Levomenol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990-09-25 to 1990-10-22

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Inoculum: Activated sludge from a laboratory waste water treatment plant using municipal sewage
- Concentration of activated sludge: 30 mg/L dry matter

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Reference substance:

aniline

Preliminary study:

Not specified

Test performance:

Not specified

Key result

Parameter:

% degradation (O2 consumption)

Value:

>= 70 - <= 80

Sampling time:

28 d

Details on results:

- Inhibition control: 74 % degradation after 28 days (no inhibition)
- Abiotic elimination control: 6 % degradation after 28 days
- Lag-phase: 14 days

- Degradation kinetic:
Time [d] Degradation [%]
14 10
15 17
24 69
28 76

Results with reference substance:

- Degradation of reference substance: 81 %
- Lag-phase: 5 days
- Degradation phase: 6 days

Table 1: Biodegradation of the test item in vessel no. 3.

time (d)	BOD/ThOD (%)
0	0
1	0
2	0
3	0
4	0
5	0
6	0
7	0
8	0
9	0
10	0
11	1
12	2
13	3
14	5
15	17
16	30
17	37
18	40
19	46
20	54
21	60
22	63
23	65
24	69
25	72
26	73
27	75
28	76

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The mean biodegradation of the test item after 28 days was 70-80% BOD/ThOD. The test item is regarded to be readily biodegradable in a ten day window and after 28 days.

Executive summary:

To assess the ready biodegradability of the test item, a Manometric Respirometer Test according to OECD Guideline 301 F and ISO 9408 was carried out. Activated sludge from a laboratory waste water treatment plant (30 mg/L dry matter per test vessel) was exposed for 28 days to a limit test item concentration of 100 mg/L (7 replicates). In addition, a positive control (with 100 mg/L of the reference substance aniline, but without the test item), a toxicity control (with inoculum; 100 mg/L of the test item and the reference substance, respectively) and an abiotic control (with the test item, but without inoculum) was performed. After 28 days, 81% of the reference compound was degradet, confirming the suitability of the test system. In the toxicity control, a biodegradation of 74% was reached. Thus, there were no indications that the test item has toxic potential to aquatic microorganisms and, hence, inhibiting properties towards sewage treatment plants. In result, the mean biodegradation of the test item after 28 days was 70-80% BOD/ThOD. Moreover, the 10-day-criterion of the test guidelines was fulfilled. Therefore, the test item is regarded to be readily biodegradable in a ten day window and after 28 days.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1990-05-17 to 1990-06-14

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

other: EEC Directive 79-831, Annex V, Part C: Methods for the Determination of Ecotoxicity, Degradation - Biotic Degradation, Manometric Respirometry

Deviations:

no

Principles of method if other than guideline:

Since biodegradation of the test item had a long lag phase under the conditions chosen, the test duration was extended to 29 days.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source: Municipal sewage treatment plant

Duration of test (contact time):

29 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

- Respirometer used: Sapromat with 5 test vessels in parallel, test volume: 250 mL
- Controls:
Sterile control (without inoculum, with test item)
Process control (with inoculum and the reference substance aniline)
Inhibition control (with inoculum, test substance and reference substance)

Reference substance:

aniline

Preliminary study:

Not performed

Test performance:

Due to a lag phase of biodegradation of the test item (10-23 days), the test duration was extended to 29 days.

Key result

Parameter:

% degradation (O2 consumption)

Remarks:

BOD*100/ThOD

Value:

73

Sampling time:

29 d

Results with reference substance:

Based on DOC-Elimination: 99%
Based on BOD*100/ThOD: 81%
(lag phase: 5 days; degradation phase: 6 days)

Validity criteria fulfilled:

not specified

Interpretation of results:

not readily biodegradable

Remarks:

but moderately biodegradable after a lag-phase of 10-23 days and an extended test duration of 29 days.

Conclusions:

The test substance was not readily biodegradable according to OECD criteria, but moderately biodegradable after a lag-phase of 10-23 days and an extended test duration of 29 days.

Executive summary:

The biodegradability of the test item was evaluated by a Manometric Respirometry Test according to EEC Directive 79-831 Annex V Part C. In a static test system, non-adapted activated sludge of an municpial sewage treatment plant was exposed to 100 mg/L of the test substance. The ThOD of the test substance was determined to be 3027 mg/g. Additionally, a postive control with the reference substance aniline, a sterile control (with the test item, but without inoculum) and an inhibition control (with inoculum, test item and reference substance) was performed. As the biodegradation of the test item had a long lag phase of 10-23 days, the test duration was extended from 28 to 29 days. In result, mean biodegradation of the test item was 73 % (based on BOD*100/ThOD) after 29 days. The reference compound was biodegraded up to 99% (based on DOC elimination; lag phase: 5 days; degradation phase: 6 days) within the test duration, confirming the suitability of the test system. There were no indications of inhibitory effects of the test item to aquatic microorganisms. In conclusion, the test substance was not readily biodegradable according to OECD criteria, but moderately biodegradable after a lag-phase of 10-23 days and an extended test duration of 29 days.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1992-01-21 to 1992-03-03

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

extended exposure period

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1991 (draft version)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)

Version / remarks:

ISO 9408:1991 (E)

Deviations:

not specified

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Concentration of inoculum: 30 mg/L dry matter

Duration of test (contact time):

42 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- pH during test: 7.2 to 8.0
- pH at the end of the test:
Blank controls: 7.4 - 7.6
Positive control: 8.0
Toxicity control: 8.0
Phs.chem control: 7.0

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 assays
- Abiotic sterile control: not performed
- Toxicity control: 1 assay (reference substance aniline: 100 mg/L; test substance: 100.4 mg/L)
- Positive control: 1 assay (reference substance aniline: 100 mg/L)
- Phys.chem. control: with 100.8 HgCL2

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

>= 60 - <= 70

Sampling time:

42 d

Details on results:

- Degradation of inhibition control: 81 %

- Degradation kinetic:
Time [d] Degradation [%]
16 0 - 10
17 10 - 20
28 50 - 60
42 60 - 70

Results with reference substance:

- Degradation of reference substance: 78 %

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test substance was not readily biodegradable according to OECD criteria, but moderately biodegradable up to 62% of the ThOD and 63% of the COD, respectively, after an extended test duration of 42 days.

Executive summary:

To assess the ready biodegradability of the test substance, a static Manometric Respirometry Test according to OECD Guideline 301 F and ISO 9408:1991 (E) was carried out in compliance with GLP principles. Non-adapted, domestic activated sludge of a laboratory scale sewage treatment plant was exposed for 42 days to the nominal test item concentration of 100 mg/L. In parallel, a blank control, a positive control and a toxicity control was performed. In result, the test substance was not readily biodegradable according to OECD criteria, but moderately biodegradable, since 62% of the ThOD and 63% of the COD, respectively, was reached after an extended test duration of 42 days. In the toxicity control, biodegradation reached 81%. In the positive control, biodegradation was 78% of the ThOD and 82% of the COD after 25 days. Thus, the test substance is not considered to be toxic to aquatic microorganisms.

Description of key information

The test substance is considered to be readily biodegradable (according to OECD criteria).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Key study

To assess the ready biodegradability of the test item, a Manometric Respirometer Test according to OECD Guideline 301 F and ISO 9408 was carried out. Activated sludge from a laboratory waste water treatment plant (30 mg/L dry matter per test vessel) was exposed for 28 days to a limit test item concentration of 100 mg/L (7 replicates). In addition, a positive control (with 100 mg/L of the reference substance aniline, but without the test item), a toxicity control (with inoculum, 100 mg/L of the test item and the reference substance, respectively) and an abiotic control (with test item, but without inoculum) was performed. After 28 days, 81% of the reference compound was degradet, confirming the suitability of the test system. In the toxicity control, a biodegradation of 74% was reached. Thus, there were no indications that the test item has toxic potential to aquatic microorganisms and, hence, inhibiting properties towards sewage treatment plants. In result, the mean biodegradation of the test item after 28 days was 70-80% BOD/ThOD. Moreover, the 10-day-criterion of the test guidelines was fulfilled. Therefore, the test item is regarded to be readily biodegradable in a ten day window and after 28 days (reference 5.2.1 -1).

Supporting studies

To evaluate the ready biodegradability of the test substance, a static Manometric Respirometry Test according to OECD Guidleine 301 F and ISO 9408:1991 (E) was carried out in compliance with GLP principles. Non-adapted, domestic activated sludge of a laboratory scale sewage treatment plant was exposed for 42 days to the nominal test item concentration of 100 mg/L. In parallel, a blank control, a positive control and a toxicity control was performed. In result, the test substance was not readily biodegradable according to OECD criteria, but moderately biodegradable since 62% of the ThOD and 63% of the COD, respectively, was reached after an extended test duration of 42 days. In the toxicity control, biodegradation reached 81%. In the positive control, biodegradation was 78% of the ThOD and 82% of the COD after 25 days. Thus, the test substance is not considered to be toxic to aquatic microorganisms (reference 5.2.1 -2).

In another experimental study, the biodegradability of the test item was evaluated by a Manometric Respirometry Test according to EEC Directive 79-831 Annex V Part C. In a static test system, non-adapted activated sludge of an municpial sewage treatment plant was exposed to 100 mg/L of the test substance (limit concentration). The ThOD of the test substance was determined to be 3027 mg/g. Additionally, a postive control with the reference substance aniline, a sterile control (without inoculum and the test item) and an inhibition control (with inoculum, test item and reference substance) was performed. As the biodegradation of the test item had a long lag phase of 10-23 days, the test duration was extended from 28 to 29 days. In result, mean biodegradation of the test item was 73 % (based on BOD*100/ThOD) after 29 days.The reference compound was biodegraded up to 99% (based on DOC elimination; lag phase: 5 days; degradation phase: 6 days) within the test duration, confirming the suitability of the test system. There were no indications of inhibitory effects of the test item to aquatic microorganisms. In conclusion, the test substance was not readily biodegradable according to OECD criteria as the 10-day-window criterion was not met, but moderately biodegradable after a lag-phase of 10-23 days and an extended test duration of 29 days (reference 5.2.1 -3).

Conclusion

Based on the most current and reliable information (reference 5.2.1 -1), the test substance is considered to be readily biodegradable (according to OECD criteria). This result is supported by two older and non-standard Manometric Respirometry Tests (reference 5.2.1-2, reference 5.2.1-3), confirming the biodegradability of the test substance (not readily, but inherently biodegradable). Furthermore, the test item is not considered to be inhibitory to sewage treatment plants, as demonstrated by the inhibition control of three Manometric Respirometry Tests (reference 5.2.1-1, reference 5.2.1-2, reference 5.2.1-3).