Multi-Walled Carbon Nanotubes (MWCNT), synthetic graphite in tubular shape

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

deviation: analytical determinations of the stability of the formulations in vaseline for administration were not performed.

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Guideline guinea pig maximisation test that followed sound scientific principles.

Test material

Test material information

Constituent 1

Reference substance name:

carbon

EC Number:

936-414-1

Molecular formula:

C

IUPAC Name:

carbon

Test material form:

solid: nanoform, no surface treatment

In vivo test system

Test animals

Species:

guinea pig

Strain:

other: Crl: HA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River (Kißlegg, Germany)
- Age at study initiation: 5-6 weeks
- Weight at study initiation: 338-390 g
- Housing: 2 or 5 animals per cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%): 40 - 70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

epicutaneous, occlusive

Vehicle:

other: vaseline

Induction 2

Concentration / amount:

1st induction: 23.8 % 
2nd induction: 23.8 %
Challenge: 23.8 %

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: vaseline

Challenge 2

Concentration / amount:

1st induction: 23.8 % 
2nd induction: 23.8 %
Challenge: 23.8 %

No. of animals per dose:

20 (test group); 10 (control group); 5 (dose-range finding group)

Details on study design:

FIRST INDUCTION (topical with regard to test substance; intradermal with regard to Freund´s adjuvant):
The dorsal region and the flanks of the guinea pigs were shorn one day prior to the application. Starting behind the nape of the neck, two injections each in a row were made on the left and the right side of the spinal column. Hypoallergenic patches (2 cm x 4 cm) were placed between the injection sites, covered with aluminium foil and held securely in place for 24 hours on the skin using a ORABAND® selfadhesive tape (Fa. Orafol).
The animals were treated as folIows:
Four injections (cranial/bilateral): complete Freund's adjuvant (DIFCO LAB.) diluted 1:1 with sterile physiological saline solution. The test item was not applicable to injections. The volume applied per injection site was 0.1 ml.
The patches were treated as folIows:
a) Test itern group: 250 mg BAYTUBES C 150 PI 1.0 ml vaseline
b) Contral graup: 0.5 ml vaseline
At the end of the 24-hour exposure period, the remaining test item was removed with sterile physiological saline. The injection sites and the treatment area between the injections were visually assessed 2 and 7 days after the injection.

SECOND INDUCTION:
The topical induction was performed one week after the intradermal induction. One day prior to topical treatment, the test areas of the animals were shorn. Hypoallergenic patches (2 cm x 4 cm) were placed between and on the injection sites, covered with aluminium foil and held securely in place on the skin using a ORABAND® self-adhesive tape (Fa. Orafol).
The patches were treated as folIows:
a) Test item group: 250 mg BAYTUBES C 150 PI 1.0 ml vaseline
b) Control group: 0.5 ml vaseline
At the end of the 48-hour exposure period, the remaining test item was removed with sterile physiological saline.

CHALLENGE:
The challenge was performed three weeks after the intradermal induction. The dorsal region and the right flank of the animals were shorn one day prior to the challenge. During the challenge a hypoallergenic patch loaded with the 23.8 % test item paste was placed on the right flank (caudal) of the animals of the test item group and the control group and held securely in place on the skin with an ORABAND® self-adhesive tape for 24 hours. A patch only loaded with 0.5 ml vaseline was placed also on the right flank (cranial) as control. At the end of the exposure period, the remaining test item was removed with sterile physiological saline and twenty-one hours later the treated areas were shorn in the zone of the challenge area.

The doses for the induction and challenge treatments were selected on the basis of the results of a dose range-finding study using 5 animals.

Challenge controls:

see "Details on study design"

Positive control substance(s):

yes

Remarks:

alpha hexyl cinnamic aldehyde

Results and discussion

Positive control results:

Using a 5% formulation of alpha hexyl cinnamic aldehyde for intradermal induction, a 25 % formulation for topical induction and 6% formulation for challenge, 90 % of the test animals exhibited dermal reactions. There was no reddening of the skin to be observed on control group animals.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

23.8 % test substance formulation

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 23.8 % test substance formulation. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Results 2

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

23.8 % test substance formulation

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 23.8 % test substance formulation. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Results 3

Reading:

1st reading

Hours after challenge:

48

Group:

negative control

Dose level:

23.8 % test substance formulation

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 23.8 % test substance formulation. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Results 4

Reading:

2nd reading

Hours after challenge:

72

Group:

negative control

Dose level:

23.8 % test substance formulation

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 23.8 % test substance formulation. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Results 5

Group:

positive control

Remarks on result:

other: 90 % of the test animals exhibited dermal reactions

Any other information on results incl. tables

Appearance and behaviour of the test itern group were not different from the control group.

At the end of the study, the mean body weight of the treatment group animals was in the same range than that of the control group animals.

After the intradermal induction of FCA (first induction) the animals in the control group and test item group showed after 48 hours at the injection sites: red wheals.

After 7 days the following effects were recorded at the injection sites in the control group and in the test item group: wheals and encrustation.

There were no skin effects (redness) on the treatment areas between the injection sites (FCA) of the first induction in the control or test item group after 48 hours and 7 days.

The challenge with the 23.8 % test item concentration did not lead to skin effects in the animals of the test item group and the control group.

Applicant's summary and conclusion

Executive summary:

In a guinea pig maximization test (GPMT) according to OECD TG 406 Baytubes C150 P (formulated in vaseline) revealed no skin sensitizing potential at a challenge concentrations of 23.8 %. None of the female test or control animals exhibited skin effects after 48 and 72 hours readings..