Patterns of certain chemical elements get into people’s hair from the food they eat and the water they drink. CBCCanadian researchers have just finished collecting samples for a database that may help police solve cold cases based on chemical information found in people’s hair.
“Hair gives a chronological indicator of your daily habits — your dietary habits and your movements,” said Michelle Chartrand, one of the two University of Ottawa researchers involved in the project.
That’s because patterns of certain chemical elements get into people’s hair from their food and the water they drink, and the record of their past habits and locations is retained as their hair grows out.
“Carbon and nitrogen indicate what you eat,” Chartrand said. “Hydrogen is an indicator of where you are.”
Chartrand and her colleague Gilles St-Jean have spent every summer since 2008 collecting hair and water samples from across Canada, and finally finished the job this summer, with sampling in B.C. and Alberta.
Once the data is analyzed and compiled into a database linking specific patterns to locations across Canada, they hope it will help generate new leads in cold cases.
'If someone drinks a glass of wine every night from Australia, for example, does that make a difference in their hair?'— Michelle Chartrand, University of Ottawa
They’ve already begun work on several cases, including the famous case of Madame Victoria, the body of a woman in her 50s found near the Royal Victoria Hospital in 2001, which was featured on CBC’s Fifth Estate in March.
“Her hair was about 43 centimetres long, so that gives us roughly 43 months of information,” Chartrand said, noting that hair grows at a rate of about a centimetre per month.
“Based on what our analyses showed us, we believe that she lived in seven distinct locations over those past 43 months.”
The researchers were able to say with confidence that she was not from western Canada
All her time was spent east of southern Manitoba or northwestern Ontario. It appeared that she started off in northern Ontario or Quebec, then moved toward the south, never returning to any of her previous locations. The analysis also showed that she had either been ill or made a major change to her diet in the four months before her death.
That was a rich amount of information, but it wasn’t enough to uncover the identity of Madame Victoria.
Still, the researchers say they’re always willing to apply their developing technique to case work. One issue at the moment is that the cost per case can be thousands of dollars, but that is expected to go down over time.
“As it becomes more mainstream or better known,” St-Jean said, “what I suspect will probably happen is forensic labs probably will start buying this type of equipment and hiring specialists that will help them do cases.”
Hair analysis relies on the fact that hydrogen — an element found in water — comes in slightly different chemical forms called isotopes. Some isotopes are heavier than others, and their proportions vary with latitude and the distance people live from either coast. That’s because heavier isotopes have a greater tendency to fall as rain.
The body of Madame Victoria was found in Montreal in 2001 and her face was reconstructed from her skull. Analysis of her hair showed she had moved seven times in 34 months, starting from northern Quebec or Ontario and moving south. CBCOver time, as clouds drift north and away from the coasts, they gain a higher proportion of lighter isotopes, which is reflected in the water sources – and the tap water – in those regions, St-Jean said. The ratios make their way into people’s hair when they drink the local water, and can be measured using a machine called an isotope ratio mass spectrometer.
Archeologists were the first to link isotope ratios in hair to geographic locations, developing the technique about 25 years ago. One of the questions they wanted to answer was whether the people buried in mass graves at ancient Mayan temples were local or captured from other regions, St-Jean said. Analysis of their hair showed they were not locals.
Applying the technique in Canada is a little trickier, the researchers acknowledge, because of the extra sources of water and other elements that enter our bodies.
“We can get food from any part of the world, any time of the year,” Chartrand said. “That’s what makes [it] much more difficult to track modern humans.”
As part of the sample collection, the researchers gave people who offered hair samples a questionnaire about their daily habits – asking what kinds of fluids they drink, including how much bottled water, how much they travel, and so on – to try and account for that.
“If someone drinks a glass of wine every night from Australia, for example, does that make a difference in their hair?” Chartrand wonders. “These are big unknowns that we are trying to compensate for.”
So far, it appears that the local water accounts for only around 27 per cent of the hydrogen isotope signal in people’s hair, she said. But that’s enough to distinguish an Albertan from a Manitoban or a person from Toronto from a person from Thunder Bay.
The technique does have limitations. For example, everyone along the Great Lakes and St. Lawrence River from southwestern Ontario to Montreal shows a similar signal due to their common water source.
“This is not an exact science,” Chartrand said. “It’s not designed to pinpoint an exact location.”
Nor is there a standard, internationally recognized method of hair analysis that will stand up in court.
But it is on its way to becoming one more technique that can be used with other forensic evidence, the researchers said.
St-Jean added, “It is a tool that helps the investigators to point their investigation in maybe a different direction than they would have thought of.”
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