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Toxicological information

Dermal absorption

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Administrative data

Endpoint:
dermal absorption in vivo
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.

Data source

Reference
Reference Type:
publication
Title:
Absorption of some organic compounds through the skin in man
Author:
Feldmann RJ and Maibach HI.
Year:
1970
Bibliographic source:
The Journal of Investigate Dermatology, Vol 54, No.5, p399-404

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The authors studied the percutaneous penetration of thiourea. The experimental method consisted of the applciation of the chemical to the human forearm and quantitating its penetration through the skin by its appearance in urine. For analytic convenience, study was performed with radiolabeled (14C) tracer doses. Measurement was made of the isotope only.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
no data
Radiolabelling:
yes
Remarks:
14C

Test animals

Species:
human
Sex:
not specified
Details on test animals and environmental conditions:
no data

Administration / exposure

Type of coverage:
open
Vehicle:
acetone
Duration of exposure:
24 hours
Doses:
The amount of chemical applied was 4 µg/cm². The anatomic site as the ventral surface of the forearm.
The standard method was to apply a 4µg/cm² dose with one microcurie to a 13 cm² circular area. When the specific radioactivity of the chemical was loo low to obtain the desired chemical concentration, the area was increased. Where the specific activity was high, carrier compound was added.
No. of animals per group:
3 humans
Details on study design:
The skin site is not protected. The subjects were asked not to wash the area for 24 hours. All urine was collected for 5 days. The carbon was measured in individual specimens. The method is: wetashing 5 ml of urine with subsequent trappings of the 14C CO2 with ethanolamine. This was added to a scintillator fluid and counted with appropriate standards in a Beckman liquid scintillation counter.

Results and discussion

Signs and symptoms of toxicity:
not specified
Dermal irritation:
not specified
Total recovery:
Thiourea was penetrated in a quantity less than 1% of the applied dose (0.88% of the applied dose). The rate of the penetration differed in each collection period.
See in the table.
Percutaneous absorption
Dose:
4 µg/cm²
Parameter:
percentage
Absorption:
0.88 %
Remarks on result:
other: 120 hrs
Remarks:
in humans

Any other information on results incl. tables

Table : Absorption after topical administration.

 

Subs-tance

Absorption rate (% dose/hr)

Total absorption

Time (hrs)

% of dose

S.D.

# of subjects

0-12

12-24

24-48

48-72

72-96

96-120

thiourea

0.046

0.035

0.10

0.008

0.007

0.007

0.88

0.22

3

Applicant's summary and conclusion

Conclusions:
Thiourea was penetrated in a quantity less than 1% of the applied dose (0.88% of the applied dose) in humans.
Executive summary:

The authors studied the percutaneous penetration of thiourea. The experimental method consisted of the application of the chemical to the human forearm and quantitating its penetration through the skin by its appearance in urine. For analytic convenience, study was performed with radiolabeled (14C) tracer doses. Measurement was made of the isotope only. The amount of chemical applied was 4 µg/cm². The anatomic site as the ventral surface of the forearm. For accurate measurement, the chemical was dissolved in acetone and applied to a marked area with a microliter syringe. The skin site is not protected. Thiourea was penetrated in a quantity less than 1% of the applied dose (0.88% of the applied dose).