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Administrative data

Endpoint:
dermal absorption in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 2002-04-10 to 2002-05-23
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well documented GLP-study, performed in the spirit of the OECD guideline 428.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report date:
2002

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 428 (Skin Absorption: In Vitro Method)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
4-hydroxymethyl-1,3-dioxolan-2-one
EC Number:
213-235-0
EC Name:
4-hydroxymethyl-1,3-dioxolan-2-one
Cas Number:
931-40-8
Molecular formula:
C4H6O4
IUPAC Name:
4-(hydroxymethyl)-1,3-dioxolan-2-one
Details on test material:
- Name of test material (as cited in study report): Glycerine carbonate technical grade material
- Physical state: Colourless liquid
- Analytical purity: 97.2 %
- Purity test date: 12 October 2001
- Lot/batch No.: CB 12240002
- Storage condition of test material: Ambient temperature in the dark
- Other: specific gravity: 1.4
Radiolabelling:
no

Test animals

Species:
pig
Strain:
not specified
Sex:
not specified

Administration / exposure

Type of coverage:
open
Vehicle:
unchanged (no vehicle)
Duration of exposure:
After application of the test material, half the membranes were rinsed off after a 0.5h contact period, with the penetration of glycerine carbonate though the membrane being assessed throughout the entire 24h exposure period, while the rest of the membranes remained in continuous contact with the dose for the entire 24h.
Doses:
The test material was applied undiluted to six skin membranes of each group at a rate of 10 µL/cm² (= 13608 µg/cm², corrected for specific gravity of 1.4 and purity of 97.2%) and left unoccluded. The remaining membranes in each group were left as untreated controls. The applications were spread over the surface of the skin using silicone rubber loops. These spreaders were extracted in water (5mL) and a sample analysed for inclusion in mass balance determination.
Details on in vitro test system (if applicable):
SKIN PREPARATION
- Source of skin: Skin of 6-8 old pigs obtained from a local abattoir was used.
- Type of skin: dermatomed pig epidermis from full thickness skin
- Preparative technique: The skins were cleaned under running water, blotted dry and the hair carefully shaved with clippers.
- Thickness of skin (in mm): 400 µm
- Membrane integrity check: The integrity of the membranes was determined by measurement of their electrical resistance accross the skin membrane. Membranes with a measured resistance of <3kΩ were regarded as having a lower integrity than normal and not used for exposure to the test material.
- Storage conditions: The full thickness skin was cut with an Aesculap Accu Dermatome set at 400 µm and stored frozen on aluminium foil, labelled with the skin number, until required for use.

PRINCIPLES OF ASSAY
- Diffusion cell: The glass diffusion cell used in this study has an exposed membrane area of 2.54 cm². Discs of approximately 3.3 cm diameter of prepared skin membrane from at least three subjects were mounted, dermal side down, in diffusion cells held together with individually numbered clamps and placed in a water bath maintained at 32 ± 1°C.
- Receptor fluid: deionized water.
- Solubility of test substance in receptor fluid: 1-10% (sufficient to ensure that the test substance can freely diffuse through the membrane and dissolve in the receptor fluid). A pretreatment sample (0.5 mL) was taken from each receptor chamber for analysis by GLC. An equal volume of fresh receptor fluid was added to each receptor chamber to replace the volume removed.

Results and discussion

Signs and symptoms of toxicity:
not examined
Dermal irritation:
not examined
Absorption in different matrices:
- Skin preparation (in vitro test system):
Experiment 1: absorption <0.750 µg/cm²/h, equivalent to <0.13%o of the applied dose (except one cell at 0.14%).
Experiment 2 : absorption was 2.10 µg/cm²/h between 8-24h (average rate over the whole 24h period: 1.51 µg/cm²/h). The proportions of the dose absorbed at 8, 12 and 24 h were 0.14 %, 0.14 % and 0.28%.
Total recovery:
Experiment 1 (contact period 0.5h; exposure period 24h): The total amount of glycerine carbonate recovered was 97.7 % of the dose, of which the majority (95.4 %) was removed from the surface of the skin and donor chamber during rinsing with water at 0.5h. No further significant amounts glycerine carbonate were washed off at 24h (<0.01%, except for one cell at 0.97 %). No glycerine carbonate (<0.003 %) was recovered from the skin membrane.

Experiment 2 (exposure period 24h): The total amount of glycerine carbonate recovered was 93.5 % of the dose, of which the majority (72.1 %) was removed from the surface of the skin and donor chamber during rinsing with water at 24h. From 3 of the cells, no glycerine carbonate (<0.003 %) was recovered from the skin membrane, however from the remaining 3 cells between 32 % and 45.3 % of the dose was extracted. These higher amounts in the skin are associated with lower amounts being washed of the skin surface. The reason for the variable effectiveness of the washing prodecure in uncertain, however the results indicate that absorption of glycerine carbonate was not affected.

Any other information on results incl. tables

Permeability coefficients:

Although this experiment was not designed to determine permeability coefficients (i.e. the dose was finite and unoccluded), since the volatility of glycerine carbonate is low and significant amounts remained on the surface of the skin at the end of the experiment, it was possible to estimate a permeability coefficient (Kp) of 1.54 x 1E-06 for the 8 -24h period.

Applicant's summary and conclusion

Conclusions:
The results obtained in this study indicate that the absorption of glycerine carbonate through dermatomed pig epidermis is extremely slow, when compared with the absorption rates of other penetrants measured through human skin using this in vitro technique (Dugard et al., 1984; Dugard and Scott, 1984). These data predict that the dermal absorption of glycerine carbonate from potential exposure would be minimal.

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