Graphene

Nanomaterial dustiness

Administrative data

Endpoint:

nanomaterial dustiness

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 Mar 2020 - 11 Mar 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EN 15051 (Workplace atmospheres - Measurement of the dustiness of bulk materials - Requirements and reference test methods)

Version / remarks:

2013

GLP compliance:

not specified

Type of method:

rotating cylinder

Details on methods and data evaluation:

The health related dustiness investigation has been performed using the 15051 Rotating Drum dustiness tester according to the European standard. The sample has been divided in eight equal lots using a rotary riffler, which is especially designed to minimize the loss of any fine dust. One of these divided lots has been used for determining the bulk density. The bulk density of the sample has been determined by accurately weighing a volume of 50 cm3 after gentle tapping at the side. This bulk density is used to convert the 3 sample mass to the required volume of approx. 35 cm3 and the sample is further divided to the required 35 cm3. A standard volume of the material (approx. 33 cm3) is weighed and then placed in the dust-generating section, where the airborne dust particles are transferred by an air flow rate of 38 L min-1 to the filter assembly during 1 minute. Each dustiness measurement is preceded by a blank run. The airborne dust released is drawn from the dust generation section, through the dust transfer section, into the special designed foam/filter assembly with successively 20 pores per inch foam, 80 pores per inch foam and a glass fibre backing filter. Dustiness is a relative term and the result obtained will depend on the used test apparatus, the properties of the material and various environmental variables.

Test material

Test material information

Constituent 1

Reference substance name:

carbon

EC Number:

801-282-5

Cas Number:

1034343-98-0

Molecular formula:

Cx

IUPAC Name:

carbon

Test material form:

solid: nanoform

Results and discussion

Dustiness index

Dustiness index 1

Mean:

6 473 mg/kg

Remarks on result:

other: Inhalable fraction

Dustiness index 2

Mean:

1 267 mg/kg

Remarks on result:

other: Thoracic fraction

Dustiness index 3

Mean:

151 mg/kg

Remarks on result:

other: Respirable fraction

Any other information on results incl. tables

The bulk density of the sample has been determined once at 0.28 g cm^-3 and the moisture content of the sample is 1.19 ± 0.34 m/m %, based on the results of three independent measurements.

According to the EN 15051 the dustiness is assessed as the average of at least three independent measurements.

The sample has been measured four times, since it appeared that the results of the initial measurement deviate from the results of the consecutive three measurements. The dustiness potential of each health-related fraction is expressed in milligrams per kilogram (mg kg^-1). The investigations are performed with representative lots of the material at a laboratory temperature of approx. 22 °C and a relative humidity in the range between 44 – 47%.

The results are summarised in Table 1 and the standard classification is shown in Table 2.

Test	Sample mass	Inhalable fraction		Thoracic fraction		Respirable fraction
	g	mg	mg kg^-1	mg	mg kg^-1	mg	mg kg^-1
1^sttest	9.2960	75.9	8167	13.1	1409	1.2	129
2^ndtest	9.2610	52.8	5700	10.2	1102	1.2	128
3^rdtest	9.5399	59.9	6282	11.4	1191	1.5	153
4^thtest	9.1137	52.3	5743	12.5	1367	1.8	195
Average	6473			1267		151
RSD %	17.9			11.4		20.7
classification	high			high		moderate

Table 1. Summary of the dustiness data of sample according to EN 15051, measured at a relative humidity of approx. 45%.

Category of dustiness	Inhalable dustiness mass fraction, mg kg^-1	Thoracic dustiness mass fraction, mg kg^-1	Respirable dustiness mass fraction, mg kg^-1
Very low	< 300	< 80	< 10
Low	300 to 650	80 to 300	10 to 60
Moderate	> 650 to 3000	> 300 to 1000	> 60 to 210
High	> 3000	> 1000	> 210

Table 2. Dustiness classification in accordance with the EN 15051 standard.

The results of the initial measurement could not be identified as an outlier and are therefore included when averaging the results. It can be seen in Table 1 that the dustiness potential of the inhalable fraction and the thoracic fraction of the sample are classified as high, while the respirable fraction yields a moderate classification. The three dustiness potentials are 6473 mg kg^-1, 1267 mg kg^-1and 151 mg kg^-1 for the inhalable, thoracic and respirable fraction, respectively.

Usually a repeatability of < 15% is obtained during the measurements. In the Table it is listed that the relative standard deviations of the inhalable and the respirable fraction are moderately higher than the repeatability. A clear reason for this higher relative standard deviation could not be found and performing additional measurements would not significantly change the results obtained.

The dustiness results listed in this report are only representative for the sample that has been delivered and upon application of the 15015-2 Rotating Drum method. The results can be considered representative for a larger bulk material, providing that the sample has been representatively obtained from this bulk. It should still be noted that, based on the total bulk material, external conditions and method of application, the dustiness potential may variate from the reported results upon handling.

Applicant's summary and conclusion

Conclusions:

The three dustiness potentials are 6473 mg kg-1, 1267 mg kg-1 and 151 mg kg-1 for the inhalable, thoracic and respirable fraction, respectively. The dustiness potential of the inhalable fraction and the thoracic fraction of the sample are classified as high, while the respirable fraction yields a moderate classification.

Executive summary:

The dustiness of the test item was tested according to the European standard method EN 15051 using the rotating drum methodology. The dustiness potential of the inhalable fraction and the thoracic fraction of the sample are classified as high, while the respirable fraction yields a moderate classification. The three dustiness potentials are 6473 mg kg^-1, 1267 mg kg^-1and 151 mg kg^-1for the inhalable, thoracic and respirable fraction, respectively.