Dichlorodicyclopentylsilane

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997-04-18 until 1997-08-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD test under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of test material (as cited in study report): Silane CP 2
- Physical state: liquid
- Analytical purity: 96.3% (GC)
- Impurities (identity and concentrations): as stated in substance data
- Composition of test material, percentage of components: as stated in substance data
- Lot/batch No.: 10466 QB
- Expiration date of the lot/batch: 1997-12-01
- Stability under test conditions: reaction to hydrolysis product
- Storage condition of test material: in original container, at room temperature, in the dark

Sampling and analysis

Analytical monitoring:

not required

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Different test substance amounts were weighed by means of a Hamilton syringe and injected into 1000 ml brown glass flasks, filled with
284 ml of deionized water and stirred by magnetic stirrers for 30 minutes.
- Controls: inoculum control; 3,5-Dichlorophenol was used a positive control

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source: domestic waste water treatment plant (ARA Ergolz II, Füllinsdorf/Switzerland)
- Method of cultivation: sludge was washed by centrifugation, the supernatant liquid phase was decanted, the solid material resuspended in tap water and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet sludge to its dry weight determined. Based on this ratio calculated aliquots of washed sludge suspension were made up with Soerensen buffer (pH 7), to obtain a concentration equivalent to 2 g dry weight basis per litre. To this mixture, 50 ml synthetic sewage feed per litre was added daily starting four days prior to use, and the sludge was kept at room temperature under continous aeration until use.
- Preparation of inoculum for exposure: Immediately before use, the dry weight of the activated sludge was determined to be 5.2 g/L, and diluted with tap water to a dry weight of 4 g/L. The pH was adjusted to 7.8 with 0.5 mol/L sulfuric acid.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

not applicable

Test conditions

Test temperature:

22 °C

pH:

8.3 - 8.5

Dissolved oxygen:

test substance: start: 4.0 - 4.8 mg O2/L; end: 6.6 - 6.7 mg O2/L
control: start: 4.6 - 5.3 mg O2/L; end: 6.7 - 7.0 mg O2/L
positve control: 4.7 - 5.7 mg O2/L; end: 6.5 - 8.7 mg O2/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 1000 ml brown glass flasks
- Aeration: immediately after filling the flasks aeration was started using compressed air (flow rate: approx. 1 L/minute)
- Test concentrations: positive control: 100, 32, 10, 3.2 mg/L; test substance: 100, 50, 24, 12, 6 mg/L
- Biomass loading rate: 1.6 g/L during the test

Reference substance (positive control):

yes

Remarks:

Dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

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

Remarks:

respiration rate

Effect concentrations 2

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

No inhibitory effect on the respiratory rate of activated sludge up to a highest test concentration of 100 mg/L has been observed.

Executive summary:

The inhibitory effect of Silane CP 2 on the respiratory rate of aerobic waste water microorganisms of activated sludge was investigated in a 3-hour respiratory test in accordance with OECD Guideline 209. This study examined five test substance concentrations (6 to 100 mg/L), three inoculum controls and four concentrations of the positve control 3,5 -Dichlorophenol (3.2 to 100 mg/L). The respiratory rate of the activated sludge was not inhibited by the test substance at all test concentrations. The 3 -hour EC50 and EC20 are clearly higher than 100 mg/L (nominal).

The 3 -hour EC50 for the positive control was found to be 19.6 mg/L and was within the range of 5 - 30 mg/L recommended by the test guideline.