Copyright© 2008 TSI Incorporated Nanoparticle Monitoring in Occupational Environments – Comparing and Contrasting Measurement Metrics TSI Incorporated

Copyright© 2008 TSI Incorporated

Nanoparticle Monitoring in Occupational Environments –

Comparing and ContrastingMeasurement Metrics

TSI Incorporated 2008

Nanotechnology and Occupational Health and Safety Education Series


Agenda

• Nanoparticle exposure • Traditional IH aerosol

measurements• What is nanotechnology?• Filtration mechanisms• Engineering controls• Current measurement metrics

for nanoparticles• Working towards best practices• Multi-metric sampling and

control approaches• Summary• References

Horizontal zinc oxide nanowires on sapphire surface

Image credit: Courtesy National Institute of Standards and Technology


Nanoparticle Exposure

• Increasing commercial development

• Worker exposure is a concern

• Nano-scale materials exhibit new properties– Follow laws of quantum physics– Determines new properties

• Occupational health risks are not clearly understood

“Buckyball” designed for drug delivery

Image credit: Courtesy LUNA Innovations



• Routes of exposure– Inhalation

• Most common/efficient• Most well understood

– Dermal contact• Less work done here• Just a few studies (e.g., Beryllium, Nano Safe II in Europe)

– Ingestion• Little interaction between pharmaceutical industry & toxicologists and

epidemiologists• Questions about adverse health effects and ingestion



• Solubility• Particle size• Particle shape• Particle number

• Surface Area• Composition• Surface coatings• Surface chemistry• Others?

Properties That Contribute to Nanoparticle Toxicity



Current research indicates that mass and bulk chemistry may be less important than particle size, surface area, and surface chemistry for nanostructured materials

(Oberdörster et al. 1992, 1994a,b; Duffin et al. 2002)



Nanoparticle Exposure Studies

• Dr. Driscoll (1996) and Dr. Oberdörster (2001) have shown that surface area (μm2/cc) plays an important role in the toxicity of nanoparticles

• Surface area is the metric that is highly correlated with particle-

induced adverse health effects (Driscoll, 1996; Oberdörster, 2001)

• Potential for adverse health effects is proportional to particle

surface area (Driscoll, 1996; Oberdörster, 2001)



What experts say

If nanoparticles can . . . i. Deposit in the lung and remain thereii. Have active surface chemistry iii. Interact with the body

. . . there is the potential for exposure and dosing



• Relatively few occupational studies– Compared to overall money spent on

nanotechnology– More are being conducted

• Most studies in research settings• Lack of exposure metrics to

compare/contrast – What is a good vs. high number?– Emerging issue for OH&S

• Monitoring equipment is available– Some not considered IH optimized



• Inadequate protection– Engineering controls or PPE

• Material handling or mixing– Increase chance of fugitive emissions

• Fugitive emissions– From non-enclosed or controlled

production or process systems

• Maintenance activities

Similar to what you already find!

Workplace Conditions Likely to Cause Exposure to Nanoparticles


Traditional IH Aerosol Measurements



Exposure limits based on mass• Size range of ~0.1 – 100 µm

• Toxicity data

• Lung deposition models relating to size selective sampling protocols



• OSHA, 2 sizes– Total dust, ≤100 µm

• Deposits in all areas of the respiratory tract

– Respirable dust, ≤4 µm• Subset of total dust,

deposits in alveolar region of the respiratory tract

• ACGIH/ISO/CEN, 3 sizes– Inhalable, ≤100 µm

• Deposits in all areas of the respiratory tract

– Thoracic, ≤10 µm • Subset of inhalable, deposits in

the tracheobronchial and alveolar regions

– Respirable, ≤4 µm• Subset of thoracic, deposits in

the alveolar region

Lung deposited size fractions



Mass measurement methods• Gravimetric sampling

– Personal air sampling systems• Worn by the worker• Breathing zone sampling for personal exposure• Personal sample pump/inlet conditioner/media

– Area air sampling systems• Work area sampling • For area sampling, baseline screening and trend analysis• Pump/inlet conditioner/media

• Personal or higher volume pump used



Mass measurement methods• Direct-reading instruments

– Photometers

• Incorporate same sampling methodologies as gravimetric– Inlet conditioners

– Personal sampling

– Area sampling



Size selective sampling• Inhalation and lung deposition

– Most common/efficient way for particles to enter

• Common to sample according to deposition• Criteria depends on aerosol being sampled

– Mechanisms of lung deposition and dosing

• Size fractions and examples– Inhalable/total, ≤100 µm > silica– Thoracic, ≤10 µm > cotton dust– Respirable, ≤4 µm > coal dust



Based on International Commission of Radiological Protection (1994) and U.S. Environmental Protection Agency (1996a).Air Quality Criteria for Particulate matter, 2004, p 6-5.

• The respiratory tract consists of 3 major regions– Extrathoracic region:

uppermost region– Tracheobronchial (TB)

region: middle region– Alveolar (A) region:

innermost region


What is Nanotechnology?

. . . .technologies, that measure, manipulate, or incorporate material or features with at least one critical dimension between ~ 1 nanometer and 100 nanometers . . .

. . . whose applications exploit properties, distinct from bulk/macroscopic systems, that arise from their scale/critical dimension . . .

Note: terminology from ASTM Committee E56, definitions are only considerations



Nanotechnology

“The art and science of building stuff that does stuff at the nanometer scale.”

Richard Smalley (1943 – 2005)

Nobel Prize Winner, Chemistry (1996)



Coarse particle – ≤10 µm

Fine particle – ≤2.5 µm

Ultrafine particle – ≤0.1 µm (100nm)

Nanoparticle

• Dimensions between 1 and 100 nm in at least one dimension

• Nanoparticle size may go up to 200 – 300 nm for occupational exposure

Note: terminology from ASTM Committee E56, definitions are only considerations



Aggregate

• A group of particles that are strongly bonded together (e.g., fused, sintered, or metallically bonded)

Agglomerate

• A group of particles held together by relatively weak forces (e.g., van der waals, capillary, etc.) that may break apart into smaller agglomerates, aggregates or primary particles upon handling



• Earth = 12756 km• Soccer ball = 0.2264 m

– Difference 1.77 x10-8

• Soccer ball = 0.2264 m• 10 nm particle = 10x10-9 m

– Difference 4.44 x 10-8

How small are nanoparticles?

Source: Professor David Pui, University of Minnesota



• Golf ball = playing card

• 25nm particles = 4 football fields

Nanoparticle surface area

Source: www.nanohorizons.com

The Scale of Things – Nanometers and More

Things Natural Things Manmade

Ant~ 5 mm

Head of a pin1 - 2 mm

Dust Mite~ 200 μm

Red blood cellswith white cell

~ 2 - 5 μm

Human Hair~ 60 - 120 μm wide

Carbon nanotube~ 1.3 nm diameter

DNA~ 2 1/2 nmDiameter

Carbon buckyball~ 1 nm Diameter

Micro Electro Mechanical(MEMS) devices10 - 100 μm wide

Adapted from Office of Basic Energy Sciences,Office of Science, U.S. Department of Energy

0.001 0.01 0.1 1 10 100Particle Size Range (micrometers)

Ty

pes

of

Par

ticl

es

BacteriaVirus

Oil Smoke

Diesel Engine Exhaust

Combustion Nuclei

Soot

Inhalable

(Total dust)

Respirable

Thoracic

Pollen

Particle Sizes

Construction ActivitiesCarbon Black

Welding Fume

4

Sea salt

Tobacco smokeCoal Dust (mining)

Paint Pigment

Vacuuming

Wind blown dust

Volcanic emissions

Environmental / Naturally Occurring Particles

Workplace / man-made Particles

Fly Ash

Nanoparticle


Nanoparticle Sources

Nanoparticles and ultrafine particles

• Capable of depositing in all areas of the lung

• Essentially the same size range– How they are produced that is different

• Look at them as one group



Naturally Occurring / Biogenic

• Forest fires• Volcanic activity• Sea-spray salt• Photochemical reactions

high in the atmosphereSt Helens erupting on May 18, 1980. Source: NASA



Manmade / Incidental• Unintentionally produced byproducts• Products of combustion/high energy

operations• Produced by chemical reactions

Examples• Combustion aerosols – many sources!

– Welding and cutting – Engine emissions – Heating/furnace emissions – Coal fired power plant emissions– Cooking exhaust– Copiers, faxes and printers



• Intentionally manufactured from homogeneous materials

Examples• Carbon nanotubes • Carbon nanowires and ropes• Buckminster fullerenes • Quantum dots• Nanocoatings• Nanolayers• Nanoshells

Engineered Nanoparticles

Source: AZONANO.com


Manufacturing Processes

• Plasma reactors• Laser ablation• Flame reactors• Flame spray pyrolysis• Furnace reactors

• Plasma heating• Sputtering• Sparking• Spray evaporation• Spray pyrolysis

Nanoparticle Manufacturing Methods


Nanoparticles vs. Large Particles

• Relatively little mass– Mass of 1 billion 10 nm

particles = mass of 10 µm particle

• Large surface area• Produced in large numbers• Quantum effects

– Change their physical, chemical, and biological properties

• Behave like gases– Stay suspended for weeks

• Disperse quickly– Reach equilibriium (high → low)– Pressure differentials provide

transport pathways

• Tend to agglomerate quickly after production

• Health effects are not completely understood

Nanoparticle Properties and Behavior


Nanoparticles vs. Large Particles

• Aerosol researchers have shown worldwide…

– 86% of the total number of particles in a unit volume of air make up <1% of the mass

– 14% of the total number of particles make up >99% of the mass


Present Nanotechnology

• Nanotechnology is now!• US is the largest producer of

nanomaterials• Material science research

focus• Intense scientific application

study– Chemical, plastics/polymers,

optical, electronics, semiconductor, pharmaceutical, biomedical

• Passive nanotechnology– Enhancement of existing

products with new properties/functions

– Products are additives/ components

• Active nanotechnology– Products change state

during operation


Nanotechnology Applications

Current applications• Longer lasting rubber compounds• Plastics (bumpers on cars)• Polymers and composites• Cement/concrete additives• Paints, pigments, inks and coatings• Stain- and wrinkle-free clothing• Sunscreen and cosmetics• Protective and glare reducing coatings• Appliances and food storage containers

– Silver nanoparticles inhibit the growth of microorganisms

www.nanotechproject.org/consumerproducts


Filtration Mechanisms

Filtration• Used extensively

– General / dilution ventilation (HVAC)– Local exhaust ventilation (engineering controls)– Respiratory protection (air purifying respirators and filtering

face pieces) • Air filters are classified as

– Mechanical filters– Electrostatic filters (not ESPs)

• There are many differences between filters although they all use fibrous media

• Many different fibers are used– Cotton, fiberglass, polyester, polypropylene



• Fibrous filters of different design are used for various applications– Flat-panel filters– Pleated filters– Pocket or bag filters– Respirator cartridges



Mechanisms• There are 4 types of collection mechanisms that

govern filter performance– Impaction occurs when a particle due to inertia deviates

from the air stream and collides with a fiber– Interception occurs when a particle due to it’s size simply

collides with a fiber in the air stream– Diffusion occurs when a particle due to random motion

causes it to collide with a fiber in the air stream– Electrostatic attraction occurs when a fiber is contacted by

a very small particle and is held in place by a weak electrostatic force



Adapted from Guidance for Filtration and Air-Cleaning Systems for Protecting

Building Environments, NIOSH



• Impaction and interception are dominant for collecting particles >0.2 µm

• Diffusion is dominant for collecting particles <0.2 µm (200 nm)

• As mechanical filters load with particles their collection efficiency increases

• The combined effects of these 3 collection mechanisms yields the classic collection efficiency curve



This figure is adapted from Lee et al. [1980].



• Particles from 0.2 – 0.4 µm, most difficult to stop

• Collection efficiency for nanoparticles by diffusion is as efficient as larger particles by inertial impaction and interception

Filter Testing Methods– Photometers, Optical Particle Counters (OPCs), and CPCs

are used in filter-testing

– CPCs and photometers are used in quantitative respirator fit-testing



Testing and current work• Current knowledge indicates the well designed

exhaust ventilation systems using HEPA filters effectively remove nanoparticles (Hinds 1999) – Apply current ACGIH ventilation design criteria for the

“control of particulate matter” for nanoparticles



Testing and current work • Respiratory protection

– No specific recommendations on types of respirators• Use P100 filters for highest level of protection

– Respirator filters are tested at 300 nm (0.3 µm) size particles• Most penetrating particle size (MPPS)

– Collection efficiencies for smaller particles should exceed the measured collection efficiency of 300 nm particles (Lee and Liu 1982)

– If a respirator works for MPPS, it should work for all particles– NIOSH tested HEPA filters with nanoparticles in 2003

• Found that P100 filters good down to at least 2.5 nm

– Quantitative CPC fit-testing with particles down to 20 nm for testing respirator fit using HEPA/P100 filter cartridges

• Uses nanoparticles as the test agent• Face seal is the leak/test point



Testing and current work • For respiratory protection the real question is:

– Are the assigned protection factors currently used for respirators good enough for nanotechnology applications

– In the absence of exposure limits it is hard to determine if an assigned protection factor is good enough for a given respirator

– Be conservative, use full-face APR or SCBA, and use engineering controls to ensure exposure is at a minimum


Engineering Controls

Fundamental Control Assumptions• Typically support engineering and maintenance

departments– IH’s provide guidance, calculations, and design assistance– Evaluate and validate systems upon start up

• Five fundamental control assumptionsi. All hazards can be controlled to some degree by some

methodii. There are alternative approaches to controliii. More than one control may be useful or requirediv. Some control methods are more cost-effective than othersv. Controls may not completely control the hazard



Engineering Control Techniques

• Ventilation – General/dilution ventilation– Local exhaust ventilation

• Substitution• Enclosure• Isolation• Process change• Process automation• Process elimination

Other controls• Prevention• Administrative controls• Work practices• Personal protective

equipment



General/Dilution Ventilation• Remove air from general area, replace with dilution air • Dilution of contaminated air with non-contaminated air

in a general area• Not as good for health hazard control as local exhaust• Limiting factors for general/dilution ventilation

– Quantity of contaminant too great to use dilution– Contaminant source too close to worker– Toxicity of contaminant must be low– Contaminant source must be constant



General/Dilution Ventilation

• Typically not good for dusts and fumes– Due to high toxicity, requires more dilution air– Higher concentrations of contaminant produced– In the past hard to measure contaminants

• Easier to do now with real time monitors



Local Exhaust Ventilation

• Proper design necessary – Capture velocity is dependent on moving air past a

contaminant source– Drawing it into an exhaust hood – Using an enclosure to capture particles

• Negative pressure used to lower exposure • Positive pressure used to increase quality and output



• Particles >10 µm settle very quickly • Coarse, fine, and nanoparticles remain airborne

– Follow air currents– Health based size range– Same applies to fumes, mists, and smokes

• Utililze local exhaust– Minimize exposure– Maximize quality and output– Improve housekeeping and maintenance



Examples• Point source/capture exhaust systems

– Snorkel exhaust– Bench top exhaust– Ventilated cabinets (negative pressure)

• Lab hoods• Process ventilation systems

– Push – pull systems– Overhead capture systems– Negative pressure enclosures



For most nanotechnology processes and job tasks• The control of airborne exposure to nanoparticles can most likely be

accomplished using a wide variety of engineering control techniques similar to those used in reducing exposure to general aerosols

(Ratherman 1996; Burton 1997)• The use of ventilation systems should be designed, tested, and maintained

using approaches recommended by ACGIH (ACGIH 2001)

• In general, control techniques such as source enclosure and local exhaust ventilation systems should be effective for capturing airborne nanoparticles, based on what is known of nanoparticle motion and behavior in air

(ACGIH 2001)• Using current control techniques based on scientific knowledge of generation,

transport, and capture of aerosols, these control techniques should be effective for controlling airborne exposures to nanoscale particles

(Seinfeld and Pandis 1998; Hinds 1999)


Nanoparticle Measurements

Applications – back to basics, JHA’s, WAA’s• Determining effectiveness of ventilation systems

– Mechanical filtering efficiency– Understanding pressure differentials– General/dilution ventilation– Local exhaust ventilation/controls

• Conduct work area monitoring– Determine specific sources of nanoparticles

• Point source location• Target potential sources and problem areas

– Particle mapping/engineering studies• Grid out work areas

– Determine infiltration of ambient sources into the workplace• Transport pathways



Applications – back to basics• Assist in characterizing, defining, and validating new production

processes• Assist with task-specific material handling operations

– Minimizing process emissions• Selecting and implementing corrective actions

– Repair equipment or engineering controls– Remove source– Remediate source– Implement engineering controls– Change worker process interactions– Implement use of PPE

• Validate corrective actions

“ALARA best practice approaches”



General Sampling Practices – back to basics• Evaluate and measure outdoor concentrations

– Determine external sources– Time of day when concentrations may go up

• Ventilation system plays a role– Check mechanical filtration efficiency– Local exhaust ventilation– Lack of ventilation

• Background/baseline measurements of the work area– Before work operations– During and after (if possible)– Can change quickly– Can bias measurements– Ideally would like background, corrected measurement data


Mass Measurements

• Why would we want to measure mass for nanoparticles?– It is a well known metric– Established substance-specific exposure limits for

larger particles


Mass Measurements

• Traditional gravimetric methods may not be effective for nanoparticles– Insignificant mass compared to larger particles– High flow rates and long sampling times required

for a quantifiable sample

http://www.skcinc.com/pumps/100-3000.asp


Mass Measurements

• Mass may not be a good indicator for nanoparticle exposure and dosing since it is based on toxicity data for large particles– Quantum chemistry and physics play a role– Do toxicity and pharmacokinetics change?– Size decreases ↔ toxicity increases

• Mass can be measured– Gravimetrically (discussed)– Photometrically


Photometry

Photometers• Photometers measure particle mass in real time• Light-scattering effects vary based on

– Particle size, size distribution, density, morphology, and refractive index

• Photometers respond linearly to mass concentration across their detection range

• Size specific aerosol fractions are measured• Size fractions > aerodynamically cut using an inlet

conditioner > cyclone or impactor


Photometry

Photometers• Typical particle size range: 0.1 – 10 µm• Typical concentration range: 0.001 – 100 mg/m3

• Size fractions using inlet conditioners – Respirable, thoracic, PM10, PM2.5 or PM1.0

• What types of aerosols will a photometer detect and measure?– Any aerosol within the size range

• Personal, hand held, table top, and fixed monitor configurations


Mass Measurements

Gravimetric Strengths• Area and personal samplers

in the nano size range• Ability to compare to

historical data• Relatively inexpensive

– Air sampling equipment– Lab analysis

Gravimetric Weaknesses• Mass measurements for

nanoparticles are difficult due to size and sampling constraints

• Not a real-time measurment• Toxicity for nanoparticles unknown

– May not have quantitative relevance as an exposure metric

• No guidelines or standards for nanoparticles


Mass Measurements

Photometer Strengths• Qualitative relevance for

agglomerated / aggregated nanoparticles: >100 nm

• Real-time measurement• Field portable, battery

operated, and easy to use• Personal or area sampling• Relatively inexpensive ~$3

-10K

Photometer Weaknesses• Not in the size range for

discrete nanoparticles: <100 nm

• Not size resolved• Not a compliance method• No guidelines or

standards for nanoparticles


Number Concentration

Why measure the number concentration of nanoparticles?– To determine if they are being released from

production processes or being re-aerosolized during bulk production use

• Point source location during production or use• Select and validate engineering controls• Compare to background/baseline measurements of the

work area



• Measure number concentration in real time

• A CPC uses a method of condensation to grow particles to an optically detectable size

• CPCs do not size particles, only count them

• Not a size resolved measurement• CPCs require a working fluid

– Alcohol or water

Condensation Particle Counters - CPC

Source: TSI Inc.



• Particle size range:

10 – 1000 nm• Concentration range:

0 – 500,000 pt/cc• What types of aerosols will a

CPC detect and measure?– Any aerosol within the size range

• Hand held and table top configurations

Condensation Particle Counters - CPC

Source: TSI Inc.



CPC Strengths• CPCs are well suited to

measuring nanoparticles in the workplace– Good qualitative measurements– Based on relative changes in concentration

• Field portable, battery operated, and easy to use

• Handheld models relatively inexpensive ~ $5 – 8K

CPC Weaknesses• CPCs are not a size

resolved measurement– Cannot determine particle size– Cannot account for

agglomeration

• No guidelines or standards exist for number concentration of nanoparticles


Size Distribution

Why measure size distribution of nanoparticles?– To know the size and number of nanoparticles produced

• Exposure information• Quality control purposes (maximize output and minimize loss)

– To determine if they are being released from production processes or being re-aerosolized during bulk production use

• Point source location• Select and validate engineering controls• Compare to background/baseline measurements of the work area

– To determine if nanoparticles are agglomerating or aggregating after production


Size Distribution

Size distribution can be measured in a number of ways– Scanning Mobility Particle Sizer (SMPS), <1 µm– Optical Particle Counter (OPC), >0.3 µm


SMPS Technology

• A SMPS uses a Differential Mobility Analyzer (DMA) and a CPC to measure size and number concentration of nanopaticles

• DMA separates particles according to charge and electrical mobility for size classification

• CPC grows the particles to a detectible size for counting


SMPS Technology

• High resolution and accuracy

• Wide size and concentration range

• Fast response time

• What type of aerosols can be detected with a SMPS?– Any aerosols within the detection range


SMPS Technology

SMPS Technology• Size ranges vary

– 2.5 – 1000 nm– 10 – 487 nm

• Multiple size bins• Fast continuous scanning


OPC Technology

• Measures the size and number concentration of particles in real time– Counts individual flashes of scattered light and the intensity of

each flash• OPCs may be able to measure nanoparticles in the

workplace– Nanoparticles must have agglomerated or aggregated to ≥0.3

µm• Typically have multiple size bins that can be arranged

to simultaneously measure size fractions– Respirable, thoracic, >10 µm, PM1.0, PM2.5 and PM10– Eliminating the need for inlet conditioners like cyclones and

impactors


OPC Technology

• Typical particle size range: 0.3 µm – ~15 µm

• Concentration range: 2x106 particles/ft3 (70 pt/cc)

• What types of aerosols will a OPC detect and measure?– Any aerosol within the size range

• Hand held, table top and fixed instruments


Size Distribution

SMPS Strengths• Particle size range

– 2 to 1000 nm

• Real-time measurement• Size resolved, quantitative

measurement– For nanoparticle production

process applications– Determine if nanoparticles are

agglomerating

• Qualitative area sampling– Locate point sources– Select and validate engineering

controls for nanoparticles

SMPS Weaknesses• No guidelines or standards

for nanoparticles• Limited field portability• Computer controlled• Expensive $60 – 80K


Size Distribution

OPC Strengths• For agglomerated/aggregated

nanoparticles, >300 nm• Size-resolved measurement• Real time measurement• Qualitative area sampling

– Relative changes in number concentration

– Locate point sources– Select and validate engineering

controls• Field portable, battery operated,

and easy to use• Relatively inexpensive ~$3 -10K

OPC Weaknesses• Not in the size range for

discrete nanoparticles, <300 nm• No guidelines or standards for

nanoparticles


Surface Area Measurements

Why measure the surface area of nanoparticles?

• To obtain exposure information based on lung deposited surface area

• To determine if they are being released from production processes or being re-aerosolized during bulk production use

• Point source location• Select and validate engineering controls• Compare to background/baseline measurements

of the work area



• Nanoparticles vs. large particles– Have relatively little mass– Have large surface area– Produced in large numbers– Quantum effects change physical, chemical, and

biological properties

• Nanoparticle exposure studies– Drs. Driscoll (1996) and Oberdörster (2001) have

shown that surface area (μm2/cc) plays an important role in the toxicity of nanoparticles



• Surface area is the metric that is highly correlated with particle-induced adverse health effects

(Driscoll, 1996; Oberdörster, 2001)

• Potential for adverse health effects is proportional to particle surface area

(Driscoll, 1996; Oberdörster, 2001)

• Emerging need to assess workplace exposure to nanoparticles based on surface area



Lung Deposition

• Inhalation is primary exposure route

• Most common/efficient way for particles to enter the body

• The respiratory tract consists of 3 major regions– Extrathoracic region: uppermost region– Tracheobronchial (TB) region: middle region– Alveolar (A) region: innermost region

• Uptake of inhaled particles according to deposition in respiratory tract


Lung Deposition

Based on International Commission of Radiological Protection (1994) and U.S. Environmental Protection Agency (1996a).Air Quality Criteria for Particulate matter, 2004, p 6-5.


Diffusion Charger Technology

• A Diffusion Charger measures the charge of the particles and calculates the surface area deposited in the TB or A regions of the lung

• Particle size range: 10 nm – 1000 nm• Measurement ranges: TB = 1 – 2,500 µm2/cc

A = 1 – 10,000 µm2/cc• What types of aerosols will a diffusion charger detect

and measure?– Any aerosol within the size range

• Desk top and hand held instruments



Diffusion Charger Strengths

• Surface area is highly correlated with observed toxic effects

• Nano size range, 10 - 1000 nm• Real time measurement• Quantitative area sampling

– Surface area dosing information

• Qualitative area sampling– Data correlates well with CPC and

SMPS measurement trends

• Field portable, battery operated, and easy to use

• Relatively inexpensive, ~ $10 - 16K

Diffusion Charger Weaknesses

• Not size resolved– Cannot determine size of particle– Does not account for agglomeration

• No guidelines or standards for nanoparticles– What’s a good number vs. a bad

number


Working Towards Best Practices

What can be done?A Proactive Approach – to managing risk• To minimize the risk of exposure, implement a risk

management program • Develop a health hazard surveillance program for

workers in nanotechnology operations• Continual reassessment of potential hazards and

exposures based on information gained is necessary to maintain the surveillance program



Program Elements1. Hazard surveillance monitoring2. Guidelines for installing and evaluating

engineering controls3. Work practices

• Education and training of workers• Establishing safe production processes and

material handling procedures

4. Procedures for selection and use of PPE (e.g., respirators, clothing and gloves)



Hazard Surveillance Monitoring• Conduct a job hazard analysis• Determine need for sampling

– Based on potential exposure areas• Leads to a decision to measure nanoparticles, keep in

mind several factors– Mass and bulk chemistry for exposure may be less important

than particle size, surface area and surface chemistry– Currently, there is no single sampling method to use to

characterize nanoparticle exposure (Brower et al., 2004)– Therefore, use a multi-metric sampling and measurement

approach to characterize workplace exposure to nanoparticles (Brower et al., 2004)



Hazard Surveillance Monitoring1. Identify source(s) of nanoparticle emissions

• Critical to get ambient background / baseline measurements regardless of monitoring metric used

• Compare against measurements taken during and after work processes

• Area, point source, and personal sampling locations

2. Once point source location(s) are identified continue using multi-metric sampling approach

• Select engineering control techniques to use • Conduct dosing and exposure measurements• Goal is to achieve ALARA conditions



Hazard Surveillance Monitoring

3. Implement and validate engineering controls using same multi-metric sampling approach

• To achieve ALARA conditions

4. Continue with hazard surveillance monitoring program on a regular basis

• Ensure engineering controls functioning• Verify process and workplace conditions have not

changed



Health Hazard Monitoring • Using a multi-metric sampling approach, assessment of

worker exposure to nanoparticles can be conducted• This multi-metric approach:

– Determines presence and identification of nanopaticles– Assists in selecting, implementing, and validating engineering

controls– Assists in characterizing the aerosol measurement metrics

• Since most nanoparticle measurements rely primarily on area sampling, some uncertainty will exist in estimating worker exposures


Multi-metric Sampling & Control Approaches

Nanotechnology Applications

1. Nanoparticle manufacturing– Bulk production of engineered nanoparticles

2. Industrial manufacturing using nanoscale

materials– Utilizing bulk nanoscale materials in products– Bulk nanoscale material handling



Nanoparticle Manufacturing Process

• Manufucturing nanoparticles in bulk

• May be a well characterized and defined production process or not

• May be a clean room manufacturing environment (R&D Lab) or, a “dirty” environment– May or may not have general/dilution ventilation



Hazard Surveillance Monitoring• Do a job hazard analysis

– Determine need and make decision to sample• What do you measure to determine sources?

– Size distribution using a SMPS• Know what size of nanoparticle being produced• Want to see if it is getting into ambient air to determine if you have

process leaks• Quality control measurement (minimize loss and maximize output)• Comparing against background measurements

– Number concentration using a CPC for locating point sources

• Qualitatively locating point sources using changes in relative nanoparticle concentration

• Comparing against background measurements



Hazard Surveillance Monitoring• Located sources now what do you measure?

– Size distribution using a SMPS• Know what size of nanoparticle being produced• Want to see if it is producing the same size particle• Quality control measurement (minimize loss and maximize output)• Comparing against background measurements

– Number concentration using a CPC for selecting, implementing, and validating engineering controls

• Qualitatively using relative changes in number concentration to achieve ALARA conditions

• Comparing against background measurements– Surface area concentration using a diffusion charger

• Conduct work area dosing and exposure measurements• Before, during, and after implementation of engineering controls• Compare against background measurements




• Continue with monitoring on a regular basis to ensure that ALARA conditions are maintained

• Reassess hazard surveillance plan periodically



Manufacturing Using Bulk Nanoscale Material• Not well characterized or defined manufacturing process

– Utilizing bulk nanomaterials in products– Bulk nanoscale material handling processes– May be dealing with agglomerates and or aggregates, >100 to

300 nm

• Typically a dirty production environment– May or may not have general/dilution ventilation– Other processes may contribute aerosol contaminants



Hazard Surveillance Monitoring• Do a job hazard analysis

– Determine need and make decision to sample• What do you measure to determine sources?

– Mass using a photometer, particles >100 nm– Size distribution using a OPC, particles >300 nm– Number conentration using a CPC, particles >10 nm– Surface area using a diffusion charger, particles >10 nm

• Qualitatively locate point sources using relative changes in concentrations for all measurements

• Locate and ruling out other contributing contaminant processes• Use any measurement that works to locate point sources• Compare against background measurements



Hazard Surveillance Monitoring• Located sources now what do you measure?

– Use any point source location measurement that works for selecting, implementing, and validating engineering controls

• Qualitatively using relative changes in number concentration to achieve ALARA conditions

• Comparing against background measurements

– Surface area concentration using a diffusion charger• Conduct work area dosing and exposure measurements

– Before, during, and after implementation of engineering controls

• Compare against background measurements




• Continue monitoring on a regular basis to ensure that ALARA conditions are maintained

• Reassess hazard surveillance plan periodically


Summary

• Nanoparticle exposures are not clearly understood • . . . mass and bulk chemistry may be less important

than particle size, surface area, and surface chemistry (or activity) for nanostructured materials. . .

• Primary route of exposure is inhalation and lung deposition

• No established exposure metrics• Filtration and engineering controls can be effective• Use multi-metric approach to assess nanotechnology

workplaces


Gregory M. Olson, Jr., M.S.Product ManagerHealth and Safety InstrumentsTSI Incorporated USA(651) [email protected]

0.001 0.01 0.1 1 10 100Particle Size Range (micrometers)

Inhalable (Total dust)

TSPRespirable

Thoracic Particle Size Range for Aerosol Instruments

Photometer

CPC-alcohol

OPC

Diffusion Charger

4

OPC: Optical Particle Counter

CPC: Condensation Particle Counter

SMPS: Scanning Mobility Particle Sizer

CPC - Water

SMPS

Nanoparticle

Photometer OPC CPC SMPS Diffusion Charger

Typical Size Range 0.1 to 10 um 0.3 to 20 um

0.0025 to 3.0 um

0.0025 to 1 um

0.02 to 0.1 um

Measures Particle Mass (estimate) Yes No No (Yes) No

Typical Mass Concentration Range 0.01 to 100 mg/m3

N/A N/A N/A N/A

Measures Particle Size No Yes No Yes No

Detects Single Particles No Yes Yes Yes No

Typical Number Concentration Range (Particles / cc)

N/A 2 x 106 1.5 x 1010 1 x 108 N/A

Upper Limit, number concentration (particles/cc)

N/A 70 500,000 1 x 108 N/A

Measures Lung-Deposited Surface Area No No No No1 Yes

OPC = Optical Particle Counter

CPC = Condensation Particle Counter

SMPS = Scanning Mobility Particle Sizer

1Surface area can be calculated using SPMS size distribution data.

Aerosol Technology

Comparisons

Application Comparison

Photometer OPC CPCDiffusion charger

Indoor Air Quality - Conventional Studies Good Good N/A N/A

Indoor Air Quality - Ultrafine Particle Tracking Poor N/A Excellent N/A

Industrial Workplace Monitoring (Conventional) Excellent Poor N/A N/A

Industrial Workplace Monitoring (Nano-Materials) Poor1/Good2 Poor1/Good2 Excellent3 Excellent3

Outdoor Environmental Monitoring Good Good Excellent3 Excellent3

Emissions Monitoring Excellent Poor Good Excellent

Respirator Fit Testing Excellent Poor Excellent N/A

Filter Testing Excellent Excellent Excellent N/A

Clean Room Monitoring Poor Excellent Excellent N/A

1 Engineered nano particles of homogenous material less than 0.1 micron (100 nm) in diameter.2 Agglomerated and aggregated nano particles greater than 0.1 microns (100 nm) diameter for photometers and greater than0.3 microns (300nm) for OPC’s.3The Health effects of engineered nano particles and ultrafine particles below 0.1 micron (100 nm) in diameter are notcompletely understood. Research suggests these ultrafine particles may cause the greatest harm. There are currently noestablished exposure limits or governmental regulations specifically addressing ultrafine or nano particles exposure.


References

• Nanotechnology Consensus Workplace Safety Guidelines– http://www.orc-dc.com/

• National Nanotechnology Initiative (NNI)– http://www.nano.gov

• USEPA – “Nanotechnology White Paper”– http://www.epa.gov/osa/nanotech.htm

• NIOSH - “Approaches to Safe Nanotechnology” – www.cdc.gov/niosh/topics/nanotech/

• UK Health & Safety Executive – “Nanoparticles: Occupational Hygiene Review”– http://www.hse.gov.uk/RESEARCH/rrhtm/rr274.htm

http://www.nano.gov/

http://www.nano.gov/

http://www.cdc.gov/niosh/topics/nanotech/

http://www.hse.gov.uk/RESEARCH/rrhtm/rr274.htm


References

• National Nanotechnology Initiative (NNI) – US Gov’t.– Started in 2000– Over $2 Billion spent on nanotechnology research since

2000– $1 Billion allocated in FY 2006– Predicting annual investment of $15 Billion per year by 2015– Estimated that 50% of all products produced will be affected

by nanotechnology within 10 years– Employment in nanotechnology is expected to grow to 2

million workers in next 10 years (US Department of Labor)


References

• NIOSH – US– Taking a leadership role for nanotechnology and OH&S

• Research to Practice

– Comprehensive nanotechnology website, including the “Nanoparticle Information Library”

– “Approaches to Safe Nanotechnologies”• Formulate guidance relevant to occupational health surveillance for

nanotechnology• Provide information that can be used to create appropriate occupational

health surveillance to fit the needs of those involved with nanotechnology

– Nanotechnology industry field studies– Research projects for nanopaticle toxicity


References

• US Environmental Protection Agency– Traffic related particle exposure and risk assessment studies

• Mass, number concentration, size distribution, and surface area

– Investigating whether or not nanomaterials should be classified as new chemicals (e.g., new CAS numbers) under TSCA, or will it be a classified as a “new use” for an existing chemical under TSCA

• ASTM, ANSI, and ISO– Working on consensus nomenclature terminology– ISO developed and released a document on information and

guidance for monitoring for nanoparticle exposures in workplace atmospheres (2006)


References

• Federal OSHA– Participating in NNI as a federal agency– Working with NIOSH as they conduct research– Future plans to develop guidance documents for

nanotech companies

• Health and Safety Laboratory (HSL/HSE) – UK– Nanotechnology industry field studies– Workplace sampling and control strategies using

control banding techniques


References

• Woodrow Wilson Institute for Scholars– Project on Emerging Nanotechnologies, started 2005– Dedicated to helping ensure that as nanotechnologies

advance, 1. Possible risks are minimized

2. Public and consumer engagement remains strong

3. The potential benefits of these new technologies are realized

– Philosophy of “responsible nanotechnology”


References

• US Food and Drug Administration (FDA)– Regulates a wide range of products, including foods,

cosmetics, drugs, devices, and veterinary products, which may utilize nanotechnology or contain nanomaterials

– Formed a task force in August 2006 “Charged with determining regulatory approaches that

encourage the continued development of innovative, safe

and effective FDA-regulated products that use

nanotechnology materials”


References

Research Work• In chronic rat inhalation studies:

– Inflammatory response induced by different particle types was found best correlated with surface area of particles retained in the alveolar space (Oberdörster, 1996)

- Total surface area of retained particles was found best dose parameter for a correlation when the endpoint was lung tumor (Driscoll, 1996)


References

Research Work• Nano-sized TiO2 induce tumor in rats

(Lee et al., 1985; Heinrich et al. 1995) – Chronic inhalation studies with nano-scale ( ~ 20 nm) and fine

TiO2 (~ 250 nm) have shown that more than ten times lower inhaled concentrations of the aggregated ultrafine particles, compared with fine particles, are sufficient to produce the same amount of tumor-induction in rats

• Nano-sized Teflon fumes (count median particle size~18nm) result in severe pulmonary inflammation and hemorrhage in rats. No toxicity observed for 100 nm particles of same material

(Oberdörster et al., 1995)


References

Research Work

• Carbon black nanoparticles cause mutations and cancer

– Large enough dosage of nano-sized carbon black capable of causing pulmonary inflammation, particle overload, lung tumors and mutations in rats

(Driscoll et al.,1996)

– Similar results seen with nano-sized quartz and TiO2 (Driscoll et al., 1995; Heinrich et al.,

1995)


References

Research Work

• Intratracheally induced carbon nanotubes cause pulmonary toxicity in mice and rats

(Warheit et al., 2004; Lam et al., 2004)

• In hamsters, inhaled nanoparticles translocate into blood (Nemmar et al., 2001)

• In humans, inhaled nanoparticles translocate into blood thus influence cardiovascular endpoints directly

(Nemmar et al., 2002)


References

References1. Donaldson, K. et al. Ultrafine (Nanometer) Particle Mediated Lung Injury, J. Aerosol Sci.

29(5/6):553-560. (1998)2. Driscoll K.E. Role of inflammation in the development of rat lung tumors in response to chronic

particle exposure. Inhal. Toxicol. 8 [suppl1: 85-98] (1996)3. Driscoll K.E. et al. Pulmonary inflammatory, chemokine, and mutagenic responses in rats after

subchronic inhalation of carbon-black. Toxicol. Appl. Pharmacol. 136, 372-380 (1996)4. Driscoll K.E. et al. Characterizing mutagenesis in the hprt gene of rat alveolar epithelial-cells.

Exp. Lung Res. 21, 941-956 (1995).5. Heinrich et al. Chronic inhalation exposure of Wistar rats and two different strains of mice to

diesel engine exhaust, carbon black, and titanium dioxide. Inhal. Toxicol. 7: 533-556 (1995)6. Lam C.W. et al. Pulmonary toxicity of single-wall carbon nanotubes in mice 7 and 90 days after

intratracheal instillation, Toxicol. Sci. 77 (1): 126-134 (2004)7. Lee K.P. et al. Pulmonary response of rats exposed to titanium dioxide by inhalation for two

years. Toxicol. Appl. Pharmacol. 79: 179-192 (1985)8. Li N. et al. Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage,

Environ. Health Persp. 111:455-460 (2003)9. Nemmar A. et al. Passage of inhaled particles into the blood circulation in humans, Circulation

105:411-414 (2002)10. Nemmar A. et al. Passage of intratracheally instilled ultrafine particles from the lung into the

systemic circulation in hamster. Am J Respir Crit Care Med (164) 1665-1668 (2001)

http://80-wos01.isiknowledge.com.floyd.lib.umn.edu/?SID=pjmipao47B1Bio2MCGM&Func=Abstract&doc=20/8




References

References11. Oberdörster E.

Manufactured nanomaterials (Fullerenes, C-60) induce oxidative stress in the brain of juvenile largemouth bass, Environ. Health Persp. 112 (10): 1058-1062 (2004)

12. Oberdörster G. Pulmonary effects of inhaled ultrafine particles. Int. Arch. Occup. Environ. Health 74:1-8 (2001)

13. Oberdörster, G. Significance of Particle Parameters in the Evaluation of Exposure-Dose-Response Relationships of Inhaled Particles, Particulate Sci. Technol. 14(2):135-151 (1996).

14. Oberdörster G. et al Association of particulate air pollution and acute mortality: involvement of ultrafine particles? Inhal. Toxicol. 7:111-124 (1995)

15. Penttinen P. et al. Number concentration and size of particles in urban air: effects on spirometric lung function in adult asthmatic subjects, Environ. Health Persp. 109:319-323 (2001)

16. Shanbhag, A. S. et al. Macrophage/Particle Interactions: Effect of Size, Composition and Surface Area, J. Biomed. Mat. Res. 28(1):81-90 (1994).

17. Utell M.J. et al. Acute health effects of ambient air pollution: the ultrafine particle hypothesis. J. Aerosol Med. 13:355-359 (2000).

18. Warheit D. B. et al. Comparative Pulmonary Toxicity Assessment of Single-wall Carbon Nanotubes in Rats, Toxicol. Sci. 77 (1): 117-125 (2004)



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