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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin irritation: in vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Effects of environmentally realistic levels of ozone on stratum corneum function
Author:
He QC, Tavakkol A, Wietech K, Begum-Gafur R, Ansari SA and
Year:
2006
Bibliographic source:
International Journal of Cosmetic Science, 28, 349–357

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Human forearm skin was exposed to ozone and the effects on vitamin E, lipid peroxide, cutaneous bacteria and several key enzymes in the stratum corneum were studied.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Ozone
EC Number:
233-069-2
EC Name:
Ozone
Cas Number:
10028-15-6
Molecular formula:
O3
IUPAC Name:
trioxygen
Test material form:
gas
Specific details on test material used for the study:
The test material was generated by passing pure oxygen through an electric discharge.

Test animals

Species:
human
Details on test animals or test system and environmental conditions:
Caucasian females between the ages of 18 and 55.

Test system

Type of coverage:
open
Preparation of test site:
other: The volunteers refrained from using cosmetics, body oils, sunscreens or moisturizers on their arms 7 days prior to the study or during the study.
Vehicle:
other: air
Controls:
yes, concurrent vehicle
Amount / concentration applied:
Arms were exposed to an atmosphere containing 0.8 ppm ozone.
Duration of treatment / exposure:
2h
Observation period:
0.5 h after exposure the arms were visually inspected for erythema, skin dryness and oedema.
Number of animals:
20 volunteers participated in the first part of the study and 19 in the second part.
Details on study design:
Forearms were exposed 2h to the gas inside a chamber with a continuous flow of ozone (0.8 ppm). The ozone concentration was on-line monitored by means of UV detection. Effects were scored according to Sharko et al., 1991 which is used for evaluation of the irritating potential of personal washing products.

Results and discussion

In vivo

Resultsopen allclose all
Irritation parameter:
erythema score
Time point:
24/48/72 h
Remarks on result:
not measured/tested
Irritation parameter:
edema score
Time point:
24/48/72 h
Remarks on result:
not measured/tested
Irritant / corrosive response data:
no data
Other effects:
Vitamin E: ozone exposure resulted in a significantly reduced recoverable amount of vitamin E, 5.13 ± 1.47 pmol/square cm vs. 1.55 ± 0.49 pmol/square cm.
Lipid hydroperoxide: ozone exposure resulted in a significantly increased recoverable amount of LPO, 1385 pmol/square cm vs. 3249 pmol/square cm.
Bacterial viability: ozone exposure resulted in a significantly reduced number of recoverale viable bacteria. 37 ± 9 CFE/square cm agar vs. 19 ± 5 CFE/square cm agar.
Stratum corneum tryptic and chymotryptic proteases and transglutaminase activity were not affected.

Applicant's summary and conclusion

Interpretation of results:
study cannot be used for classification
Conclusions:
2 hours of 0.8 ppm ozone exposure to humans forearms significantly reduced vitamin E, lipid peroxide, cutaneous bacteria and several key enzymes in the stratum corneum. Half an hour after exposure, visually scoring revealed no skin irritation. Further, the study provides supportive information that acute high ambient ozone levels react with antioxidants and oxidizes lipids without affecting stratum corneum enzymes.
Executive summary:

The present research study, published in a peer-reviewed journal, was designed to study the effects of 2 hours exposure to 0.8 ppm ozone to humans forearms on stratum corneum vitamin E, lipid peroxide, cutaneous bacteria and several key stratum corneum enzymes as well as visual scoring of irritating effects. Using a specially designed O(3) exposure chamber, the study provides evidence that exposure of human skin to O3 (0.8 ppm, 2-h time-weighted average) significantly reduced vitamin E by 70% and concomitantly increased lipid hydroperoxides by 2.3 fold in the superficial stratum corneum (SC). Although the dose of O3 used here reduced the resident microflora population by 50% and created a state of oxidative stress within the SC, it did not affect several key enzymes involved in SC homeostasis including the redox-sensitive transglutaminase and the SC tryptic (KLK5) and chymotryptic (KLK7) proteases. Importantly, no signs of skin dryness or erythema were observed. The authors hypothesize that the limited effects of low doses of O3 on SC function is attributable to several factors including: (i) protection provided by the anti-oxidant defence system; (ii) inability of O(3) to penetrate the SC; and (iii) limited water available to catalyse the Criegee reaction. Although chronic exposure to O3 may produce a different outcome than that reported here, our data suggest that exposure to environmentally relevant doses of O3, at best, induces a moderate state of oxidative stress, without producing a visible clinical response.

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