test and a cumulative total of 113.2 % was achieved by test termination.

Modified Sturm Test, Cumulative % Biodegradation for Test and Reference Materials and Toxicity Control:

Day No.	Test material LZ937	Reference Material Sodium Benzoate	Toxicity Control
2	0.6	21.3	15.5
5	28.8	47.8	32.2
7	49.3	66.5	49.7
9	59.9	75.6	60.4
12	61.6	81.6	61.8
14	64.1	91.7	63.6
19	67.3	103.7	65.4
23	69.7	113.2	66.9
29	69.7	113.2	66.9

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

As the test item has achieved over 60% biodegradability within the 10 day window it can be concluded that ACMe is readily biodegradable under the conditions of the test.

Executive summary:

The ready biodegradability of ACMe was assessed over a 28 day period by the Modified Sturm Test. The test was performed according to OECD Guideline 301 B, in year 1999. A total of 6 bioreactors were used, two vessels each for LZ937 and controls, 1 each for the reference material and toxicity control. In this test, ACMe commenced biodegradation activity after day 2, and had biodegraded by 61.6 % on day 12. As the substance had achieved over 60 %

biodegradability within the 10day window it can be concluded that ACMe is readily biodegradable under the conditions of the test. The reference material was readily biodegradable, 75.6 % biodegradability was achieved by day 9 in this test and a cumulative total of 113.2 % was achieved by test termination.

Description of key information

As the test item has achieved over 60% biodegradability within the 10 day window it can be concluded that ACMe is readily biodegradable under the conditions of the test.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater