4-morpholinopropanesulphonic acid

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:

2014-04-30 to 2014-06-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

version adopted July 17, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from a biologic sewage treatment plant
- Laboratory culture: The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf
- Pretreatment: The sludge was filtrated, washed with tap water twice, then washed with and re-suspended in test medium. It was then aerated until use. The dry matter was determined with 4400 mg suspended solids/litre.
- Concentration of sludge: 24.9 mg/L

Duration of test (contact time):

28 d

Initial conc.:

51.7 mg/L

Based on:

test mat.

Remarks:

corresponds to 20.1 mg organic C/L

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: According to the OECD TG 301D (In solution b) CaCl2*2H2O was used and in solution d) 0.4g Na2EDTA were added).
- Test temperature: 21.4 – 24.0 °C
- pH: 6.9 – 7.5 (on day 28)
- pH adjusted: no
- Aeration of dilution water: for 72 h
- Suspended solids concentration: 24.9 mg/L

TEST SYSTEM
- Culturing apparatus: glass flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration with purified, CO2-scrubbed, moistened air
- Measuring equipment: CO2 was measured by IC using a carbon analyser
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: no
- Details of trap for CO2 and volatile organics: scrubber flasks

SAMPLING
From each front scrubber flask, ten samples were taken in order to determine the emitted CO2 (on days 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). The sample volume was 1 mL.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Test flasks: 2
- Abiotic control: 1
- Toxicity control: 1

Reference substance:

aniline

Key result

Parameter:

% degradation (CO2 evolution)

Value:

1

Sampling time:

29 d

Remarks on result:

not determinable

Details on results:

No observations were made which might cause doubts concerning the validity of the study outcome.
The result of the test can be considered valid.

Results with reference substance:

The reference item aniline was sufficiently degraded to a mean of 68.1 % after 14 days, and 76.9 % after 28 days of incubation, thus, confirming the suitability of the used activated sludge inoculum.
In the toxicity control containing both, the test item and the reference item, a biodegradation of 35 % was observed after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms.

Validity

All validity parameters and values are presented in the following table:

Parameter	Criterion	Found	Assessment
IC content of test item solution in medium	< 5 % of TC	< 1 %	valid
CO2 emitted by the controls	< 70 mg/L	13.2 mg/L	valid
Difference within replicates	< 20 %	< 1 %	valid
Degradation of positive control > 60 %	< 14 days	9 days	valid
Degradation in the toxicity flask on day 14	> 25 %	35.0 %	valid

 

Degradation Values

Ready degradability is defined in the guidelines as degradation surpassing 60 % within 10 days after reaching a level of 10 %. Therefore, the test item cannot be considered as “readily biodegradable”. Degradation missed 60 % within 28 days, too. Therefore, the test item is not considered as “biodegradable within 28 days”, either.

 

In the following table, the percentage biodegradation is presented:

Table 1: Degradation values in %

Day	Positive Control 1	Positive Control 2	Positive Control Mean	Test 1	Test 2	Test Mean	Abiotic Control	Toxicity Control
2	-0.8	-0.2	-0.5	0.1	1.3	0.7	0.0	0.1
4	13.2	23.2	18.2	2.0	1.3	1.6	0.1	8.6
7	42.1	48.2	45.1	3.4	1.8	2.6	0.5	22.2
9	65.9	64.0	65.0	3.2	1.2	2.2	0.3	29.3
11	68.1	67.6	67.9	3.6	1.7	2.7	1.0	30.6
14	67.9	68.4	68.1	2.1	2.7	2.4	0.7	35.0
18	77.1	78.5	77.8	3.3	2.9	3.1	1.0	39.8
23	74.8	71.0	72.9	2.1	2.3	2.2	0.9	38.5
29	79.2	74.6	76.9	1.3	0.5	0.9	0.6	39.8

 

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The substance was found to be not readily biodegradable.

Executive summary:

The ready biodegradability of the test item was investigated in a study according to OECD TG 301 B under GLP conditions using a test item concentration of nominal 20 mg organic carbon/L (corresponding to 51.5 mg test item/L). The biodegradation was followed by the CO₂-evolution. As a reference item aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. Activated sludge was used as inoculum (concentration in the test 24.9 mg dry matter/L). The test item in a mineral medium was inoculated and incubated under aerobic conditions in the dark and the test was left running for 28 days. The amount of DOC in the test solution due to the inoculum was kept as low as possible compared with the amount of organic carbon due to the test item. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without test item. Measurements were taken at sufficiently frequent intervals to allow the identification of the beginning and end of biodegradation. All validity criteria were met. The reference item aniline was sufficiently degraded to a mean of 68.1 % after 14 days, and 76.9 % after 28 days of incubation, thus, confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, a biodegradation of 35 % was observed after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms. No degradation was detected within the 10-day window. The test item emitted almost no CO₂, so that the biodegradation after 29 days was determined as 1 %. Ready degradability is defined in the guidelines as degradation surpassing 60 % within 10 days after reaching a level of 10 %. Therefore, the test item cannot be considered as “readily biodegradable”. Degradation of the test item missed 60 % within 28 days, too. Therefore, the test item is not considered as “biodegradable within 28 days”, either.

Description of key information

The substance was found to be not readily biodegradable (references 5.2.1-1).

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Key Study

The ready biodegradability of the test item was investigated in a study according to OECD TG 301 B under GLP conditions using a test item concentration of nominal 20 mg organic carbon/L (corresponding to 51.5 mg test item/L). The biodegradation was followed by the CO₂-evolution. As a reference item aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. Activated sludge was used as inoculum (concentration in the test 24.9 mg dry matter/L). The test item in a mineral medium was inoculated and incubated under aerobic conditions in the dark and the test was left running for 28 days. The amount of DOC in the test solution due to the inoculum was kept as low as possible compared with the amount of organic carbon due to the test item. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without test item. Measurements were taken at sufficiently frequent intervals to allow the identification of the beginning and end of biodegradation. All validity criteria were met. The reference item aniline was sufficiently degraded to a mean of 68.1 % after 14 days, and 76.9 % after 28 days of incubation, thus, confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, a biodegradation of 35 % was observed after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms. No degradation was detected within the 10-day window. The test item emitted almost no CO₂, so that the biodegradation after 29 days was determined as 1 %. Ready degradability is defined in the guidelines as degradation surpassing 60 % within 10 days after reaching a level of 10 %. Therefore, the test item cannot be considered as “readily biodegradable”. Degradation of the test item missed 60 % within 28 days, too. Therefore, the test item is not considered as “biodegradable within 28 days”, either.

 

Supporting Study

The test substance was investigated for its ready biodegradability in a study according to OECD TG 301 E under GLP conditions. The biodegradation was determined by measuring the DOC removal. As reference item aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The degradation of the reference item aniline was 99 % after four days, thus confirming the suitability of the used activated sludge inoculum. The degradation of the toxicity control was 45 % at the end of the test, thus the test item can be stated as not toxic towards inoculum. Degradation values for the test item below 0 % were calculated (mean at 28 days: - 6.8). This was due to the fact that the measurement errors of test flasks (slightly higher DOC values were measured at the end of the test, compared with the values at the start of the test) and blank flasks add up when using the equation proposed in the guideline. Under the test conditions, no degradation of the test item was observed within the 28 days of exposure and the criteria of 10 % degradation for the start of the 10 d window were not fulfilled. Therefore, the test item is not considered readily biodegradable.

 

Other Information

The ready biodegradability of the test item was investigated in a study according to OECD TG 301 D and EU method C.4 under GLP conditions using a test item concentration of 3.44 mg/L (corresponding to a theoretical oxygen consumption of 6.1 mg/L). The biodegradation was determined by measuring the O₂-uptake caused by nitrification. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. Activated sludge was used as inoculum (concentration in the test 0.5 mL/L). The test item in a mineral medium was inoculated and incubated under aerobic conditions in the dark and the test was left running for 28 days. All validity criteria were met. The reference item sodium benzoate was sufficiently degraded  (> 60 %) after 14 days, and to approx. 78 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, a biodegradation of 32 % was observed after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms. The O₂-concentration in the test vessels increased during the test. As it only occurred in vessels with test item, it can be assumed that it was caused by the test item (and not by aeration). The reasons for this unknown. As a result, biodegradation of the test item could not be quantified and no conclusion on the ready biodegradability can be made. The biodegradation of the test item could not be quantified and no conclusion on the ready biodegradability can be made.