title: Industrial worker exposure to airborne particles during the packing of pigment and nanoscale titanium dioxide.
abstract: BACKGROUND
  Titanium dioxide (TiO₂) factory workers' source specific exposure and dose to airborne particles was studied extensively for particles between 5 nm and 10 μm in size.
  
  
  OBJECTIVE
  We defined TiO₂ industry workers' quantitative inhalation exposure levels during the packing of pigment TiO₂ (pTiO₂) and nanoscale TiO₂ (nTiO₂) material from concentrations measured at work area.
  
  
  METHODS
  Particle emissions from different work events were identified by linking work activity with the measured number size distributions and mass concentrations of particles. A lung deposit model was used to calculate regional inhalation dose rates in units of particles min⁻¹ and μg min⁻¹ without use of respirators.
  
  
  RESULTS
  Workers' average exposure varied from 225 to 700 μg m⁻³ and from 1.15 × 10⁴ to 20.1 × 10⁴ cm⁻⁴. Over 90% of the particles were smaller than 100 nm. These were mainly soot and particles formed from process chemicals. Mass concentration originated primarily from the packing of pTiO₂ and nTiO₂ agglomerates. The nTiO₂ exposure resulted in a calculated dose rate of 3.6 × 10⁶ min⁻¹ and 32 μg min⁻¹ where 70% of the particles and 85% of the mass was deposited in head airways.
  
  
  CONCLUSIONS
  The recommended TiO₂ exposure limits in mass by NIOSH and in particle number by IFA were not exceeded. We recommend source-specific exposure assessment in order to evaluate the workers' risks. In nTiO₂ packing, mass concentration best describes the workers' exposure to nTiO₂ agglomerates. Minute dose rates enable the simulation of workers' risks in different exposure scenarios.
authors.affiliation: Finnish Institute of Occupational Health, Nanosafety Research Centre, Helsinki, Finland. joonas.koivisto@ttl.fi
authors.forename: A J
authors.initials: AJ
authors.lastname: Koivisto
authors.forename: J
authors.initials: J
authors.lastname: Lyyränen
authors.forename: A
authors.initials: A
authors.lastname: Auvinen
authors.forename: E
authors.initials: E
authors.lastname: Vanhala
authors.forename: K
authors.initials: K
authors.lastname: Hämeri
authors.forename: T
authors.initials: T
authors.lastname: Tuomi
authors.forename: J
authors.initials: J
authors.lastname: Jokiniemi
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis* / Q000493:pharmacokinetics / Q000633:toxicity; D001331:Automation; D002617:Chemical Industry / Q000379:methods; D004396:Coloring Agents / Q000008:administration & dosage* / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D005387:Finland; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects; D008168:Lung / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000032:analysis / Q000633:toxicity; D008954:Models, Biological; D016273:Occupational Exposure / Q000009:adverse effects*; D010316:Particle Size; D052638:Particulate Matter / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity; D019064:Product Packaging; D020545:Respiratory Mucosa / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D018570:Risk Assessment / Q000379:methods; D053260:Soot / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity; D014018:Tissue Distribution; D014025:Titanium / Q000008:administration & dosage* / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity; D000078329:Workforce
chemical_list: D000395:Air Pollutants, Occupational; D004396:Coloring Agents; D052638:Particulate Matter; D053260:Soot; C009495:titanium dioxide; D014025:Titanium