Fatty acids, tall-oil, reaction products with pentaethylenehexamine

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:

2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP 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 of a predominantly domestic sewage

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant of Mannheim, Germany was collected on 10 Oct 2012 from the aeration tank of the plant. The activated sludge suspension was sieved with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over night at room temperature. At the next day the sludge suspension was washed once with drinking water and the suspension was adjusted to 3 g/L dry matter.

An aliquot of this suspension was added to the test vessels to obtain a sludge concentration of 1.5 g/L dry substance.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Details on test conditions:

Test concentrations:
1000, 500, 250, 125, 62.5 mg/L as nominal concentration based on test substance without correction of purity or composition.

Test replicates:
4 replicates for the Control
2 replicates for each test substance concentration
2 replicates for each reference substance concentration

Incubation time: 3 hours
Test temperature: 20.8 – 21.7 °C
Test vessels: Glas-beakers (nominal volume 1L)
Test volume: 500 mL
Synthetic medium: 16 mL/test vessel of 100-fold concentrated OECD medium
Oxygen concentration during aeration: > 2 mg/L
Oxygen concentration immediately before measurement: > 7 mg/L
Duration of the measurement of oxygen consumption: 8 - 10 min
Sludge concentration in the test vessel: 1.5 g/L

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

350 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

470 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

640 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):

The EC50 of 3,5-dichlorophenol is in the range of 2-25 mg/L

Validity criteria fulfilled:

yes

Description of key information

The inhibition of the degradation acitivity of activated sludge is not anticipated when introduced in appropriate low concentrations. 

Additional information

Toxicity to microorganisms was assessed in an OECD 209 guideline study according to GLP. The results are based on the loading rates due to uvcb character of the test substance. After 3 h of exposure, the EC50 of the test substance was calculated to be 470 mg/L. The low effect concentrations, EC10 and EC20 were calculated to be 300 mg/L and 350 mg/L, respectively.