Nanoparticles In The Environment: The Measurement Challenge

Nanoparticles in the Environment: The Measurement Challenge Richard C. Flagan Chemical Engineering and Environmental Science and Engineering California Institute of Technology Pasadena, CA USA

Is Nanotechnology a Hazard to the Environment? ●

Entry into the environment –

Nanoparticles

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Nanotubes

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Transport

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Transformations –

Dissolution

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Agglomeration

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Exposure

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Response

Present day nanoparticles in the environment ●

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Airborne nanoparticles –

Emissions from high temperature sources

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Atmospheric nucleation

Waterborne –

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Colloidal & “dissolved” particles

Mineral –

Asbestos

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Nanocrystals

Biological –

Virus

Exposure assessment ●

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Instruments exist for aerosol nanoparticle measurements –

Size distribution

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Number concentration

Measurements of particles in liquids or on surfaces –

Dynamic light scattering

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Electron or scanning probe microscopy

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Nanoparticles translocate into cells and throughout the body Mechanisms not fully understood Stealth entry of toxic materials into cells –

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Nanoparticles dissolve after entry into cell

Nanoparticle therapeutics <10nm eliminated through kidneys –

Entry into wastewater

Moore, Environment International 32 (2006) 967–976

Cytotoxicity (murine macrophage cell viability) versus concentration

K.F. Soto, A. Carrasco, T.G. Powell, K.M. Garza and L.E. Murr. J. Nanoparticle Res. (2005) 7: 145–169

What evidence is there for direct effects of inhaled nanoparticles on human health?

What evidence is there for direct effects of inhaled nanoparticles on human health? Ambient air pollution exposures

Present-Day Nanoparticle Exposure ●

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6e4

150 m downwind

dN dlogD

dN dlogD

Combustion –

Diesel engines

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Power plants

High temperature processes – –

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30 m downwind

2e5

Metallurgical Welding

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Grinding

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Ski waxing

Rapid decay with distance from source

0 1

10

100 nm

60 m downwind

1.2e5

0 1 1e4

10

100 nm

300 m downwind

dN dlogD

dN dlogD 0 1

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100 nm

90 m downwind 1.2e5

0 1 1e4

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100 nm

300 m upwind

dN dlogD

dN dlogD 0 1

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100 nm

0 1

Zhu, Hinds, Kim and Sioutas J. Air & Waste Manage. Assoc. 52:1032-1042

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100 nm

Wind Direction

Nanoparticle Exposures are Transient 

Exposures on Los Angeles freeways

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DMA size distribution measurements

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Ambient and filtered, incabin data

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Low nanometer particles difficult to measure

Homogeneous Nucleation in the Atmosphere

Boy and Kulmala, Atmos. Chem. Phys. 2: 1-16 (2002)

Nanoparticles ●

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Adverse health effects –

Cardiovascular effects

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Translocate across cell membranes

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Bypass blood-brain barrier

Produced by homogeneous nucleation from the vapor phase –

Combustion systems, high temperature processes

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Photochemical smog

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Nanotechnology

Limited data on environmental/health implications of nanotechnology –

Toxicity

DMA

DMA

CPC

RDMA

Opposed Migration Aerosol Classifier

Flagan, RC. 2004. Opposed Migration Aerosol Classifier (OMAC).

Aerosol Sci. Technol. 38 (9): 890-899.

Can we extend these measurements to particles in water?

Radial-Symmetric FFE

Double Layer + + + + + + + + + + + + + + + + + + -

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Differential mobility analyzer will not work in water, but there are other approaches that do.

Free Flow Electrophoresis

Peterson and Cliffel (2005) Analytical Chemistry. 77: 4378.

Electrophoretic Separations of Nanoparticles in Water are Possible, but ●

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Charge depends on particle and solution chemistry Single particle detection is not available Optical detection of ensemble is strongly size dependent New methods are needed to enable nanoparticle measurements in the aqueous environment

Conclusions ●

Nanoparticles can cause health problems but

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We don't know the risks of engineered nanomaterials Risks may depend on –

Composition

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Size

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Morphology

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State of aggregation

Data are needed to assess risks

Conclusions ●

Most risks of nanotechnology should be manageable but

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The cost of not identifying potential risks may be high Will nanotechnology become the next genetically modified crop?

Conclusions ●

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Real-time measurements of airborne nanoparticles are now possible –

Size distribution

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Chemical composition as a function of particle size

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Expensive and complex

New instruments should soon become Measurements of nanoparticles in water or on surfaces are not well developed –

Dynamic light scattering

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Electron microscopy

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Electrophoretic separations ●

Need detection technology

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Charge???

Acknowledgments ●

Nick Brunelli

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Donald Collins (Texas A&M University)

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Andrew Downard

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Harmony Gates

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Lynn Russell (Scripps)

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Jian Wang (Brookhaven)

Support ●

Office of Naval Research

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Davidow Foundation

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Coordinating Research Council

Capillary Electrophoresis Electrode

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Power Supply