The new study suggests that alternative butter flavourings that have been touted as possible replacements for the potentially harmful compound diacetyl have similar sensitisation responses and may not be safe to use as alternatives.
“Since the responses were comparable to those for diacetyl, this suggests that structurally similar chemicals may not be safe alternatives in regards to hypersensitivity responses,” said the research team.
Diacetyl (also known as 2,3-butanedione, dimethyl diketone, and 2,3-diketobutane) is commonly used in the flavouring industry to add a buttery odour and flavour to food products – especially microwave popcorn. However concerns were raised that the ingredient was associated with an increased risk of lung disease clinically resembling bronchiolitis obliterans in food manufacturing workers, while further reports also suggested that the compound may be associated with Alzheimer’s disease.
Writing in Food and Chemical Toxicology researchers from the same lab that initially investigated the potential safety issues relating to diacetyl as far back as 2002 - the US National Institute for Occupational Safety and Health (NIOSH) – evaluated the dermal irritation and sensitisation potential of diacetyl alternatives such as 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione and 2,3-heptanedione in mice.
Previous research by NIOSH has suggested that 2,3-pentanedione may be an ‘inhalation hazard’ that could present comparable risks to diacetyl in terms of respiratory toxicity.
The new study found that all of the structurally similar alternatives to diacetyl had carried similar risk of sensitisation.
“Our finding that skin sensitisation potential is a shared characteristic of diacetyl and structurally-related potential substitutes supports the NIOSH recommendation that potential substitutes for hazardous flavourings should be evaluated for toxicity before they are used,” said the authors – led by Stacey Anderson of NIOSH.
The team used a mouse model to evaluate the skin sensitisation potential of structurally similar alternative flavouring chemicals in an effort to begin to assess their potential role in the development of allergic disease and their safety as alternatives for diacetyl.
Anderson and her colleagues reported no chemical-related deaths, changes in body weights, or clinical signs of toxicity in mice following exposure concentrations as high as 50% of 2,3-pentanedione, diacetyl, 2,3-hexanedione, 3,4-hexanedione, or 2,3-heptanedione.
In addition, they noted that there were no biologically significant changes in liver, kidney, thymus or spleen weights following exposure to any of the butter flavourings.
“Neither dermal irritation nor systemic toxicity were induced following in vivo skin exposure to any of the flavourings tested,” they revealed – noting that similar to diacetyl all of the compounds were identified as weak sensitising chemicals.
“Since the responses were comparable to those for diacetyl, this suggests that structurally similar chemicals may not be safe alternatives in regards to hypersensitivity responses,” they concluded.
Source: Food and Chemical Toxicology
Volume 62, Pages 373–381, 10.1016/j.fct.2013.08.053
"Evaluation of the hypersensitivity potential of alternative butter flavorings"
Authors: Stacey E. Anderson, Jennifer Franko, J.R. Wells, Ewa Lukomska, B. Jean Meade