Zinc oxide

Nanomaterial dustiness

Administrative data

Endpoint:

nanomaterial dustiness

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The method is recommended in the respective ECHA guidance and was regarded as suitable to determine the distribution of particles of respirable or inhalable size. However, only limited documentation of the data evaluation was provided in the full study report.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

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:

2006

Deviations:

not specified

GLP compliance:

no

Type of method:

rotating cylinder

Details on methods and data evaluation:

The dustiness of the sample powder will be carried out using the rotating drum method specified in the new European standard of the dustiness of bulk samples (EN15051). This device uses two porous size-selective foam stages and a filter to provide information about the dustiness of the powders in terms of the inhalable, thoracic and respirable fractions of the dust dispersed. Three replicate tests of the powder will be carried out to obtain an estimate of the precision of the measurements. The standard also requires simple moisture content measurements to be made for each material, as dustiness has been found to be a function of moisture content. Analysis is carried out at 50+5% relative humidity. For each measurement 35 ml will be tested.

Test material

Test material information

Constituent 1

Test material form:

solid: nanoform

Results and discussion

Any other information on results incl. tables

Table1. Mean and SD of the dustiness results (in terms of the inhalable, thoracic and respirable fractions of dust dispersed) and moisture content of the PROSPEcT sample powders.

Sample Name	Supplier	Batch number	Inhalable fraction (mg kg−1)		Thoracic fraction (mg kg−1)		Respirable fraction (mg kg−1)		Moisture content (%)
			Mean	SD	Mean	SD	Mean	SD	Mean	SD
NM110	BASF,	ZC250#78	2905	371	599	239	27	3	0.5	0.10
NM111	BASF,	ZB250#64	5880	610	1340	241	138	105	0.3	0.00
NM112	Micronisers,	ZA250#30	1095	222	317	37	42	8	1.2	0.20
NM113	Sigma,	ZrA250#33	166	26	34	10	10	2	0.4	0.10

 

Table2. The calculated coefficient of variation (COV) values of the results inTable1. The coefficient of variation is the ratio of the standard deviation to the mean. It is a measure of variability in relation to the mean and is used to compare the relative dispersion in one type of data with the relative dispersion in another type of data. The data to be compared may be in the same units, in different units, with the same mean, or with different means.* 

Sample Name	Inhalable fraction (mg kg−1)	Thoracic fraction (mg kg−1)	Respirable fraction (mg kg−1)	Moisture content (%)
	COV (%)	COV (%)	COV (%)	COV (%)
NM110	12.8	39.9	12.7	21
NM111	10.4	18.0	76.2	0
NM112	20.3	11.5	19.9	18
NM113	15.8	29.5	17.6	34

 

Applicant's summary and conclusion

Executive summary:

NPL, 2010 investigated the dustiness of the nanomaterials. The dustiness of the sample powder was carried out using the rotating drum method specified in the new European standard of the dustiness of bulk samples (EN15051). Three replicate tests of the powder were carried out to obtain an estimate of the precision of the measurements. The standard also requires simple moisture content measurements to be made for each material, as dustiness has been found to be a function of moisture content. Analysis was carried out at 50 + 5 % relative humidity. For each measurement 35 mL was tested. Test results of the dustiness studies showed a significant difference in the inhalable dustiness levels. The respirable dustiness index, however, was quite comparable and possibly influenced by larger variation than the inhalable dust fraction. The inhalable dustiness index is classified to be at the high end of “low” dustiness (NM‑110) to just “moderate” (NM‑111). This compares approximately to the levels of nanoparticle powders of goethite, organoclay and talc compared to dustiness data on other test nanomaterials. For Respirable dust both samples are in the lower “moderate” dustiness range (range: 50 to 250 mg/kg).