A new study published in The American Journal of Gastroenterology shows that these rates in the U.S. closely mirrored trends of increased carbohydrate intake and obesity from 1973-2001.

The study illustrates what may be a public heath concern as the composition of U.S. diets changes and total carbohydrate and refined carbohydrate intakes increase. Obesity is a risk factor for many types of cancer, and a diet that includes a high percentage of calories from refined carbohydrates is a common contributor to obesity. Carbohydrates were also unique in that no other studied nutrients were found to correlate with esophageal cancer rates.

The causes of esophageal cancer remain largely unknown. Despite recent advances in treatment, esophageal cancer has a poor prognosis. The five-year rate of survival for esophageal cancer remains below 20 percent and is the eighth-leading cause of cancer related death in American men.

If we can reverse the trends in refined carbohydrate intake and obesity in the U.S., we may be able to reduce the incidence of esophageal cancer, says Dr. Li Li, senior author of the study.

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Regions with the highest amounts of hydrogen-2 and oxygen-18 in drinking water and hair were southern Oklahoma, north-central Texas, Florida, south Georgia and southern South Carolina. Heavy isotope levels are high there because most water falls as summer rain and some evaporates from lakes, leaving more of the heavier isotopes behind in drinking water.

The method already is being used by police to learn where unidentified murder victims might have been prior to their deaths.

On Oct. 8, 2000, hunters found the remains of a female murder victim near Interstate-80 along the south end of the Great Salt Lake west of Salt Lake City. Detectives recovered 26 bones, some hair, a T-shirt and a necklace.

A few months later, they created a facial reconstruction and publicized it nationally, but the woman's identity remains unknown. She was about 5 feet tall, age 17 to 20.

We don't know who she is, says Park. We don't even know the cause of death.

After hearing of Ehleringer's research, Park contacted the scientist and arranged for the isotope analysis of the victim's hair to determine where she traveled prior to her death.

The samples I gave to Jim told me her approximate location for the last two years of her lifetime, Park says. She moved around within the Northwest “ mainly in the Idaho-Montana-Wyoming area and maybe into Oregon and Washington.

After the scientists conduct more tests for oxygen isotopes in the woman's teeth “ isotopes that may reveal where her teeth formed and thus where she grew up “ Park will examine missing persons records in areas the victim visited in hopes of identifying her.

Every little bit helps, the detective says. You put pieces of the puzzle together to get a whole picture. And this is definitely something that will give us a piece of the puzzle.

Another use of the new method is to analyze hair from a person or animal to learn about their past movements.

In the study, the researchers analyzed a hair sample from a person who moved from Beijing to Salt Lake City. Hair grown during three months before the move contained relatively high levels of oxygen-18 and hydrogen-2, reflecting high concentrations of those isotopes in Beijing drinking water. But in hair closer to the scalp “ hair that grew after the move to Utah “ the concentrations of those isotopes dropped significantly, consistent with lower levels in Salt Lake City's drinking water.

Police could use this technique to check an accused criminal's alibi that he had not been in the region where the crime occurred.

Ehleringer says anthropologists and archaeologists may use the method to analyze ancient hair samples to reveal where Native Americans migrated or show a Mormon settler's movement from Missouri to Utah. Cerling says analyzing preserved bison hair may reveal more about their migration patterns when they were abundant.

To understand how drinking water affects isotope levels in hair, the researchers had to learn how foods influence isotopes in hair. As a result, archaeologists might analyze the hair of ancient people or animals to learn how much protein they ate, whether their diet was seafood or land-based, or what social class they occupied based on whether their diet was rich on meat protein or plant material.

There could be medical uses of the new method. Cerling says that because diabetics drink a lot of water, the proportions of oxygen in their hair from water and food would be different than in non-diabetics. Hair also might record isotope changes due to worsening symptoms of a dietary disease, Ehleringer notes.

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