title: Polyisocyanates in occupational environments: a critical review of exposure limits and metrics.
abstract: BACKGROUND
  Determination of polyisocyanates is important because they are a major contributor of exposure to the isocyanate functional group in many workplace environments and are capable of inducing sensitization and asthma. However, with multiple different measurement metrics in use, comparison of isocyanate exposure data between studies and development of occupational exposure limits (OELs) for polyisocyanates is difficult.
  
  
  METHODS
  An analysis of existing problems in the measurement and regulation of isocyanates is presented based on the published analytical, toxicological, and regulatory literature, and the authors' own analytical data and experience with isocyanates.
  
  
  RESULTS
  This analysis supports a need for standardization of isocyanate measurement metrics and provides a framework for the development of an OEL for polyisocyanates.
  
  
  CONCLUSIONS
  The total isocyanate group (microg NCO/m(3)) is recommended as the most feasible and practical metric (unit) by which to express polyisocyanate exposures for research, control, and regulatory purposes. The establishment of a comprehensive isocyanate OEL that simplifies the current agent-by-agent approach and expands coverage to polyisocyanates is also recommended.
authors.affiliation: University of Massachusetts Lowell, Work Environment Department, KI 200, One University Avenue, Lowell, MA 01854, USA. Dhimiter_Bello@uml.edu
authors.forename: Dhimiter
authors.initials: D
authors.lastname: Bello
authors.forename: Susan R
authors.initials: SR
authors.lastname: Woskie
authors.forename: Robert P
authors.initials: RP
authors.lastname: Streicher
authors.forename: Youcheng
authors.initials: Y
authors.lastname: Liu
authors.forename: Meredith H
authors.initials: MH
authors.lastname: Stowe
authors.forename: Ellen A
authors.initials: EA
authors.lastname: Eisen
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ellenbecker
authors.forename: Judy
authors.initials: J
authors.lastname: Sparer
authors.forename: Fred
authors.initials: F
authors.lastname: Youngs
authors.forename: Mark R
authors.initials: MR
authors.lastname: Cullen
authors.forename: Carrie A
authors.initials: CA
authors.lastname: Redlich
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D000818:Animals; D001249:Asthma / Q000139:chemically induced; D004784:Environmental Monitoring / Q000379:methods; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology; D017953:Isocyanates / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D008452:Maximum Allowable Concentration; D015394:Molecular Structure; D016273:Occupational Exposure; D017132:Workplace
chemical_list: D000395:Air Pollutants, Occupational; D017953:Isocyanates