Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23 Aug 2018- 24 August 2018
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
other: MEP, P.R. China, the Guidelines for the Testing of Chemicals, Effects on Biotic Systems (the Second Edition), No. 209 "Activated Sludge, Respiration Inhibition Test". (2013.8).
Version / remarks:
Second Edition
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
Version / remarks:
2010
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Boronic acid, B-(2-fluoro-3-methoxyphenyl)-
EC Number:
609-099-0
Cas Number:
352303-67-4
Molecular formula:
FC6H3(OCH3)B(OH)2
IUPAC Name:
Boronic acid, B-(2-fluoro-3-methoxyphenyl)-
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
Lot number: 18051400
Appearance: Off-white powder
Purity: 100.2%
Storage: Room temperature. 15-25°C. Container closed when not in use.

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
The activated sludge was derived from a treatment plant receiving predominantly domestic sewage. A fresh sample of activated sludge was collected from the aeration tank of Shenyang North Sewage Treatment Plant 1 day before the test was started.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
DOC for total respiration during 10 minutes measurement period after three hours.

Test conditions

Test temperature:
19.8 - 21.3 C
pH:
6.55- 7.33
Dissolved oxygen:
After 3 hrs, the concentration of dissolved oxygen was continuously measured and recorded for 10 minutes.
Nominal and measured concentrations:
In the preliminary test, the test concentrations included 10, 100, 300, 1000 mg/L. According to the result of the preliminary test, significant inhibition of oxygen consumption by the test substance was observed at the concentrations of 10- 1000 mg/L. Therefore, the definitive test was carried out at 6 nominal concentrations of 1, 4, 16, 63, 251 and 1000 mg/L with 5 replicates.
Details on test conditions:
The inoculums blank controls (FBT), reference item mixtures (FRT) and test item mixtures (FTT) were prepared. Each incubation was started in tum at intervals of about 15 minutes. The exposure was considered to begin with the initial contact of the activated sludge inoculum with the other constituents of the final mixture.

6 DO probes were used for the measurement of the dissolved oxygen, which facilitated multiple simultaneous measurements. Inoculum was added at the same time to 6 test vessels at each time interval.

After the exposure period of 3 hours, a sample from the first aeration vessel was transferred to the measuring cell, an oxygen probe with a sleeve adaptor was then inserted into the neck of the flask, and the magnetic stirrer was started, while the concentration of dissolved oxygen was immediately measured. The concentration of dissolved oxygen was continuously measured and recorded for 10 minutes.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol (3,5-DCP) was used as a reference item

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
47.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
3.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Results with reference substance (positive control):
Results with the reference substance: 3, 5 dichlorophenol EC50 (3 hours) in the definite test indicated 4.6 mg/l.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The validity criteria have been satisfied.
Conclusions:
Moderate concern for toxicity of micro organisms due to the reported EC50 (3 hrs) was found to be 47.9 mg/L (> 10mg/L (high concern) and < 100 mg/L (low concern))
Executive summary:

The  study was  conducted  to  determine  the  inhibition  effect  of FMPBA on micro-organisms  from  activated sludge (largely bacteria) by measuring  their total respiration rate. The contact time for exposure was 3 hours.


In the preliminary test, the test concentrations included 10,  100, 300, 1000 mg/L. The 10,  100, 300 mg/L concentrations were tested with 1   replicate,  1000 mg/L was tested  with  triplicate  and  an  abiotic  control  at  concentration  of 1000  mg/L  was performed. 


According to the result of the preliminary test, significant inhibition of oxygen consumption by the test substance was observed at the concentrations of 10-  1000 mg/L. Therefore, the definitive test was carried out at 6 concentrations of 1, 4, 16, 63, 251  and 1000 mg/L with 5 replicates.  Inoculums blank controls were performed with 6 replicates and prepared  at the beginning,  middle and end of the exposure period.


Results with the reference substance: 3, 5 dichlorophenol EC50 (3 hours) in the definite test indicated 4.6 mg/l.


Results with the test substance: FMPBA EC10 (3 hours) in the definite test indicated 3.9 mg/l and a EC50 of 47.9 mg/l.