Non-graphitic carbon fibre

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-06-29 to 2011-09-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)

GLP compliance:

yes (incl. QA statement)

Type of method:

determination of fibre length and diameter distributions

Remarks:

microscopic examination

Type of distribution:

counted distribution

Mass median aerodynamic diameter:

21.39 µm

Percentile:

D10

Mean:

17.2 µm

Remarks on result:

other: According to their mass 90% of the fibres have an aerodynamic diameter of >17.20 µm.

Percentile:

D50

Mean:

21.39 µm

Remarks on result:

other: According to their mass 50% of the fibres have an aerodynamic diameter of >21.39 μm; 99% of the fibres have an aerodynamic diameter of >11.45 μm.

Percentile:

D90

Mean:

23.9 µm

Remarks on result:

other: According to their mass 10% of the fibres have an aerodynamic diameter of >23.90 µm.

The length weighted diameter and length distribution are listed in Table 1 as mean values and in Table 2 as percentile values. In addition, the length weighted diameter distribution is shown in a histogram in Figure 1 (see attachment).

Table 1          Size distribution of fibres (weighting by length, mean values)

Sample	Fibre length [µm]				Fibre diameter [µm]
	Arithmetric		Geometric		Arithmetric		Geometric		Geometric Mean - 2 x SE
	Mean	Std	Mean	Std	Mean	Std	Mean	Std
milled carbonised PAN based fibre C30 M150 UNS	61.89	27.53	54.17	1.77	7.80	0.69	7.77	1.10	7.71

Table 2          Size distribution of fibres (weighting by length, percentile values)

Sample	n	Fibre length [µm]				Fibre diameter [µm]				Aerodynamic diameter (mass)* [µm]
		1%<	10%<	50%<	90%<	1%<	10%<	50%<	90%<	1%<	10%<	50%<	90%<
milled carbonised PAN based fibre C30 M150 UNS	501	8.5	24.5	63.5	100.1	5.59	7.03	7.87	8.51	11.45	17.20	21.39	23.90

* weighting by mass

Conclusions:

No fibre typical carcinogenic effect in the lung tissue can be expected for the test item (carbonised PAN based fibre, milled).

Executive summary:

The length weighted geometric mean diameter of the test item (carbonised PAN based fibre, milled) minus two standard errors is 7.71 μm.

According to Regulation (EC) No 1272/2008, Note R, the classification as a carcinogenic material is not applicable to mineral fibres if the length weighted geometric mean diameter minus two standard errors is above the limit of 6 µm. In analogy to mineral fibres this criterion can also be used for the carbon fibre in this study.

The mass fraction of WHO fibres is 0.006% of the total fibre mass which is significantly below 0.1 mass%. In the German regulation the classification of inorganic fibre dust as carcinogenic is limited to WHO fibres [Technical Rules for Hazardous Substances (TRGS) 905, section 2.3, revised in May 2008].

In the German Hazardous Substances Ordinance (Deutsche Gefahrstoffverordnung, dated 26 Nov 2010, Appendix II No. 5) the ban of use for man-made mineral fibres is only valid for preparations and products if the mass content is above 0.1%.

The calculated concentration of WHO fibres of 524 fibres per mg total fibre mass of the sample is very low.

In Table 2 the aerodynamic diameter is listed by using mass weighting. The 50% percentile value of the aerodynamic diameter is the mass median aerodynamic diameter (MMAD) of this fibre material. As the MMAD of 21 µm for the tested fibre is one magnitude higher then the preferred value, e.g. in OECD 413 (1–3 µm) for the subchronic inhalation test, the performance of an inhalation test is not useful for this test substance. As 99% of the mass have an aerodynamic diameter of > 11.45 µm this material has no significant fraction which is lung respirable. After inhalation these fibres will be deposited only in the nasal cavity and in the upper part of the tracheo-bronchial tree. In these parts of the respiratory tract particles (and fibres) will be cleared very fast (half-time < 1 day) by mucociliary clearance. Therefore, no accumulation of fibres will be possible in these regions. In studies with asbestos and man-made vitreous fibres no fibre specific effects were detected in the nasal cavity or in the upper tracheo-bronchial tract (IARC 1987, 2002).

Reference 2

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-06-30 to 2011-09-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)

GLP compliance:

yes (incl. QA statement)

Type of method:

determination of fibre length and diameter distributions

Remarks:

microscopic examination

Type of distribution:

counted distribution

Mass median aerodynamic diameter:

28.99 µm

Percentile:

D10

Mean:

20.7 µm

Remarks on result:

other: According to their mass 90% of the fibres have an aerodynamic diameter of >20.70 µm.

Percentile:

D50

Mean:

28.99 µm

Remarks on result:

other: According to their mass 50% of the fibres have an aerodynamic diameter of >28.99 µm; 99% of the fibres have an aerodynamic diameter of >10.27 µm.

Percentile:

D90

Mean:

35.1 µm

Remarks on result:

other: According to their mass 10% of the fibres have an aerodynamic diameter of >35.10 µm.

The length weighted diameter and length distribution are listed in Table 1 as mean values and in Table 2 as percentile values. In addition, the length weighted diameter distribution is shown in a histogram in Figure 1 (see attachment).

 

Table 1          Size distribution of fibres (weighting by length, mean values)

Sample	Fibre length [µm]				Fibre diameter [µm]
	Arithmetric		Geometric		Arithmetric		Geometric		Geometric Mean - 2 x SE
	Mean	Std	Mean	Std	Mean	Std	Mean	Std
milled carbonised viscose based VCC fibre	53.62	26.84	44.95	1.95	11.43	1.95	11.24	1.21	11.05

 

Table 2          Size distribution of fibres (weighting by length, percentile values)

Sample	n	Fibre length [µm]				Fibre diameter [µm]				Aerodynamic diameter (mass)* [µm]
		1%<	10%<	50%<	90%<	1%<	10%<	50%<	90%<	1%<	10%<	50%<	90%<
milled carbonised viscose based VCC fibre	500	5.6	17.2	54.9	86.1	5.71	9.03	11.55	13.74	10.27	20.70	28.99	35.10

* weighting by mass

Conclusions:

No fibre typical carcinogenic effect in the lung tissue can be expected for the test item (carbonised viscose based VCC fibre, milled).

Executive summary:

The length weighted geometric mean diameter of the test item (carbonised viscose based VCC fibre, milled) minus two standard errors is 11.05 µm.

According to Regulation (EC) No 1272/2008, Note R, the classification as a carcinogenic material is not applicable to mineral fibres if the length weighted geometric mean diameter minus two standard errors is above the limit of 6 µm. In analogy to mineral fibres this criterion can also be used for the carbon fibre in this study.

The mass fraction of WHO fibres is 0.004% of the total fibre mass which is significantly below 0.1 mass%. In the German regulation the classification of inorganic fibre dust as carcinogenic is limited to WHO fibres [Technical Rules for Hazardous Substances (TRGS) 905, section 2.3, revised in May 2008].

In the German Hazardous Substances Ordinance (Deutsche Gefahrstoffverordnung, dated 26 Nov 2010, Appendix II No. 5) the ban of use for man-made mineral fibres is only valid for preparations and products if the mass content is above 0.1%.

The calculated concentration of WHO fibres of 673 fibres per mg total fibre mass of the sample is very low.

In Table 2 the aerodynamic diameter is listed by using mass weighting. The 50% percentile value of the aerodynamic diameter is the mass median aerodynamic diameter (MMAD) of this fibre material. As the MMAD of 29 µm for the tested fibre is one magnitude higher then the preferred value, e.g. in OECD 413 (1–3 µm) for the subchronic inhalation test, the performance of an inhalation test is not useful for this test substance. As 99% of the mass have an aerodynamic diameter of > 10.27 µm this material has no significant fraction which is lung respirable. After inhalation these fibres will be deposited only in the nasal cavity and in the upper part of the tracheo-bronchial tree. In these parts of the respiratory tract particles (and fibres) will be cleared very fast (half-time < 1 day) by mucociliary clearance. Therefore, no accumulation of fibres will be possible in these regions. In studies with asbestos and man-made vitreous fibres no fibre specific effects were detected in the nasal cavity or in the upper tracheo-bronchial tract (IARC 1987, 2002).

Reference 3

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-06-30 to 2011-09-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)

GLP compliance:

yes (incl. QA statement)

Type of method:

determination of fibre length and diameter distributions

Remarks:

microscopic examination

Type of distribution:

counted distribution

Mass median aerodynamic diameter:

24.02 µm

Percentile:

D10

Mean:

19.38 µm

Remarks on result:

other: According to their mass 90% of the fibres have an aerodynamic diameter of >19.38 µm.

Percentile:

D50

Mean:

24.02 µm

Remarks on result:

other: According to their mass 50% of the fibres have an aerodynamic diameter of >24.02 µm; 99% of the fibres have an aerodynamic diameter of >12.61 µm.

Percentile:

D90

Mean:

28.61 µm

Remarks on result:

other: According to their mass 10% of the fibres have an aerodynamic diameter of >28.61 µm.

The length weighted diameter and length distribution are listed in Table 1 as mean values and in Table 2 as percentile values. In addition, the length weighted diameter distribution is shown in a histogram in Figure 1 (see attachment).

 

Table 1          Size distribution of fibres (weighting by length, mean values)

Sample	Fibre length [µm]				Fibre diameter [µm]
	Arithmetric		Geometric		Arithmetric		Geometric		Geometric Mean - 2 x SE
	Mean	Std	Mean	Std	Mean	Std	Mean	Std
milled carbonised viscose based GFA fibre	59.85	28.63	51.75	1.80	9.24	1.26	9.16	1.15	9.04

 

Table 2          Size distribution of fibres (weighting by length, percentile values)

Sample	n	Fibre length [µm]				Fibre diameter [µm]				Aerodynamic diameter (mass)* [µm]
		1%<	10%<	50%<	90%<	1%<	10%<	50%<	90%<	1%<	10%<	50%<	90%<
milled carbonised viscose based GFA fibre	503	8.3	22.8	57.2	106.0	6.48	7.78	9.19	10.79	12.61	19.38	24.02	28.61

* weighting by mass

Conclusions:

No fibre typical carcinogenic effect in the lung tissue can be expected for the test item (carbonised viscose based GFA fibre, milled)

Executive summary:

The length weighted geometric mean diameter of the test item (carbonised viscose based GFA fibre, milled) minus two standard errors is 9.05 µm.

According to Regulation (EC) No 1272/2008, Note R, the classification as a carcinogenic material is not applicable to mineral fibres if the length weighted geometric mean diameter minus two standard errors is above the limit of 6 µm. In analogy to mineral fibres this criterion can also be used for the carbon fibre in the present study.

The mass fraction of WHO fibres is 0.000% as no WHO fibres were detected in this sample. In the German regulation the classification of inorganic fibre dust as carcinogenic is limited to WHO fibres [Technical Rules for Hazardous Substances (TRGS) 905, section 2.3, revised in May 2008].

In the German Hazardous Substance Ordinance (Deutsche Gefahrstoffverordnung, dated 26 Nov 2010, Appendix II No. 5) the ban of use for man-made mineral fibres is only valid for preparations and products if the mass content is above 0.1%.

The calculated concentration of WHO fibres is 0 fibres per mg total fibre mass of the sample as no WHO fibres were detected.

In Table 2 the aerodynamic diameter is listed by using mass weighting. The 50% percentile value of the aerodynamic diameter is the mass median aerodynamic diameter (MMAD) of this fibre material. As the MMAD of 24 µm for the tested fibre is one magnitude higher then the preferred value, e.g. in OECD 413 (1–3 µm) for the subchronic inhalation test, the performance of an inhalation test is not useful for this test substance. As 99% of the mass have an aerodynamic diameter of > 12.6 µm this material has no significant fraction which is lung respirable. After inhalation these fibres will be deposited only in the nasal cavity and in the upper part of the tracheo-bronchial tree. In these parts of the respiratory tract particles (and fibres) will be cleared very fast (half-time < 1 day) by mucociliary clearance. Therefore, no accumulation of fibres will be possible in these regions. In studies with asbestos and man-made vitreous fibres no fibre specific effects were detected in the nasal cavity or in the upper tracheo-bronchial tract (IARC 1987, 2002).

Description of key information

The study was performed at the Fraunhofer Institute for Toxicology and Experimental Medicine, D-30625 Hannover, Germany, according to the standard operating procedure 060118 which is equivalent/similar to the OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions).

The determined particle size distributions (aerodynamic diameters, percentile values) are as follows:
- carbonised PAN based fibre, milled: D10 = 17.20 µm, D50 = 21.39 µm, D90 = 23.90 µm
- carbonised viscose based VCC fibre, milled: D10 = 20.70 µm, D50 = 28.99 µm, D90 = 35.10 µm
- carbonised viscose based GFA fibre, milled: D10 = 19.38 µm, D50 = 24.02 µm, D90 = 28.61 µm