4-Methanesulfonyl-2-(trifluoromethyl)benzaldehyde

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 2016 - Feb 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Test guideline 3

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-methanesulfonyl-2-(trifluoromethyl)benzaldehyde

EC Number:

812-681-9

Cas Number:

1215310-75-0

Molecular formula:

C9H7F3O3S

IUPAC Name:

4-methanesulfonyl-2-(trifluoromethyl)benzaldehyde

Test material form:

solid: particulate/powder

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

After the 3-hour contact time, the oxygen consumption was
recorded for a period of approximately 10 minutes. During
measurement, the sample was not aerated but continuously
stirred on a magnetic stirrer.
The pH was determined in the remaining part of the reaction
mixture. This procedure was repeated for all test/reference item
concentrations and blank controls.
The medium temperature was recorded continuously in a
temperature control vessel(s). The temperature control vessel(s)
was/were identically prepared compared to the blank control
vessels. A temperature control vessel with a REES sensor was
placed in each fume cupboard of the climate room.
Oxygen recording Determination of oxygen was performed with multiple oxygen
probes connected to a BlueBox (GO-Systemelektronik GmbH,
Germany), a multichannel measuring and controlling system.

Test solutions

Vehicle:

yes

Remarks:

Milli-RO water

Details on test solutions:

The batch of QAW039-C2 tested was a yellowish powder with a purity of 99.7%. No
correction was made for the purity/composition of the test item.
The test item was not sufficiently soluble to allow the preparation of a 10 g/L stock solution
in water. Therefore, 1 litre test bottles were filled with 200 mL of test item mixtures in Milli-
RO water (tap water purified by reverse osmosis; Millipore Corp., Bedford, Mass., USA)
with initial loading rates of 2.5 times the final loading rate. These mixtures were stirred in
closed dark brown bottles for approximately 24 hours. Subsequently, 16 mL synthetic
medium made up to 50 mL with Milli-RO water and 250 mL sludge were added resulting in
the required loading rates. Optimal contact between the test item and
test organisms was ensured applying continuous aeration and stirring.

In a combined limit/range-finding test loading rates of 10, 100 and 1000 mg/L were tested.
The highest loading rate was tested in triplicate, lower loading rates consisted of one
replicate. In addition, a blank control (6 replicates) and an abiotic control (1 replicate) were
tested.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The sludge was coarsely sieved (1 mm) and allowed to settle. The supernatant was removed and ISO-medium was added. A small amount of the sludge was weighed and dried overnight at ca. 105°C to determine the amount of suspended solids (3.0 g/L of sludge, as used for the test). The batch of sludge was used one day after collection; therefore 50 mL of synthetic medium (=sewage feed) was added per litre of activated sludge at the
end of the collection day. The sludge was kept aerated at test temperature until use. The pH was 5.9 on the day of testing.
The sludge was buffered to a pH of 7.1 using a 70 g/L sodium bicarbonate solution. Before the sludge was used the respiration
rate of the sludge was determined to verify the quality of the sludge. The respiration rate was in agreement with the validity criteria.

Adjusted ISO-medium, formulated using RO-water (tap water purified by reverse osmosis; GEON Waterbehandeling, Berkel-
Enschot, The Netherlands) with the following composition:
CaCl2.2H2O 211.5 mg/L
MgSO4.7H2O 88.8 mg/L
NaHCO3 46.7 mg/L
KCl 4.2 mg/L

Study design

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test conditions

Test temperature:

20 and 22°C

pH:

7.1 and 8.1

Nominal and measured concentrations:

The combined limit/range-finding test showed 8, 8 and an average of 44% inhibition of the respiration rate at a loading rate of 10, 100 and 1000 mg/L, respectively. The inhibition observed at 1000 mg/L was statistically significant; the EC50 was determined to be higher than 1000 mg/L. There was no significant oxygen uptake from abiotic processes.

Details on test conditions:

Contact time 3 hours, during which aeration and stirring took place.
Vessels All glass open bottles/vessels.
Milli-RO water Tap water purified by reverse osmosis (Millipore Corp., Bedford, Mass., USA).
Synthetic medium 16 g peptone
(=sewage feed) 11 g meat extract
3 g urea
0.7 g NaCl
0.4 g CaCl2.2H2O
0.2 g MgSO4.7H2O
2.8 g K2HPO4
Dissolved in Milli-RO water, made up to 1 litre and filtered. The pH was within 7.5 ± 0.5.
Air supply Clean, oil-free air.
Aeration The aeration was adjusted in such a way that the dissolved oxygen concentration at the start was above 60-70% saturation
(60% of air saturation is > 5 mg/L at 20°C) and to maintain the sludge flocs in suspension.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this present test the EC50 of QAW039-C2 was determined to be above 1000 mg/L.