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Toxicity to microorganisms

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Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
May 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This robust summary has a reliability rating of 1 because the study followed a standard guideline, followed GLP guidelines, and was conducted without deviations that would invalidate the study.
Justification for type of information:
A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
other: Developed by Huls AG (Dr. Schoberl)
Deviations:
not specified
Principles of method if other than guideline:
Effects were measured by comparing oxygen consumption by the bacterium, Pseudomonas putida, over 5 hours incubation in test systems that contained varying amounts of test substance in comparison to test systems that contained no test substance (control).
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
Test systems were 100 ml bottles containing medium. All test systems were stirred through the exposure period. Four innoculated bottles were established per test substance concentration. Two of these bottles at each concentration also contained HgCl2 and acted as autooxidation controls. Four innoculated bottles without test substance and with HgCl2 also acted as controls. Five innoculated bottles without test substance and HgCl2 also acted as controls. All test systems were stirred during the test.
Test organisms (species):
Pseudomonas putida
Details on inoculum:
The original culture was obtained from the Institut fur Wasser-, Boden- und lufthygiene des BGA (Berlin, Germany).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
5 h
Post exposure observation period:
None
Test temperature:
25.3
Nominal and measured concentrations:
Nominal loading levels were 100, 500, 1000, and 2000 ul/L.
Duration:
5 h
Dose descriptor:
other: EL0
Effect conc.:
2 other: ml/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
5 h
Dose descriptor:
other: EL10
Effect conc.:
> 2 other: ml/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
5 h
Dose descriptor:
other: EL50
Effect conc.:
> 2 other: ml/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
5 h
Dose descriptor:
other: EL100
Effect conc.:
> 2 other: ml/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Reported statistics and error estimates:
None were needed as no effect was measured.
Validity criteria fulfilled:
yes
Conclusions:
The test substance at the highest loading rate, 2 ml/L, did not inhibit the respiration rate of Pseudomonas putida over an exposure period of 5 hours.
Executive summary:

The test substance at the highest loading rate, 2 ml/L, did not inhibit the respiration rate of Pseudomonas putida over an exposure period of 5 hours.

Endpoint:
toxicity to microorganisms, other
Remarks:
QSAR
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
Not applicable, calculated value
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.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The aquatic toxicity was estimated by a QSAR, the Petrotox computer model. 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:
The data were calculated by a computer model
Analytical monitoring:
not required
Vehicle:
no
Test organisms (species):
Tetrahymena pyriformis
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Key result
Duration:
48 h
Dose descriptor:
other: EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Validity criteria fulfilled:
yes
Conclusions:
The hydrocarbons, 10-C13, isoalkanes, cyclics, <2% aromatics, estimated protozoan, Tetrahymena pyriformis, 48-hr EL50 value for this substance is >1000 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 hydrocarbons, C10-C13, isoalkanes, cyclics, <2% aromatics, estimated protozoan, Tetrahymena pyriformis, 48-hr EL50 value for this substance is >1000 mg/L based on growth inhibition.

Description of key information

Isododecane at the highest loading rate, 2 ml/L, did not inhibit the respiration rate of Pseudomonas putida over an exposure period of 5 hours. These data are used as read-across data to hydrocarbons, C10-C13, isoalkanes, cyclics, <2% aromatics.

The hydrocarbons, C10-C13, isoalkanes, <2% aromatics, estimated protozoan, Tetrahymena pyriformis, 48-hr EL50 value for this substance is  >1000 mg/L based on growth inhibition.

Key value for chemical safety assessment

Additional information

Isododecane at the highest loading rate, 2 ml/L, did not inhibit the respiration rate of Pseudomonas putida over an exposure period of 5 hours. These data are used as read-across data to hydrocarbons, C10-C13, isoalkanes, cyclics, <2% aromatics.

The hydrocarbons, C10-C13, isoalkanes, cyclics, <2% aromatics, estimated protozoan, Tetrahymena pyriformis, 48-hr EL50 value for this substance is >1000 mg/L based on growth inhibition.