title: Correcting diacetyl concentrations from air samples collected with NIOSH method 2557.
abstract: Diacetyl (2,3-butanedione), a diketone chemical used to impart a buttery taste in many flavoring mixtures, has been associated with bronchiolitis obliterans in several industrial settings. For workplace evaluations in 2000-2006, National Institute for Occupational Safety and Health (NIOSH) investigators used NIOSH Method 2557, a sampling and analytical method for airborne diacetyl utilizing carbon molecular sieve sorbent tubes. The method was subsequently suspected to progressively underestimate diacetyl concentrations with increasing sampling site humidity. Since underestimation of worker exposure may lead to overestimation of respiratory health risk in quantitative exposure-effect analyses, correction of the diacetyl concentrations previously reported with Method 2557 is essential. We studied the effects of humidity and sample storage duration on recovery of diacetyl from experimental air samples taken from a dynamically generated controlled test atmosphere that allowed control of diacetyl concentration, temperature, relative humidity, sampling duration, and sampling flow rate. Samples were analyzed with Method 2557, and results were compared with theoretical test atmosphere diacetyl concentration. After fitting nonlinear models to the experimental data, we found that absolute humidity, diacetyl concentration, and days of sample storage prior to extraction affected diacetyl recovery as did sampling flow rate to a much smaller extent. We derived a mathematical correction procedure to more accurately estimate historical workplace diacetyl concentration based on laboratory-reported concentrations of diacetyl using Method 2557, and sample site temperature and relative humidity (to calculate absolute humidity), as well as days of sample storage prior to extraction in the laboratory. With this correction procedure, quantitative risk assessment for diacetyl can proceed using corrected exposure levels for air samples previously collected and analyzed using NIOSH Method 2557 for airborne diacetyl.
authors.affiliation: Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1095 Willowdale Road, Morgantown, WV 26505–2888, USA. jjc8@cdc.gov
authors.forename: Jean
authors.initials: J
authors.lastname: Cox-Ganser
authors.forename: Gary
authors.initials: G
authors.lastname: Ganser
authors.forename: Rena
authors.initials: R
authors.lastname: Saito
authors.forename: Gerald
authors.initials: G
authors.lastname: Hobbs
authors.forename: Randy
authors.initials: R
authors.lastname: Boylstein
authors.forename: Warren
authors.initials: W
authors.lastname: Hendricks
authors.forename: Michael
authors.initials: M
authors.lastname: Simmons
authors.forename: Mary
authors.initials: M
authors.lastname: Eide
authors.forename: Greg
authors.initials: G
authors.lastname: Kullman
authors.forename: Chris
authors.initials: C
authors.lastname: Piacitelli
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis*; D000465:Algorithms; D002623:Chemistry Techniques, Analytical; D003931:Diacetyl / Q000032:analysis*; D005421:Flavoring Agents; D006813:Humidity; D008962:Models, Theoretical; D009314:National Institute for Occupational Safety and Health, U.S.; D016273:Occupational Exposure / Q000032:analysis*; D016272:Occupational Health; D014481:United States
chemical_list: D000395:Air Pollutants, Occupational; D005421:Flavoring Agents; D003931:Diacetyl