Heavy Stable Isotope Levels in Hair (IMAGE) University of Utah Caption The two maps here show predicted average hydrogen (top) and oxygen (bottom) isotope levels in human hair across the continental United States -- isotopes that vary with geography because of different isotope levels in local drinking water. The ratios of heavy, rare hydrogen-2 to lighter, common hydrogen -1 are highest in red and orange areas in the top map, and lowest in the blue and darker green areas. The ratios of heavy, rare oxygen-18 to lighter, common oxygen-16 are highest in red and orange areas of the bottom map, and lowest in the blue and darker green areas. Credit University of Utah Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.