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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
three hours contact time
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 (Carbon and Ammonium Oxidation))
GLP compliance:
yes
Specific details on test material used for the study:
Lot/Batch number: 20111104
Sponsor: Victrex Manufacturing Ltd
Date of receipt: 01 June 2017
Expiry date: 31 December 2017
Percentage composition and CAS no: Purity => 99.5%. CAS # 611-99-4
Vehicle:
no
Details on test solutions:
Since the test substance was of limited solubility concentrations of 10, 32, 100, 320 and 1000mg/l were prepared by direct addition into the test vessels.
The pH was measured on the day prior to the definitive test in sacrificial beakers (containing test material, sewage feed and high purity deionised water but without sludge inoculum). Values of 7.41, 7.40, 7.40, 7.39 and 7.39 were recorded for 10, 32, 100, 320 and 1000mg/l respectively.
Test organisms (species):
activated sludge
Details on inoculum:
The day before the test, activated sludge was taken from an aeration tank of Cambridge Sewage Treatment Works (STW), Cowley Road, Cambridge, UK..
The sludge was sieved using an 850μm sieve and centrifuged at about 4000rpm for about ten minutes. The supernatant was discarded and the sludge was resuspended in dechlorinated tap water and re-centrifuged. This stage was repeated once more. After discarding the supernatant the sludge solids were homogenised thoroughly by mechanical stirring (spoon).
Test type:
static
Water media type:
other: High purity deionised water
Total exposure duration:
3 h
Test temperature:
Required temperature: 20 ± 2°C
Actual temperature: 21.4– 21.5°C (preliminary test), 21.8 – 21.9°C (definitive)
Reference substance (positive control):
yes
Remarks:
A 1g/l stock of 3,5-Dichlorophenol was prepared in dilution water.
Key result
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
54 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat. (total fraction)
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
162 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat. (total fraction)
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
other: EC80
Effect conc.:
602 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat. (total fraction)
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (total fraction)
Basis for effect:
inhibition of total respiration
Details on results:
ECx values calculated by linear interpolation in ToxCalc™ Version 5.0, 95% confidence limits are shown here
4,4-Dihydroxybenzophenone; EC20 = 54 (48-60), EC50 = 162 (143-176), EC80 = 602 (480-674)
Results with reference substance (positive control):
3,5-DCP (Reference) EC20 = 0.98 (0.87-1.18), EC50= 3.59 (2.90-4.69), EC80 = 17.54
Validity criteria fulfilled:
yes
Conclusions:
The study was conducted according to the test guideline. In the preliminary test, 4,4-Dihydroxybenzophenone exhibited respiration inhibition and a dose response was observed. 4,4-Dihydroxybenzophenone also demonstrated no abiotic response.
The 3-hour EC50 of 4,4-Dihydroxybenzophenone to activated sludge respiration inhibition was determined to be 162mg/l with 95% confidence limits of (143-176mg/l) during the definitive test.
The NOEC for 4,4-Dihydroxybenzophenone was determined to be 10mg/l.
As there was no significant oxygen uptake in the preliminary test abiotic controls were not performed in the definitive test.

Description of key information

The study was conducted according to the test guideline. In the preliminary test, 4,4-Dihydroxybenzophenone exhibited respiration inhibition and a dose response was observed. 4,4-Dihydroxybenzophenone also demonstrated no abiotic response.

The 3-hour EC50 of 4,4-Dihydroxybenzophenone to activated sludge respiration inhibition was determined to be 162mg/l with 95% confidence limits of (143-176mg/l) during the definitive test.

The NOEC for 4,4-Dihydroxybenzophenone was determined to be 10mg/l.

As there was no significant oxygen uptake in the preliminary test abiotic controls were not performed in the definitive test.

Key value for chemical safety assessment

EC50 for microorganisms:
162 mg/L
EC10 or NOEC for microorganisms:
10 mg/L

Additional information