Toxicity studies of acetoin and 2,3-pentanedione administered by inhalation to Wistar Han [Crl:WI(Han)] rats and B6C3F1/N mice.

Acetoin and 2,3-pentanedione are highly volatile components of artificial butter flavoring (ABF). Concerns over the inhalation toxicity of these compounds originate from the association between occupational exposures to ABF and adverse fibrotic lung effects, specifically obliterative bronchiolitis (OB) in the distal airways. 2,3-Pentanedione has been used as a replacement for 2,3-butanedione (diacetyl) in some ABF due to concerns about the respiratory toxicity of 2,3-butanedione. However, 2,3-pentanedione is structurally similar to 2,3-butanedione and has been shown to exhibit potency similar to 2,3-butanedione regarding airway toxicity following acute inhalation (whole-body) exposure. This report describes a series of studies to evaluate the 2-week inhalation toxicity of acetoin and the 3-month inhalation toxicity of acetoin and 2,3-pentanedione. (Abstract Abridged).