1,1,2,2,3,3,4-heptafluorocyclopentane

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:

From 1997-10-22 to 1998-01-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

4 April 1984

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Batch No.: 9705-2A
Purity: 98.18%

Analytical monitoring:

yes

Details on sampling:

In order to assess the exposure concentration of test item, independently prepared control mixtures (nominal concentration, 100 mg/L) containing the test material, injected into dilution water alone, were established under test conditions. Samples for analysis (40 mL) were removed before and after the three-hour aeration period.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Appropriate volumes were injected, using a microsyringe, into test beakers containing dilution water maintained at the test temperature.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: maintained under aerobic conditions until required.
- Name and location of sewage treatment plant where inoculum was collected: Oakley sewage treatment works
- Preparation of inoculum for exposure: On the day of collection, aliquots (25 mL) of the activated sludge were filtered through dried and preweighed Whatman's GFC filter papers which were then dried again at approximately 105°C for at least one hour, allowed to cool in a desiccator and reweighed. The mixed liquor suspended solids (MLSS) content of the activated sludge was then calculated and adjusted to 4g/L by the removal of supernatant. Synthetic sewage (50 mL/L) was added and the mixture aerated overnight.
- Initial biomass concentration: 4g/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Hardness:

60 mg/L

Test temperature:

19.0-19.9 °C

pH:

7.1-8.1

Nominal and measured concentrations:

Nominal: 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: one-litre glass beakers, fill volume: Ca. 500 mL
- Aeration: aerated using a Pasteur pipette connected to a laboratory supply of oil-free compressed air
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 2
- No. of vessels per abiotic control (replicates): 1
- Sludge concentration (weight of dry solids per volume): 1.6 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The dilution water used to prepare stock solutions of the test material was tap water that had been softened and treated by reverse osmosis (Elga Ltd, Prima 4 reverse osmosis unit) and then purified (Elga Ltd, UHP) to give a conductivity of 18 Megohm/cm.

OTHER TEST CONDITIONS
- Adjustment of pH: no

EFFECT PARAMETERS MEASURED:
Following the exposure period, a well-mixed sample of each mixture was transferred to a biochemical oxygen demand (BOD) bottle (capacity; 270 mL) and its rate of oxygen consumption over a period of approximately ten minutes was measured using a Yellow Springs Instruments (YSI) dissolved oxygen meter, with temperature probe and self-stirring bottle probe, connected to a chart recorder. The pH and temperature ofthe samples were measured at the start and end of the test.

Reference substance (positive control):

yes

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- Inhibitory effect: No significant inhibitory effect on the respiration rate of activated sludge at an initial nominal concentration of 100 mg/L. Respiration rates in mixtures containing test item were reduced, at most, by 5% of the mean control value.
- Blank controls oxygen uptake rate: 30.0 mgO2/g/hr at the end of the test was 102% of the rate of that established at the start (29.3 mgO2/g/hr).
- Coefficient of variation of oxygen uptake rate in control replicates: < 15%

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 3h-EC50: 8.8 mg/L (95% confidence limits 7.1 - 10.8 mg/L)
- Other: acceptable EC50 range 5 to 30 mg/L

Levels of test item estimated by Total Carbon analysis and Chemical Oxygen Demand were low (0.01 - 0.02% ofthe nominal level) at both the start and end of the aeration period. Since the material was known to be miscible with water, these results suggest that test item may not have been oxidised under the conditions employed in these analyses.The measured levels of test item at the start and end of the aeration period (25.4 and 0 mg/L respectively) indicated that material had not completely dissolved at the start and was readily lost from the mixture over three hours as a result of its volatility.

Validity criteria fulfilled:

yes

Conclusions:

The test item had no significant inhibitory effect on the respiration rate of activated sludge. The EC20, EC50 and EC80 of the test material could not therefore be calculated but these must be greater than 100 mg/L.

Executive summary:

The effect of test item on the respiration rate of activated sludge was assessed by the methods detailed in OECD Test Guideline 209.

Triplicate samples of activated sludge (suspended solids 1.6 g/L), fed with synthetic sewage, were exposed to the test material at a nominal level of 100 mg/L for three hours.

The measured levels of test item at the start and end of the aeration period (25.4 and 0 mg/L respectively) indicated that material had not completely dissolved at the start and was readily lost from the mixture over three hours as a result of its volatility.

The test item had no significant inhibitory effect on the respiration rate of activated sludge. The EC20, EC50 and EC80 of the test material could not therefore be calculated but these must be greater than 100 mg/L.

Description of key information

The effect of test item on the respiration rate of activated sludge was assessed by the methods detailed in OECD Test Guideline 209.

The 3h EC20, EC50 and EC80 of the test material could not therefore be calculated but these must be greater than 100 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L