A mixture of: propan-2-one-O,O'(methoxyvinylsilandiyl)dioxime; propan-2-one-O-(dimethoxyvinylsilyl)oxime; propan-2-one-O,O',O''-(vinylsilantriyl)trioxime

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:

October 5, 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

According to OECD Guideline 209, with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.6800 (Modified Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals)

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

- Concentrations: 7.6, 19.2, 48.0, 120.0 and 300.0 mg of the test substance/L
- Sampling method: The appropriate amounts of the test substance were added to the sludge samples at the beginning of the incubation
- Sample storage conditions before analysis: to assure that the non altered test substance was tested as far as possible, no stock solution was prepared.

Vehicle:

no

Details on test solutions:

The test substance was poorly soluble in water and hydrolyses and polymerises quickly when in contact with water. To assure that the non altered testsubstance was tested as far as possible, no stock solution/suspension was prepared but the appropriate amounts of the test substance were added to the sludge samples at the beginning of the incubation. This treatment is in accordance with the EPA-Guideline OPPTS 850.6800.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Preparation of inoculum for exposure: A sample of activated sludge was collected one day before the test. The container for transportation was only about 2/3 filled in order to maintain the contact with air. At arrival in the laboratory (less than 1 hour after sample collection), the supernatant over the sludge was decanted, the sludge was diluted with tap water and aerated by means of compressed air. 50 mL of synthetic sewage concentrate were added per litre each day. On the day of the test the sludge was allowed to sediment and the supernatant was decanted.
On the basis of this calculation the concentration of suspended solids was adjusted to 4 g/L with tap water

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

The temperature in the samples was 18 ºC

pH:

The pH of the incubation mixtures after the 3 hour incubation was between 8.29 and 8.37, the pH of the negative control samples was 8.39 and 8.34. The test substance did not influence the pH.

Dissolved oxygen:

Negative controls: 6.98-7.56 mg/mL
Test substance: 6.37-7.51 mg/mL
Positive controls: 6.79 -8.74 mg/L

Nominal and measured concentrations:

nominal concentrations: 7.7, 19.2, 48, 120, and 300 mg/mL

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: Glass beakers with a nominal volume of 1000 mL
- Aeration: the samples were aerated at flow rate of 0.7 L/min
- Type of flow-through (e.g. peristaltic or proportional diluter): oil free compressed air and a Pasteur-pipette as aeration device
- Renewal rate of test solution (frequency/flow rate): Samples were aerated for 3 hours.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): the amount of dry substance in the standardized activated sludge. The pH of the standardized sludge, and the temperature in the samples.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

189 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

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: The EC50 of 3,5-dichlorophenol was in the accepted range of 5 to 30 mg/L. The actual values of the EC20, EC50 and EC80 for 3,5-dichlorophenol were: EC20 = 6.2 mg/L, EC50 = 12.8 mg/L, EC80 = 26.4 mg/L

Reported statistics and error estimates:

For each sample a linear regression was calculated from the linear part of the graph time versus oxygen content. From the oxygen content at the begin and at the end of this regression line the respiration rates (expressed in mg O2.L-1.h-1) were calculated.
The concentrations of the test substance around 50 % inhibition (if such data exist) and the concentrations of the positive control are converted to log10. These values and the corresponding percentage of inhibition are subjected to linear regression analysis. These analyses are used to obtain the regression coefficients and the respective EC20, EC50 and EC80 values.

Respiration rate and inhibition of the samples

Negative values indicate enhanced respiration compared to the control cultures.

sample	final concentr. (mg/L)	linear range (minutes)	mg O2/ L at begin	mg O2/ L at end	respiration rate (mg O2. L^-1. h^-1)	percent respiration inhibitio
neg. control 1	0.0	8.04	6.98	2.63	32.46	3.42
test substance 1	7.6	9.48	7.09	2.15	31.27	6.98
test substance 2	19.2	7.00	7.03	3.25	32.40	3.61
test substance 3	48.0	7.44	6.37	2.35	32.42	3.55
test substance 4	120.0	8.00	6.94	3.11	28.73	14.54
test substance 5	300.0	7.96	7.51	4.19	25.03	25.55
neg. control 2	0.0	7.56	7.06	2.68	34.76	-3.42
DCP 1	4.9	7.96	6.79	2.62	31.43	6.49
DCP 2	11.9	9.52	7.69	5.26	15.32	54.44
DCP 3	29.2	6.60	8.74	8.02	6.55	80.53

DCP: 3,5-dichlorophenol

Validity criteria fulfilled:

yes

Conclusions:

EC20: 189 mg/L; EC50: > 300 mg/L and EC80: > 300 mg/L

Executive summary:

The study was performed to estimate possible effects of"WASOX-VMAC2"on aerobic microbial sewage treatment plants. The test was performed according to the OECD Guideline for Testing of Chemicals 209 "Activated Sludge, Respiration Inhibition Test" and the EU-Commission Directive 87/302/EEC, using activated sludge from a sewage treatment plant treating predominantly domestic sewage.

Five concentrations of the test substance (7.6, 19.2, 48.0, 120.0 and 300.0 mg/L) were tested versus two negative controls (tap water).

As positive control substance 3,5-dichlorophenol was used and tested in three concentrations (4.9, 11.9 and 29.2 mg/L). The test results fulfilled the criteria for validity.

The following EC_values were obtained EC20: 189 mg/L; EC50: > 300 mg/L and EC80: > 300 mg/L.

Description of key information

The EC_values were obtained EC20: 189 mg/L; EC50: > 300 mg/L and EC80: > 300 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

300 mg/L

Additional information

The study was performed to estimate possible effects of "WASOX-VMAC2" on aerobic microbial sewage treatment plants.The test was performed according to the OECD Guideline for Testing of Chemicals 209 "Activated Sludge, Respiration Inhibition Test" and the EU-Commission Directive 87/302/EEC, using activated sludge from a sewage treatment plant treating predominantly domestic sewage.

Five concentrations of the test substance (7.6, 19.2, 48.0, 120.0 and 300.0 mg/L) were tested versus two negative controls (tap water).