cis-4-[3-(p-tert-butylphenyl)-2-methylpropyl]-2,6-dimethylmorpholine

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:

16.11. - 24.11.1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Specific details on test material used for the study:

Batch No: N 103, production date: 03/98
Purity: 96.6%

Analytical monitoring:

no

Details on test solutions:

The test substance was added in the required amount to the test vessel with about 180 ml deionized water.
The mixture was stirred for 22 ± 2 hours to obtain an optimal solution. Then synthetic medium was added , the pH-value was adjusted to 7.5 ± 0.5, the inoculum was added and the test started.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Activated sludge from laboratory wastewater plant treating municipal sewage. Concentration of dry substance 1 g/l.
- Preparation of inoculum for exposure: The inoculum was washed, brought to a concentration of 5 g/l dry substance and aerated for about 24 hours. 50 ml were added to a total volume of 250 ml to obtain a concentration of 1 g/l dry substance in the test.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

180 min

Test temperature:

20 ± 2 °C

pH:

7.5 ± 0.5

Dissolved oxygen:

> 6,5 mg/L

Nominal and measured concentrations:

nominal: 100, 500 and 1000 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer-vessel (nominal volume 250 ml)
- Test volume: 250 ml
- Aeration: Yes
- No. of vessels per control (replicates): 3

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

180 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

180 min

Dose descriptor:

other: EC80

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

180 min

Dose descriptor:

other: EC20

Effect conc.:

ca. 960 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The EC20 in the activated sludge respiration inhibition test is >100 mg/l. Disturbances in the biodegradation process of activated sludge are not to be expected if the test substance is correctIy introduced into adapted wastewater treatment plants at low concentrations.

Validity criteria fulfilled:

yes

Description of key information

For the test substance fenpropimorph the EC20 in the activated sludge respiration inhibition test is >100 mg/l, the EC50 is >1000 mg/l. Disturbances in the biodegradation process of activated sludge are not to be expected if the test substance is correctly introduced into adapted wastewater treatment plants at low concentrations.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The effects of test substance on aquatic microorganisms were investigated in a short-term respiration test similar to OECD 209 using activated domestic sludge. Based on nominal concentrations an EC20 (180 min) of 960 mg/L was determined.