Methyl α-D-mannopyranoside

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:

from 2020-10-19 to 2020-11-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Version / remarks:

1992-07-17

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

Standard activated sludge was purchased from the Chemicals Evaluation and Research Institute, Japan on October 21, 2020 and preparation started on the same day.
- Water used: purified water (water conforming to the Japanese Pharmacopoeia)
- Amount of sludge used per bottle: 30 mg

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: For the basic culture medium, 6 mL each of solutions A, B, C, and D of the composition specified in JIS K 0105-2016,21 were added to 1976 mL of purified water (water conforming to the Japanese Pharmacopoeia), and adjusted to pH 7.0.
- Additional substrate: no
- Solubilising agent: not used
- Test temperature: 25 ±1 °C
- pH: 7.0 (for basic medium)
- pH adjusted: pH of 7.0 was confirmed after test substance was added but no adjustment was described.
- CEC (meq/100 g): not specified
- Aeration of dilution water: not specified
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: culture bottle
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: not specified
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: Oxygen consumption: Okura Electric's closed system oxygen consumption measurement device Coulometer OM-3100A" (Identification No. 8)
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: no, in closed system for oxygen consumption measurement

SAMPLING
- Sampling frequency: Oxygen consumption was measured over time. Results from measurements on day 7, 14 and 28 were reported. Dissolved organic carbon concentration was measured on day 28.
- Sampling method: Oxygen consumption: using device detailed above; Dissolved organic carbon concentration: 30 mL collected with a whole pipette
- Sample storage before analysis: Samples were analysed directly.
- Details for dissolved organic carbon concentration
After 28 days of incubation, 30 mL of each test solution except for the aniline degradation zone was collected with a whole pipette, centrifuged (4000 g, 15 min) and 25 mL of the supernatant was separated and used as a sample for measuring dissolved organic carbon concentration.

ANALYTICAL EQUIPMENT AND CONDITIONS FOR DISSOLVED ORGANIC CARBON CONCENTRATION
- Measuring equipment: Total Organic Carbon Analyzer TOC-L (Shimadzu Corporation)
- TC furnace temperature: 680 °C
- Air flow rate: 150 mL/min
- Injection volume: 50 µL

CONTROL AND BLANK SYSTEM
- Inoculum blank: 1, containing basic culture medium and activated sludge
- Water stability control: 1, containing test substance and purified water
- Toxicity control: no
- Positive control: 1

STATISTICAL METHODS: No statistical analysis performed.

Reference substance:

aniline

Test performance:

The difference between the maximum and minimum degradability of the test substance after 28 days was 3 %, which was less than 20 %, and thus the test was considered valid.

Parameter:

% degradation (DOC removal)

Value:

97

Sampling time:

28 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

86

Sampling time:

28 d

Details on results:

The degree of decomposition of the three test substance decomposition zones calculated from the oxygen consumption was 84 %, 87 %, and 87 %, respectively. Therefore, the average degradation rate from oxygen consumption was 86 %.
The degree of decomposition of the three test material decomposition zones calculated from the amount of dissolved organic carbon was 97 %, 97 %, and 98 %, respectively. Therefore, the average degradation rate from the amount of dissolved organic carbon was 97 %.
As a result of direct quantification by HPLC, 100 % of the test substance was detected in the water stability zone relative to the amount prepared. Since the test substance was not detected in the three degradation zones, the degree of degradation was 100 %, 100 %, and 100 %, respectively. Therefore, the degree of degradation of the test substance calculated from the direct quantification was 100 % on average.

Results with reference substance:

The degree of degradation of aniline was 65 % on day 7 and 74 % on day 14, and the oxygen consumption curve was also normal, thus the degradation activity of the activated sludge was judged to be normal.

Table 1: Degree of decomposition calculated from oxygen consumption

Culture bottle No.	Item	Theoretical oxygen demand [mg]	7 days		14 days		21 days		28 days
			Measured value [mg]	Decomposition degree [%]	Measured value [mg]	Decomposition degree [%]	Measured value [mg]	Decomposition degree [%]	Measured value [mg]	Decomposition degree [%]
1	Test substance decomposition zone 1	37.1	27.9	54	38.0	74	40.8	79	43	84
2	Test substance decomposition zone 2	37.1	28.1	55	38.1	74	41.4	80	44.2	87
3	Test substance decomposition zone 3	37.1	30.1	60	38.8	76	42	82	44.2	87
4	Aniline decomposition zone	90.6	66.7	65	77.1	74	78.6	74	79	74
5	Basal respiratory zone	-	7.7	-	10.5	-	11.6	-	12	-
6	In-water stability zone	-	0	-	0	-	0.3	-	0.3	-

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test substance is judged to be a good degradant and readily biodegradable.

Executive summary:

A biodegradability test according to OECD 301 C with the test substance was conducted for 28 days. The oxygen consumption was determined using a closed system oxygen consumption measurement device. Furthermore, as the test substance dissolved under the test conditions, the dissolved organic carbon concentration was measured for the test solution after 28 days to determine the degree of decomposition. The residual concentration of the test substance in the test solution after 28 days of incubation was determined by HPLC method. 3 flasks with a concentration of 100 mg/L test substance and 30 mg/L activated sludge were used. In addition aniline was used as positive control and a blank control and water stability control were included. The degree of decomposition of the three test substance decomposition flasks calculated from the oxygen consumption on day 28 was 84 %, 87 %, and 87 %, respectively. Therefore, the average degradation rate from oxygen consumption was 86 %. The average degradation rate from the amount of dissolved organic carbon was 97 % (97 %, 97 %, 98 %). As a result of direct quantification by HPLC, 100 % of the test substance was detected in the water stability control relative to the amount prepared. Since the test substance was not detected in the three test flasks, the degree of degradation was 100 %, 100 %, and 100 %, respectively. Therefore, the degree of degradation of the test substance calculated from the direct quantification was 100 % on average. The degree of degradation of aniline was 65 % on day 7 and 74 % on day 14, and the oxygen consumption curve was also normal, thus the degradation activity of the activated sludge was judged to be normal. In addition, the difference between the maximum and minimum degradability of the test substance after 28 days was 3 %, which was less than 20 %, and thus the test was considered valid. With the conducted test, it was determined that the test substance underwent biodegradation and became mineralized based on the results of degradation from oxygen consumption, dissolved organic carbon, and direct determination by HPLC under the test conditions. Therefore, the test substance is judged to be a good degradant and readily biodegradable.

Description of key information

The test substance is readily biodegradable (reference 5.2.1-1).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

A biodegradability test according to OECD 301 C with the test substance was conducted for 28 days. The oxygen consumption was determined using a closed system oxygen consumption measurement device. Furthermore, as the test substance dissolved under the test conditions, the dissolved organic carbon concentration was measured for the test solution after 28 days to determine the degree of decomposition. The residual concentration of the test substance in the test solution after 28 days of incubation was determined by HPLC method. 3 flasks with a concentration of 100 mg/L test substance and 30 mg/L activated sludge were used. In addition aniline was used as positive control and a blank control and water stability control were included. The degree of decomposition of the three test substance decomposition flasks calculated from the oxygen consumption on day 28 was 84 %, 87 %, and 87 %, respectively. Therefore, the average degradation rate from oxygen consumption was 86 %. The average degradation rate from the amount of dissolved organic carbon was 97 % (97 %, 97 %, 98 %). As a result of direct quantification by HPLC, 100 % of the test substance was detected in the water stability control relative to the amount prepared. Since the test substance was not detected in the three test flasks, the degree of degradation was 100 %, 100 %, and 100 %, respectively. Therefore, the degree of degradation of the test substance calculated from the direct quantification was 100 % on average. The degree of degradation of aniline was 65 % on day 7 and 74 % on day 14, and the oxygen consumption curve was also normal, thus the degradation activity of the activated sludge was judged to be normal. In addition, the difference between the maximum and minimum degradability of the test substance after 28 days was 3 %, which was less than 20 %, and thus the test was considered valid. With the conducted test, it was determined that the test substance underwent biodegradation and became mineralized based on the results of degradation from oxygen consumption, dissolved organic carbon, and direct determination by HPLC under the test conditions. Therefore, the test substance is judged to be a good degradant and readily biodegradable.