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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
Study period:
no details given
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2011

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
GLP compliance:
not specified
Remarks:
no information on GLP compliance available in this publication

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: nanomaterial
Details on test material:
MWNT-7, with a mean diameter of 60 nm and BET surface area of 23 m2/g, was purchased from Mitsui & Co. Ltd. (Tokyo, Japan).

Test animals

Species:
rabbit
Strain:
other: Kbl:NZW
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Kitayama Labes Co. Ltd. (Ina, Japan)
- Age at study initiation: 17 weeks
- Weight at study initiation: 2.7 - 3.6 kg
- Housing: individually in standard aluminum cages
- Diet: LRC4; Oriental Yeast Co. Ltd., Tokyo, Japan, ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: 6 days prior to the start of the experiment

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.0-25.0 °C
- Humidity (%): 40-70%
- Air changes (per hr): ventilation of 15-21 air changes/h
- Photoperiod (hrs dark / hrs light): 12-h light (7:00-19:00)/dark (19:00-7:00) cycle

Test system

Type of coverage:
semiocclusive
Preparation of test site:
clipped
Vehicle:
other: olive oil
Controls:
not specified
Amount / concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): MWCNT-7 was moistened with a minimum amount of olive oil to prepare a paste for dermal application. The paste contained 2% MWCNT-7. This amount of MWCNT-7 was the maximum not leading to overlow when patched and the sample fully coated the skin. Olive oil was used to prepare the paste, because the olive oil was highly refined (neutral, denatured, and free of antioxidants) and widely used as the negative control in these expermiments.
An area of about 10 x 15 cm on the back of each rabbit was made free of fur using electric clippers and an electric shaver 24 h prior to testing. The MWCNT-7 paste (0.5 g) was evenly spread on a lint cloth (2.5 x 2.5 cm), applied to the skin, and covered with a gauze patch, which was held in place with non-irritating elastic bandage (Silkytex, Alcare Co. Ltd., Tokyo Japan).
Duration of treatment / exposure:
4 hours
Observation period:
Test sites were evaluated for signs of dermal irritation approximately 60 min, 24, 48, and 72 h after test substance removal.
Number of animals:
3
Details on study design:
TEST SITE
- Area of exposure: 6.25 cm2 (2.5 x 2.5 cm) clipped area of skin
- Type of wrap if used: gauze patch which was held in place with non-irritating elastic bandage

REMOVAL OF TEST SUBSTANCE
- Time after start of exposure: 4 h

OBSERVATION TIME POINTS
60 min, 24 h, 48 h, and 72 h

SCORING SYSTEM: Test sites were evaluated according to OECD TG 404.

Results and discussion

In vivo

Results
Irritation parameter:
primary dermal irritation index (PDII)
Basis:
mean
Time point:
24/48/72 h
Score:
0.6
Reversibility:
fully reversible within: 72 h
Irritant / corrosive response data:
No clinical signs or changes in body weight gain were observed in any groups treated with MWCNT-7. No dermal responses, including erythema/eschar or edema, were found in rabbits treated with MWNT-7. The PII was calculated to be 0.
Other effects:
None

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
No clinical signs or changes in body weight gain were observed. No dermal responses, including erythema/eschar or edema, were found in rabbits treated with MWNT-7. The PII was calculated to be 0.
Executive summary:

Acute dermal irritation was analyzed in a study performed according to method described in OECD guideline 404. New Zealand white rabbits received doses of 0.5 g of MWCNT-7-pastes containing 2% MWCNT-7 by application to a clipped area of the skin.

No clinical signs or changes in body weight gain were observed in any groups treated with MWCNT-7. No dermal responses, including erythema/eschar or edema, were found in rabbits treated with MWNT-7. The PII was calculated to be 0 in these group.

Hence based on the above findings MWCNT-7 test item was considered as non irritant to the skin of rabbits.

According to the criteria of Classification, Labelling and Packaging of Substances and Mixtures Regulation (EC) No 1272/2008 (CLP Regulation), classification as skin irritant is not warranted.