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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Test Material: Terpenes and terpenoids, turpentine oil, alpha-pinene fraction oligomers
CAS 70750-57-1
Sample Ref: AN 672-79-21
Description: Extremely viscous pale amber coloured liquid
Batch: 0910002624
Purity: 100%
Expiry date: Indefinite
Storage Conditions: Room Temperature in the dark
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The test item was dispersed directly in water. Water used was deionized reverse osmosis water. They were subjected to ultrasonication for approx 15 minutes followed by magnetic stirring for 24 hours to maximise dissolved test item concentration. Synthetic sewage, activated sewage sludge and water were added, with a final test item concentration of 10 100 and 1000 mg/L
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Mixed population of activated sewage sludge microorganisms obtained from Severn Trent Water plc sewage treatment plant at Loughborough. Activated sewage sludge maintained on continuous aeration in the laboratory at 21°C. overnight prior to test. Activated sewage sludge was fed synthetic sewage sludge. pH on the day of the test was measured as 7.9.Suspended solids concentration was determined as 3.0 g/L prior to use.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
20 +- 2°C
pH:
pH of test item dipesions adjusted to pH 7.0 - 8.0
pH during test: 7.4 - 8.2
Nominal and measured concentrations:
Nominal concentrations: 10, 100 and 1000 mg/L
Details on test conditions:
Three replicates were used per test item concentration. The reference item, 3,5-dichlorophenol, was included at concentrations of 3.2, 10 and 32 mg/L. Two control vessels were prepared, then reference item vessels, test vessels and a further two control vessels. After 3 hours contact, an aliquot was removed from each flask and the rate of respiration measured. Rate of respiration was measured over the linear portion of the oxygen consumption trace (where possible between approx. 7.0 and 2.0 mg O2/L). In cases with rapid oxygen consumption measurements may be outside this range but oxygen consumption was always within the linear portion of the respiration curve.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
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
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
No statistically significant effects were shown at the test concentrations used in the range finder test and therefore no definitive test was codnucted.
Results with reference substance (positive control):
The EC50 for the reference substance was 10 mg/L.
Reported statistics and error estimates:
Dissolved oxygen concentrations after 30 minutes contact time were above 60 - 70% except in controls R1, R3 and R4 (48 - 58% saturation) and all test item vessels (44 - 52% saturation). Deviation is not considered to have affected the study adversely as oxygen consumption values were measured over the linear portion of the traces.
Validity criteria fulfilled:
yes
Remarks:
Initial and final dissolved O2 concs were sometimes outside those recommended in the guideline (7.0 mg O2/L and 2.0 mg O2/L). This is not believed to have affected the study results as O2 consumption was determined over the linear portion of the curve
Conclusions:
Terpenes and terpenoids, turpentine oil, alpha-pinene fraction oligomers was tested in an activated sludge respiration inhibition study. The 3-hour EC50 was >1000 mg/L and the NOEC was 1000 mg/L.
Executive summary:

A GLP-compliant study following OECD guideline 209 was conducted using the test material Terpenes and terpenoids, turpentine oil, alpha-pinene fraction oligomers.

The activate sludge was exposed to an aqueous dispersion of the test material at concentrations of 10, 100 and 1000 mg/L (3 replicates of the 100 mg/L test concentrations) for a period of 3 hours at a temperature of 20 +/- 2 °C with the addition of a synthetic sewage as a respiratory substrate. The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item.

The result of the study showed that the effect of the test item Terpenes and terpenoids, turpentine oil, alpha-pinene fraction oligomers on the respiration of activate sewage sludge was 3 -hour EC50 >1000 mg/L and the NOEC was 1000 mg/L.

Description of key information

A GLP-compliant study following OECD guideline 209 was conducted using the test material Terpenes and terpenoids, turpentine oil, alpha-pinene fraction oligomers.

The activate sludge was exposed to an aqueous dispersion of the test material at concentrations of 10, 100 and 1000 mg/L (3 replicates of the 100 mg/L test concentrations) for a period of 3 hours at a temperature of 20 +/- 2 °C with the addition of a synthetic sewage as a respiratory substrate. The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item.

The result of the study showed that the effect of the test item Terpenes and terpenoids, turpentine oil, alpha-pinene fraction oligomers on the respiration of activate sewage sludge was 3 -hour EC50 >1000 mg/L and the NOEC was 1000 mg/L.

Key value for chemical safety assessment

Additional information