bis(2-ethylhexyl) (4-hydroxy-3,5-dimethoxybenzyl)malonate

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

dermal absorption in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008-02-06 to 2008-06-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 428 (Skin Absorption: In Vitro Method)

Version / remarks:

adopted March 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: SCCP/0970/06

Version / remarks:

adopted 28 March 2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Type of coverage:

open

Vehicle:

other: Cosmetic formulation

Duration of exposure:

24 hours

Doses:

Concentration of test material in Vehicle: 4%

Signs and symptoms of toxicity:

not examined

Dermal irritation:

not examined

Key result

Time point:

24 h

Parameter:

percentage

Absorption:

0.937 %

Conclusions:

Based on the results of this in vitro skin penetration test, the dermal absorption of the test item is 1.44 ± 1.69 μg/cm2 or 0.937 ± 1.16 % (mean value of 8 diffusion cells corresponding to 8 donors).

Executive summary:

The present study was designed to examine the in vitro percutaneous absorption of the test material through viable porcine skin. The test material was tested as a standard cosmetic formulation (LA-129/07-0-1-1) at 4 %.

Two independent experiments were performed on fresh dermatomed pig skin samples under static conditions with 6 diffusion cells per experiment. The thickness of the skin used was approximately 450 μm. The conductivity across the skin samples of each cell was determined before treatment and after the last sampling as a measure of skin integrity. Five (5) μL of the test item were applied on each skin sample, left on the skin for 24 hours and then washed off using 9 x 1 mL extraction solution (water : methanol, 40 : 60, v/v). The receptor solution used was 5 % BSA (w/v)/ 20 % (v/v) EtOH in PBS. The solubility of the test material in 5 % BSA (w/v) in PBS (containing 20 % organic solvent) was shown under the RCC Cytotest Cell Research GmbH study number 1139801 (non-GLP study) and is given up to 2.5 μg/mL. The dermal absorption was monitored over 24 hours under non-occluded static conditions.

The stratum corneum was separated by tape stripping from the epidermis and dermis. The tape stripes (2 x 5 stripes per sample) were pooled as two batches and each extracted for

analysis, respectively, as well as the remaining skin compartments.

The various sample solutions from the skin dermal absorption assay were analysed by LCMS/MS for the presence of the test material. Not all chambers met the

acceptance criteria for the recovery (100±15% of total amount applied) and, therefore, 8 chambers were used for the analysis of the test material. The LOD in receptor

solution was defined as 8.0 ng/mL and in extraction solution as 2.5 ng/mL. The LLOQ was 10.0 ng/mL in receptor solution and 5.0 ng/mL in extraction solution, respectively.

After the application of a formulation containing 4% test material for 24 hours, the vast majority of the test material was detected in the wash-off samples of any chamber. No test material was detected in the receptor fluid. However, for worst-case considerations the LOD in receptor solution was used for the calculation. Small amounts of the test material were detected in the stratum corneum (< 0.5 %) and the viable layers (< 1 %) of the skin. Details are provided in the following summary table:

Amount of test material in                                   Expressed as μg/cm2 of skin surface mean ± S.D. (n = 8)                     Expressed as % of dose mean ± S.D. (n = 8)

[μg/cm²]                                                                                              [%]

Amount applied                                                                                    165 ± 24.6                                                                                        100

Washing solution (after 24 hours)                                                        152 ± 14.9                                                                                    92.9 ± 8.54

Receptor fluid 1) (after 24 hours)                                                 0.0336 ± 0.00090                                                                             0.0207 ± 0.00306

Stratum corneum (isolated by tape stripping)                                   0.639 ± 0.969                                                                                    0.413 ± 0.642

Epidermis + Dermis (after 24 hours)                                                 1.40 ± 1.69                                                                                    0.917 ± 1.16

Recovery                                                                                           159 ± 13.6                                                                                    97.1 ± 8.43

Dermal absorption 2)                                                                       1.44 ± 1.69                                                                                        0.937 ± 1.16

1) Based on the LOD in receptor fluid

2) Dermal absorption is defined as the amount of test item in the receptor fluid, epidermis and dermis excluding tape strips

Under the reported conditions, the dermal absorption of the test item is 1.44 ± 1.69 μg/cm2 or 0.937 ± 1.16 % (mean value of 8 diffusion cells corresponding to

8 donors).

Description of key information

Based on the results of an in vitro skin penetration test, the dermal absorption of the test item is 1.44 ± 1.69 μg/cm2 or 0.937 ± 1.16 % .

Key value for chemical safety assessment

Absorption rate - dermal (%):

0.937