banding nano

Applying control banding in the determination of control

measures in laboratories using nanoparticles

Scott Hollenbeck, John Jankovic, Randy Ogle Center for Nanophase Materials Sciences,

Oak Ridge National Laboratory

The 234th ACS National Meeting, Boston, MA, August 21, 2007

This presentation:

• Overview of basics of Control Banding • How Control Banding has been applied

to Operations at the Center for Nanophase Materials Sciences

• Examples of other uses of Control Banding in the R&D Environment.

Control Banding Control Banding - increased national and international

attention – as a practical approach to controlling hazardous agents in a

changing world; – an approach complementary to the traditional methods of air

sampling and analysis. – Provides a formal process for incorporating professional

judgment and monitoring. • The concept - initially developed by the pharmaceutical

industry and later adapted for use by small businesses and developing countries, an approach that was appealing to many large industries involving chemical manufacture.

• NIOSH leads U.S. efforts

“Control Banding 101”, NIOSH http://www.cdc.gov/niosh/topics/ctrlbanding/

• Control banding - a process in which a single control technology is applied to one range or band of exposures to a chemical (such as 1−10 mg/m3) that falls within a given hazard group (such as skin and eye irritants or severely irritating and corrosive).

• Four main control bands have been developed for exposure to chemicals by inhalation

“Control Banding 101”, NIOSH cont. • The most developed CB model for control banding has been

established by the Health and Safety Executive (HSE) of the United Kingdom.

– http://www.coshh-essentials.org.uk/

• “Easy & qualitative”, First applied to dangerous chemicals, chemical mixtures, and fumes.

• Emphasizes the controls needed to prevent hazardous substances from causing harm to people at work.

• The greater the potential for harm, the greater the degree of control needed to manage the situation and make the risk “acceptable.”

CB can be applied to categories of chemicals or their mechanism of toxicity (Table 1 =Inhalation) Application can be prospective, based on anticipated exposures; or retrospective based on measured exposures; and should be periodically be re-evaluated

From NIOSH

Does control banding work? YES

• The German authority (Bundesanstalt für Arbeitsschutz und Arbeitsmedizin - BAuA) evaluated the system based on about 1,000 personal measurements from field studies in 18 industrial applications. They found that for solids (dusts and powders) and medium-scale use (liter quantities) of liquids, exposures were within the range predicted by the CB process.

• A study of another control banding tool, the International Labor Organization (ILO) Toolkit, was conducted in the United States. The study found small safety margins for the hazard bands that included high-potency chemicals.

Design and Application of Controls Center for Nanophase Materials Sciences (CNMS)

• CNMS Laboratories, designed to provide high level of control • Designed for nanotechnology R&D hazards • For normal R&D operations the goal is to achieve a control status

of 2 or less

CNMS method for CB in prospect

• Research Safety Summary (RSS) process, flag priority chems.

• At project planning, do CB (or other hazard analysis) and determine need for IH monitoring.

• Document in RSS, IH handles informing employees

A Conceptual Idea for Conducting Exposure Assessment as Part of the CNMS Work Control Process Using Control

Banding to Achieve a Desired Control Status

WORK CONTROL

EXPOSURE ANALYSIS

CONTROL BANDS

CONTROL

EXPOSURE

A Control Band (CB) designation reflects a belief about the level of control for a particular process. Validation of the process’s CB designation determines the actual control status (CS).

CS (0)

CS (1)

CS (3)

CS (4)

CS (5) Likely (100% + OEL or Unk) CB (5)

Possible (50% < 100% OEL) CB (4)

Unlikely (10% < 50% OEL) CB (3)

Highly unlikely (< 10% OEL) CB (2) CS (2)

No Exposure Potential CB(0)

Remote (<< 10% OEL) CB (1)

Assignment of a CB of 3 or less permits start-up and interim operation of a process under surveillance.

Validation as a CS of 3 or less permits continued operation of a process.

Belief (exp potential +

toxicity)

The initial CB designation may be assigned on the basis of process knowledge, exposure data from a similar exposure group/task, modeling, or a combination thereof.

Belief (process knowledge,

exposure data, modeling)

Specified Set of Controls

Control Band Assignment

Add to specified controls to achieve a CB designation of 3 or lower.

Validate Control Band

Selection

Initial Control Band Assignment

(0 – 3)

Feedback

Once a control band is validated it represents the control status of the operation. Only a CS of 3 or lower is acceptable for routine process operation. The control status is reevaluated on a periodic basis commensurate with the CS level.

CB becomes Control Status. Document and

Determine Reevaluation

Schedule

Sampling data Cutting and Cold Forming Cadmium Sheet Metal ORNL bldg. 7012 sheet metal working (1991-1995)

Date Sample Time (min)

Cadmium (µ g)

TWA Cnct’n. (µ g/M3)

7/26/91 176 ND <1.1 7/26/91 165 ND <1.1 8/21/91 440 ND <1.1 8/21/91 400 ND <1.1 1/11/95 400 ND <1.1 1/11/95 400 ND <1.1 Detection limit for Cd was approximately 1 µ g

Sheets of cadmium were sheared, bent, and rolled to specified sizes and shapes for use as shielding in HFIR fuel storage containers. Six (approx 2' x 4') sheets of cadmium metal were cut and formed using a sheet metal shear and a hand operated break. Breathing zone exposure monitoring was conducted during this activity.

Assign a CB of 1

Developing belief about a process/activity based on:

Process Knowledge

Cutting and Cold Forming Cadmium Sheet Metal is not a likely mechanism to produce cadmium

fume or aerosolize respirable particulates

Assigned CB activity exposure

1 cutting 5% of the exposure limit

1 Bending/shaping <1% of the exposure limit

1 installing <1% of the exposure limit

Developing belief about a process/activity based on:

Bayesian analysis of the sampling data combined with professional judgment suggests the control band.

Control Status 1 calls for: • 2 samples per sampling cycle • 24 month sampling interval • 5-10% of SEG/SET per cycle • exposures < 10% of OEL = no change in control status

Selection of initial control band (process knowledge and prior monitoring)

Control Status determination drives additional assessment

+

Initial Control Band Assignment

(1)

Prior

Exposure Rating0 1 2 3 4

Decis

ion

Prob

abilit

y

1

0.80.6

0.40.2

0

0.2

0.6

0.140.04 0.02

Previous monitoring of process indicates CB as 1-2

location activity time (min)

job concentration

8 h 2d average % of AL

employee # 922470 cutting 290 1.72 gCd/m3 0.51 gCd/m3 2 employee # 924275 installing 245 no Cd detected <0.10gCd/m3 <0.4 on wall inside tank installing 516 no Cd detected < 0.14 gCd/m3 <0.6

Process knowledge and monitoring from similar ops is used to assign an initial CB

Sampling combined with process knowledge verifies CB 1 designation

Posterior


Decis

ion

Prob

abilit

y

10.80.6

0.40.2

0

0.000

0.901

0.0980.001 0

CB 1 becomes CS 1

Likelihood


Decis

ion

Prob

abilit

y

10.80.6

0.40.2

0

0.001

0.677

0.315

0.006 0.000

EXAMPLE

Process control band validation feeds back into data bases ensuring initial designations reflect actual work places and practices.

Control Band 1

Manual Cutting and Cold Forming Cadmium Sheet Metal is not a likely mechanism to produce cadmium fume or aerosolize respirable particulates

Posterior


Dec

isio

n P

roba

bilit

y

10.80.6

0.40.2

0

0.000

0.901

0.0980.001 0

For future use from the book of control bands:

Controls flow both into and from control band designation

HAZCOM is required in the JHA process. Initial monitoring is not required for the planned operation. Wet wiping the cadmium sheets before handling is desirable but not required. Respiratory protection is not required for the planned operation. Personal hygiene and the use of gloves (cotton is acceptable) Hand washing before eating or smoking. Provision of company clothes or coveralls is desirable but not required.

Note: Conclusions are based on the assumption that the task to be preformed will involve cutting with shears and cold forming. Any activities that might abrade or otherwise produce cadmium particles which could become airborne are outside the scope of this assessment.

Two CB examples, from the CNMS

• First example is a polymer processing system and determining if CB/Controls are sufficient.

• Second, is application of CB to carbon nanotube synthesis

Polymer Collection using solvent systems in fully enclosed process system. Minimal personnel contact during fills and decanting. System and work takes place in laboratory hood.

Similar Exposure Group or Task Control Band 0

(exposure belief < < OEL)

General Process Description: Polymers are formed in an enclosed system. Various solvents contained in the same system are used to separate reacted polymeric material. The system is opened for filling/recharge, final collection of polymer, and disposal of spent solvents. Skin/eye contact with solvents is possible during solvent transfer steps.

Other possible hazards include glass apparatus manipulations involving cutting and heating with open flame torch.

Solvent exposures in breathing zone are expected to be << 10% of the OEL as task concentrations without time weighting.

Monitoring to validate control band designation and associated controls.

Table 1. Results of air monitoring

location activity time (min)

job concentration % of AL

Researcher BZ standing at hood face- arms occasionally inside hood opening.

Monitoring/adjusting apparatus

5 ND (<0.1 total VOC) ND

Researcher BZ standing at hood face –head occasionally inside plane of hood opening.

Opening glass vessel <5 ND (<0.1 total VOC) ND

Researcher BZ standing at hood face–head occasionally inside plane of hood opening.

Pouring off solvent <5 ND (<0.1 total VOC) ND

Prior


Dec

isio

n P

roba

bilit

y

1

0.80.6

0.40.2

0

0.6

0.2 0.150.04 0.01

Likelihood


Dec

isio

n P

roba

bilit

y

10.80.6

0.40.2

0

0 0

0.945

0.038 0.017

Posterior


Dec

isio

n P

roba

bilit

y

10.80.6

0.40.2

0

0 0

0.988

0.01 0.001

Polymer Collection using solvent systems in fully enclosed process system. Minimal personnel contact during fills and decanting. System and work takes place in laboratory hood.

Similar Exposure Group or Task Control Band 2

(exposure belief < < OEL)

Monitoring to validate control band designation combined with belief about process control indicates control band 2 for this task. This change reflects the low exposure limit (high toxicity) of benzene, and the high detection limit of the monitoring equipment.

Minimum controls: Hazcom, PPE to prevent skin contact, and general ventilation. Process enclosure is recommended but not required.

Resample within 24 months / 3 samples / acceptable control demonstrated if results < 50% or OEL. More sensitive analytical method may allow for reduction of control band.

Ambient background outside clean room (11,000 p/cc)

Clean room background (25 p/cc)

Carbon Laser Ablation Process

Moving into clean room

530 p/cc limit (OSHA limit for graphite)

Justification described in corresponding poster.

HEPA vacuum used to move all nano material from quartz tube into collection chamber.

Collection chamber removed, ends covered – highest potential for employee exposure during this step.

Industrial Hygiene Controls

TWA = 120 particles/cc

Industrial Hygiene Controls

Harvesting nano materials by enclosing collection chamber in bag and working in hood

Overall process TWA = 310 p/cc

Traditional industrial hygiene controls (clean room under HEPA filtration, local exhaust ventilation, process enclosure,

HEPA vacuum) effectively control inhalation exposure.

Nano material created is larger than 100 nm

Hazard Assessment

Therefore, majority of material is deposited in head airways rather than penetrating deep into the lungs.

Ensuring Exposure Control for a New Process

Initial hazard assessment initiated in research safety summary – a document created jointly with researchers and occupational health professionals that describes process, risks, and controls

A preliminary control band is assigned based on similar task group

Control bands incorporate requisite controls based on toxicity, exposure potential, monitoring capability, process stability, and professional judgment

Control band designation is validated by process monitoring and changed as appropriate

Validated control band incorporates air sampling at requisite resample frequency to ensure continued process control

Similar Exposure Group or

Task

Prior


Decis

ion

Prob

abilit

y

1

0.80.6

0.40.2

0

0.030.17

0.6

0.170.03

Likelihood


Decis

ion

Prob

abilit

y

10.80.6

0.40.2

0

0

0.52 0.48

0 0+ Posterior


Decis

ion

Prob

abilit

y

10.80.6

0.40.2

0

0

0.235

0.765

0 0

Professional judgment Process evaluation

combined

Laser ablation nano particle generation & harvesting

Control Band 2

• Process is controlled using existing methods (clean room, HEPA vacuum, enclosure, local exhaust ventilation).

• Inhalation hazard is low for agglomerated particulate as size is less than 100 nm; therefore, does not penetrate into lungs.

• Operational exposure limit (530 p/cc) is protective and achievable.

• Monitoring results combined with professional judgment using Bayesian techniques confirm control band 2 is justified for operations whenever controls as specified are implemented.

• Resample every year or with any change in process by performing a spot check (three breathing zone measurements). If median is less than or equal to 265 p/cc process is considered to continue as well controlled.

Summary for laser ablation

Conclusions

• Efficient and effective method for hazard analysis in the R&D environment

• Provides a formal process for incorporating pre- and post judgment regarding a task

• Ranks tasks based on degree of hazard control

• Provides a method of conducting and documenting hazard assessments

banding nano

Business