4-[fluoro(dimethyl)silyl]butanenitrile

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 18 - December 16, 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

adopted 22. Jul. 2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-[fluoro(dimethyl)silyl]butanenitrile

EC Number:

812-925-4

Cas Number:

1639345-42-8

Molecular formula:

C6H12FNSi

IUPAC Name:

4-[fluoro(dimethyl)silyl]butanenitrile

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
First Experiment (Pre-Test): The test item was added to the test vessels directly. In the treatments 1000 mg/L and 100 mg/L, the test item was added with a pipette (0.5 mL and 0.05 mL, based on a density
of 1 g/mL, stated in the MSDS). In the lower concentrated treatments the test item was weighed directly into the test vessel.

Second Experiment (Main Test): The test item was added to the test vessels directly. In the treatments 320 / 100 / 32 mg/L, the test item was added with a pipette (0.16 mL, 0.05 mL and 0.016 mL, based on a density
of 1 g/mL, stated in the MSDS). In the lower concentrated treatments the test item was weighed directly into the test vessel.

- Controls: yes

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Pretreatment:
The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant in D-67435 NW-Lachen-Speyerdorf.
Upon arrival in the test facility, the sludge was filtrated, washed with tap water 3 times and re-suspended in tap water. The activated sludge was aerated until usage in the test and fed daily with 50 mL synthetic sewage feed /L.

- Preparation of inoculum for exposure:
On the day before the experiment, the inoculum was taken from its source, washed, aerated and the dry matter was determined. Volume was adapted to the desired content of dry matter. The nutrient solution was thawed and the sludge was fed with 50 mL/L sludge.
On the day of the experiment, the dry matter was determined once more. The stock solution of the positive control was prepared.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

21.6 - 22.5 °C (first experiment)
21.1 - 22.6 °C (second experiment)

pH:

7.6 - 5.2 (first experiment)
7.0 - 7.5 (second experiment)

Nominal and measured concentrations:

first experiment: 1 / 10 / 100 / 1000 mg/L
second experiment: 320 / 100 / 32 / 10 / 3.2 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 2000 mL Schott-flasks were used as test vessels.

- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 2


In the control vessels, 16 mL nutrient solution was mixed with 234 mL water. The positive control vessels and the treatments were prepared by putting the appropriate amount of
positive control solution respectively the appropriate amount of test item into the respective test vessel, adding 16 mL nutrient solution and water to give 250 mL. Then, 250 mL inoculum
was added in 5 minute intervals and the mixtures were closed with sealed lids.
After 3 hours, the content of the first vessel is shaken vigorously for 30 seconds, then poured in a 250 mL narrow-neck bottle and the respiration rate was determined by measurement
of the O2-concentration over a period of max. 5 minutes1. The following vessels were measured likewise in 5 minute intervals.

OTHER TEST CONDITIONS
- Adjustment of pH:no

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

6.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

inhibition of total respiration

Remarks on result:

other:

Remarks:

second experiment

Effect concentrations 2

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

240 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

inhibition of total respiration

Remarks on result:

other:

Remarks:

second experiment

Results with reference substance (positive control):

EC50 of 9.1 mg/L

Reported statistics and error estimates:

not determinable

Any other information on results incl. tables

Two valid experiments were performed.

In the first experiment, which was performed as the range finding test, the test item was tested using 4 concentrations ranging from 1000 to 1 mg/L nominal concentration. Because

strong inhibition was observed in the 2 highest concentrated treatments, a second experiment, conducted as a main test. In the second experiment the test item was tested

using 5 concentrations ranging from 320 to 3.2 mg/L nominal concentration. For each concentration 5 replicates were used.

Significant inhibition was observed in the 2 highest concentrated treatments. In the lower concentrated treatments in some replicates slight stimulation of the respiration of the inoculum

was observed whereas in some replicates inhibition of respiration was observed. The mean inhibition of treatment 32 mg/l can be stated as not significant. NOEC was determined

by comparing of the respective treatment with the blank control. Statistically insignificant variation is considered as “no observed effect”, although the EC10 which is read from

the graph toxicity vs. concentration was lower.

All validity criteria were met. For the estimation of the EC50 of the positive control, the fits showed good statistical correspondence of the data with the dose-response-equation. The

positive control gave an EC50 of 8.6 mg/L in the first and 9.1 mg/L in the second experiment which lie within the recommended range of 2 – 25 mg/L. The coefficient of variation

of oxygen uptake rate in control replicates was below 30% at the end of the test. The oxygen uptake rate of the blank controls was above 20 mg O2 per gram activated sludge in 1 hour.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

An 3 h EC10 of 6.2 mg/L and a 3 h EC50 of 240 mg/L has been determined for the effects of the test substance on respiration rate of activated sludge microorganisms. The results are expressed relative to nominal concentrations of the test substance. However, the substance is subject to rapid hydrolysis and under the test conditions it is therefore likely that exposure will have been to its hydrolysis products.