Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Batch number : 0900250090
Date of receipt : 2017-02-06
Expiry date : 2018-01-20
Water solubility : 7.398 g/L
Analytical monitoring:
no
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Type : mixed population of aquatic microorganisms (activated sludge)
Origin : aeration tank of a domestic waste water treatment plant (Municipal WWTP Cologne-Stammheim)
Date of collection : 2017-07-17
Microbial inoculum : The sludge was settled and the supernatant was decanted. After centrifuging the sludge (15 min at 3500 rpm and 20°C) the supernatant was decanted again. Approximately 1 g of the wet sludge was dried in order to calculate the amount of wet sludge to achieve a concentration of activated sludge of 3 g/L (dry weight) suspended solids. The calculated amount of sludge was dissolved in synthetic medium and then filled up to a defined end volume with deionised water.
Storage of sludge : aeration of the activated sludge at 20 ± 2 °C, daily fed with synthetic medium
pH of the suspension before application : 7.5
Test type:
other: rapid screening method whereby substances which may adversely affect aerobic microbial treatment plants can be identified and to indicate suitable non-inhibitory concentrations of test items to be used in biodegradability tests
Water media type:
other: deionised water
Limit test:
yes
Total exposure duration:
3 h
Remarks on exposure duration:
Stirring period of the test item before start of incubation time: 17 hours, Incubation time: 3 hours with permanent aeration
Test temperature:
20 ± 2 °C
pH:
7.4 - 8.5
Nominal and measured concentrations:
Test item concentration: 100 mg/L, 3 replicates
100 mg/L with ATU, 2 replicates
Details on test conditions:
To measure the oxygen consumption, 250 mL of sludge with the test item (or control or reference compound) was incubated for 3 h in 300 mL closed Erlenmeyer flasks (with air inlet and outlet) and aerated through a glass tube at 50-100 L/h with clean oil-free air. For the measurement, the content of the Erlenmeyer flasks was completely transferred to 250 mL BOD bottles and oxygen content was measured with an oxygen meter (redox electrode).
Six controls without the test item were included in the test design, three at the start and the others at the end of the test series.
A limit test was performed with 3 replicates with a test item concentration of 100 mg/L. Each batch of activated sludge was checked using 5 concentrations in the range of 2.5 – 40 mg/L of 3,5-Dichlorophenol as a reference compound.
The oxygen uptake rates of four additional controls and two replicates of the test item concentration 100 mg/L, all in the presence of N-allylthiourea, were prepared and measured after the exposure period. These values represent the heterotrophic respiration.
Since some substances may consume oxygen by chemical reactivity, a physico-chemical oxygen consumption control was carried out additionally. In order to be able to differentiate between physico-chemical oxygen consumption and biological oxygen consumption (respiration), at least the maximum concentration of the test item was tested without activated sludge.

Exposure conditions
Test item concentration/s : 100 mg/L, 3 replicates
100 mg/L with ATU, 2 replicates
Control : 6 replicates
4 replicates with ATU
Test item concentration in physico-chemical oxygen consumption control : 100 mg/L
Concentration of reference compound 3,5-Dichlorophenol : 2.5, 5, 10, 20 and 40 mg/L
Test vessels : 300 mL glass Erlenmeyer flasks
Method of application : direct weighing
Test concentration of the activated sludge : 1200 mg/L suspended solids
Test temperature : 20 ± 2°C
Stirring period of the test item before start of incubation time : 17 hours
Incubation time : 3 hours with permanent aeration
Reference substance (positive control):
yes
Remarks:
Reference compound : 3,5-Dichlorophenol (Acros Organics), Purity : 99.9 %, Expiry date : 2020-03-24
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks on result:
other: At a test item concentration of 100 mg/L
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks on result:
other: At a test item concentration of 100 mg/L
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks on result:
other: At a test item concentration of 100 mg/L
Details on results:
As no inhibition was observed for the total oxygen consumption at 100 mg/L no differences between the heterotrophic and the nitrification oxygen uptake rates have to be calculated.
Reported statistics and error estimates:
The No Observed Effect Concentration was calculated according to STUDENT-t test for Homogeneous Variances using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10). The EC50 value for the reference substance was calculated from the respiration rates at different test item concentrations using the same statistics programme
Validity criteria fulfilled:
yes
Remarks:
Oxygen uptake rate is 36.825mg oxygen per one gram of activated sludge (dry weight of suspended solids) in an hour; Coefficient of variation of oxygen uptake in the control replicates was 3.8%; EC50 of reference compound was 18.167mg/L; Thus test is valid
Conclusions:
Resorcindiacetat showed 0.0 % respiration inhibition of activated sludge at a test item concentration of 100 mg/L with a EC50 value higher than 100 mg/L.
Executive summary:

A study was performed to assess the toxicity of Resorcindiacetat to bacteria. The study was conducted in accordance with OECD Guideline 209. The activated sludge was exposed to Resorcindiacetat at a limit test item concentration of 100 mg/L. The respiration rate of each mixture was determined after aeration periods of 3 hours. Resorcindiacetat showed 0.0 % respiration inhibition of activated sludge at a test item concentration of 100 mg/L. The EC50 is higher than 100 mg/L. The NOEC is equal or higher than 100 mg/L.

The effect value relates to a nominal concentration, since no analytical monitoring was performed.

Description of key information

Resorcindiacetat showed 0.0 % respiration inhibition of activated sludge at a test item concentration of 100 mg/L with a EC50 value higher than 100 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
100 mg/L
EC10 or NOEC for microorganisms:
100 mg/L

Additional information