Influence of relative humidity and physical load during storage on dustiness of inorganic nanomaterials: implications for testing and risk assessment
- 228 Downloads
Dustiness testing using a down-scaled EN15051 rotating drum was used to investigate the effects of storage conditions such as relative humidity and physical loading on the dustiness of five inorganic metal oxide nanostructured powder materials. The tests consisted of measurements of gravimetrical respirable dustiness index and particle size distributions. Water uptake of the powders during 7 days of incubation was investigated as an explanatory factor of the changes. Consequences of these varying storage conditions in exposure modelling were tested using the control banding and risk management tool NanoSafer. Drastic material-specific effects on powder respirable dustiness index were observed with the change in TiO2 from 30 % RH (639 mg/kg) to 50 % RH (1.5 mg/kg). All five tested materials indicate a decreasing dustiness index with relative humidity increasing from 30 to 70 % RH. Test of powder water uptake showed an apparent link with the decreasing dustiness index. Effects of powder compaction appeared more material specific with both increasing and decreasing dustiness indices observed as an effect of compaction. Tests of control banding exposure models using the measured dustiness indices in three different exposure scenarios showed that in two of the tested materials, one 20 % change in RH changed the exposure banding from the lowest level to the highest. The study shows the importance of powder storage conditions prior to tests for classification of material dustiness indices. It also highlights the importance of correct storage information and relative humidity and expansion of the dustiness test conditions specifically, when using dustiness indices as a primary parameter for source strength in exposure assessment.
KeywordsDustiness Rotating drum Exposure assessment Powder storage Occupational health Nanotechnology
This work was conducted as part of the Strategic Research effort at the National Research Centre for the Working Environment and the Danish Centre for Nanosafety (20110092173/3) from the Danish Working Environment Research Foundation and the EU Framework seven Programme HINAMOX (228825).
- Aitken RA, Bassan A, Friedrichs S et al (2011) Specific advice on exposure assessment and hazard/risk characterisation for nanomaterials under REACH (RIP-oN 3)Google Scholar
- BS EN:15051 (2006) EN15051 Workplace atmospheres: measurement of the dustiness of bulk materials—requirements and reference test methodsGoogle Scholar
- Kristensen HV, Jensen KA, Koponen IK et al (2010) Nanopartikler i arbejdsmiljøet - Viden og inspiration om håndtering af nanomaterialer. Industriens Branchearbejdsmiljøråd, Branchearbejdsmiljørådet for Undervisning og Forskning samt Universitets og Bygningsstyrelsen, CopenhagenGoogle Scholar
- Liguori B, Hansen SF, Baun A, Jensen KA (Submitted) Comparative analysis of occupational exposure estimation tools for nanomaterials and their applicability for reach Google Scholar
- Nishii K, Horio M (2007) Chapter 6 Dry granulation. In: Salman AD (ed) Handbook of Powder Technology. Elsevier Science B.V., pp 289–322 Google Scholar
- Pujara CP (1997) Determination of factors that affect the generation of airborne particles from bulk pharmaceutical powders. Theses Diss Available ProQuest pp 1–155Google Scholar
- Rasmussen K, Mech A, Mast J et al (2013) Synthetic amorphous silicon dioxide (NM-200, NM-201, NM-202, NM-203, NM-204): characterisation and physico-chemical properties JRC Repository: NM-series of representative manufactured nanomaterialsGoogle Scholar
- Rasmussen K, Mast J, de Temmerman P-J et al (2014) Titanium dioxide, NM-100, NM-101, NM-102, NM-103, NM-104, NM-105: characterisation and physico-chemical propertiesGoogle Scholar
- Singh C, Friedrichs S, Levin M et al (2011) NM-series of representative manufactured nanomaterials—zinc oxide NM-110, NM-111, NM-112, NM-113: characterisation and test item preparationGoogle Scholar
- Van Duuren-Stuurman B, Vink SR, Verbist KJM et al (2012) Stoffenmanager nano version 1.0: a web-based tool for risk prioritization of airborne manufactured nano objects. Ann Occup Hyg 56(5):525–541 Google Scholar
- Witschger O, Jensen KA, Brouwer DH et al (2014) DUSTINANO: a CEN pre-normative research project to harmonize methods for manufactured nanomaterial powders. Aerosol Technology 2014, Karlsruhe. Abstract T230A09. Session APPVI Dustiness and Resuspension: http://www.gaef.de/AT2014/