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Toxicological information

Dermal absorption

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Administrative data

Endpoint:
dermal absorption in vivo
Type of information:
other: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
Not reported
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Read across study
Justification for type of information:
Refer to Section 13 for details of the read-across justification.

Data source

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 427 (Skin Absorption: In Vivo Method)
Deviations:
not specified
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Radiolabelling:
yes

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male
Details on test animals or test system and environmental conditions:
- Source: Charles River Laboratories, Inc. (Raleigh, NC)
- Age at study initiation: 72 to 75 d
- Housing: Individual glass metabolism chambers, which allowed separate collection of carbon dioxide, urine, and feces.
- Individual metabolism cages: Yes
- Diet: Purina Rodent Chow (no. 5002), ad libitum
- Water: Ad libitum

Administration / exposure

Type of coverage:
open
Vehicle:
ethanol
Duration of exposure:
72 h
Doses:
- Actual doses: 50, 100, 200 and 800 mg/kg bw
- Dose volume: 50 µL of 50, 100 and 200 mg/kg bw and 30 µL of 800 mg/kg bw
No. of animals per group:
Four
Control animals:
no
Details on study design:
DOSE FORMULATION: 2 to 17 µCi radiolabel, an appropriate amount of unlabelled LDEA and 95% ethanol for a total volume of about 50 µL per dose


VEHICLE
- Concentration (if solution): 95%


TEST SITE
- Preparation of test site: Application site had been clipped of hair the previous day
- Area of exposure: 1 x 1 inch
- Type of cover / wrap if used: A non-occlusive protective appliance, glued over the dose area with cyanoacrylate adhesive.


SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: No


REMOVAL OF TEST SUBSTANCE: No



SAMPLE COLLECTION: Dose site skin was excised and thoroughly rinsed with ethanol, then gently wiped with cotton gauzes soaked with soapy water. Gauzes and aliquots of urine, dermal rinse solutions, feces, tissues (liver and kidney) and digested skin samples (in 2N ethanolic sodium hydroxide) were collected and analysed for radiochemical content by adding to vials containing scintillation cocktail (Ultima Gold, Packard Instrument Company).


ANALYSIS
- Method type(s) for identification: Liquid scintillation counting

Results and discussion

Signs and symptoms of toxicity:
not examined
Dermal irritation:
not examined
Absorption in different matrices:
After 72 h of exposure, 50 to 70% of the applied doses were absorbed and there were no statistically significant differences in absorption across the range of doses. The disposition of substance in the tissues was similar across the four dose levels.
Total recovery:
Approximately 91, 85, 88 and 85% at 50, 100, 200 and 800 mg/kg bw, respectively.
Percutaneous absorptionopen allclose all
Key result
Time point:
72 h
Dose:
50 mg/kg bw
Parameter:
percentage
Absorption:
ca. 49.1 %
Key result
Time point:
72 h
Dose:
100 mg/kg bw
Parameter:
percentage
Absorption:
ca. 66.8 %
Key result
Time point:
72 h
Dose:
200 mg/kg bw
Parameter:
percentage
Absorption:
ca. 69.1 %
Key result
Time point:
72 h
Dose:
800 mg/kg bw
Parameter:
percentage
Absorption:
ca. 50.2 %
Conversion factor human vs. animal skin:
No data

Applicant's summary and conclusion

Conclusions:
After 72 h of exposure, 50 to 70% of the applied doses were absorbed and there were no statistically significant differences in absorption across the range of doses. The disposition of substance in the tissues was similar across the four dose levels.

Executive summary:

A study was conducted to evaluate the dermal absorption of the (14C) radiolabelled read across substance N,N-bis(2-hydroxyethyl)dodecanamide (C12 DEA, also know as LDEA) in B6C3F1 mice. Four male mice were exposed to a single dose of 50, 100, 200 or 800 mg/kg bw of the substance placed on a 1x1 inch surface of previously clipped skin, covered with a non-occlusive patch. After 72 h of exposure, gauzes and aliquots of urine, faeces, dermal rinse solutions and digested skin samples (in 2N ethanolic sodium hydroxide) were collected and analysed for radiochemical content by liquid scintillation counting. After 72 h of exposure, 50 to 70% of the applied doses were absorbed and there were no statistically significant differences in absorption across the range of doses. The disposition of substance in the tissues was similar across the four dose levels (Mathews, 1996).