After years of study, earlier this month the National Institute for Occupational Safety and Health (NIOSH) released recommendations for employee exposure to diacetyl and a related chemical. Diacetyl is a naturally occurring substance, but is used by the food industry to provide butter flavoring in a range of products. In recent years, a number of employees working in microwave popcorn manufacturing facilities have experienced significant lung damage from workplace exposure to diacetyl.

NIOSH set the recommended exposure limit for diacetyl at 25 ppb, and 31 ppb for a related chemical, 2,3-pentanedione, over a 15 minute time weighted exposure period. Although the recommendation does not result in any direct compliance obligation on the part of employers, it could be used as the basis for a General Duty Clause citation by OSHA. Some food manufacturers have already commented that the recommended limit is so low that it will make continuing use of these products difficult.

Other manufacturers have already reacted by reducing or eliminating use of diacetyl in many products. Unfortunately, substitute additives have raised similar concerns with respect to employee exposure. The new NIOSH recommendations will likely cause manufacturers to redouble their efforts to reduce employee exposure to these substances through engineering controls and personal protective equipment such as respirators.