Ethyl 3-[[bis(1-methylethoxy)phosphinothioyl]thio]propionate

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:

1988-11-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: non GLP (performed 1988), minor deviations from guideline, substance not dissolved but distributed in test medium

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

Instead of centrifuged sludge a settled sludge was used. Substance was tested at one concentration (100 mg/l) in duplicate samples. The substance was not dissolved but distributed in the test medium

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Preparation of inoculum for exposure: The sludge was separated from the aqueous layer by settling
- Initial biomass concentration: 1.7 g/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

20+/- 2°C

Nominal and measured concentrations:

nominal 100.5 and 125.0 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel:BOD-flask with gas inlet
- Type : closed
- Material, size, headspace, fill volume: 250 mL
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- No. of vessels per positive control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dechlorinated drinking water
-Nutrient solution:
16 g Peptone
11 g Meat extract
3.0 g Urea
0.7 g NaCl
0.4 g CaCl2 - 2 H2O
0.2 g MgSO4 - 7 H2O
2.8 g K2HPO4
per liter water

TEST CONCENTRATIONS
- Test concentrations: 100.5 and 125.0 mg/l

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

other: IC20

Effect conc.:

>= 100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

>= 100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: IC80

Effect conc.:

>= 100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The results from test item at 125 mg/mL was not considered in the IC calculation

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: IC50=10mg/mL

Substance	Concentration mg/L	Consumption rate mg/L/h	Inhibition %
Blank 1	0.0	64.62	0
Reference	32.0	8.73	86
Reference	10	28.38	56
Reference	3.2	57.00	12
Blank 2	0.0	64.62	0
Test item	100.5	55.86	14
Test item	125.0	65.33	-1

Validity criteria fulfilled:

yes

Conclusions:

Graphically determined: IC50≥ 100 mg/l

Description of key information

In an activated sludge, respiration inhibition test, the toxicity to microorganisms of the test item was determined according to OECD 209 over three hours. The IC50 value was determined to be greater than 100 mg/L.  

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

In an activated sludge, respiration inhibition test, the toxicity to microorganisms of the test item was determined according to OECD 209 over three hours. The test substance was tested in the nominal concentrations of 100.5 mg/L and 125.0 mg/L. The IC50 value was determined to be greater than 100 mg/L.