2-Propenoic acid, 2-methyl-, tris(1-methylethyl)silyl ester

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 February to 25 February 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Recent study conducted by a GLP certified laboratory in accordance with a suitable study guideline.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

Sludge concentration of 4 g/L (dry weight) was added instead of 2-4g/L and the time interval between the last test solution flask and the second control was more than 15 minutes. Neither of these things are presumed to effect the study.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Tripropan-2-ylsilyl 2-methylprop-2-enoate

EC Number:

700-182-8

Cas Number:

134652-60-1

Molecular formula:

C13 H26 O2 Si

IUPAC Name:

Tripropan-2-ylsilyl 2-methylprop-2-enoate

Details on test material:

- Name of test material (as cited in study report): TIS-M
- Analytical purity: 97.95 %
- Lot/batch No.: 9925
- Expiration date of the lot/batch: 2 December 2010
- Storage condition of test material: At room temperature (15-25ºC)

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: One test solution with a final volume of 330 mL was tested per treatment in a glass flask. 10.56 mL synthetic sewage and an adequate amount of the test item or an adequate volume of the stock solution of the reference item was filled up with deionised water to 198 mL before the start of the test. At the start of the test 132 mL activated sludge inoculum with a sludge concentration of 4 g/L (dry weight) was added,
- Controls: Untreated Control (C1 and C2): Two controls (deionised water, synthetic sewage and inoculum, but without addition of the test item) were tested in parallel. Reference control: In parallel to the study with the test item, the reference item 3,5-Dichlorophenol was tested (the nominal test concentrations of 5, 16 and 32 mg/L) under otherwise identical test conditions.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Study design

Test type:

static

Water media type:

not specified

Limit test:

yes

Total exposure duration:

3 h

Post exposure observation period:

Ten minutes so that the oxygen concentration and consumption could be determined.

Test conditions

Hardness:

Not specified.

Test temperature:

19.1 – 20.2 °C (during the incubation) and 20.1 – 20.9 °C (during oxygen measurement). The temperature was measured in the climate chamber with a min/max thermometer during the incubation period. The water temperature was recorded during the oxygen measurement in all BOD bottles.

pH:

The pH of the activated sludge inoculum was determined to be pH 7.22. The pH was determined at the start and at the end of the incubation period in all treatments.

Dissolved oxygen:

Aerated compressed air (approximately 1 litre per minute). The oxygen concentration was determined at the start and at the end of the incubation period in all treatments.

Salinity:

Not specified.

Nominal and measured concentrations:

Before the start of the test defined amounts of the test item were directly weighed into the test flasks and mechanically dispersed using short ultrasonic bath treatment for 5 min. The test concentrations (10, 31, 100, 313 and 1000 mg/L) were chosen to permit the determination of the EC50. Concentrations in excess of nominal 1000 mg test item/L were not tested.

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer bottles for incubation and BOD bottles with special neck for the measurement of respiration rate.
- Type: closed
- Material, size, headspace, fill volume: Glass - approximately 350 mL volume for Erlenmeyer bottles and 300 mL volume for the BOD bottles.
- Aeration: With compressed air (approximately 1 litre per minute) for the 3 hour incubation period, after which there was no further aeration.
- No. of vessels per concentration: 1
- No. of vessels per control: 2

Synthetic Sewage Feed (ratio of composition of culture media referring to 1000 mL)
Peptone 16.0 g
Meat extract 11.0 g
Urea 3.0 g NaCl 0.7 g
CaCl2 x 2H2O 0.4 g
MgSO4 x 7H2O 0.2 g
K2HPO4 2.8 g
Deionised water add 1000.0 mL

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Varied as concntrations used are 10, 31, 100, 313 and 1000 mg/L
- Test concentrations:10, 31, 100, 313 and 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol: 5, 16 and 32 mg/L

Results and discussion

Effect concentrations

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between 1.8 % and 18.2 % in the examined nominal
test concentration range (10 - 1000 mg/L). Concentrations exceeding 1000 mg/L nominal were not tested. Based on measured inhibition rates it
can be stated that the 3-hour EC20, EC50 and EC80 were higher than 1000 mg/L.

The NOEC was determined to be 100 mg/L. The NOEC for respiration rates was not based on the results of a statistical analysis, but it is biologically
justified. The respiration rates were inhibited and influenced dose dependently in the whole concentration range, and the observed slight inhibition
(9.1 %) at the concentration level of 100 mg/L was evaluated as reflecting the biological variability in the test. The calculated respiration rate, 0.500 (at 100 mg/L) was in the historical control data range (0.518 ± 0.074), and the deviation from the control was within +/- 15 %, can be considered as a biological variability of the test system.

Results with reference substance (positive control):

The following nominal concentrations of the positive reference control 3,5-Dichlorophenol were tested on the same activated sludge and under identical conditions as the test item: 5, 16 and 32 mg/L. In comparison to the controls the respiration rate of the activated sludge was inhibited by 20.0 % at the lowest nominal concentration of 5 mg/L. At the nominal concentrations of 16 and 32 mg/L, the respiration rate was inhibited by 61.8 % and 81.8 %, respectively. The 3-hour EC50 of 3,5-Dichlorophenol was calculated to be 12.19 mg/L with 95% confidence limits of 10.29 to 14.43 mg/L.

Reported statistics and error estimates:

The 3-hour EC50 of the reference item with 95 %-confidence limits were calculated by Probit analysis using TOXSTAT software.

Any other information on results incl. tables

Determination of the Inhibitory Effects:

The inhibitory effect of the test item respectively of the reference item at a particular concentration on the respiration rate were expressed as percentage of the mean value of the respiration rates of the two controls according to:

(1 – (2Rs/Rc1 -Rc2)) * 100 = % inhibition 

where: Rs = oxygen consumption rate at tested concentration of test item Rc1 = oxygen consumption rate of control 1 Rc2 = oxygen consumption rate of control 2 The 3-hour EC50 of the reference item with 95 %-confidence limits were calculated by Probit analysis using TOXSTAT software. The 3-hour EC20, EC50 and EC80 of the test item could not be calculated.

_{Based on measured inhibition rates it can be stated that the 3-hour EC20, EC50 and EC80 were higher than 1000 mg/L.}

_{Validity Criteria:}

_{-The respiration rates of the two controls did not differ by more than 15 %}

_{- The 3-hour EC50 of the reference item 3,5-Dichlorophenol for the used activated sludge batch was determined to be in the range of 5 to 30 mg/L.}

_{- The concentration of dissolved oxygen did not drop below 2.5 mg O2/L during the incubation period, and just before the measurements of the respiration rates the oxygen concentrations were at least 7.0 mg O2/L.}

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Based on measured inhibition rates it can be stated that the 3-hour EC20, EC50 and EC80 were higher than 1000 mg/L.

Executive summary:

The respiration inhibition rates of microorganisms in sewage when exposed to TIS-M were assessed according to EU Method C.11. A positive control substance 3,5-Dichlorophenol was also used. The 3-hour EC20, EC50 and EC80 were determined to be higher than 1000 mg/L based on measured inhibition rates.