α,α'-propylenedinitrilodi-o-cresol

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:

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

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Activated sludge from laboratory wastewater plants treating municipal sewage
- Concentration of dry substance 1 g/L

PREPARATION OF INOCULUM
- Inoculum was washed, brought to a concentration of 5 g/L dry substance and aerated for ca. 24 h
- 50 ml were added to total volume of 250 ml to obtain concentration of 1 g/L dry substance in the test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

180 min

pH:

6.6 - 7.8

Dissolved oxygen:

7.2 - 8.7 mg O2/L

Nominal and measured concentrations:

Concentrations (mg/L): 1000, 500, 101, 50, 10 (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessels: Erlenmeyer-vessel (nominal volume 250 ml)
- Test volume: 250 ml
- Synthetic medium: 8 ml/vessel 100-fold concentrated OECD medium
- Test substance was added in required amount to test vessel with about 180 ml deionized water; mixture was stirred for 22 +/- 2 h to obtain optimal solution; then, inoculum and synthetic medium was added and test started

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

180 min

Dose descriptor:

other: EC20

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

180 min

Dose descriptor:

EC50

Effect conc.:

50 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.:

170 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

OXYGEN MEASUREMENTS
- Oxygen consumption rate (mg O2/L*6 min): 0.2 - 2.2
- Oxygen consumption rate (mg O2/L*h): 2 - 22
- Change in oxygen consumption rate compared with blank control (%): 0 - 91

Results with reference substance (positive control):

EC VALUES
- 180 min EC50 4.5 mg/L nominal test mat.

OXYGEN MEASUREMENTS
- Oxygen consumption rate (mg O2/L*6 min): 0.2 - 1.7
- Oxygen consumption rate (mg O2/L*h): 2 - 17
- Change in oxygen consumption rate compared with blank control (%): 23 - 91

Validity criteria fulfilled:

yes

Conclusions:

For ´α,α'-propylenedinitrilodi-o-cresol´ the influence on the respiration of microorganisms was investigated in a GLP guideline study according to OECD 209. The study was conducted with activated sludge from laboratory wastewater plants treating municipal sewage.

After 3 hours of incubation the EC20 was 18 mg/L and EC50 = 50 mg/l based on nominal concentration.

Description of key information

The influence of the substance on the respiration of microorganisms was investigated in a GLP guideline study according to OECD 209. The study was conducted with activated sludge from laboratory wastewater plants treating municipal sewage.

After 3 hours of incubation, the EC20 was 18 mg/l and the EC50 was 50 mg/l basedon nominal concentration.

Key value for chemical safety assessment

EC50 for microorganisms:

50 mg/L

EC10 or NOEC for microorganisms:

18 mg/L

Additional information

Depending on local conditions and existing concentrations, disturbances in the biodegradation process of activated sludge are possible.