Triglycerides, C16-18 (even numbered), reaction products with diethylenetriamine

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vitro / ex vivo

Type of 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:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Publication on percutaneous absorption of anionic surfactants (soaps) is presented due to presence in and potential release of fatty acids C16-18 from the registered substance due to metabolic activation and presence of small quantities within the UVCB.

Data source

Reference

Reference Type:

publication

Title:

The percutaneous absorption of some anionic surfactants

Author:

D. Howes

Year:

1975

Bibliographic source:

J. Soc. Cosmet. Chem. 1975, 26, 47-63

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

In vitro penetration through rat skin

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium palmitate

EC Number:

206-988-1

EC Name:

Sodium palmitate

Cas Number:

408-35-5

Molecular formula:

C16H32O2.Na

IUPAC Name:

sodium palmitate

Constituent 2

Reference substance name:

Sodium stearate

EC Number:

212-490-5

EC Name:

Sodium stearate

Cas Number:

822-16-2

Molecular formula:

C18H36O2.Na

IUPAC Name:

sodium stearate

Test material form:

solid

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

Weight at study initiation: 100-120 g

Administration / exposure

Type of coverage:

open

Vehicle:

water

Remarks:

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 study design:

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)).
Assay: Diffusion cell, similar to those described by Ainsworth (J Soc Cosmet Chem 11:69 (1960))
Receptor fluid: saline

Results and discussion

Signs and symptoms of toxicity:

no effects

Dermal irritation:

no effects

Percutaneous absorption

Percutaneous absorption 1

Key result

Time point:

24 h

Dose:

86.73 µg fatty acid C16:0/cm²

Parameter:

percentage

Absorption:

0.2 %

Percutaneous absorption 2

Key result

Time point:

24 h

Dose:

91.84 µg fatty acid C18:0/cm²

Parameter:

percentage

Absorption:

< 0.1 %

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. 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 C16 and C18 fatty acids (as aqueous sodium salt solutions) through rat skin decreases with increasing chain length. At 86.73 µg fatty acide C16/cm² and 91.84 µg fatty acid C18/cm², about 0.2% and less than 0.1% of the C16 and C18 sodium soap solutions is absoberd after 24 h exposure, respectively.