Mutation Research xxx (2006) xxx–xxx Molecular analysis of hprt mutations induced by chromium picolinate in CHO AA8 cells Virginia H. Coryell, Diane M. Stearns ∗ Department of Chemistry and Biochemistry, Northern Arizona University, PO Box 5698, Flagstaff, AZ 86011-5698, United States Accepted 5 June 2006 Abstract Chromium picolinate (CrPic) is a popular dietary supplement, marketed to the public for weight loss, bodybuilding, and control of blood sugar. Recommendations for long-term use at high dosages have led to questions regarding its safety. Previous studies have reported that CrPic can cause chromosomal aberrations and mutations. The purpose of the current work was to compare the mutagenicity of CrPic as a suspension in acetone versus a solution in DMSO, and to characterize the hprt mutations induced by CrPic in CHO AA8 cells. Treatments of 2% acetone or 2% DMSO alone produced no significant increase in 6-thioguanine (6-TG)-resistant mutants after 48 h exposures. Mutants resistant to 6-TG were generated by exposing cells for 48 h to 80 g/cm 2 CrPic in acetone or to 1.0 mM CrPic in DMSO. CrPic in acetone produced an average induced mutation frequency (MF) of 56 per 10 6 surviving cells relative to acetone solvent. CrPic in acetone was 3.5-fold more mutagenic than CrPic in DMSO, which produced an MF of 16.2. Characterization of 61 total mutations in 48 mutants generated from exposure to CrPic in acetone showed that base substitutions comprised 33% of the mutations, with transversions being predominant; deletions made up 62% of the mutations, with one-exon deletions predominating; and 1–4 bp insertions made up 5% of the characterized mutations. CrPic induced a statistically greater number of deletions and a statistically smaller number of base substitutions than have been measured in spontaneously generated mutants. These data confirm previous studies showing that CrPic is mutagenic, and support the contention that further study is needed to verify the safety of CrPic for human consumption. © 2006 Elsevier B.V. All rights reserved. Keywords: Chromium picolinate; hprt; Mutational spectrum; Genotoxicity; Chinese hamster ovary 1. Introduction Chromium picolinate (CrPic) is a popular dietary sup- plement, originally advertised to the public as an aid for weight loss and bodybuilding. The use of CrPic as an anabolic agent was originally patented in 1992 [1]. Sales of chromium supplements in the US were reported to be ∗ Corresponding author. Tel.: +1 928 523 4460; fax: +1 920 523 8111. E-mail address: Diane.Stearns@nau.edu (D.M. Stearns). second only to those of calcium supplements in 1999 [2], with sales of chromium-based supplements exceed- ing $500 million in that year [3]. It is estimated that 10 million Americans take some form of chromium supple- ment [2], with CrPic being the most popular. In spite of its marketing success, clinical studies have not supported the efficacy of CrPic for weight loss or muscle building. A recent meta-analysis [4] found only a minor effect, if any, of CrPic on weight loss relative to placebo in 10 randomized, double-blind, placebo-controlled trials [5–14]. The mounting evidence against CrPic’s efficacy for weight loss has recently led 1383-5718/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.mrgentox.2006.06.020 MUTGEN-401162; No. of Pages 10