Levomenol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1989-08-31 to 1989-08-31

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

8192 Part B, draft 1984

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

Not specified

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: As the test substance is poorly water soluble, it was weighed directly into the test vessels.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source: municipal sewage treatment plant (date of collection: 1989-08-30)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Post exposure observation period:

Post exposure not performed

Hardness:

Not specified

Test temperature:

20-25 °C

pH:

Not specified

Dissolved oxygen:

Not specified

Salinity:

Not applicable

Conductivity:

Not specified

Nominal and measured concentrations:

Nominal test item concentrations: 100 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Not specified
- No. of vessels per concentration (replicates): 1
- Sludge concentration in test vessel: 1000 mg/L dry substance

EFFECT PARAMETERS MEASURED: respiration inhibition

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Range finding study: Not performed

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorphenol

Duration:

30 min

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: respiration inhibition: 3.4%

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- Any observations that might cause a difference between measured and nominal values: Not specified
- Blank controls oxygen uptake rate: Not specified
- Coefficient of variation of oxygen uptake rate in control replicates: Not specified

Results with reference substance (positive control):

EC50 = 45 mg/L

Validity criteria fulfilled:

not specified

Conclusions:

The NOEC of the test substance was determined to be 1000 mg/L. The 30-min EC10 and EC50 of the test item is considered to be > 1000 mg/L. In conclusion, the test item has no toxic potential to aquatic microorganisms.

Executive summary:

To assess the toxic potential of the test substance to aquatic microorganisms, a test for Inhibition of oxygen consumption of activated sludge according to ISO guideline ISO/DIS 8192 Part B (draft 1984) was carried out in compliance with GLP principles. Non-adapted activated sludge of a municipal sewage treatment plant was exposed to test substance concentrations of 100 and 1000 mg/L, respectively (one vessel per concentration). In addition, a positive control with the reference substance 3,5 -dichlorphenol was performed. The mean blind value for the respiration rate was determined to be 29 mg/L*h. In result, the EC50 of the reference substance was found to be 45 mg/L, confirming the suitability of the test system. At the concentration level of 100 mg test substance/L, no inhibitory effects on respiration were observeable. At the highest concentration of the test substance, a respiration inhibition of 3.4% was noted. Thus, the NOEC was determined to be 1000 mg/L. Consequently, the 30-min EC10 and EC50 is considered to be >1000 mg/L. In conclusion, the test item is not considered to be toxic to aquatic microorganisms, since the respiriation inhibition at the highest concentration tested was far below 20 %. Therefore, no inhibitory effect of the test substance to sewage treatment plants is to be expected.

Description of key information

The 30-min EC50 and the EC10 of the test item is considered to be >1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

To assess the toxic potential of the test substance to aquatic microorganisms, a test for Inhibition of oxygen consumption of activated sludge according to ISO guideline ISO/DIS 8192 Part B (draft 1984) was carried out in compliance with GLP principles. Non-adapted activated sludge of a municipal sewage treatment plant was exposed to test substance concentrations of 100 and 1000 mg/L, respectively (one vessel per concentration). In addition, a positive control with the reference substance 3,5 -dichlorphenol was performed. The mean blind value for the respiration rate was determined to be 29 mg/L*h. In result, the EC50 of the reference substance was found to be 45 mg/L, confirming the suitability of the test system. At the concentration level of 100 mg test substance/L, no inhibitory effects on respiration were observeable. At the highest concentration of the test substance, a respiration inhibition of 3.4% was noted. Thus, the NOEC was determined to be 1000 mg/L. Consequently, the 30-min EC10 and EC50 is considered to be >1000 mg/L. In conclusion, the test item is not considered to be toxic to aquatic microorganisms, since the respiriation inhibition at the highest concentration tested was far below 20 %. Therefore, no inhibitory effect of the test substance to sewage treatment plants is to be expected (reference 6.1.7 -1).