Occupational Health and Safety Decisions in the face of Nanomaterials Uncertainties. Outline

Transcription

1 Occupational Health and Safety Decisions in the face of Nanomaterials Uncertainties Greener Nano 2008 Mark McCulloch CIH Hewlett-Packard Outline Pre-Nano (Existing) Situation! Standards, Toxicology, Measurement, Application of Controls New / Future Nano-specific Situation! Precautionary Principle! ASTM Standards Applying Industrial Hygiene Principles 1

2 Pre Nano Based on bulk material (mass per ) :! Exposure Standards (TLV, PEL)! Exposure assessment & measurement! Applicable toxicology studies / data Pre Nano Standard IH approach for controls! Engineering (exhaust)! PPE a.! Gloves based on permeability b.! Respirators - TLV & PEL based Protection factors! Procedures / Best Practices 2

3 New / Future Nano-specific Situation 1. Lack of applicable exposure standards & tox data 2. Precautionary Principle! Reflected in EU regulations (nano)! Shows up in ASTM standard Precautionary Principle: Since the hazards are unknown, exposures to unbound nanoscale particles (UNP) should be as low as reasonably practicable In Radiation Safety: ALARA = As Low As Reasonably Achievable Ex: Chemistry lab, use of lab fume hoods as standard practice; esp. unknowns How does this work for Nanoscale Particles? 3

4 New / Future Nano-specific Situation New ASTM Standards:! E Standard Guide for Handling Unbound Engineered Nanoscale Particles in Occupational Settings! E Terminology for Nanotechnology E2535 Handling Guide Scope: 1.! Applicable where relevant standards do not exist 2.! Applicable where robust risk information does not exist 3.! Materials included: unbound* engineered nanoscale* particles or their respirable* aggregates! Fullerenes! Nanotubes! Nanowires! Quantum dots 4

5 E2535 Handling Guide cont d 4.!Materials not in scope a.!unp incapable of becoming airborne b. Aggregates of UNP not of respirable size (e.g. paint droplet) c. Materials w/ nanoscale surface features but no UNP! Nanoscale lithography products! Nanoelectronic structures / materials comprised of nanoscale layers E2535 Handling Guide cont d Materials not in scope cont d d.!unps which exist in nature (Volcanic ash?) f.! UNPs unintentionally produced by human activities (e.g. combustion processes) f. Materials with established exposure control programs (e.g. biological agents) or applicable published exposure limits (e.g. welding fume) 5

6 E2535 Handling Guide cont d Definitions:! Nanoscale - one or more dimensions nm! Respirable - small enough to enter alveolar space; aerodynamic equivalent dia. < 10 um! Unbound - not contained within a matrix that would prevent particle from being mobile E2535 Handling Guide cont d Summary of Guide:! Use standard industrial hygiene principles! Apply hazard communication concepts! Use the precautionary principle; establish management commitment to it 6

7 Precautionary Principle + Industrial Hygiene Principles! identification! evaluation!! qualitative (+)!! quantitative (-)! substitution or control (+) + Unique Issues with Nanoscale Particles Exposure Measurement Conundrum: A method before a standard? TSI products total surface area (models 3550 and Aerotrack) 7

8 Applying IH / Controls 1.! Exhaust - Removal of all unwanted material Carbon nano - tubes Face Velocity 120 fpm I lost my Buckyballs! Solution: Glove box with on / off exhaust 8

9 Applying IH / Controls 2. Protective Gloves Normal approach for glove / chemical compatibility! Permeation breakthrough time! Degradation Test cell for glove permeation testing per ASTM F 739 9

10 Applying IH / Controls 2. Protective Gloves cont d Normal approach for Glove / chemical compatibility Type of health effect, dosage, uptake! Acute? (e.g. localized from corrosive / warning)! Chronic? (delayed, systemic effect; toxicity)! Absorbed through skin? *** > DMSO (carrier for other chemicals) Protective Gloves cont d Issues:! Carrier solvents (e.g. Quantum dots & Toluene)! Holes in glove material! Lack of health hazard data - MSDS for carbon nanotube often uses exposure limit for elemental carbon. 10

11 5000 x SEM image of thin nitrile glove, inner surface 5 U 5000 X SEM image of thin nitrile glove, inner surface stretched 5 U 11

12 5000 X SEM image of thin nitrile glove, outer surface 5 U 6500 X SEM image of thin nitrile glove, outer surface stretched 2 U 12

13 Applying IH / Controls 3. Respirators! Some prelim data on HEPA efficiency! 3M working on treated HEPA!! Exercise caution if relying on respirators ( at this time) 4. Exhaust with HEPA filters Summary Comments / Advice for Health & Safety Staff! Partnering with researchers who use these materials! Leverage off of Chemical Hygiene Plans ( lab safety practices)! Applying Hazard Communication; explaining why there are changes ( MSDS example)! Use knowledge from asbestos (exposure toxicology & control measures) 13

14 Acknowledgements: Tom Etheridge (HP) Neal Meyer (HP) Questions? Thank You! 14