This is an open-label, parallel group, single-center study. The study design consists of a screening and a treatment period. A total of 42 (approximately 21 of each sex) non-smoking healthy volunteers aged 18 - 35, will be selected for treatment. Potential subjects will be assessed for exposure to ionizing radiation or working with cytotoxic chemicals, or who have cell cycle times that fall outside the range of 13 ± 1.5 hours or subjects with stable chromosomal rearrangements and/or abnormally high background chromosomal aberration frequencies. Approximately 30 subjects (10 per arm) are estimated to be needed for analysis.