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Environmental fate & pathways

Distribution modelling

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Administrative data

Endpoint:
distribution modelling
Type of information:
(Q)SAR
Adequacy of study:
key study
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:
1. SOFTWARE
EPI suite (v4.10)

2. MODEL (incl. version number)
different models are used within the EPI suite for Mackay III calculations
Mackay III is not based on QSAR but some input values are (Henry's law constant, AOP, evaporation for surface water)
corresponding QMRFs are attached
respective QMRF FOR AOP is attached in the IUCLID endpoint 5.1.1 Phototransformation in air AOP

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Hexadecane: CCCCCCCCCCCCCCCC
5-ethyl-6-propylundecane: CCCCC(CC)C(CCC)CCCCC
4,5-diethyl-3,4,5,6-tetramethyloctane: CCC(C)C(CC)(C)C(CC)(C)C(C)CC
3,4,5,6,7,8-hexamethyldecane: CCC(C(C(C(C(C(CC)C)C)C)C)C)C


4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
see QMRFs attached

5. APPLICABILITY DOMAIN
see QMRFs attached

6. ADEQUACY OF THE RESULT
see QMRFs attached

Data source

Materials and methods

Model:
calculation according to Mackay, Level III
Calculation programme:
EPI suite (v4.10)
Release year:
2 011
Media:
other: air - water - soil

Test material

Details on test material:
Four representative structures of Tetrabutane (C16) with different amount of branching are listet with corresponding SMILES
Hexadecane: CCCCCCCCCCCCCCCC
5-ethyl-6-propylundecane: CCCCC(CC)C(CCC)CCCCC
4,5-diethyl-3,4,5,6-tetramethyloctane: CCC(C)C(CC)(C)C(CC)(C)C(C)CC
3,4,5,6,7,8-hexamethyldecane: CCC(C(C(C(C(C(CC)C)C)C)C)C)C
Specific details on test material used for the study:
Hexadecane: CCCCCCCCCCCCCCCC
5-ethyl-6-propylundecane: CCCCC(CC)C(CCC)CCCCC
4,5-diethyl-3,4,5,6-tetramethyloctane: CCC(C)C(CC)(C)C(CC)(C)C(C)CC
3,4,5,6,7,8-hexamethyldecane: CCC(C(C(C(C(C(CC)C)C)C)C)C)C

Study design

Test substance input data:
Input: SMILES for the 4 substances specified above
other parameter calculated by EPI suite (v4.10)
Environmental properties:
EPI suite (v4.10) default settings

Results and discussion

Percent distribution in media

Other distribution results:
Volatilization half-life from natural water for C16-Tetradecane isomers is highest for lake with 143 hours.
Total persistence times for emission only to water is highest for 3,4,5,6,7,8-hexamethyldecane (compared to the other 3 substances) with 581 hours.
(see table below "Any other information on results inc. tables"

Any other information on results incl. tables

EPI Suite 4.10:

Water Volatilization Model
Volatilisation from 

river and lake

3-methyl, 4-ethyl, methyl, 5-ethyl, methyl, 6-methyl, octane

3,4,5,6,7,8-hexamethyldecane

5-ethyl-6-propylundecane

hexadecane

Volatilization From Water

River

half-life [h]

1,5

1,5

1,5

1,5

Volatilization From Water

Lake

half-life [h]

142,9

142,9

142,9

143

EPI Suite 4.10:

persistence time for different emission scenarios

3-methyl, 4-ethyl, methyl, 5-ethyl, methyl, 6-methyl, octane

3,4,5,6,7,8-hexamethyldecane

5-ethyl-6-propylundecane

hexadecane

Mackay III:

persistence time [h]

Emissions to:

Air/Water/Soil

1000/1000/1000

211

206

93,1

191

Mackay III:

persistence time [h]

Emissions to:

Air/Water/Soil

0/1000/0

577

581

238

239

Mackay III:

persistence time [h]

Emissions to:

Air/Water/Soil

0/0/1000

31,2

22,4

25,9

321

Mackay III:

persistence time [h]

Emissions to:

Air/Water/Soil

1000/0/0

23,9

14,8

15

13

Applicant's summary and conclusion

Conclusions:
For the worst case scenario "all emissions to water" the highest environmental persistence time (calculated according to Mackay III) is 581 hours for 3,4,5,6,7,8-hexamethyldecane. "All emissions to water" is also the szenario with the highest persistence time for 3-methyl, 4-ethyl, methyl, 5-ethyl, methyl, 6-methyl, octane and 3,4,5,6,7,8-hexamethyldecane and 5-ethyl-6-propylundecane. For hexadecane, "all emission to soil" is the szenario with the highest persistence time of 321 hours.
Other scenarios considered are "all emissions to air" "equal emissions to air, water, soil" as well as all emissions to two compartements.
Executive summary:

For 4 representative Tetrabutane (C16) structures with different degree of branching, the non-equilibrium, steady state distribution according to Mackay Level III was calculated. The calculation results in the steady state distribution of a chemical in the environment as well as persistence time, considering degradation, advection and intermedia transfer.

Input parameters for the Mackay III calculations of the 4 substances were obtained from Epi suite (v4.10) (based on SMILES).

Different emission scenarios are calculated - in particular all emissions to air resp. water resp. soil.

For the scenario "all emissions to water" the highest environmental persistence times are found:

for 3,4,5,6,7,8-hexamethyldecane 581 hours

for 4,5-diethyl-3,4,5,6-tetramethyloctane 577 hours

for 5-ethyl-6-propylundecane 238 hours.

Whereas for hexadecane, "all emission to soil" is the scenario with the highest persistence time of 321 hours.

Other scenarios considered are "all emissions to air" "equal emissions to air, water, soil" as well as all emissions to two compartements.

(However, the latter was not shown here with figures. The figures are included in the annexes).