2,3-Pentanedione is widely used as a flavoring agent in sweet foods like chocolate and cookies, and it occurs naturally in the aroma of freshly ground, roasted coffee beans. With its buttery scent, it’s easy to underestimate the potential danger it poses—but like its chemical cousin diacetyl, 2,3-pentanedione has been linked to Bronchiolitis Obliterans, a severe and irreversible lung disease commonly referred to as "popcorn lung."
The National Institute for Occupational Safety and Health (NIOSH) currently recommends limiting worker exposure to below 9.3 parts per billion (ppb) over an 8-hour workday. Interestingly, this threshold was set below the detection limit of the analytical methods used in the original studies. Thanks to advancements in instrumentation, our current analytical methods offer far greater sensitivity—comparable to those used for diacetyl.
Given these improved capabilities, we advocate for a more conservative exposure threshold:
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5 ppb over an 8-hour time-weighted average
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25 ppb for short-term (15-minute) exposure
To measure 2,3-pentanedione, we use the same validated method applied to diacetyl monitoring: air is sampled using Tenax-TA sorbent tubes and analyzed via thermal desorption GC-MS. This approach allows for precise detection even at trace levels.
On a practical note, I’ll soon be grinding a 2.5 lb bag of coffee beans at a local big box store—using their large in-store grinder to prep espresso grind. It's the perfect chance to test short-term exposure using our sampling system. If 2,3-pentanedione is being released during grinding, our method will catch it.
Stay tuned for the data—real-world exposure levels might surprise you.