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Toxicological information

Dermal absorption

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Administrative data

Endpoint:
dermal absorption in vitro / ex vivo
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication which meets basic scientific principles.

Data source

Reference
Reference Type:
publication
Title:
The percutaneous absorption of some anionic surfactants
Author:
Howes, D.
Year:
1975
Bibliographic source:
J. Soc. Cosmet. Chem. 26:47-63

Materials and methods

Principles of method if other than guideline:
In vitro penetration through rat skin
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Sodium salts of Decanoic acid (C10:0), Dodecanoic acid (C12:0), Tetradecanoic acid (C14:0), Hexadecanoic acid (C16:0), Octadecanoic acid (C18:0)
- Analytical purity: Pure biochemical grade
- Specific activity (if radiolabelling): 14 mCi/mM
- Locations of the label (if radiolabelling): 1-Alkyl position with 14C (1-14C)
Radiolabelling:
yes

Test animals

Species:
rat
Strain:
Wistar
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Weight at study initiation: 100-120 g

Administration / exposure

Type of coverage:
open
Vehicle:
other: The test materials were applied as soap solutions (sodium salts).
Duration of exposure:
24 h
Doses:
- Nominal doses: 300 µg C10:0, 325 µg C12:0, 375 µg C14:0, 425 µg C16:0 and 450 µg C18:0/4.9 cm² skin
- Dose volume: 0.051 ml/cm²
No. of animals per group:
not specified
Control animals:
no
Details on in vitro test system (if applicable):
SKIN PREPARATION
- Source of skin: rat dorsal skin
- Type of skin: full thickness skin
- Preparative technique: Dorsal skin was clipped 24 h before cervical dislocation. The skin was excised and mounted in 2.5 cm penetration cells similar to those described by Ainsworth (J Soc Cosmet Chem 11:69 (1960)).



PRINCIPLES OF ASSAY
- Diffusion cell: similar to those described by Ainsworth (J Soc Cosmet Chem 11:69 (1960)).
- Receptor fluid: saline
- Occlusion: no

Results and discussion

Percutaneous absorptionopen allclose all
Dose:
61.22 µg C10:0/cm²
Parameter:
percentage
Absorption:
ca. 14 %
Remarks on result:
other: 24 h
Remarks:
8.6 ± 3.4 µg C10:0/cm² absorbed (n=3)
Dose:
66.33 µg C12:0/cm²
Parameter:
percentage
Absorption:
ca. 10.9 %
Remarks on result:
other: 24 h
Remarks:
7.2 ± 3.7 µg C12:0/cm² absorbed (n=3)
Dose:
76.53 µg C14:0/cm²
Parameter:
percentage
Absorption:
ca. 9 %
Remarks on result:
other: 24 h
Remarks:
6.9 ± 3.0 µg C14:0/cm² absorbed (n=3)
Dose:
86.73 µg C16:0/cm²
Parameter:
percentage
Absorption:
0.2 %
Remarks on result:
other: 24 h
Remarks:
0.2 ± 0.1 µg C16:0/cm² absorbed (n=3)
Dose:
91.84 µg C18:0/cm²
Parameter:
percentage
Absorption:
< 0.1 %
Remarks on result:
other: 24 h
Remarks:
< 0.1 µg C18:0/cm² absorbed (n=3)
Conversion factor human vs. animal skin:
no data

Any other information on results incl. tables

The results show no measurable penetration of the C18:0 soap through rat skin up to 24 h after application, but 0.2 µg/cm² of the C16:0 soap had penetrated at 24 h. Some 7.5 µg of the C10:0, C12:0 and C14:0 soaps had penetrated per cm² at 24 h but the results were not significantly different for the three soaps. For the three soaps which penetrated the skin there was a lag time of 1 h before any measurable penetration occurred, but after this the rate of penetration steadily increased. At the

end of the experiment,i .e. 24 h after application, between 60 and 70% of the applied [14C] soaps were rinsed from the skin and 30-40% was associated with the skin.

Applicant's summary and conclusion

Conclusions:
The in vitro penetration of C10, C12, C14, C16 and C18 fatty acids (as sodium salt solutions) through rat skin decreases with increasing chain length. At 86.73 µg C16/cm² and 91.84 µg C18/cm², about 0.23% and less than 0.1% of the C16 and C18 soap solutions is absoberd after 24 h exposure, respectively.