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Toxicity to microorganisms

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Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
May 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This summary has a reliability of 2 because the results are estimated using a computer model that is appropriate for use with this hydrocarbon substance
Justification for type of information:
The aquatic toxicity was estimated by a QSAR, the Petrotox computer model (v. 3.06). This model combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components 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.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The aquatic toxicity was estimated by a QSAR, the Petrotox computer model (v. 3.06). This model combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components 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.
GLP compliance:
no
Remarks:
QSAR
Specific details on test material used for the study:
No data.
Analytical monitoring:
no
Details on sampling:
No data.
Vehicle:
no
Details on test solutions:
No data.
Test organisms (species):
Tetrahymena pyriformis
Test type:
other:
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
No data.
Test temperature:
No data.
pH:
No data.
Dissolved oxygen:
No data.
Salinity:
No data.
Nominal and measured concentrations:
No data.
Details on test conditions:
No data.
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
other: EL50
Effect conc.:
10.11 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Details on results:
No data.
Results with reference substance (positive control):
No data.
Reported statistics and error estimates:
No data.

The composition used to run the Petrotox model is below, derived from GCxGC data for the substance;

 Carbon Number  MoAr  NMAr  DiAr
 9  73.599  
 10  23.035  1.129  2.237
Validity criteria fulfilled:
yes
Conclusions:
The estimated protozoan, Tetrahymena pyriformis, 48-hr EL50 value for this substance is 10.11 mg/L based on growth inhibition.
Executive summary:

The aquatic toxicity was estimated using the Petrotox computer model, which combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components as a function of substance loading 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 estimated protozoan,Tetrahymena pyriformis, 48-hr EL50 value for this substance is 10.11 mg/L based on growth inhibition.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
May 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This summary has a reliability of 2 because the results are estimated using a computer model that is appropriate for use with this hydrocarbon substance
Justification for type of information:
The aquatic toxicity was estimated by a QSAR, the Petrotox computer model (v. 3.06). This model combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components 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.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The aquatic toxicity was estimated by a QSAR, the Petrotox computer model (v. 3.06). This model combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components 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.
GLP compliance:
no
Remarks:
QSAR
Specific details on test material used for the study:
No data.
Analytical monitoring:
no
Details on sampling:
No data.
Vehicle:
no
Test organisms (species):
Tetrahymena pyriformis
Test type:
other: QSAR modelled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
No data.
Hardness:
No data.
Test temperature:
No data.
pH:
No data.
Dissolved oxygen:
No data.
Salinity:
No data.
Nominal and measured concentrations:
No data.
Details on test conditions:
No data.
Reference substance (positive control):
not required
Key result
Duration:
48 h
Dose descriptor:
other: NOELR
Effect conc.:
2.64 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Details on results:
No data.
Results with reference substance (positive control):
No data.
Reported statistics and error estimates:
No data.

The composition used to run the Petrotox model is below, derived from GCxGC data for the substance;

 Carbon Number  MoAr  NMAr  DiAr
 9  73.599  
 10  23.035  1.129  2.237
Validity criteria fulfilled:
yes
Conclusions:
The estimated protozoan, Tetrahymena pyriformis, 48-hr NOELR value for this substance is 2.64 mg/L based on growth inhibition.
Executive summary:

The aquatic toxicity was estimated using the Petrotox computer model, which combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components as a function of substance loading 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 estimated protozoan, Tetrahymena pyriformis, 48-hr NOELR value for this substance is 2.64 mg/L based on growth inhibition.

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study done according to OECD Guideline 209.
Justification for type of information:
Hydrocarbons, C9-C10, aromatics, >1% Naphthalene are a combination of Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics. Read across data is available for Hydrocarbons, C9 Aromatics and Hydrocarbons, C10-C12 Aromatics and the worst case scenario for each end point has been presented.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
yes
Remarks:
Due to the high vapor pressure of the test substance, the substance would have been lost to volatilization during the standard 3 hr exposure. Instead the test substance was injected directly into the oxygen uptake for an exposure duration of 10 min.
GLP compliance:
yes (incl. certificate)
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
90% domestic sewage from Chester Sewage Works (Welsh Water) collected on day of the test. The mixed liquor suspended solids content was 3.64 g dry solids/l.
Test type:
static
Limit test:
yes
Total exposure duration:
10 min
Test temperature:
20 +/- 0.6°C
pH:
7.5-7.7
Nominal and measured concentrations:
Nominal: 1.1, 3.3, 9.9, 33, 99 mg/l
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Key result
Duration:
10 min
Dose descriptor:
NOEC
Effect conc.:
> 99 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
10 min
Dose descriptor:
EC50
Effect conc.:
> 99 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
- Effect concentrations exceeding solubility of substance in test medium: yes
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: 3-hr EC50 = 14 mg/l

 Concentration Respiration Rate (mg O2/g dry solids/h)  Inhibition % 
Control  17.8 
1.1   18.8 
3.3  18.6 
9.9  18.6 
33  18.0 
99  18.0 
Validity criteria fulfilled:
yes
Conclusions:
Hydrocarbons,C9, Aromatics is not expected to be toxic to aerobic sewage treatment. The NOEC is >99 mg/L (nominal). The EC50 is also > 99 mg/L (nominal).
Executive summary:

This study was done to determine if Shellsol A had an inhibitory effect on the respiration rate of activated sludge. Activated sludge was exposed to 1.1, 3.3, 9.9, 33, or 99 mg/L of test substance. The exposure duration, 10 min, was much less than the normal duration of 3 hrs. However, due to the high volatility of the substance, it would be rapidly lost to volitization during the vigorous aeration of the activated sludge process. The test substance showed no inhibition of respiration as compared to negative controls. The positive control substance inhibited respiration up to 93.2%. Therefore, the results of the study are considered valid, and the substance is not expected to be toxic to aerobic sewage treatment, and the NOEC and EC50 are both >99 mg/L (nominal).

Description of key information

Petrotox has been run on the substance Hydrocarbons, C9-C10, aromatics, >1% Naphthalene and is presented below.

 

The estimated protozoan, Tetrahymena pyriformis, 48-hr EL50 value for hydrocarbons, C9-C10, aromatics, >1% napthalene is 10.11 mg/L, based on growth inhibition.

 

The estimated protozoan, Tetrahymena pyriformis, 48-hr NOELR value for hydrocarbons, C9-C10, aromatics, >1% naphthalene is 2.64 mg/L, based on growth inhibition.

Key value for chemical safety assessment

Additional information

The aquatic toxicity was estimated using the Petrotox computer model, which combines a partitioning model used to calculate the aqueous concentration of hydrocarbon components as a function of substance loading 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 hydrocarbons, C9-C10, aromatics, >1% naphthalene estimated protozoan, Tetrahymena pyriformis, 48-hr EL50and NOELR values are 10.11 and 2.64 mg/L, respectively, based on growth inhibition.