Soda Could Help Liquid Sleuths Solve Cold Cases

(July 7) -- Scientists who can precisely measure hydrogen and oxygen isotopes in water and other beverages can tell where a dead woman spent the last two years of her life, whether expensive wine is worth the price and where the milk sold in fast-food stores came from.

These are just some of the skills that biologists, geologists and analytical chemists at the University of Utah and a Salt Lake City laboratory called IsoForensics Inc. are using to assist homicide and cold-case detectives and food-quality investigators.

The key to their investigatory effort thus far is water: rainwater, surface water, well water, the clear liquid that flows from the tap and all the beverages, alcoholic and otherwise, made with it.

The body removes hydrogen and oxygen atoms from water and beverages that contain it and leaves a natural chemical imprint or fingerprint, Lesley Chesson and colleagues explain in the current issue of the American Chemical Society's Journal of Agricultural and Food Chemistry.

"What we found is that human hair records the isotopic composition of the water that you drink," she said.

These isotopes of hydrogen and oxygen in water vary in a predictable way that differs geographically by latitude, elevation and proximity to a coastal region, Chesson, an analytical chemist and the lead author of the study, told AOL News.

These isotope patterns in beverages, including the local tap water, tend to vary from city to city in ways that give communities in different regions characteristic "iso-signatures," Chesson said.

So this means that the water, microbrew or soda you drank in Pittsburgh is going to leave different chemical marker or imprints that what you drink in Denver, Seattle or Boston.

"A distinct chemical fingerprint in your hair could be used to track your travels," she said.

Death and Cold Cases

The first criminal case on which the Utah team tried to use these this technology involved a woman whose body was found in 2000 in an old bathhouse on the shores of the Great Salt Lake. It had been converted into a concert hall called Saltair.

In 2007 a medical examiner gave the researchers about a dozen hairs from the victim. They were sectioned sequentially, cut into small slivers about 2.5 millimeters, or 2/25ths, of an inch long, which is about a week's worth of growth. Depending on its length, a hair can provide months or years of data.

The researchers used an isotope ratio mass spectrometer to analyze the minute pieces of hair for the hydrogen and oxygen stable isotope ratios from water.

"We were able to get a snapshot of the victim's life back through time, you know week by week, determine what she drank and thus her location during the period," Chesson said.

They found that the victim had made periodic moves in the two years leading up to her death, back and forth between two regions every six or eight months along 300 miles or so of the I-15 corridor – maybe between Pocatello, Idaho, and Fillmore, Utah.

The case remains open.

Their second case was a body that had been found in the Berkeley, Calif., area in 1971.

"The sheriff's department over there had heard of our work and sent us 12 or 15 hairs for us for analysis," Chesson recalled. "What we found was that this victim did not change her location before her death. We told the investigators they were probably looking for someone who was local or who had been in that region for at least two years prior to her death."

Eventually, that case was solved and the isotopes helped fill in the picture of the victim, she said.

Building the Wet Database

In 2007, Chesson began collecting water and hair samples from across the United States.

Beverage manufacturers usually use local or regional water sources in producing their products, including water from private wells, a lake or river, or what is supplied through the tap by the community's water company.

In February 2008, she hit the road again to 33 U.S. cities and collected samples of beverages found in almost every community -- Dasani brand bottled water, Coca-Cola Classic soda and Budweiser beer.

The Utah team knew that beverages in many cities are isotopically almost identical to the local tap water, so they collected a database of the chemical characteristics of drinking water in 450 U.S. communities.

The team's research found that Bud might not be a reliable brew on which to pin precise geography because Anheuser-Busch Inc. operates 12 breweries in the U.S. and that beer a consumer drank may have traveled several hundred miles from brewery to supermarket shelf.

However, Chesson and her colleagues confirmed that the soda, bottled and tap water offer a far more consistent and accurate database.

Finding Fraudulent Food

The Utah team is collecting honeycomb from beekeepers across the country to create a method to accurately identify where the honey originated. If this method can be developed, federal criminal investigators from U.S. Customs and Border Protection and the Food and Drug Administration will have a long-sought-after tool in efforts to halt the smuggle of mislabeled and adulterated Chinese honey.

Wine is another agricultural product that derives much of its commercial value from the geographic location and year of grape production.

Three scientists from the University of Utah and IsoForensics -- Jason West, James Ehleringer and Thure Cerling -- used the technique of measuring hydrogen and oxygen-stable isotopes to detect and confirm the origin of wine.

They analyzed wine from Northern and Southern California, Oregon and Washington state, finding that the water in the wine provides a record of the source of the water used to grow the grapes and the climate in which the grapes were grown. Both are useful tools for independently verifying claims of regional origin and vintage. The technique showed that the wines were clearly distinguishable by growing region.

In broadening the technology for use in other food products, the Utah team succeeded in using stable isotope analysis to examine the source of milk.

Team members collected milk and cow drinking-water samples from eight locations in six states and Puerto Rico, then purchased milk from supermarkets in 30 cities within 18 states.

They found that the water in milk records a molecular fingerprint of the cow's environmental drinking water and thus allows scientists to predict the region of origin for a milk sample.

"This analysis of milk can allow companies, consumers and food safety investigators to quickly and easily verify the geographic regions of origin of liquid milk in the market," Chesson said.

Now food companies can quickly verify the geographic origins of wholesale milk purchases with a high degree of confidence.

Ehleringer, CEO of IsoForensics, says that when the technology is matched with a high-speed isotope analyzer, for example, it will allow a Wisconsin cheddar cheese company to independently screen its supply chain for milk that does not come from Wisconsin.

The ability to use the analysis of stable isotopes to determine the origin of numerous products is not just bench-top science to generate fodder for scientific journal articles.

It goes far beyond the gee whiz of medical examiners doing their CSI things.

With consumers and government regulators becoming increasing concerned over adulteration, mislabeling and traceability of food, this tracking technology is not limited to vintners or milk producers but to everyone concerned with the authenticity and safety of the food supply.

(Much of this story was originally researched for Schneider's food safety site, The Food Watchdog.)