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One Centimetre is enough

25.06.2008
Did you eat fish last year that contained high mercury levels? A researcher at the Norwegian University of Science and Technology has developed an innovative test that uses hair to provide the answer

Blond or dark, long or short, curly or straight: Hair is far more than just an ornament atop your head. In fact, a single strand of hair amounts to an entire biological information bank. And the longer the hair, the more information it contains.

Like a multiple - year blood test

Trace metals such as iron, zinc, copper, nickel, mercury, manganese or molybdenum are found in the body in extremely small amounts. They serve a variety of functions, and are consumed through food and drink. The body doesn’t produce these substances on its own. Currently, if for some reason you want to check the trace metal levels in your body, you have to go to the doctor, who will take the centilitres of blood needed for a test, and send them off to be analysed.

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But now Kristin Gellein, a PhD student at the Norwegian University of Science and Technology (NTNU), has developed a new and better analytical method to measure trace metals and other elements in the body. And all she needs is a tiny little strand of hair. Just one centimetre is enough – from that Gellein can sift out and quantify up to 30 different trace metals.

The significance of Gellein’s test is this: the substances found in hair mirror the substances found in the blood. And because hair grows at a rate of about one centimetre per month, Gellein can conduct a retrospective blood analysis by testing hair centimetre by centimetre. A single strand of hair thus becomes a kind of time machine, allowing Gellein to track a person’s trace metal exposure back in time.

A regular blood test just provides information on a person’s blood levels at the time that the blood test is taken. But an analysis of hair is more like a continuous blood test – and if the strand is long enough, the information it stores can span years.

A mystery

“I’ve analysed hair strands as long as 36 centimetres for my research, and have found three years worth of information”, the researcher explains. This particular long hair came from an Indian woman who had lived in Norway for some time.

Gellein started with the top part of woman’s hair strand, which had been nearest to the head and thus was the most recent. What was amazing was that the hair contained a great deal of strontium. The further down the hair strand that the researcher measured, the higher the strontium levels. The reason is that strontium is found naturally in drinking water, and the water in India contains relatively high levels of strontium. Normally, Norwegian water contains about 27 micrograms of strontium per litre of water, but in India this amount is 1 300 micrograms per litre of water.

Fishing for an answer

Gellein found large differences in the amounts of mercury and selenium in another research subject. This particular individual’s hair was 26 centimetres long, which represented well over two years of “data”. “The surprising thing was that the highest concentrations came in two sequences, and between these concentrations, the values were considerably lower. And I found when I measured the hair length, that the amounts climbed in the summer months”, Gellein said. The connection became clear when the hair’s owner reported that he was an enthusiastic fisherman and ate quite a lot of marine fish in the summer, Gellein says. In this way, a hair analysis is more than just a test of an individual’s exposure – it also can be used as a kind of pollution indicator.

The tests are analysed with a machine called an HR-ICP-MS, a specialised instrument able to detect trace metals in extremely low concentrations. Another advantage is that the test is highly precise. Gellein has succeeded in taking advantage of these characteristics in the way that she concentrates her samples. The method involves exposing the samples to high pressure and temperature. This process breaks down all the organic material, and all the trace metals are converted to their ionic forms in a clear liquid.

Sick from metals?

This measurement method can be quite useful both in work-related and forensic medicine. But researchers see the test’s biggest potential in helping to make the connection between environment and illness. That’s the opinion of Tore Syversen, a professor in the Department of Neuroscience at NTNU’s Faculty of Medicine, and one of the project’s coordinators. Neurologists have long suspected that there might be a connection between trace metals and neurological diseases such as MS (multiple sclerosis), ALS (amyotrophic lateral sclerosis) and Parkinson’s and Alzheimer’s disease.

Patients with these types of diseases can have high variations in the levels of trace metals in their bodies. Experts haven’t managed to figure out why this is true, and what the significance is of these levels in terms of illness. A central question is whether patients become sick because their bodies concentrate metals at levels that are higher than normal, or whether it is the illness itself that causes the body to be unable to handle trace metals in a normal way. Gellein’s improvements to the analytical method may be an important tool in furthering this area of research.

More than just hair

In addition to studying hair, the test method can be used with minute amounts of blood, spinal fluid and urine. In her PhD research, Gellein has analysed blood and spinal fluid from patients with Skogholt’s disease, a neurological illness that has many similarities to MS, but that also has clear differences. Patients experience a gradual weakness in their muscles, in their ability to speak and their memory. The illness has affected one specific family and was discovered by a community doctor in Sør-Odal. Initially it was thought that the illness was inherited from the mother’s side of the family, but a number of other cases have also been discovered

Gellein’s material is comprised of samples from 11 people who range from 28-50 years old. She found that the spinal fluid from these patients showed elevated levels of all trace metals, particularly copper, iron and zinc. The levels were three times higher than normal for copper and iron, and twice normal levels for zinc. But these same differences were not found in the blood tests. This is useful information for those in pursuit of the reasons for and mechanisms behind the disease. If the increased levels of trace metals were due to external influences and environmental pollution, they would have first been detected by the blood tests.

Better and more certain diagnoses

Metal analyses can reflect three conditions. The first is if the patient has been overexposed to metals through his or her work or from the environment. The second is if the patient has a restricted or a special diet, because the right levels of trace metals require eating a balanced diet. Lastly, the analyses can show how the body handles trace elements – and any variations that might be due to genetic tendencies or possibly the use of pharmaceutical drugs.

“The thing that is new with Gellein’s method is that we can measure many trace elements at the same time, and at extremely low levels. Because many trace elements are mutually dependent upon each other, this kind of multi-element analysis is a much better tool than what we have had in the past”, Syversen says.

Kristin Gellein | alfa
Further information:
http://www.chem.ntnu.no

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