The National Institute for Occupational Safety and Health (NIOSH) is seeking comments on a draft document that would lay the groundwork for a standard on diacetyl and other food flavorings. Comments on Criteria for a Recommended Standard: Occupational Exposure to Diacetyl and 2,3-pentanedione are due by Oct. 14.

According to a report on the American Industrial Hygiene Association website, the draft document includes the following recommendations:

• A recommended exposure limit (REL) of 5 ppb of diacetyl as an eight-hour, time-weighted average (TWA) during a 40-hour workweek. The short-term exposure limit (STEL) is 25 ppb for a 15-minute time period.
  
  
• An REL of 9.3 ppb for 2,3-pentanedione as an eight-hour TWA during a 40-hour workweek. That REL is based on the lowest level at which the substance reliably can be detected using the existing analytical method. It does not imply that 2,3-pentanedione is of lower toxicity than diacetyl. The STEL is 31 ppb to limit peak exposures for 2,3-pentanedione.
  

NIOSH offers background information on food flavorings at http://www.cdc.gov/niosh/topics/flavorings.