Cyclopentane, methoxy-

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:

20 November 2002 - 08 January 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD and EC test guidelines, and in compliance with GLP, and so the data is considered reliable without restrictions.

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Analytical purity: 99.9%
- Lot/batch No.: 020618

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Preparation of inoculum for exposure: An aliquot was taken and passed through a pre-wieghed filter this filter was dried and re-weighed to determine the mixed liquor suspended solids (MLSS) content, which was then adjested to 4 g/L by removal of the supernatant.
- Initial biomass concentration: 4 g/L

Test type:

static

Water media type:

freshwater

Total exposure duration:

30 min

Test temperature:

Definitive test: 18.4 - 20.2°C

pH:

Definitive test: 7.8 - 8.0

Nominal and measured concentrations:

Nominal: 10, 32,100, 320, 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Conical flasks
- Material, size, headspace, fill volume: 2L nominal volume, 500 mL fill volume
- No. of vessels per concentration (replicates): 1 (the 100 mg/L level was tested in triplicate during the preliminary study only)
- No. of vessels per control (replicates): 2 (single vessels, at the start and end of the test sequence).
- Biomass loading rate: MLSS = 4 g/L

OTHER TEST CONDITIONS
- Adjustment of pH: No

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Dissolved oxygen (respiration rate calculated as change in dissolved oxygen over time)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Half-log scale (spacing factor approximately 3.2)
- Range finding study
A preliminary test was conducted in which the mean respiration rate of activated sludge was decreased by 16% after 30 minutes, and by 17% after three hours' exposure to mixtures containing 100 mg/L NZE. A 30-minute exposure period was employed in the definitive test as there was no apparent difference inchange in respiration rates between the 30-minute and 3-hour exposure times.
The rangefinding study was performed at 1, 10, and 100 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (3,5-DCP)

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50, 30 minutes = 12.3 mg/L

Validity criteria fulfilled:

yes

Conclusions:

Observed respiration rate decreases were less than 20% under each test condition measured, so the exact values for EC20, EC50, and EC80 could not be determined exactly, however they must be greater than 1000 mg/L, the highest concentration tested.

Description of key information

EC50 (30 min) > 1000 mg/L

EC50 (3 hours) > 100 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

An Activated Sludge Respiration Inhibition Test (ASRIT) was conducted (Huntingdon Life Sciences, 2003) to determine the effect of the substance on microorganisms. The test was conducted according to OECD test guideline 209, EC Directive 88/302 (method C11), and in compliance with GLP.

Activated sludge was taken from a sewage treatment plant which treated predominantly domestic waste. Cultures were exposed to the substance at concentrations 1, 10, and 100 mg/L for 30 minutes and 3 hours in the preliminary test and 10, 32, 100, 320, and 1000 mg/L for 30 minutes in the definitive test. It was noted that the inhibition in respiratory rate for the 100 mg/L cultures in the preliminary test was approximately equal following 3 hours' exposure when compared to 30 minutes' exposure, so it was concluded that the definitive test would be conducted over 30 minutes, as there was no apparent difference between the exposure periods.

Mean specific respiration rates were inhibited by 17% after three hours' exposure to the substance at 100 mg/L in the preliminary test, and by 15% after 30 minutes' exposure to the substance at 1000 mg/L in the definitive test. On the basis of these results, it was not possible to determine the EC₂₀, EC₅₀, or EC₈₀ of the substance to microorganisms, however each of these values must be higher than 1000 mg/L, the highest concentration tested. The substance was concluded to have had no adverse effect on the specific respiration rate of activated sludge at any of the concentrations tested.