Response to “Comment on ‘Flavoring Chemicals in E-Cigarettes: Diacetyl, 2,3-Pentanedione, and acetoin in a Sample of 51 Products, Including Fruit-, Candy-, and Cocktail-Flavored E-Cigarettes’”

Introduction:
This text is a response to a letter to the editor from Pierce et al. regarding a previous study on the presence of diacetyl and other flavoring chemicals in e-cigarettes. The authors of the response take the opportunity to address several points raised by Pierce et al. and clarify any misconceptions. The reader will learn about the key findings of the study and the inappropriateness of using occupational exposure limits (OELs) for the evaluation of diketone exposure in e-cigarettes.

Key Points:

* Pierce et al. failed to identify any factual errors in the original study.
* The original study found a flavored e-cigarette with a diacetyl concentration of 238 µg/e-cigarette, which exceeds the OEL of 176 µg/day calculated by Pierce et al.
* at least 25% of flavored e-cigarettes samples in a study by Farsalinos et al. (2015) would exceed the 176 µg/day limit derived by Pierce et al.
* NIOSh has stated that OELs are not intended to establish safe exposure concentrations for consumers or the general public.
* Pierce et al. misrepresented their own findings regarding diacetyl and 2,3-pentanedione levels in cigarettes and coffee.
* The exposure data reported in Pierce et al. (2015) were collected in a kitchen with a low ventilation rate, not in a coffee shop.
* Several workers at a coffee processing workplace were recently diagnosed with bronchiolitis obliterans, and NIOSh found a 2.7-fold elevated standard mortality ratio for obstruction for workers at this site.

Main Message:
The main message of the text is that the use of OELs for evaluating diketone exposure in e-cigarettes is inappropriate. The authors reiterate the potential hazards associated with diacetyl and other flavoring chemicals in e-cigarettes and emphasize the importance of evaluating this potential hazard further, restricting access by youth, and providing consumers with information and warnings. The authors also highlight the misrepresentation of the findings in Pierce et al.'s letter and the need for accurate representation of scientific data.

allen, Joseph G., Skye S. Flanigan, Mallory LeBlanc, Jose Vallarino, Piers MacNaughton, James h. Stewart, and David C. Christiani. “Response to ‘Comment on “Flavoring Chemicals in E-Cigarettes: Diacetyl, 2,3-Pentanedione, and acetoin in a Sample of 51 Products, Including Fruit-, Candy-, and Cocktail-Flavored E-Cigarettes.”’” Environmental health Perspectives 124, no. 6 (June 2016). https://doi.org/10.1289/EhP348.