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Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP compliant, guidelines study, available as unpublished report, acceptable with restrictions
Qualifier:
according to guideline
Guideline:
other: OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
yes
Remarks:
clarifications and exceptions provided but would not affect result
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No data reported
Analytical monitoring:
no
Details on sampling:
No concentration verification was performed since the test substance is poorly soluble in water.
Vehicle:
no
Details on test solutions:
Glass distilled water (gd H2O) was used as the carrier.
Mineral salt solutions: Phosphate buffer - pH 7.2, Ferric chloride - 0.025%, Magnesium sulfate - 2.25%, Calcium chloride - 2.75%
Test medium: The test medium was prepared one day before the test began. 15 liters of glass distilled water was amended with mineral salt solutions and inoculum.
Positive control substance stock solution: A stock solution of sodium benzoate at a concentration of approximately 10,000 mg/L was prepared in glass distilled water.
The test substance was injected directly into the test flasks containing test medium with a syringe. Each flask was sealed immediately after addition of the test substance to avoid loss due to volatilization. No aqueous stock solutions were prepared for the test substance because of its poor solubility in water.
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Fresh activated sludge was obtained from the Clinton Sanitary Wastewater Treatment Plant, Annandale, New Jersey which with domestic sewage. There were no known contaminants in the fresh activated sludge believed to be present at levels high enough to interfere with this study. The inoculum was mixed for 2 minutes in a blender at low speed.

The manometric cells were rinsed with two portions of acetone, filled with soapy water and allowed to stand for a few hours. The cells were then rinsed with glass distilled water followed by acetone then air dried.

The Total Suspended Solids (TSS) content of the inoculum mixture was not determined because of the limited amount of mixture available. The Easicult® TTC dip slide results indicated an average bacterial population of 10^4 colony forming units (CFU)/mL.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
56 d
Post exposure observation period:
None
Hardness:
No data reported
Test temperature:
22 ± 1°C
pH:
The pH of the test medium was 7.32.The initial pH of individual systems was not determined due to the poor solubility of the test substance in water.
Dissolved oxygen:
The test medium was aerated for approximately 24 hours prior to testing.
Salinity:
Not applicable
Nominal and measured concentrations:
Low DCPD resin oil and positive control substances (sodium benzoate) were tested at mean concentrations of 47.20 mg/L and 51.49 mg/L, respectively. Blank test systems, which did not contain the test or positive control substance, were run concurrently in triplicate.
Details on test conditions:
The consumption of oxygen was determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask, or from the change in volume or pressure (or a combination of the two) in the apparatus. The amount of oxygen consumed was recorded at each hourly interval for each test system using the CES aerobic respirometer.

The sample was placed in a sample flask, which was then sealed by a manometric cell/CO2 trap and immersed in a temperature stabilized water bath. For the duration of the experiment, the sample was stirred by a magnetically coupled stirrer. Testing was extended to 56 days due to the continued oxygen consumption of the test systems.
Reference substance (positive control):
yes
Remarks:
Sodium benzoate was administered to the respective test systems as an aliquot of an aqueous stock solution.
Key result
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
47.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
56 d
Dose descriptor:
NOEC
Effect conc.:
47.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
The toxicity control vessel in the biodegradation study reached a mean percentage biodegradation of 34.86% after 28 days and 51.66% after 56 days.
Results with reference substance (positive control):
The positive control vessel in the biodegradation study reached a mean percentage biodegradation of 81.52% after 28 days and 80.17% after 56 days.
Reported statistics and error estimates:
The percent biodegradation values were calculated by the respirometer softwar using: the ThOD, and the mass of positive control or test substance added and the hourly logged oxygen uptake value.
Validity criteria fulfilled:
not applicable
Remarks:
Validity criteria of biodegradation study fulfilled
Conclusions:
The 56 day NOEC for the toxicity of CAS# 68477-54-3 to microorganisms is 47.2 mg/L.
Executive summary:

On the basis of the toxicity control vessel in the biodegradation study, the substance is considered not to inhibitory to micro-organisms at a concentration of 47.2 mg/L. The results are taken from a GLP-compliant, biodegradation study following OECD guideline 301F and is considered reliable and suitable for use for this endpoint.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See Attached Justification
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version:
See Field 'Attached justification'
- Model(s) used:
See Field 'Attached justification'
- Model description: See Field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Remarks:
The data were calculated by a computer model
Specific details on test material used for the study:
HC Block Type Carbon Number Concentration (%w/w)
Mono-Aromatic (MoAr) 7 2.49
8 4.24
9 66.33
10 5.12
Naphthenic Mono-Aromatic (NMAr) 9 19.58
Total 97.76

The constituents that could fit in more than one HC block, or that did not fit in any specific block, were placed in a relevant block that presented the highest toxicity.
Analytical monitoring:
not required
Test organisms (species):
activated sludge
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
15 h
Duration:
15 h
Dose descriptor:
other: EL50
Effect conc.:
44.6 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction value
Duration:
15 h
Dose descriptor:
other: EL10
Effect conc.:
8.55 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction result
Validity criteria fulfilled:
yes
Conclusions:
The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) for activated sludge were 44.6 and 8.55 mg/L, respectively.
Executive summary:

The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) of the UVCB substance for Activated Sludge were 44.6 and 8.55 mg/L, respectively. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See Attached Justification
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version:
See Field 'Attached justification'
- Model(s) used:
See Field 'Attached justification'
- Model description: See Field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Remarks:
The data were calculated by a computer model
Specific details on test material used for the study:
HC Block Type Carbon Number Concentration (%w/w)
Mono-Aromatic (MoAr) 6 0.44
7 2.99
8 5.10
9 83.11
10 0.95
Naphthenic Mono-Aromatic (NMAr) 9 2.40
Di-Aromatic (DiAr) 10 1.13
n-Olefin 10 0.54
n-Paraffin (n-P) 10 0.14
11 0.33
Total 97.12

The constituents that could fit in more than one HC block, or that did not fit in any specific block, were placed in a relevant block that presented the highest toxicity.
Analytical monitoring:
not required
Test organisms (species):
activated sludge
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
15 h
Duration:
15 h
Dose descriptor:
other: EL50
Effect conc.:
42 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction value
Duration:
15 h
Dose descriptor:
other: EL10
Effect conc.:
8 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction result
Validity criteria fulfilled:
yes
Conclusions:
The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) for active sludge were 42 and 8 mg/L, respectively.
Executive summary:

The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) of the UVCB substance for Activated Sludge were 42 and 8 mg/L, respectively. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See Attached Justification
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version:
See Field 'Attached justification'
- Model(s) used:
See Field 'Attached justification'
- Model description: See Field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Remarks:
The data were calculated by a computer model
Specific details on test material used for the study:
HC Block Type Carbon Number Concentration (%w/w)
Mono-Aromatic (MoAr) 7 1.55
8 31.91
9 17.86
10 2.89
12 2.29
13 0.67
Di-Aromatic (DiAr) 10 1.03
13 0.28
14 0.24
15 0.28
n-Olefin 5 0.27
10 21.06
11 0.41
i-Olefin 9 0.30
Total 81.03

The constituents that could fit in more than one HC block, or that did not fit in any specific block, were placed in a relevant block that presented the highest toxicity.
Analytical monitoring:
not required
Test organisms (species):
activated sludge
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
15 h
Duration:
15 h
Dose descriptor:
other: EL50
Effect conc.:
113 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction value
Duration:
15 h
Dose descriptor:
other: EL10
Effect conc.:
2.18 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction result
Validity criteria fulfilled:
yes
Conclusions:
The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) for activated sludge were 113 and 2.18 mg/L, respectively.
Executive summary:

The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) of the UVCB substance for Activated Sludge were 113 and 2.18 mg/L, respectively. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See Attached Justification
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version:
See Field 'Attached justification'
- Model(s) used:
See Field 'Attached justification'
- Model description: See Field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Remarks:
The data were calculated by a computer model
Specific details on test material used for the study:
HC Block Type Carbon Number Concentration (%w/w)
Mono-Aromatic (MoAr) 6 0.57
7 0.19
9 0.50
12 0.98
13 0.31
Di-Aromatic (DiAr) 10 0.27
n-Olefin 5 0.63
10 62.38
11 23.68
Total 89.52

The constituents that could fit in more than one HC block, or that did not fit in any specific block, were placed in a relevant block that presented the highest toxicity.
Analytical monitoring:
not required
Test organisms (species):
activated sludge
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
15 h
Duration:
15 h
Dose descriptor:
other: EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction value
Duration:
15 h
Dose descriptor:
other: EL10
Effect conc.:
40.4 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction result
Validity criteria fulfilled:
yes
Conclusions:
The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) for activated sludge were >1000 and 40.4 mg/L, respectively.
Executive summary:

The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) of the UVCB substance for Activated Sludge were >1000 and 40.4 mg/L, respectively. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See Attached Justification
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version:
See Field 'Attached justification'
- Model(s) used:
See Field 'Attached justification'
- Model description: See Field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Remarks:
The data were calculated by a computer model
Specific details on test material used for the study:
HC Block Type Carbon Number Concentration (%w/w)
Mono-Aromatic (MoAr) 7 0.75
8 35.64
9 17.80
10 2.99
12 0.35
13 0.23
Di-Aromatic (DiAr) 10 0.22
n-Cyclohexane (n-CC6) 7 0.11
iso-Naphthenic (i-N) 8 0.10
n-Olefin 5 0.58
6 0.17
9 0.61
10 23.76
i-Olefin 6 0.21
n-Paraffin (n-P) 7 0.12
8 0.18
9 0.30
Total 84.13

The constituents that could fit in more than one HC block, or that did not fit in any specific block, were placed in a relevant block that presented the highest toxicity
Analytical monitoring:
not required
Test organisms (species):
activated sludge
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
15 h
Duration:
15 h
Dose descriptor:
other: EL50
Effect conc.:
126 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction value
Duration:
15 h
Dose descriptor:
other: EL10
Effect conc.:
3.1 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction result
Validity criteria fulfilled:
yes
Conclusions:
The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) for activated sludge were 126 and 3.1 mg/L, respectively.
Executive summary:

The QSAR predicted 15 -h EL50 (inhibition of total respiration) and 15 -h EL10 (inhibition of total respiration) of the UVCB substance for Activated Sludge were 126 and 3.1 mg/L, respectively. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See Attached Justification
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version:
See Field 'Attached justification'
- Model(s) used:
See Field 'Attached justification'
- Model description: See Field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Remarks:
The data were calculated by a computer model
Specific details on test material used for the study:
[HC Block Type Carbon Number Concentration (%w/w)
n-olefin 5 0.57
9 1.24
10 76.50
11 14.84
12 1.21
Total 94.37

The constituents that could fit in more than one HC block, or that did not fit in any specific block, were placed in a relevant block that presented the highest toxicity.
Analytical monitoring:
not required
Test organisms (species):
activated sludge
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
15 h
Duration:
15 h
Dose descriptor:
other: EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction value
Duration:
15 h
Dose descriptor:
other: EL10
Effect conc.:
5.09 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction result
Validity criteria fulfilled:
yes
Conclusions:
The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) for activated sludge were >1000 and 5.09 mg/L, respectively.
Executive summary:

The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) of the UVCB substance for Activated Sludge were >1000 and 5.09 mg/L, respectively. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See Attached Justification
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version:
See Field 'Attached justification'
- Model(s) used:
See Field 'Attached justification'
- Model description: See Field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Remarks:
The data were calculated by a computer model
Specific details on test material used for the study:
HC Block Type Carbon Number Concentration (%w/w)
Mono-Aromatic (MoAr) 8 1.51
9 42.57
10 7.04
Naphthenic Mono-Aromatic (NMAr) 9 0.98
10 0.36
Di-Aromatic (DiAr) 10 8.24
11 0.85
n-Olefin 5 0.22
9 0.13
10 26.65
11 4.67
Total 93.21

The constituents that could fit in more than one HC block, or that did not fit in any specific block, were placed in a relevant block that presented the highest toxicity.
Analytical monitoring:
not required
Test organisms (species):
activated sludge
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
15 h
Duration:
15 h
Dose descriptor:
other: EL50
Effect conc.:
86.7 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction value
Duration:
15 h
Dose descriptor:
other: EL10
Effect conc.:
2.81 mg/L
Nominal / measured:
estimated
Conc. based on:
other: QSAR prediction
Basis for effect:
inhibition of total respiration
Remarks on result:
other: QSAR prediction result
Validity criteria fulfilled:
yes
Conclusions:
The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) for activated sludge were 86.7 and 2.81 mg/L, respectively.
Executive summary:

The QSAR predicted 15-h EL50 (inhibition of total respiration) and 15-h EL10 (inhibition of total respiration) of the UVCB substance for Activated Sludge were 86.7 and 2.81 mg/L, respectively. The model used for the calculations was the PETROTOX v4.0 model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Description of key information

The 56 day NOEC for the toxicity of CAS No. 68477-54-3 to activated sludge of a predominantly domestic sewage is 47.2 mg/L.

 

In addition to the experimental data, the aquatic toxicity was predicted by a QSAR, the PETROTOX v4.0 computer model. PETROTOX is a well-documented and peer reviewed model that is widely used across the chemicals industry. The substances of this category fit within the criteria of the model and there are no reservations about the validity of the model runs. The predicted LL50 values for Activated Sludge ranged from 42 to >1000 mg/L. The predicted EL10 values for Activated Sludge ranged from 2.18 to 40.4 mg/L.
 

Key value for chemical safety assessment

Additional information

Experimental data:

On the basis of the toxicity control vessel in the biodegradation study, CAS No. 68477-54-3 is considered not to be inhibitory to micro-organisms at a concentration of 47.2 mg/L. The results are taken from a GLP-compliant, biodegradation study (ACC, 2004i) following OECD guideline 301F and is considered reliable and suitable for use for this endpoint.

QSAR predictions:

 
The PETROTOX v4.0 model combines a partitioning model used to calculate the aqueous concentration of hydrocarbon constituents with the Target Lipid Model used to calculate acute and chronic toxicity of non-polar narcotic chemicals. PETROTOX computes toxicity based on the summation of the aqueous-phase concentrations of hydrocarbon block(s) that represent a hydrocarbon substance and membrane-water partition coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism.
 
The predicted values were:
Species Substance CAS No. LL50 (mg/L) EL10 (mg/L)
Activated Sludge 68516-20-1 126 3.10
Activated Sludge 101316-62-5 44.6 8.55
Activated Sludge 68526-56-7 >1000 5.09
Activated Sludge 68477-54-3 113 2.18
Activated Sludge 94733-07-0 86.7 2.81
Activated Sludge 68478-10-4 >1000 40.4
Activated Sludge 65996-79-4 42.0 8.00