“…Historically, efforts have concentrated largely on neurotransmitters and their metabolites on the premise that stress, including radiation stress, should trigger the release of neurotransmitter molecules. Examples include 5-hydroxyindoleacetic acid (13–17), indoxyl sulfate (15), 3-methoxy-4-hydroxymandelic acid, 3-methoxy-4-hydroxyphenylglycol, metanephrine, normetanephrine, and homovanillic acid (18). More recently, urinary markers of DNA damage and repair have been identified, including thymine glycol (19, 20), thymidine glycol (19), and 8-hydroxyguanine (20).…”