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Long-term toxicity to aquatic invertebrates

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Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
reference to same study
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
July - August 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This robust summary has a reliability rating of 2 because the study followed a standard guideline and was conducted without deviations that would invalidate the study. However, the study did not follow GLP guidelines.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
other: OECD guideline 202 section 2: Effects on biotic systems (1984)
Deviations:
yes
Remarks:
The deviation did not impact the scientific integrity of the study
GLP compliance:
no
Analytical monitoring:
yes
Details on sampling:
Samples of the control and the Water Accomodated Fractions (WAFs) prepared on each loading rate were taken on days 0, 2, 5, 7 and 14 from the stirring vessels and at termination (composite of replicates) for analysis.
Vehicle:
no
Details on test solutions:
The test solutions were prepared as WAFs (water accomodated fractions). Individual WAFs were prepared by adding the appropriate amount of the test substance to 3.5 L of dilution water in a 4 L size glass aspirator bottle. The mixtures were stirred for approximately 24 hours on a magnetic stirplate with a Teflon coated stirbar. Stirring was initiated using a vortex of <10% of the static liquid depth (1.5 cm). Each vesesl was stoppered with a foil covered neoprene stopper. All mixtures appeared clear during the stirring period.
After stirring, WAFs were removed through the outlet at the bottom of the vessel and added to test chambers. New WAF solutions were prepared for each 24-hour renewal.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Source: cultured in the Environmental Toxicology and Chemistry Laboratory of Exxon Biomedical Sciences, INC.
- Age of parental stock: 16 days
- Feeding during test
- Food type: Selenastrum capricornutum (algae)
- Amount: 2.32*10^5 cells/mL on days 0-6 and 1.56*10^5 cells/mL on days 7-21
- Frequency: daily

ACCLIMATION
- Acclimation period: no acclimation period (daphnia <= 24 hours old)

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES
Young were observed, counted and removed daily.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21
Remarks on exposure duration:
d
Post exposure observation period:
No post exposure period
Hardness:
No data
Test temperature:
Mean test temperature (water): 20°c (sd=0.05), continuously monitored by computer in test area.
pH:
6.6 TO 7.8
Dissolved oxygen:
5.2 TO 9.3 mg/L
Salinity:
Freshwater study
Nominal and measured concentrations:
Range finding test: Nominal concentrations (loading rates): 50, 10, 2.5, 1 and 0.5 mg/L. Samples of the control and the 50 mg/L loading were analyzed for the test substance by gas chromatography with flame ionization detection (GC-FID). The results of the analysis showed that the levels of the test susbtance were below the practical quantitation limit of 0.2 mg/L.
Definitive test: 0, 1, and 5 mg/L (nominal concentrations = loading rates)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: closed (flasks stoppered with foil covered neoprene stoppers on days 0-6; flasks covered with plexiglass sheets on days 7-21)
- Material, size, headspace, fill volume: 500 mL size glass erlenmeyer flasks, containing approximately 560mL of solution on days -6 (no head space) and 500 mL solution on days 7-21; test chambers rinsed with reverse osmosis water after renewals to remove food substrates
- Aeration: no aeration
- Renewal rate of test solution: renewal of the test solutions was performed on Monday, Wednesday and Friday by transferring the adult daphnids to new solutions via pipette.
- No. of organisms per vessel: range-finding test: 5; definitve test: 10
- No. of vessels per concentration (replicates): range-finding test: 2 (two trials); definitive test: 4
- No. of vessels per control (replicates): range-finding test: 2 (two trials); definitive test: 4
- Biomass loading rate: definitive test: 1 daphnid per approximately 50 to 56 mL of solution

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: BW3 supplemented with vitamin B12 and selenium
- Culture medium different from test medium: no
- Intervals of water quality measurement: The quality of the dilution water used in culture and testing is monitored at weekly, monthly, semi-annual and annual intervals.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16h ightL/ 8 h Dark with gradual intensity conversion between periods
- Light intensity: approximately 630 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Adult mortality / immobilization
- Percent reduction in reproduction (based on cumulative young per adults)

RANGE-FINDING STUDY
- Test concentrations: 0, 0.5, 1.0, 2.5, 10, and 50 mg/L
- Loadings used for the definitive study: 0, 1, and 5 mg/L
Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
EL50
Effect conc.:
> 5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(loading rate)
Basis for effect:
reproduction
Remarks:
cumulative average young per adult
Duration:
21 d
Dose descriptor:
EL50
Effect conc.:
> 5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(loading rate)
Basis for effect:
immobilisation
Remarks on result:
other: (adults)
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(loading rate)
Basis for effect:
reproduction
Remarks:
cumulative average young per adult
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(loading rate)
Basis for effect:
immobilisation
Remarks on result:
other: (adults)
Details on results:
The first brood were observed in the control and each loading after 7 days. By day 14 a cumulative average of 20 young per female were produced in the control. A cumulative average of 54 young per female were produced in the control by day 21.
Other details on results in §Remarks on results including tables and figures.
Results with reference substance (positive control):
No reference susbtance
Reported statistics and error estimates:
The No Observed Effect Loading Rate (NOELR) was determined using Dunnett's procedure of SAS.

Table 1. Definitive test: Percent adult mortality / immobilization and percent reduction in reproduction (based on cumulative youngs per adult) for the 14- and 21-day period.

 

Loading rate (mg/L)

% Adult Mortality / Immobilization

% Reduction in reproduction

14 days

21 days

14 days

21 days

Control

7.5

17.5

N/A

N/A

1.0

10

12

0

9

5.0

10

25

25

28

N/A - Not applicable, % reduction in reproduction as compared to the controls.

Validity criteria fulfilled:
yes
Remarks:
Dissolved oxygen fell below 60% sat. on day 12 in old solution. Since treatment was renewed, not believed to have effect on study. At day 21, 54 young per adult rather than 60, but believed sufficient young were produced for evaluation.
Conclusions:
The 21-day EL50s based on adult immobilization and reduction in reproduction were >5 mg/L. The 21-day No Observed Effect Loading Rates (NOELRs) based on adult immobilization and reduction in reproduction was 5 mg/L.
Executive summary:

The 21-day EL50s based on adult immobilization and reduction in reproduction were >5 mg/L loading. The 21-day No Observed Effect Loading Rates (NOELRs) based on adult immobilization and reduction in reproduction was 5 mg/L.

The study was performed to evaluate the toxicity of the water accomodated fraction (WAF) of the test substance to the daphnid, Daphnia magna, in a semi-static system for a 21-day period. The loading rates for this test were 1 mg/L and 5 mg/L. A control of laboratory dilution water was also tested. Individual WAFs were prepared by adding the appropriate amount of the test substance to 3.5 liters of BW3 in a 4 L size glass aspirator bottle. The mixtures were then stirred for approximately 24 hours on a magnetic stirplate with a Teflon coated stirbar. Stirring was initiated using a vortex of <10% of the static liquid depth (1.5 cm). Each vessel was stoppered to prevent loss of volatiles. After stirring, the WAF was removed from the outlet at the bottom of the vessel.

Four replicates chambers were prepared per treatment by completely filling the test chambers with WAF (no headspace). Samples were removed from each WAF and the control on day 0, 2, 5, 7, 14, and at termination (composite of the replicate test chambers) for chemical analysis by gas chromatography with flame ionization detection (GS-FID). The results of the analysis showed that the levels of the test substance were below the practical quantitation limit of 0.2 mg/L.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
reference to same study
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
reference to same study
Reason / purpose:
read-across: supporting information
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
reference to same study
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
reference to same study
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
reference to same study
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
reference to same study
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key 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.
Justification for type of information:
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.
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.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate nor analogue material
Analytical monitoring:
not required
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
Daphnia magna
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable (calculated data)
Hardness:
Not applicable (calculated data)
Test temperature:
Not applicable (calculated data)
pH:
Not applicable (calculated data)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable (calculated data)
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Duration:
21 d
Dose descriptor:
NOELR
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No details (calculated data) - See inforamtion on substance composition in "Overall Remarks" section
Results with reference substance (positive control):
No reference substance required
Reported statistics and error estimates:
Not applicable

No other information

Validity criteria fulfilled:
yes
Conclusions:
Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility
Executive summary:

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that this substance will not produce toxicity at or below its maximum attainable water solubility.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
from 2001-07-24 to 2001-08-1
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Well documented study. However, information on the substance is lacking, particularly the density of the susbtance would have been necessary to be able to calculate the end-point values as concentrations (mg/L for instance) instead of % WAF as it is in the study report. MSDS needed.
Justification for type of information:
The justification for read across is provided as an attachment in IUCLID Section 13.
Reason / purpose:
read-across: supporting information
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
other: EPA 1002.0: Ceriodaphnia survival and reproduction test
Deviations:
no
Principles of method if other than guideline:
Ceriodaphnia dubia are exposed to the substance and the test is ended when 60% of the surviving control females produced 3 broods of young.
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No test surrogate or analogue material
Analytical monitoring:
no
Details on sampling:
Not applicable (no analytical monitoring)
Vehicle:
no
Details on test solutions:
Water accommodated fractions (WAFs) were prepraed on alternate days durinfg testing accoding to methods described by Anderson et al. (Anderson, 1974). Ten parts of the test water and one part of the test material were combined to prepare each WAF; actual volumes of liquids were dependent on the volume needed for testing. The solutions were mixed for 20 +/- 1 hours using a magnetic stir bar and a stir plate. The vortex produced during mixing was not allowed to exceed 25% of the distance from the liquid surface to the bottom of the mixing chamber. After mixing, the WAFs were extracted from a point near the bottom of the mixing chambers by siphoning.
Test organisms (species):
Ceriodaphnia dubia
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Source: obtained from in-house cultures at the Fort Collins Environmental Toxicology Laboratory
- Age: At the time of test initiation, the test organisms were less than 24-hour old
- Feeding during test
- No feeding during the range-finding test
- Feeding during the definitive test:
- Food type: yeast-trout chow-cereal leaves/algae mix
- Amount: 0.2 ml per test chamber
- Frequency: daily


ACCLIMATION
- Acclimation period: 24 h after hatching
- Acclimation conditions: same as test
- Health during acclimation (any mortality observed): Good physical condition
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
6 d
Post exposure observation period:
Data were gathered through 7 days, although 60% of the surviving control females had third brood by day 6, when the test should have been terminated.
Hardness:
96-106 mg/L CaCO3
Test temperature:
20+/- 1°C
pH:
8.0-8.3
Dissolved oxygen:
>=6.9 mg/L
Salinity:
Conductivity: 339-346 µS/cm
Nominal and measured concentrations:
0, 12.5, 25, 50, 75 and 100% WAF
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 30 mL plastic beakers with 15 mL test medium
- No aeration during any of the tests
- Renewal rate of test solution (frequency/flow rate): daily
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates):10


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted moderatly hard water (USEPA, 1994. Short-term methods for estimating the chronic toxicity of effluents and receiving water to freshwater organisms. EPA/600/4-91/002)
- Chlorine <0.05 mg/L
- Alkalinity: 66-69 mg/L CaCO3
- Conductivity:339-364 µS/cm
- Intervals of water quality measurement: daily


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod:16 h L / 8 h D (fluorescent lighting)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Mortality of adults (defined as no visible movement after gentle prodding with a blunt probe
- Total number of young produced per adult


RANGE-FINDING STUDY
- Test concentrations: 0, 1, 10 and 100% WAF for 24 hours
- Results used to determine the conditions for the definitive study: the high concentration for the definitive test is set at 100% WAF.
Reference substance (positive control):
yes
Remarks:
Sodium chloride NaCl
Duration:
6 d
Dose descriptor:
EL50
Effect conc.:
> 100 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Not reached
Duration:
6 d
Dose descriptor:
other: EL25
Effect conc.:
> 100 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Not reached
Duration:
6 d
Dose descriptor:
LOELR
Effect conc.:
> 100 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: No statistical differences between control and treated
Duration:
6 d
Dose descriptor:
NOELR
Effect conc.:
> 100 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: No statistical differences between control and treated
Duration:
6 d
Dose descriptor:
EL50
Effect conc.:
> 100 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Not reached
Duration:
6 d
Dose descriptor:
other: EL 25
Effect conc.:
80.9 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Determined by linear interpolation
Duration:
6 d
Dose descriptor:
LOELR
Effect conc.:
> 100 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: No statistical differences between control and treated
Duration:
6 d
Dose descriptor:
NOELR
Effect conc.:
> 100 other: % WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: No statistical differences between control and treated
Details on results:
- Mortality of parent animals: see table 1 (§ Remarks on results including tables and figures)
- No. of offspring produced per day per female: see table 1 (§ Remarks on results including tables and figures)
Results with reference substance (positive control):
IC25 = 554 mg/L (95% Confidence interval: 136-745) (NaCl as mg/L Cl-)
Reported statistics and error estimates:
See table 2 (§ Remarks on results including tables and figures)

Table 1. Chronic exposure ofCeriodaphnia dubiato Vista C13-C16: Definitve test results

 

Test concentration (% WAF)

Survival (%) on each test day

 

Mean young per female

1

2

3

4

5

6

0 (Control)

100

100

100

100

90

90

18.0

12.5

100

100

100

100

100

100

16.8

25

100

100

100

90

90

90

15.7

50

100

100

100

100

90

90

13.0

75

100

100

100

100

100

90

15.8

100

100

100

100

100

100

100

10.6

 

 

Table 2. Chronic exposure ofCeriodaphnia dubiato Vista C13-C16: Statistical methods

 

End point

Comparison

Procedure

Survival

Significant reduction relative to the dilution water control

Inspection

Treshold inhibition concentration (IC25/EL25)

Inspection

Reproduction

Normality

Chi-Square test (α=0.01)

Homogeneity of variance

Bartlett’s test (α=0.01)

Significant reduction relative to the dilution water control

Dunnett’s test (α=0.05)

Treshold inhibition concentration (IC25/EL25)

Linear interpolation

Validity criteria fulfilled:
yes
Conclusions:
The NOELR for Ceriodaphnia dubia exposed to Vista C13-C16 was >100% WAF based on mortality and reproduction (no statistical differences between treatment groups)
Executive summary:

The study was performed to evaluate the toxicity of the water accommodated fractions (WAFs) of the test substance Vista C13-C16 to the water fleaCeriodaphnia dubia, in a semi-static system. The test was ended when 60% of the control females had produced 3 broods (6 days).

The water accommodated fractions were prepared by mixing 1 volume of the test substance with 10 volumes of dilution water. The dilution water was reconstituted moderately hard water prepared in the laboratory according to USEPA (USEPA, 1994. Short-term methods for estimating the chronic toxicity of effluents and receiving water to freshwater organisms. EPA/600/4-91/002). A range-finding test with 0, 1, 10 and 100 % WAF allowed setting the high concentration at 100% WAF for the definitive test. The definitive test was performed with 0, 12.5, 25, 50, 75 and 100 % WAF. The stock solution was prepared on alternate days as WAF by mixing 1 volume of test substance to 10 volumes of dilution water. The solution was mixed for 20±1 hours and the WAF was extracted from a point near the bottom of the mixing chamber by siphoning.

10 replicates, each containing one organism, were tested for each treatment. The test media were renewed daily. Mortality and reproduction were assessed daily.

 

An EL25(reported as IC25in the study report) was calculated for reproduction by linear interpolation:

EL25= 80.9 % WAF

 

However, the statistical study showed that there was no statistical difference between treatment groups (including control group) for mortality as well as for reproduction. Therefore, the No Observed Effect Loading Rate based on adult mortality and reproduction (expressed as number of young per female) was set at > 100 % WAF.

NOELR = 100% WAF

Description of key information

C14-20 Aliphatics (≤2% aromatic) are poorly soluble and made of constituents with various water solubilities. As a consequence, exposures were performed with Water Accommodated Fractions (WAFs). Therefore, the results are based on nominal loadings and no NOEC value can be given.

The 21-day EL50s for Hydrocarbons, C13-C16, isoalkanes, cyclics, <2% aromatics, based on adult immobilization and reduction in reproduction were >5 mg/L. The 21-day No Observed Effect Loading Rates (NOELRs) based on adult immobilization and reduction in reproduction was 5 mg/L.

The 21-day NOELR for Hydrocarbons, C13-C18, n-alkanes, isoalkanes, cyclics, <2% aromatics in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that Hydrocarbons, C13-C18, n-alkanes, isoalkanes, cyclics, <2% aromatics will not produce toxicity at or below its maximum attainable water solubility.

The 21-day NOELR for Hydrocarbons, C14-C17, n-alkanes, <2% aromatics in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that Hydrocarbons, C14-C16, n-alkanes, <2% aromatics will not produce toxicity at or below its maximum attainable water solubility.

The 21-day NOELR for Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, <2% aromatics in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that Hydrocarbons, C14-C18, n-alkanes, isoalkanes, cyclics, <2% aromatics will not produce toxicity at or below its maximum attainable water solubility.

The 21-day NOELR for Hydrocarbons, C14-C20, n-alkanes, <2% aromatics in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show Hydrocarbons, C14-C20, n-alkanes, <2% aromatics will not produce toxicity at or below its maximum attainable water solubility.

The 21-day NOELR for Hydrocarbons, C14-C20 (even numbered), n-alkanes, isoalkanes, <2% aromatics in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show Hydrocarbons, C14-C20 (even numbered), n-alkanes, isoalkanes, <2% aromatics will not produce toxicity at or below its maximum attainable water solubility.

The 21-day NOELR for Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, <2% aromatics in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, <2% aromatics will not produce toxicity at or below its maximum attainable water solubility.

The 21-day NOELR for Icosane in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that Icosane will not produce toxicity at or below its maximum attainable water solubility.

The 21-day NOELR for Isohexadecane in Daphnia magna is >1000.0 mg/L. Results of computer modelling to estimate chronicity in a 21-day freshwater invertebrate study, based on reproduction, show that Isohexadecane will not produce toxicity at or below its maximum attainable water solubility.

The NOELR for Ceriodaphnia dubia exposed to Hydrocarbons, C12-C15, n-alkanes, <2% aromatics was >100% WAF based on mortality and reproduction (no statistical differences between treatment groups).

The NOELR for Ceriodaphnia dubia exposed to Hydrocarbons, C14-C17, n-alkanes,<2% aromatics was >100% WAF based on mortality and reproduction (no statistical differences between treatment groups).

Key value for chemical safety assessment

Additional information

The aquatic toxicity of 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 partitioning coefficients (KMW) that describe the partitioning of the hydrocarbons between the water and organism.