Exposures and Emissions in Coffee Roasting Facilities and Cafés: Diacetyl, 2,3-Pentanedione, and Other Volatile Organic Compounds

Abstract

Roasted coffee and many coffee flavorings emit volatile organic compounds (VOCs) including diacetyl and 2,3-pentanedione. Exposures to VOCs during roasting, packaging, grinding, and flavoring coffee can negatively impact the respiratory health of workers. Inhalational exposures to diacetyl and 2,3-pentanedione can cause obliterative bronchiolitis. This study summarizes exposures to and emissions of VOCs in 17 coffee roasting and packaging facilities that included 10 cafés. We collected 415 personal and 760 area full-shift, and 606 personal task-based air samples for diacetyl, 2,3-pentanedione, 2,3-hexanedione, and acetoin using silica gel tubes. We also collected 296 instantaneous activity and 312 instantaneous source air measurements for 18 VOCs using evacuated canisters. The highest personal full-shift exposure in part per billion (ppb) to diacetyl [geometric mean (GM) 21 ppb; 95th percentile (P95) 79 ppb] and 2,3-pentanedione (GM 15 ppb; P95 52 ppb) were measured for production workers in flavored coffee production areas. These workers also had the highest percentage of measurements above the NIOSH Recommended Exposure Limit (REL) for diacetyl (95%) and 2,3-pentanedione (77%). Personal exposures to diacetyl (GM 0.9 ppb; P95 6.0 ppb) and 2,3-pentanedione (GM 0.7 ppb; P95 4.4 ppb) were the lowest for non-production workers of facilities that did not flavor coffee. Job groups with the highest personal full-shift exposures to diacetyl and 2,3-pentanedione were flavoring workers (GM 34 and 38 ppb), packaging workers (GM 27 and 19 ppb) and grinder operator (GM 26 and 22 ppb), respectively, in flavored coffee facilities, and packaging workers (GM 8.0 and 4.4 ppb) and production workers (GM 6.3 and 4.6 ppb) in non-flavored coffee facilities. Baristas in cafés had mean full-shift exposures below the RELs (GM 4.1 ppb diacetyl; GM 4.6 ppb 2,3-pentanedione). The tasks, activities, and sources associated with flavoring in flavored coffee facilities and grinding in non-flavored coffee facilities, had some of the highest GM and P95 estimates for both diacetyl and 2,3-pentanedione. Controlling emissions at grinding machines and flavoring areas and isolating higher exposure areas (e.g., flavoring, grinding, and packaging areas) from the main production space and from administrative or non-production spaces is essential for maintaining exposure control.

Keywords: 2,3-pentanedione (acetyl propionyl); cafe; coffee roasting and packaging; diacetyl; exposure assessment; volatile organic compounds.

Figure 1

Full-shift TWA personal exposures to diacetyl and 2,3-pentanedione among café, production and non-production workers in flavoring and non-flavoring facilities in samples analyzed using modified OSHA Method 1013/1016. From left to right, number of samples n = 18 for café, n = 6 for non-production flavoring, n = 41 for non-production non-flavoring, n = 91 for production flavoring, and n = 259 for production non-flavoring. By compound, connecting letters indicate groups not statistically different.

Figure 2

Linear regression of OSHA Methods 1013/1016 diacetyl and 2,3-pentanedione air concentrations (log-concentration in ppb). Shaded area indicates 95% confidence interval. Dotted lines represent 95% confidence limits.

Figure 3

Heatmap of personal instantaneous activity exposures for select VOCs (log-concentration in ppb) using canisters (NMAM 3900).

Figure 4

Heatmap of instantaneous area source concentrations for select VOCs (log-concentration in ppb) using canisters (NMAM 3900).