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EC number: - | CAS number: -
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
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- Endpoint summary
- Stability
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- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
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- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
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- Repeated dose toxicity
- Genetic toxicity
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- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
![](https://poisoncentres.echa.europa.eu/o/diss-blank-theme/images/factsheets/A-REACH/factsheet/print_ecotoxicological-information.png)
Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
- Endpoint:
- activated sludge respiration inhibition testing
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Remarks:
- experimental data of read across substances
- Justification for type of information:
- Data for the target chemical is summarized based on the read across chemicals
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Qualifier:
- according to guideline
- Guideline:
- other: as mentioned below
- Principles of method if other than guideline:
- WoE report is based on two toxicity to microorganism studies as-
WoE 2 and WoE 3. - GLP compliance:
- not specified
- Analytical monitoring:
- no
- Details on sampling:
- WoE 2 and WoE 3:
- Concentrations: 10, 100, 1000 mg/L
- Sampling method: The measurement of the respiration rate in a well-mixed aerated sample of each treatment was performed after exactly 3 hours incubation time. The treatment sample was not further aerated. The oxygen concentration was measured with O2 electrode (working based on LDO method) under stirred conditions and was recorded for about 5.5 - 10 minutes. The measurement was carried out in completely filled Winkler bottles. For practical reason more O2 electrode were used. Simultaneous (a maximum of four vessels were investigated in parallel) measurements were performed; the test vessels were investigated in 6 cycles with the available four O2 electrodes. The oxygen consumption rate (in mg O2/L/hour) was determined from the linear part of the respiration curve (in the range between approximately 2 - 7 mg O2/L).
- Sample storage conditions before analysis: no data - Vehicle:
- no
- Details on test solutions:
- WoE 2 and WoE 3:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: At the start of the test defined amounts of test item (1 x 3 mg; 1 x 30 mg and 3 x 300 mg, that correspond to 10, 100 and 1000 mg test item/L concentrations) were directly weighed (administered) into each test flask (empty containers that were filled up to a final volume of 300 mL with water and synthetic sewage, just before the inoculation). The subsequent calculations refer to the initial weighed nominal concentration. Concentrations in excess of nominal 1000 mg test item/L were not tested.
- Eluate: Distilled water
- Differential loading: no
- Controls: Two controls containing only tap water, synthetic sewage feed and inoculum were tested in parallel to single test concentration of the test item under identical test conditions. - Test organisms (species):
- activated sludge of a predominantly domestic sewage
- Details on inoculum:
- WoE 2:
- Laboratory culture: The (controlled) activated sludge was supplied by the sewage plant for domestic sewage in Balatonfüred, Hungary
- Method of cultivation: the activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in isotonic saline solution with shaking and again centrifuged. This procedure was repeated twice.
- Preparation of inoculum for exposure: An aliquot of the final sludge suspension was weighed (6.004 g wet weight), dried and the ratio of wet sludge to dry weight (0.4984 g dry weight) determined. Based on this ratio, calculated amount of wet sludge (24 g dry weight that was equivalent to 289 g wet sludge) was suspended in isotonic saline solution (ad. 8 L) to yield a concentration equivalent to about 3 g/L (on dry weight basis).
(In the test containers (300 mL final volume) the final concentration of suspended solids, containing 150 mL inoculum was 1.5 g per litre on dry weight basis.)
The above concentration calculation accounts for the dilution resulting from feeding with synthetic sewage.
The activated sludge was not used on the day of the collection, but continuously aerated (2 L/minute) at the test temperature (20 ± 2 °C) for about 24 hours (one day) and fed with 50 mL synthetic sewage/L activated sludge.
The pH of the activated sludge inoculum was checked after preparation (pH: 7.38). pH adjustment of the inoculum was considered not necessary
- Pretreatment: none
WoE 3:
- Laboratory culture: The (controlled) activated sludge was supplied by the sewage plant for domestic sewage in Balatonfüred, Hungary
- Method of cultivation: The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The coarse particles were removed by settling for 10 minutes, and the upper layer of finer solids was decanted. The solid material was re-suspended in isotonic saline solution with shaking and again centrifuged. This procedure was repeated twice.
- Preparation of inoculum for exposure: An aliquot of the final sludge suspension was weighed (6.004 g wet weight), dried and the ratio of wet sludge to dry weight (0.4984 g dry weight) determined. Based on this ratio, calculated amount of wet sludge (24 g dry weight that was equivalent to 289 g wet sludge) was suspended in isotonic saline solution (ad. 8 L) to yield a concentration equivalent to about 3 g/L (on dry weight basis). (In the test containers (300 mL final volume) the final concentration of suspended solids, containing 150 mL inoculum was 1.5 g per litre on dry weight basis). The above concentration calculation accounts for the dilution resulting from feeding with synthetic sewage.
The activated sludge was not used on the day of the collection, but continuously aerated (2 L/minute) at the test temperature (20 ± 2 °C) for about 24 hours (one day) and fed with 50 mL synthetic sewage/L activated sludge.
The pH of the activated sludge inoculum was checked after preparation (pH: 7.38). pH adjustment of the inoculum was considered not necessary.
- Pretreatment: none
- Initial biomass concentration: no data - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 3 h
- Test temperature:
- WoE 2: 18.0 - 22.0 °C
WoE 3: 20.1 - 21.0 °C - pH:
- WoE 2: 7.29 - 10.25
WoE 3: 7 - 8 - Dissolved oxygen:
- WoE 2: 7 - 8.60 mg O2/L
WoE 3: 2 - 7 mg O2/L - Nominal and measured concentrations:
- WoE 2 and WoE 3: Nominal concentrations of 10, 100 and 1000 mg/L
- Details on test conditions:
- WoE 2 and WoE 3:
TEST SYSTEM
- Test vessel: Erlenmeyer bottles
- Material, size, headspace, fill volume: Erlenmeyer bottles of approximately 300 mL volume
- Aeration: With compressed air (0.5 litre per minute)
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 1
- No. of vessels per vehicle control (replicates): 1
- No. of vessels per abiotic control (replicates): 1
- Nitrification inhibitor used: N-allylthiourea
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to test guideline
OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: no data
- Light intensity: no data
EFFECT PARAMETERS MEASURED: The respiration rates (total, heterotrophic and nitrification oxygen uptake rates)
TEST CONCENTRATIONS
- Test concentrations: 10, 100 and 1000 mg/L - Reference substance (positive control):
- yes
- Remarks:
- 3,5-dichlorophenol
- Key result
- Duration:
- 3 h
- Dose descriptor:
- NOEC
- Effect conc.:
- ca. 1 000 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: inhibition of oxygen consumption
- 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:
- other: inhibition of oxygen consumption
- Results with reference substance (positive control):
- - Results with reference substance valid? Yes
- Relevant effect levels: The 3-hour EC50 of 3,5-Dichlorophenol was calculated to be 10.16 mg/L, (95 % confidence limits: 8.60 – 12.11 mg/L). - Validity criteria fulfilled:
- not specified
- Conclusions:
- On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the 3 hr NOEC and EC50 value can be expected to be 1000 mg/l and < 1000 mg/l.
- Executive summary:
Data available of the read across chemicals has been reviewed to determine the effect of the test chemical on toxicity to microorganisms. The studies are as mentioned below:
In a 3-hour pre-test test according to OECD 209 the influence of the test item on the activity of the activated sludge was evaluated by measuring the respiration rate under defined conditions. The respiration rates (total, heterotrophic and nitrification oxygen uptake rates) of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. This pre-test was used to estimate the range of concentrations of the test item needed in a possible definite test for determining the inhibition of oxygen consumption. The test item was investigated in this study at the nominal concentrations of 10, 100 and 1000 mg/L. Defined amounts of the test item were added directly into the test vessels. Triplicate vessels were prepared and investigated at the highest examined test item concentration. In parallel with the test item treatments 3,5-dichlorophenol as positive reference control in concentrations of 2, 7 and 24.5 mg/L; furthermore blank (inoculum) control, nitrification controls and abiotic controls were investigated. The test was performed without pH adjustment. All validity criteria of the study were met. The observed oxygen consumption rates consequently the specific respiration rates were in the range of the blank controls, no inhibitory effect was noticed at 10 and 100 mg/L (the observed slight, 0.18 and 3.70 % inhibitions were considered as being within the biological variability of the applied test system), but the inhibition was in average 86.16 % at 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate. The test was performed including abiotic controls. The abiotic controls were investigated at the test item concentration of 1000 mg/L and no remarkable abiotic oxygen consumption was noticed. The test item had unequivocal influence on the pH at the concentrations of 100 and 1000 mg/L. Before inoculum addition the pH of the test item containing test mixtures at these concentration levels was above the acceptable pH 7 - 8 range. Based on measured oxygen consumption values and calculated specific respiration rates, unequivocal test item effect was established at the highest examined concentration of 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate; however the 3-hour EC50 values of the test item is < 1000 mg/L. Due to the statistically significant differences (2-Sample T-test (α=0.05)) in the comparison with the blank control and 1000 mg/L concentration values exact NOEC value could not be determined. During the performance of the pre-experiment unequivocal, significant test item effect on the pH was realized especially at the concentrations of 100 and 1000 mg/L. In conclusion, these pre-test results demonstrate the significant inhibition of oxygen consumption by the test substance in the examined concentration range; therefore, a definite test with parallel test series (with and without pH adjustment) was considered as necessary. The definite test will be performed under a new study code; the concentration levels to be examined in the definite test will be based on the results of the present pre-experiment.
In a another study, a 3-hour pre-test according to OECD 209 the influence of the test item on the activity of the activated sludge was evaluated by measuring the respiration rate under defined conditions. The respiration rates (total, heterotrophic and nitrification oxygen uptake rates) of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. This pre-test was used to estimate the range of concentrations of the test item needed in a possible definite test for determining the inhibition of oxygen consumption. The test item was investigated in this study at the nominal concentrations of 10, 100 and 1000 mg/L. Defined amounts of the test item were added directly into the test vessels. Triplicate vessels were prepared and investigated at the highest examined test item concentration. In parallel with the test item treatments 3,5-dichlorophenol as positive reference control in concentrations of 2, 7 and 24.5 mg/L; furthermore blank (inoculum) control, nitrification controls and abiotic controls were investigated. The test was performed without pH adjustment. All validity criteria of the study were met. The observed oxygen consumption rates consequently the specific respiration rates were in the range of the blank controls, no inhibitory effect was noticed at 10 and 100 mg/L (the observed 5.26 and 3.31 % inhibitions were considered as being within the biological variability of the applied test system), but the inhibition was in average 85.90 % at 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate. The test was performed including abiotic controls. The abiotic controls were investigated at the test item concentration of 1000 mg/L and no remarkable abiotic oxygen consumption was noticed. The test item had influence on the pH in all examined concentration levels. Before inoculum addition the pH of the test item containing test mixtures was above the acceptable pH 7 - 8 range. The examined concentrations covered the appropriate inhibition range for EC10, EC50 and EC80 calculations. The EC10 was calculated as 241 mg/kg soil dry weight, the EC50 was calculated as 654 mg/kg soil dry weight and the EC80 value was calculated as 926 mg/kg soil dry weight. The above ECx values will be further refined in the definite test. The EC50 value was determined as: EC50 < 1000 mg/L. Based on measured oxygen consumption values and calculated specific respiration rates, strong test item effect was established at the highest examined concentration of 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate; however the 3-hour EC50 values of the test item is < 1000 mg/L. Due to the statistically significant differences (2-Sample T-test (α=0.05)) in the comparison with the blank control and 1000 mg/L concentration values exact NOEC value could not be determined. During the performance of the pre-experiment significant test item effect on the pH was realized in whole examined concentration range of 10 - 1000 mg/L. In conclusion, these pre-test results demonstrate the significant inhibition of oxygen consumption by the test substance in the examined concentration range; therefore, a definite test with parallel test series (with and without pH adjustment) was considered as necessary. The definite test will be performed under a new study code; the concentration levels to be examined in the definite test will be based on the results of the present pre-experiment.
On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the 3 hr NOEC and EC50 value can be expected to be 1000 mg/l and < 1000 mg/l.
Reference
WoE 2:
Table 1: The Oxygen Concentrations and pH Values in the Test Item Treatment Groups and Controls
Identifi-cation |
Concentration (mg/L) |
Oxygen concentration (mg O2/L) |
pH |
|||
Start of the 3-hour aeration |
End of the 3-hour aeration |
Before the addition of inoculum |
Start of the 3-hour aeration |
End of the 3-hour aeration |
||
CBA |
0.00 |
7.65 |
7.02 |
7.40 |
7.55 |
8.16 |
CBB |
|
7.64 |
7.47 |
7.37 |
7.59 |
8.14 |
CBC |
|
7.71 |
7.64 |
7.36 |
7.60 |
8.14 |
CBD |
|
7.77 |
7.69 |
7.37 |
7.57 |
8.15 |
CBE |
|
8.29 |
7.44 |
7.54 |
7.46 |
7.76 |
CBF |
|
8.36 |
7.27 |
7.54 |
7.66 |
8.12 |
CBG |
|
8.18 |
7.15 |
7.54 |
7.76 |
8.16 |
CBH |
|
8.39 |
7.28 |
7.55 |
7.80 |
8.12 |
CNA |
11.6 mg ATU/L |
8.40 |
7.62 |
7.46 |
7.65 |
8.21 |
CNB |
|
8.20 |
7.09 |
7.59 |
7.84 |
8.13 |
R1 |
2 mg 3,5-DCP/L |
8.23 |
7.28 |
7.31 |
7.66 |
7.93 |
R2 |
7 mg 3,5-DCP/L |
8.08 |
7.00 |
7.36 |
7.59 |
7.93 |
R3 |
24.5 mg 3,5-DCP/L |
8.21 |
7.99 |
7.29 |
7.58 |
7.93 |
T1 |
10 mg Test Item/L |
8.47 |
7.42 |
7.47 |
8.13 |
8.12 |
T2 |
100 mg Test Item/L |
8.13 |
7.06 |
8.75 |
8.51 |
8.27 |
T3/A |
1000 mg Test Item/L |
8.21 |
8.25 |
10.24 |
9.64 |
9.13 |
T3/B |
|
8.09 |
8.54 |
10.27 |
9.68 |
9.18 |
T3/C |
|
8.32 |
8.57 |
10.35 |
9.69 |
9.20 |
CAA |
1000 mg Test Item/L |
8.61 |
8.54 |
- * |
10.28 |
9.73 |
CAB |
|
8.50 |
8.23 |
- * |
10.29 |
9.77 |
CAC |
|
8.43 |
8.62 |
- * |
10.30 |
9.68 |
3,5-DCP: 3,5-dichlorophenol
ATU: N-allylthiourea
Remarks: * At the Abiotic controls no inoculum was added; therefore, one pH measurement was carried out at the start of the test.
Table 2: The Q1, Q2 and the applied Δt values in the Test Item Treatment and Control Groups; the Oxygen Consumption Rate (R), and % Inhibition of R
Identifi-cation |
Concentration (mg/L) |
Oxygen concentration (mg O2/L) |
Δt (min) |
Oxygen Consumption Rate (R) (mg O2/Lh) |
Average R (mg O2/Lh) |
Inhibition of R (%) |
||||||
Q1 |
Q2 |
|||||||||||
CBA |
0.00 |
7.02 |
2.25 |
5.5 |
52.04 |
46.68 |
0.00 |
|||||
CBB |
7.04 |
2.19 |
6 |
48.50 |
|
|
||||||
CBC |
7.22 |
2.03 |
6.5 |
47.91 |
|
|
||||||
CBD |
7.30 |
2.27 |
6.5 |
46.43 |
|
|
||||||
CBE |
7.02 |
2.35 |
5.5 |
50.95 |
|
|
||||||
CBF |
7.27 |
2.04 |
7.5 |
41.84 |
|
|
||||||
CBG |
7.15 |
2.27 |
7 |
41.83 |
|
|
||||||
CBH |
7.28 |
2.15 |
7 |
43.97 |
|
|
||||||
CNA |
11.6 mg ATU/L |
7.21 |
2.35 |
6 |
48.60 |
47.80 |
-2.39 |
|||||
CNB |
7.09 |
2.39 |
6 |
47.00 |
|
|
||||||
R1 |
2 mg 3,5-DCP/L |
7.28 |
2.09 |
7 |
44.49 |
44.49 |
4.71 |
|||||
R2 |
7 mg 3,5-DCP/L |
7.00 |
2.14 |
9.5 |
30.69 |
30.69 |
34.25 |
|||||
R3 |
24.5 mg 3,5-DCP/L |
7.99 |
6.62 |
10 |
8.22 |
8.22 |
82.39 |
|||||
T1 |
10 mg Test Item/L |
7.02 |
2.36 |
6 |
46.60 |
46.60 |
0.18 |
|||||
T2 |
100 mg Test Item/L |
7.06 |
2.19 |
6.5 |
44.95 |
44.95 |
3.70 |
|||||
T3/A |
1000 mg Test Item/L |
8.25 |
7.21 |
10 |
6.24 |
6.46 |
86.16 |
|||||
T3/B |
8.54 |
7.54 |
10 |
6.00 |
|
|
||||||
T3/C |
8.57 |
7.38 |
10 |
7.14 |
|
|
||||||
CAA |
1000 mg Test Item/L |
8.54 |
8.63 |
10 |
-0.54 |
-0.54 |
101.16 |
|||||
CAB |
8.23 |
8.32 |
10 |
-0.54 |
|
|
||||||
CAC |
8.62 |
8.71 |
10 |
-0.54 |
|
|
Q1: the oxygen concentration at the beginning of the selected section of the linear phase (mg/L);
Q2: the oxygen concentration at the end of the selected section of the linear phase (mg/L);
Δt: the time interval between these two measurements (min.).
3,5-DCP: 3,5-dichlorophenol
ATU: N-allylthiourea
Table3: The Specific Respiration Rate (RS) in the Test Item Treatment and Control Groups
Identification |
Concentration (mg/L) |
Specific Respiration Rate (mg O2/gh) |
Average RS (mg O2/gh) |
CBA |
0.00 |
34.69 |
|
CBB |
32.33 |
31.212 CV(%) = 8.34 |
|
CBC |
31.94 |
||
CBD |
30.95 |
||
CBE |
33.96 |
||
CBF |
27.89 |
||
CBG |
27.89 |
||
CBH |
29.31 |
||
CNA |
11.6 mg ATU/L |
32.40 |
31.87 CV(%) = 2.37 |
CNB |
31.33 |
||
R1 |
2 mg 3,5-DCP/L |
29.66 |
29.66 |
R2 |
7 mg 3,5-DCP/L |
20.46 |
20.46 |
R3 |
24.5 mg 3,5-DCP/L |
5.48 |
31.07 |
T1 |
10 mg Test Item/L |
31.07 |
29.97 |
T2 |
100 mg Test Item/L |
29.97 |
|
T3/A |
1000 mg Test Item/L |
4.16 |
|
T3/B |
4.00 |
4.31 * CV(%)= 9.30 |
|
T3/C |
4.76 |
||
CAA |
1000 mg Test Item/L |
-0.36 |
-0.36 CV(%) = 0.00 |
CAB |
-0.36 |
||
CAC |
-0.36 |
3,5-DCP: 3,5-dichlorophenol
ATU: N-allylthiourea
CV: Coefficient of variation
*: There is a statistically significant difference between the test item treatment (1000 mg/L) and blank control (2-Sample t-Test; 2-sided; α = 0.05)
WoE 3:
Table 1: The Oxygen Concentrations and pH Values in the Test Item Treatment Groups and Controls
Identifi-cation |
Concentration (mg/L) |
Oxygen concentration (mg O2/L) |
pH |
|||
Start of the 3-hour aeration |
End of the 3-hour aeration |
Before the addition of inoculum |
Start of the 3-hour aeration |
End of the 3-hour aeration |
||
CBA |
0.00 |
7.65 |
7.02 |
7.40 |
7.55 |
8.16 |
CBB |
7.64 |
7.47 |
7.37 |
7.59 |
8.14 |
|
CBC |
7.71 |
7.64 |
7.36 |
7.60 |
8.14 |
|
CBD |
7.77 |
7.69 |
7.37 |
7.57 |
8.15 |
|
CBE |
8.29 |
7.44 |
7.54 |
7.46 |
7.76 |
|
CBF |
8.36 |
7.27 |
7.54 |
7.66 |
8.12 |
|
CBG |
8.18 |
7.15 |
7.54 |
7.76 |
8.16 |
|
CBH |
8.39 |
7.28 |
7.55 |
7.80 |
8.12 |
|
CNA |
11.6 mg ATU/L |
8.40 |
7.62 |
7.46 |
7.65 |
8.21 |
CNB |
8.20 |
7.09 |
7.59 |
7.84 |
8.13 |
|
R1 |
2 mg 3,5-DCP/L |
8.23 |
7.28 |
7.31 |
7.66 |
7.93 |
R2 |
7 mg 3,5-DCP/L |
8.08 |
7.00 |
7.36 |
7.59 |
7.93 |
R3 |
24.5 mg 3,5-DCP/L |
8.21 |
7.99 |
7.29 |
7.58 |
7.93 |
T1 |
10 mg Test Item/L |
8.30 |
7.66 |
8.19 |
7.58 |
8.18 |
T2 |
100 mg Test Item/L |
8.12 |
7.58 |
8.59 |
7.89 |
8.16 |
T3/A |
1000 mg Test Item/L |
8.07 |
8.03 |
9.98 |
9.07 |
9.32 |
T3/B |
8.12 |
8.68 |
9.99 |
9.12 |
9.20 |
|
T3/C |
8.47 |
8.41 |
10.06 |
9.17 |
9.25 |
|
CAA |
1000 mg Test Item/L 8.44 |
8.54 |
8.51 |
- * |
9.98 |
9.80 |
CAB |
8.49 |
8.35 |
- * |
9.99 |
9.63 |
|
CAC |
8.67 |
- * |
9.97 |
9.53 |
|
3,5-DCP: 3,5-dichlorophenol
ATU: N-allylthiourea
Remarks: * At the Abiotic controls no inoculum was added; therefore, one pH measurement was carried out at the start of the test.
Table 2: The Q1, Q2 and the applied Δt values in the Test Item Treatment and Control Groups; the Oxygen Consumption Rate (R), and % Inhibition of R
Identifi-cation |
Concentration (mg/L) |
Oxygen concentration (mg O2/L) |
Δt (min) |
Oxygen Consumption Rate (R) (mg O2/Lh) |
Average R (mg O2/Lh) |
Inhibition of R (%) |
||
Q1 |
Q2 |
|||||||
CBA |
0.00 |
7.02 |
2.25 |
5.5 |
52.04 |
46.68 |
0.00 |
|
CBB |
7.04 |
2.19 |
6 |
48.50 |
|
|
||
CBC |
7.22 |
2.03 |
6.5 |
47.91 |
|
|
||
CBD |
7.30 |
2.27 |
6.5 |
46.43 |
|
|
||
CBE |
7.02 |
2.35 |
5.5 |
50.95 |
|
|
||
CBF |
7.27 |
2.04 |
7.5 |
41.84 |
|
|
||
CBG |
7.15 |
2.27 |
7 |
41.83 |
|
|
||
CBH |
7.28 |
2.15 |
7 |
43.97 |
|
|
||
CNA |
11.6 mg ATU/L |
7.21 |
2.35 |
6 |
48.60 |
47.80 |
-2.39 |
|
CNB |
7.09 |
2.39 |
6 |
47.00 |
|
|
||
R1 |
2 mg 3,5-DCP/L |
7.28 |
2.09 |
7 |
44.49 |
44.49 |
4.71 |
|
R2 |
7 mg 3,5-DCP/L |
7.00 |
2.14 |
9.5 |
30.69 |
30.69 |
34.25 |
|
R3 |
24.5 mg 3,5-DCP/L |
7.99 |
6.62 |
10 |
8.22 |
8.22 |
82.39 |
|
T1 |
10 mg Test Item/L |
7.29 |
2.13 |
7 |
44.23 |
44.23 |
5.26 |
|
T2 |
100 mg Test Item/L |
7.22 |
2.33 |
6.5 |
45.14 |
45.14 |
3.31 |
|
T3/A |
1000 mg Test Item/L |
8.03 |
7.08 |
10 |
5.70 |
6.58 |
85.90 |
|
T3/B |
8.68 |
7.56 |
10 |
6.72 |
|
|
||
T3/C |
8.41 |
7.19 |
10 |
7.32 |
|
|
||
CAA |
1000 mg Test Item/L |
8.51 |
8.66 |
10 |
-0.90 |
-0.72 |
101.54 |
|
CAB |
8.35 |
8.44 |
10 |
-0.54 |
|
|
||
CAC |
8.67 |
8.79 |
10 |
-0.72 |
|
|
Q1: the oxygen concentration at the beginning of the selected section of the linear phase (mg/L);
Q2: the oxygen concentration at the end of the selected section of the linear phase (mg/L);
Δt: the time interval between these two measurements (min.).
3,5-DCP: 3,5-dichlorophenol
ATU: N-allylthiourea
Table 3: The Specific Respiration Rate (RS) in the Test Item Treatment and Control Groups
Identification |
Concentration (mg/L) |
Specific Respiration Rate (mg O2/gh) |
Average RS (mg O2/gh) |
|
CBA |
0.00 |
34.69 |
31.12 CV (%) = 8.34 |
|
CBB |
32.33 |
|||
CBC |
31.94 |
|||
CBD |
30.95 |
|||
CBE |
33.96 |
|||
CBF |
27.89 |
|||
CBG |
27.89 |
|||
CBH |
29.31 |
|||
CNA |
11.6 mg ATU/L |
32.40 |
31.87 CV(%) = 2.37 |
|
CNB |
31.33 |
|||
R1 |
2 mg 3,5-DCP/L |
29.66 |
29.66 |
|
R2 |
7 mg 3,5-DCP/L |
20.46 |
20.46 |
|
R3 |
24.5 mg 3,5-DCP/L |
5.48 |
5.48 |
|
T1 |
10 mg Test Item/L |
29.49 |
29.49 |
|
T2 |
100 mg Test Item/L |
30.09 |
30.09 |
|
T3/A |
1000 mg Test Item/L |
3.80 |
|
|
T3/B |
4.48 |
|||
T3/C |
4.88 |
|||
CAA |
1000 mg Test Item/L |
-0.60 |
-0.48 CV(%) = -25.00 |
|
CAB |
-0.36 |
|||
CAC |
-0.48 |
3,5-DCP: 3,5-dichlorophenol
ATU: N-allylthiourea
CV: Coefficient of variation
*: There is a statistically significant difference between the test item treatment (1000 mg/L) and blank control (2-Sample t-Test; 2-sided; α = 0.05)
Description of key information
On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the 3 hr NOEC and EC50 value can be expected to be 1000 mg/l and < 1000 mg/l.
Key value for chemical safety assessment
- EC10 or NOEC for microorganisms:
- 1 000 mg/L
Additional information
Data available of the read across chemicals has been reviewed to determine the effect of the test chemical on toxicity to microorganisms. The studies are as mentioned below:
In a 3-hour pre-test test according to OECD 209 the influence of the test item on the activity of the activated sludge was evaluated by measuring the respiration rate under defined conditions. The respiration rates (total, heterotrophic and nitrification oxygen uptake rates) of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. This pre-test was used to estimate the range of concentrations of the test item needed in a possible definite test for determining the inhibition of oxygen consumption. The test item was investigated in this study at the nominal concentrations of 10, 100 and 1000 mg/L. Defined amounts of the test item were added directly into the test vessels. Triplicate vessels were prepared and investigated at the highest examined test item concentration. In parallel with the test item treatments 3,5-dichlorophenol as positive reference control in concentrations of 2, 7 and 24.5 mg/L; furthermore blank (inoculum) control, nitrification controls and abiotic controls were investigated. The test was performed without pH adjustment. All validity criteria of the study were met. The observed oxygen consumption rates consequently the specific respiration rates were in the range of the blank controls, no inhibitory effect was noticed at 10 and 100 mg/L (the observed slight, 0.18 and 3.70 % inhibitions were considered as being within the biological variability of the applied test system), but the inhibition was in average 86.16 % at 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate. The test was performed including abiotic controls. The abiotic controls were investigated at the test item concentration of 1000 mg/L and no remarkable abiotic oxygen consumption was noticed. The test item had unequivocal influence on the pH at the concentrations of 100 and 1000 mg/L. Before inoculum addition the pH of the test item containing test mixtures at these concentration levels was above the acceptable pH 7 - 8 range. Based on measured oxygen consumption values and calculated specific respiration rates, unequivocal test item effect was established at the highest examined concentration of 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate; however the 3-hour EC50 values of the test item is < 1000 mg/L. Due to the statistically significant differences (2-Sample T-test (α=0.05)) in the comparison with the blank control and 1000 mg/L concentration values exact NOEC value could not be determined. During the performance of the pre-experiment unequivocal, significant test item effect on the pH was realized especially at the concentrations of 100 and 1000 mg/L. In conclusion, these pre-test results demonstrate the significant inhibition of oxygen consumption by the test substance in the examined concentration range; therefore, a definite test with parallel test series (with and without pH adjustment) was considered as necessary. The definite test will be performed under a new study code; the concentration levels to be examined in the definite test will be based on the results of the present pre-experiment.
In a another study, a 3-hour pre-test according to OECD 209 the influence of the test item on the activity of the activated sludge was evaluated by measuring the respiration rate under defined conditions. The respiration rates (total, heterotrophic and nitrification oxygen uptake rates) of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. This pre-test was used to estimate the range of concentrations of the test item needed in a possible definite test for determining the inhibition of oxygen consumption. The test item was investigated in this study at the nominal concentrations of 10, 100 and 1000 mg/L. Defined amounts of the test item were added directly into the test vessels. Triplicate vessels were prepared and investigated at the highest examined test item concentration. In parallel with the test item treatments 3,5-dichlorophenol as positive reference control in concentrations of 2, 7 and 24.5 mg/L; furthermore blank (inoculum) control, nitrification controls and abiotic controls were investigated. The test was performed without pH adjustment. All validity criteria of the study were met. The observed oxygen consumption rates consequently the specific respiration rates were in the range of the blank controls, no inhibitory effect was noticed at 10 and 100 mg/L (the observed 5.26 and 3.31 % inhibitions were considered as being within the biological variability of the applied test system), but the inhibition was in average 85.90 % at 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate. The test was performed including abiotic controls. The abiotic controls were investigated at the test item concentration of 1000 mg/L and no remarkable abiotic oxygen consumption was noticed. The test item had influence on the pH in all examined concentration levels. Before inoculum addition the pH of the test item containing test mixtures was above the acceptable pH 7 - 8 range. The examined concentrations covered the appropriate inhibition range for EC10, EC50 and EC80 calculations. The EC10 was calculated as 241 mg/kg soil dry weight, the EC50 was calculated as 654 mg/kg soil dry weight and the EC80 value was calculated as 926 mg/kg soil dry weight. The above ECx values will be further refined in the definite test. The EC50 value was determined as: EC50 < 1000 mg/L. Based on measured oxygen consumption values and calculated specific respiration rates, strong test item effect was established at the highest examined concentration of 1000 mg/L. For demonstration of a clear dose related inhibitory effect, the concentration spacing of this pre-test was not appropriate; however the 3-hour EC50 values of the test item is < 1000 mg/L. Due to the statistically significant differences (2-Sample T-test (α=0.05)) in the comparison with the blank control and 1000 mg/L concentration values exact NOEC value could not be determined. During the performance of the pre-experiment significant test item effect on the pH was realized in whole examined concentration range of 10 - 1000 mg/L. In conclusion, these pre-test results demonstrate the significant inhibition of oxygen consumption by the test substance in the examined concentration range; therefore, a definite test with parallel test series (with and without pH adjustment) was considered as necessary. The definite test will be performed under a new study code; the concentration levels to be examined in the definite test will be based on the results of the present pre-experiment.
On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the 3 hr NOEC and EC50 value can be expected to be 1000 mg/l and < 1000 mg/l.
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