Registration Dossier

Diss Factsheets

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 Jan 2019 - 05 Feb 2019
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes

Test material

1
Chemical structure
Reference substance name:
cis-N-methyl-N-(1H-pyrrolo[2,3-d]pyrimidin-4-yl)cyclobutane-1,3-diamine phosphate (1:1)
EC Number:
951-920-2
Molecular formula:
C11H15N5* H3PO4
IUPAC Name:
cis-N-methyl-N-(1H-pyrrolo[2,3-d]pyrimidin-4-yl)cyclobutane-1,3-diamine phosphate (1:1)
Specific details on test material used for the study:
Batch (Lot) Number: GR13472
Expiry date: 31 March 2020 (expiry date)
Physical Description: White to off-white solid
Purity/Composition: 100%
Storage Conditions: At room temperature

Test solutions

Vehicle:
no
Details on test solutions:
100, 180, 320, 560 and 1000 mg/L

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h

Test conditions

Test temperature:
Between 19.9 and 23.3°C
pH:
7.2 average. The pH in all test vessels, before addition of sludge, was between 6.5 and 7.7. After the 3 hour exposure period the pH was between 6.9 and 7.8.
Details on test conditions:
During the test, and was slightly outside the range prescribed by the Study Plan (20 ± 2°C)
Reference substance (positive control):
yes

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
ca. 222 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
ca. 180 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
The combined limit/range-finding showed no inhibition of the respiration rate at a concentration of 10 and 100 mg/ L. Mean inhibition of the respiration rate observed at 1000 mg/L was 42%. Therefore, the expected EC50 was above 1000 mg/L. Since the inhibition of the respiration rate observed at 1000 mg/L was statistically significant, a full test was performed to determine the NOEC.
The effects observed in the final test for determination of the NOEC were slightly lower then what was expected based on the results of the combined limit/range-finding test. The results of this test allowed for reliable determination of a NOEC and ECx values. No statistically significant inhibition of the respiration rate of the sludge was recorded at or below 180 mgPF-03817968-09 per liter. At higher concentrations the inhibitory effect ofPF-03817968-09 on aerobic waste water
(activated sludge) bacteria increased with increasing concentration, ranging from 12% inhibition at 320 mg/L to 25% at 1000 mg/L
Results with reference substance (positive control):
The batch of activated sludge was checked for sensitivity by testing the reference item 3,5-dichlorophenol. The EC50 of 3,5-dichlorophenol was in the accepted range of 2 to 25 mg/L for total respiration (3.6 mg/L in the final test)

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In conclusion, under the conditions of the present test PF-03817968-09 was not toxic to waste water bacteria (activated sludge) at or below a concentration of 180 mg/L (NOEC).
The EC10 was 222 mg/L (95% confidence interval: 144 - 344 mg/L).
The EC20 was 679 mg/L (95% confidence interval: 509 - 907 mg/L).
The EC50 was above 1000 mg/L.
Executive summary:

The objective of the study was to evaluate PF-03817968-09 for its ability to adversely affect aerobic microbial treatment plants and, if possible, to determine the EC50 and/or the no - observed effect concentration (NOEC). The influence of PF-03817968-09 on the respiration rate of activated sludge was investigated after a contact time of 3 hours. The study procedures described in this report were based on the OECD guideline No. 209, 2010. The batch ofPF-03817968-09 tested was a white to off-white solid with a purity of 100%. No correction was made for the purity/composition of the test item. The test item was not sufficiently soluble to allow preparation of an aqueous solution at a concentration of 10 g/L. Therefore, weighed amounts were added to the test bottles containing Milli-ROwater. The test item – Milli-ROwater mixtures were magnetically stirred for a short period. Subsequently, synthetic medium, sludge and Milli- ROwater were added, resulting in the required concentrations. Optimal contact between the test item and test medium was ensured by applying continuous aeration and stirring during the 3 hour exposure period. Thereafter, oxygen consumption was recorded for approximately 10 minutes. The final test was performed based on the result of a preceding combined limit/range-finding test. Five concentrations were tested, ranging from 100 to 1000 mg/L and increasing with a factor 1.8. Five replicates per concentration and six replicates for an untreated control group were tested. No statistically significant inhibition of the respiration rate of the sludge was recorded at or below 180 mgPF-03817968-09 per liter. At higher concentrations the inhibitory effect of PF-03817968-09 on aerobic waste water (activated sludge) bacteria increased with increasing concentration, ranging from 12% inhibition at 320 mg/L to 25% at 1000 mg/L. The batch of activated sludge was tested for sensitivity with the reference item 3,5-dichlorophenol, and showed normal sensitivity. The study met the acceptability criteria prescribed by the Study Plan and was considered valid. PF-03817968-09 was not toxic to waste water (activated sludge) bacteria at a concentration of 180 mg/L (NOEC).