title: Potential for occupational exposure to engineered carbon-based nanomaterials in environmental laboratory studies.
abstract: BACKGROUND
  The potential exists for laboratory personnel to be exposed to engineered carbon-based nanomaterials (CNMs) in studies aimed at producing conditions similar to those found in natural surface waters [e.g., presence of natural organic matter (NOM)].
  
  
  OBJECTIVE
  The goal of this preliminary investigation was to assess the release of CNMs into the laboratory atmosphere during handling and sonication into environmentally relevant matrices.
  
  
  METHODS
  We measured fullerenes (C60), underivatized multiwalled carbon nanotubes (raw MWCNT), hydroxylated MWCNT (MWCNT-OH), and carbon black (CB) in air as the nanomaterials were weighed, transferred to beakers filled with reconstituted freshwater, and sonicated in deionized water and reconstituted freshwater with and without NOM. Airborne nanomaterials emitted during processing were quantified using two hand-held particle counters that measure total particle number concentration per volume of air within the nanometer range (10-1,000 nm) and six specific size ranges (300-10,000 nm). Particle size and morphology were determined by transmission electron microscopy of air sample filters.
  
  
  CONCLUSIONS
  After correcting for background particle number concentrations, it was evident that increases in airborne particle number concentrations occurred for each nanomaterial except CB during weighing, with airborne particle number concentrations inversely related to particle size. Sonicating nanomaterial-spiked water resulted in increased airborne nanomaterials, most notably for MWCNT-OH in water with NOM and for CB.
  
  
  CONCLUSIONS
  Engineered nanomaterials can become airborne when mixed in solution by sonication, especially when nanomaterials are functionalized or in water containing NOM. This finding indicates that laboratory workers may be at increased risk of exposure to engineered nanomaterials.
authors.affiliation: U.S. Army Engineer Research and Development Center, Environmental Laboratory, Vicksburg, Mississippi 39180, USA. David.R.Johnson@usace.army.mil
authors.forename: David R
authors.initials: DR
authors.lastname: Johnson
authors.forename: Mark M
authors.initials: MM
authors.lastname: Methner
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Kennedy
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Steevens
mesh_terms: D000336:Aerosols / Q000009:adverse effects / Q000032:analysis; D000395:Air Pollutants, Occupational / Q000009:adverse effects* / Q000032:analysis; D004738:Engineering; D004782:Environmental Health; D037741:Fullerenes / Q000009:adverse effects / Q000032:analysis; D006801:Humans; D006900:Hydroxylation; D007753:Laboratories; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology; D037742:Nanotubes, Carbon / Q000009:adverse effects* / Q000032:analysis / Q000648:ultrastructure; D016273:Occupational Exposure; D010316:Particle Size; D012996:Solutions; D013010:Sonication / Q000009:adverse effects; D053260:Soot / Q000009:adverse effects / Q000032:analysis
chemical_list: D000336:Aerosols; D000395:Air Pollutants, Occupational; D037741:Fullerenes; D037742:Nanotubes, Carbon; D012996:Solutions; D053260:Soot