Registration Dossier

Administrative data

Endpoint:
dermal absorption in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to Guideline study with acceptable restrictions (no details about the test substance; skin temperature 34 °C [32 °C recommended]; 3 replicates but at least 4 recommended).

Data source

Reference
Reference Type:
publication
Title:
Permeability of commercial solvents through living human skin
Author:
Ursin C, Hansen CM, Van Dyk JW, Jensen PO, Christensen IJ, Ebbehoej J
Year:
1995
Bibliographic source:
Am Ind Hyg Assoc J 56: 651-660

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 428 (Skin Absorption: In Vitro Method)
Deviations:
yes
Remarks:
No details about the test substance; skin temperature 34°C (instead of 32°C); 3 replicates instead of 4
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Specific details on test material used for the study:
- Name of test material: dimethylacetamide (DMAC)
- Composition of test material, percentage of components: highest available commercial quality
No further details available.
Radiolabelling:
no

Test animals

Species:
human
Sex:
female
Details on test animals and environmental conditions:
Skin specimen of women were used; living skin was obtained during plastic surgery of the breast.

Administration / exposure

Type of coverage:
other: in vitro cell; cap prevented pressure build-up in the challenge half cell, containing the test substance
Vehicle:
unchanged (no vehicle)
Duration of exposure:
Sampling was performed 0.16, 0.33, 0.5 (or 0.66), 1, 2, 4, 6 h after application of the test substance (0.5 mL of the receptor fluid).
Doses:
Undiluted test substance was placed in the challenge half of the cell.
No. of animals per group:
3 measurements were conducted using the skin samples of the same donor.
Control animals:
yes
Remarks:
control for leakage of skin
Details on study design:
The exposed skin area was 0.64 cm².
Details on in vitro test system (if applicable):
SKIN PREPARATION
- Source of skin: skin obtained during plastic surgery of the breast
- Ethical approval if human skin: no data
- Type of skin: skin of the breast
- Preparative technique: dermal tissue removed from the epidermis using a Downs-Watson dermatome
- Thickness of skin in the cell: 300-600 µm
- Membrane integrity check: yes, relative permeability was tested with 3H water for 2 h.
- Viability test: Skin viability was detemined prior to experiments by assessing the ability of the skin cells to engage in DNA synthesis as measured by incorporation of BrdU.

PRINCIPLES OF ASSAY
- Diffusion cell: Franz diffusion cell
- Receptor fluid: isotonic, nourished, saline solution (Dulbecco's medium) with gentamycin (50 µg/mL)
- Solubility od test substance in receptor fluid: yes
- Static system: yes
- Test temperature: 37 °C of the bath resulting in 34 °C of the skin
- Occlusion and humidity: cap prevented pressure build-up in the challenge half cell.

Results and discussion

Signs and symptoms of toxicity:
not specified
Remarks:
(in vitro)
Dermal irritation:
not specified
Remarks:
(see freetext for cell viability at termination)
Absorption in different matrices:
not applicable, in vitro
Total recovery:
not applicable, in vitro
Percutaneous absorption
Remarks on result:
other: at steady state
Remarks:
Permeability constant: 107 ± 19 g/m²/h (mean ± SD, n = 3)
Conversion factor human vs. animal skin:
Human skin was used.

Any other information on results incl. tables

Prior to the permeability test, no leakage of skin and cell viability was given. Skin cell viability was checked after the permeability test (DNA synthesis as measured by incorporation of BrdU);

Result: no labelling of cells (not clearly discussed by the authors).

A normalization procedure was used to assess the effects of 3H-water on permeability: after normalisation the permeability constant was 217 ± 84 g/m²/h.

In in vitro skin absorption experiments, the skin of a female donor was used. Viability and skin integrity check was performed prior to experiments. In the diffusion cell the skin was exposed to undiluted test substance and 0.5 mL samples of receptor fluid were collected 0.16, 0.33, 0.5 (or 0.66), 1, 2, 4, 6 h after application of the test substance. Totally 3 trials were performed.

The authors calculated a permeability constant of 107 ± 19 g/m²/h (mean ± SD of 3 trials).

Applicant's summary and conclusion