Dr. Candace SJ Tsai September 11, 2012 OEL Workshop 2012
Dr. Candace SJ Tsai
September 11, 2012
OEL Workshop 2012
Manufacturing facility/R&D
Pilot scale facility/ Chem lab
Clean room
Facilities associated with Center for High-rate Nanomanufacturing
Background level- baseline concentration
Above baseline
Below baseline
After adjust / modify controls and practices
? NO exposure?
Why do we measure? Measure worker exposure to nanomaterials for Check-up and evaluation Epidemiological study, medical surveillance
Seek solution? Evaluate efficacy of controls to reduce exposure
What do we measure? Measure number, surface area, volume and mass concentrations. Identify particle size, composition and morphology.
5 TSI Fast Mobility Particle Spectrometer (FMPS)
TSI Aerodynamic Particle Sizer Spectrometer (APS)
Electrostatic Precipitator
Source: CJ. Tsai et al. ES&T 2012
Aerosol counters - SMPS - FMPS - CPC - Dust track - p-track - Surface area counter
Aerosol collection tools - Filter sampler - Electrostatic precipitator - Thermal precipitator - Impactor
Different…. o Metric? o Concentration magnitude o Size distribution o Collecting duration
Different…. o Collection efficiency o Collecting duration
Source: Asbach et al., JNR, 2009
At different instrument settings
Compare 4 mobility sizers
Source: Jeong and Evans, Aerosol Sci Tech, 2009
Conc. FMPS > SMPS
TEM
SEM
Energy Dispersive Spectroscopy Analysis (EDS), elemental composition
Carbon analysis, total, organic, and elemental carbon
Airborne CNT released from CNT synthesis
Instrument cost is high
Various samplers being used
Various sample analysis
Time consuming
Standard Operation Procedure (SOP) for exposure measurement? Harmonize methodology used for exposure measurement.
Particle 2
0
500
1,000
1,500
2,000
2,500
0 1 2 3 4 5 6 7 8 9 10
Fe Ka Cu Kb 1
Fe Kb 1
Cu Ka
CNT Product Carbon filament, cluster, iron-encapsulated particles
Elemental response from Iron catalyst
Iron and carbon
0.E+00
1.E+06
2.E+06
3.E+06
4.E+06
5.E+06
6.E+06
7.E+06
8.E+06
1 10 100 1,000 10,000 100,000
Diameter, Dp[nm]
Pa
rtic
le n
um
be
r co
nce
ntr
atio
n 1
dN
/dlo
g D
p [ p
art
icle
/cm
3]
0
10
20
30
40
50
60
70
80
90
100
Pa
rtic
le n
um
be
r co
nce
ntr
atio
n 1
dN
/dlo
g D
p [p
art
icle
/cm
3]
L temp-A L temp-B H temp-B
L temp-A L temp-B H temp-B
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1 10 100 1000
Diameter, Dp [nm]
Part
icle
mass c
oncentr
atio
n
dM
/dlo
gD
p [µ
g/m
³]Tsai et al., ES&T 2009
Number conc.
Mass conc.
Compare to in vivo study of Fe2O3 (<200nm) (Sotiriou et al., 2011) Total conc. 2-3 x 105 particle/cm3
Mass conc. 100-200 g/m3 Cause increased relative reactive oxygen species (ROS) in lungs (in vivo chemiluminescence (IVCL) 60 times higher), oxidative stress (11-fold) was present in the heart.
1 g/m3
Exposure concentration:
Alumina oxide 1,000 particle/cm3 during handling
particle diameter is 100 nm density of 3,600 kg/m3 The estimated mass concentration is 2 µg/m3
For 12,000 particle/cm3 , 200 nm mass concentration would be 180 µg/m3
Nanosilver 150 nm, mass concentration is 120 µg/m3
(Tsai 2009)
The lowest concentration for in vivo study is about 100 µg/m3 (Gangwal
2011)
Manufacturing facility/R&D
Pilot scale facility/ Chem lab
Clean room
Facilities associated with Center for High-rate Nanomanufacturing
From instrument uses, e.g. conc. measurements, aerosol collection.
Workplace conditions, control variables, worker practices.
Questions? What data/ information need to be documented ? How much detailed information needs to be documented?
What to be measured on site is not what to be studied for
biological response.
If sampler can be combined with biological assays and
provide dose response.
Develop IH in field direct reading instruments with SOP.
Acknowledgement NSF Nanoscale Science and Engineering Centers Program
(Award no. NSF-0425826)
THANK YOU !!