Non-graphitic carbon fibre

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-10-09 to 2013-01-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Version / remarks:

Commission Regulation (EC) No 761/2009, Annex III, B.46

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

carbon

EC Number:

701-026-1

Cas Number:

7440-44-0

Molecular formula:

C up to (C80N5H16O)n

IUPAC Name:

carbon

Test material form:

solid: fibres

Details on test material:

- milled carbonised PAN based fibre (Sigrafil C30 M150 UNS)
- for further details on the test material, see section 1.4, endpoint "Non-graphitic carbon fibre (carbonised PAN based fibre, milled)", attached document "Analytics_milled_carbonised_PAN_based_fibre.pdf"

Test animals

Species:

other: reconstructed human epidermal skin model

Details on test animals or test system and environmental conditions:

not applicable

Test system

Type of coverage:

other: not applicable

Preparation of test site:

other: not applicable

Amount / concentration applied:

approx. 25 mg of test item per well

Duration of treatment / exposure:

60 +/- 1 min

Observation period:

MTT assay performed 42 hrs (in total) after incubation

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Value:

106.4

Negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Table 1: Individual measured values of the optical density (OD) and percentages of the viability derived from these during the MTT assay of the main investigation as well as the additional investigation

Test substance	Tissue n	Measured OD values		Blank-corrected OD		Ø of the aliquots	Viability [%]
		Aliquot 1	Aliquot 2	Aliquot 1	Aliquot 2
Negative control	1	2,612	2,600	2,581	2,569	2,575	97,9
	2	2,642	2,616	2,611	2,585	2,598	98,8
	3	2,700	2,796	2,669	2,765	2,717	103,3
Positive control	1	0,101	0,100	0,070	0,069	0,070	2,6
	2	0,095	0,094	0,064	0,063	0,064	2,4
	3	0,104	0,103	0,073	0,072	0,073	2,8
MILLED CARBONISED PAN BASED FIBRE; SIGRAFIL C30 M150 UNS	1	2,735	2,695	2,704	2,664	2,684	102,1
	2	2,953	2,873	2,922	2,842	2,882	109,6
	3	2,895	2,825	2,864	2,794	2,829	107,6
MILLED CARBONISED PAN BASED FIBRE; SIGRAFIL C30 M150 UNS	1^step2	0,035	0,034	0,004	0,003	0,004
	2^step2	0,033	0,033	0,002	0,002	0,002
	3^step2	0,033	0,033	0,002	0,002	0,002

OD = optical density, Ø = mean,^step2 without MTT and incubated in medium only (step 2)

Table 2: Means of the optical density (OD) and viabilities during the MTT assay of the main investigation as well as the additional investigation (step 2)

Test substance	Ø of the OD	σ of the OD	Ø of the viability [%]	σ of the viability	CV % [%]
Negative control	2,630	0,076	100,0	2,90	2,90
Positive control	0,069	0,005	2,6	0,17	6,69
MILLED CARBONISED PAN BASED FIBRE; SIGRAFIL C30 M150 UNS	2,798	0,103	106,4	3,90	3,66
MILLED CARBONISED PAN BASED FIBRE; SIGRAFIL C30 M150 UNS^step2	0,003	0,001	0,1 % ≈ relative ODTI= 100 % x 0,003/2,630

OD = optical density, Ø = mean, σ = standard deviation, CV = coefficient of variation, ^step2 without MTT and incubated in medium only (step 2), TI = test item

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

No deviations from the test protocols are reported and GLP criteria are fullfilled. Therefore, the study and the results are regarded as valid.
Based on the results described and according to the criteria of the Comission Regulation (EC) No.761/2009 the test item (milled carbonised PAN based fibre) shall not be classified into one of the GHS categories.

Executive summary:

The skin irritating potential of the test item (milled carbonised PAN based fibre) was investigated in accordance with the methods of the Commission Regulation (EC) No. 761/2009 Annex III B.46., the MatTek protocol EPI-200-SIT, the OECD guideline 439 as well as the draft updated guideline 439.

An amount of approx. 25 mg of the test item was applied on reconstructed human epidermis EpiDerm moistened with 25 µL DBPS. The reference items [negative control = Dulbecco's phosphate buffered saline (DPBS), positive control = 5 % Sodium Dodecyl Sulfate (SDS)] were applied on non-moistened EpiDerm tissues in an amount of 30 µL. After the termination of the 60 minute exposure time the test substances were removed from the skin surface by washing with DPBS. Subsequently, the treated tissue models were post-incubated in medium for 42 hours. Afterwards, the viability of the treated EpiDerm tissues was determined using the MTT assay (MTT = 3 -(4,5 -dimethylthiazol-2 -yl)-2,5 -diphenyltetrazolium bromide).

A MTT viabilty of 106,4% was determined for the test item.

In an additional investigation, the coloured test item was tested on three more viable EpiDerm tissues which were not incubated in MTT solution but in medium only. Thereby, it was revealed that the test item was alomst completely removable from the tissues after the 60 minute exposure time and had no appreciable influence of the MTT endpoint determination. The relative optical density caused by the coloured test item was approx. 0.1% only and a correction calculation of the MTT viability not necessary.

Based on the results described and according to the criteria of the Comission Regulation (EC) No.761/2009 the test item shall not be classified into one of the GHS categories.