Evaluation of a Standardized Micro- Vacuum Sampling Method for Collection of Surface Dust Kevin Ashley, 1 Greg Applegate, 1,2 Tami Wise, 1 Joe Fernback 1 and Mike Goldcamp 2 1 Centers for Disease Control and Prevention, National Institute for f Occupational Safety and Health, Cincinnati, Ohio 2 Wilmington College, Department of Chemistry, Wilmington, Ohio
Disclaimers Mention of company names or products does not constitute endorsement by the Centers for Disease Control and Prevention. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.
Introduction Background Reasons for vacuum surface sampling (e.g., Be) Substrate characteristics, sampling media Method standardization Surface sampling by micro-vacuum technique Evaluation of method by gravimetric analysis Numerous representative substrates tested Performance data for standardized method Discussion & summary Attributes & limitations Recommendations / future directions
Surface sampling of beryllium: Evidence of skin sensitization by exposure to beryllium particles Subsequent inhalation of beryllium may lead to chronic beryllium disease (CBD) Assess potential exposures to beryllium on surfaces from sampling and analysis data
Surface Sampling - Metals Use to estimate surface contamination of (for example): Lead Arsenic Cadmium Aluminum Mercury Nickel Cobalt Silver Zinc Tin Chromium Manganese Molybdenum Uranium Platinum
Surface Sampling Techniques Wipe sampling Widely used for smooth / hard surfaces Application to rough / porous surfaces questionable Collection medium may be a factor in subsequent analysis Vacuum sampling Alternative to wipe sampling Consider substrate to be sampled Micro-vac performance data previously unavailable
National Technology Transfer and Advancement Act of 1995 (NTTAA) Public Law 104-113 113 (enacted 1996); directs federal agencies to: (A) Use voluntary consensus standards in lieu of in-house procedures (B) Participate in the development of relevant voluntary consensus standards
Wipe Sampling Standard ASTM International voluntary consensus standard: ASTM D6966, Standard Practice for Collection of Settled Dust using Wipe Sampling Methods for Subsequent Determination of Metals
Vacuum sampling: Consensus standards ASTM D7144 ASTM D5438
ASTM D7144 Micro-vacuum sampler evaluation (Ashley et al., JOEH 2007) Sampler: Filter cassette fitted with collection nozzle Sample at 2.5 L/min
PVC inserts (Accu( Accu-capcap TM ) for gravimetric analysis
Substrates Micro-vacuum sampling performance evaluation
Micro-vacuum sampling Performance data (soft / rough surfaces) Substrate material Industrial carpet Plush carpet SRM 1579 22 (10) 36 (30) SRM 1648 32 (14) 34 (24) SRM 2583 27 (8) 41 (16) Car seat material Denim 31 (18) 45 (17) 49 (12) 37 (13) 49 (12) 55 (21) Concrete block 64 (210) 69 (37) 87 (72) Concrete block, painted 33 (14) 45 (21) 43 (26)
Micro-vacuum sampling Performance data (hard / smooth surfaces) Substrate material Glass SRM 1579 59 (11) SRM 1648 43 (10) SRM 2583 50 (14) Tile 51 (27) 42 (35) 50 (18) Steel 51 (10) 39 (9) 38 (21) Linoleum 41 (21) 28 (10) 30 (15) Vinyl 38 (18) 33 (13) 38 (18) Wood 34 (19) 33 (10) 49 (23)
Micro-vacuum sampling Collection nozzles (soft / rough surfaces) Substrate material Industrial carpet Plush carpet SRM 1579 13 (5) 23 (9) SRM 1648 25 (6) 39 (16) SRM 2583 13 (4) 28 (13) Car seat material Denim 24 (9) 26 (9) 29 (12) 44 (12) 28 (9) 30 (9) Concrete block 41 (41) 44 (25) 43 (44) Concrete block, painted 22 (16) 27 (23) 16 (26)
Micro-vacuum sampling Collection nozzles (hard / smooth surfaces) Substrate material Glass SRM 1579 28 (7) SRM 1648 45 (9) SRM 2583 26 (9) Tile 26 (17) 46 (26) 35 (11) Steel 21 (6) 44 (7) 33 (9) Linoleum 30 (9) 42 (9) 26 (9) Vinyl 26 (11) 41 (13) 27 (4) Wood 21 (8) 43 (5) 26 (6)
NIST SRM Morphologies Scanning Electron Microscopy (SEM): SRM 1579: ~1 µm m to > 100 µm Individual particles & aggregates of widely varying size SRM 1648: ~1 µm m to ~25 µm Finely divided particles; less aggregation SRM 2583: ~2 µm m to ~75 µm Individual particles predominant; very little aggregation
Micro-vacuum sampling Cassette plus collection nozzles (soft / rough surfaces) Substrate material Industrial carpet Plush carpet Approx. % collected, SRM 1579 35 59 Approx. % collected, SRM 1648 57 73 Approx. % collected, SRM 2583 50 69 Car seat material Denim 55 71 78 81 77 85 Concrete block 105 113 130 Concrete block, painted 55 72 59
Micro-vacuum sampling Cassette plus collection nozzles (hard / smooth surfaces) Substrate material Glass Approx. % collected, SRM 1579 87 Approx. % collected, SRM 1648 88 Approx. % collected, SRM 2583 76 Tile 77 88 85 Steel 72 83 71 Linoleum 71 70 56 Vinyl 64 74 65 Wood 55 76 75
Micro-vacuum sampler: Recommended design improvements? (e.g., Creek et al., JEM 2006) 1. Incorporate collection nozzle in with cassette, weigh entire contents 2. Use conductive collection nozzle (reduce static effects), analyze cassette contents 3. Use high-volume sampling pump to increase pick-up efficiency
Summary Focus here has been on available voluntary consensus standards for sampling of metals on surfaces, esp. evaluation of the micro-vacuum collection method. Performance data intended to support the consensus micro-vacuum standard. Design-based procedure Improvements possible, but performance data needed for modifications
ASTM International Conference on Surface Sampling Methods Boulder, Colorado [August 2008] Topics: Applications (e.g., indoor environments; dermal exposures; homeland security) Analytes (e.g., chemical [inorganic / organic], nano,, bio, radiation hazards) Sampling & Analysis aspects Research, Development, Policy issues etc.
Acknowledgments BHSC & ASTM International: Kathy Creek & Gary Whitney, Los Alamos N. L. Elton Hewitt, Fluor Hanford Geoff Braybrooke,, US Army CHPPM Mike Brisson,, Washington Savannah River Co. Kenn White, AIHA Fellow CDC/NIOSH: Martin Harper, Rob McCleery,, Ken Martinez, Doug Evans, Gene Kennedy