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Dermal absorption

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dermal absorption
Type of information:
experimental study
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Experimental details and results are not presented in great detail; several aspects remain unclear: (i) Information on actually applied dose not clear: “70µg/cm² of silver nanoparticles dispersed in ethanol absolute 0.14 wt% and diluted 1:10 with synthetic sweat at pH 4.5 to reproduce in vivo conditions”. It is unclear whether this refers to 70 µg silver or 70 µg of of the suspension, or 70 µg of the diluted suspension per cm². Is it 0.14% (wt) Ag in ethanol? Or is there 0.14% (wt) ethanol added to the silver? Based on other sections in the text, one may assume that it is 70 µg Ag/cm², and this dose has been used to calculated the percutaneous absorption rate in %. (ii) no justification given for the selection of the dose (relation to potential exposure of workers or members of the general population?) and for rather long exposure time (24h) (iii) number of replicates per test is not reported. (iv) no raw data / primary analytical results presented. (v) no mass balance is presented.

Data source

Reference Type:
Human skin penetration of silver nanoparticles through intact and damaged skin
Larese, F. et al.
Bibliographic source:
Toxicology 255, 33-37

Materials and methods

Principles of method if other than guideline:
Percutaneous absorption study in-vitro, human skin, with polyvinylpirrolidone coated AgNPs applied as "0.14% (wt.) dispersion in ethanol absolute"; mean particle size 25nm.

Test material

Constituent 1
Reference substance name:
nanosilver, polyvinylpirrolidone coated
nanosilver, polyvinylpirrolidone coated
Test material form:
other: nanomaterial, 25±7.1 nm, Source: self-synthesised
Details on test material:
Silver nanoparticles synthesis was carried out according to the method described by Graf et al. (2003)*.
Synthesis included a stabilization step to prevent irreversible particle aggregation on dispersion in an aqueous medium. Stabilization
was achieved by coating the nanoparticle core with polyvinylpirrolidone. A 0.14 wt% silver coated nanoparticles solution in ethanol absolute 99% was used. TEM measurements revealed that silver nanoparticles were as small as 25±7.1 nm, 25–75th percentiles 19.5–29.3, minimum 9.8 nm, maximum 48.8nm with 5% larger than 36.6 nm.

* Reference:
Graf, C., Vossen, D.L.J., Imhof, A., van Blaaderen, A., 2003: A general method to coat colloidal particles with silica. Langmuir 19, 6693–6700.

Results and discussion

Absorption in different matrices:
Silver nanoparticles absorption through intact and damaged skin was very low but detectable. Permeation of particles was higher through damaged skin than through intact skin.
Total recovery:
no data
Percutaneous absorptionopen allclose all
70 µg/cm^2
ca. 0.001 %
Remarks on result:
other: 24h
For intact skin: Calculated from an applied dose of 70 µg/cm^2, and using the reported median penetrated amount during 24h of 0.46 ng/cm^2.
70 µg/cm^2
ca. 0.003 %
Remarks on result:
other: 24h
For damaged skin: Calculated from an applied dose of 70 µg/cm^2, and using the reported median penetrated amount during 24h of 2.32 ng/cm^2.

Applicant's summary and conclusion