Our body processes the water into two parts, hydrogen and oxygen, and these two elements remain in our hair, fingernails, and tissues. Hydrogen and oxygen molecules can differ in how much they weigh. Different forms of an element are called isotopes. Depending on where you live, tap water contains distinctive isotopes, and scientists believe that these differences are recorded in a person’s hair. To find out if hair contains the isotopic variations found in different regions, James R. Ehleringer, an environmental chemist at the University of Utah in Salt Lake City, collected hair samples from 65 barbershops in 18 states. The scientist assumed that the hair samples were from people who live in the collection area. Although people drink a lot of bottled water, the food we eat is cooked in local tap water. Other liquids we drink, such as milk and sodas, contain water that comes from the local area. Scientists compared the isotopic variations in peoples’ hair with data they already had about water composition in the United States (see map). They found that around 86% of the water in hair maches the isotopes in the water where the hair sample is from. The technique is not accurate, because similar types of water appear in large regions across the United States and also the world. But authorities can now use the method to analyze hair samples of criminals and crime victims to get more information. Based on the new discovery, Jurian A. Hoogewerff, a chemist at the University of East Anglia in Norwich, England, gave this advice: “If you’re a criminal, shave.” _________________________________________ Glossary tissue: n. Organic body matter made up of many cells. |