London, July 1 (IANS): A method to decode an individual's unique sense of smell which they call an "olfactory fingerprint" has been found, says new research.

The method has been developed by a team of Israeli scientists.

This "olfactory fingerprinting", in addition to help identify individuals, can detect diseases such as Parkinson's and Alzheimer's early.

"It can also lead to non-invasive methods of initial screening as to whether bone marrow or organs from live donors are a good match," said lead researcher Lavi Secundo from Weizmann Institute of Technology in Israel.

The method is based on how similar or different two odours are from one another.

In the first stage, volunteers were asked to rate 28 different smells according to 54 different descriptive words, for example, "lemony" or "masculine".

The 28 odours made for 378 different pairs, each with a different level of similarity.

This provided them with a 378-dimensional fingerprint. Using this highly sensitive tool, the scientists found that each person indeed has an individual unique pattern - an "olfactory fingerprint".

Could this finding extend to millions of people?

According to the researchers, 28 odours alone can be used to "fingerprint" some two million people and just 34 odours would be enough to identify any of the seven billion individuals on the planet.

The next stage of the research suggests that our olfactory fingerprint may tie in with another system of ours in which we all differ - the immune system.

Each of us has about six million smell receptors of around four hundred different types in our nose. The distribution of these receptors varies from person to person - so much so that each person's sense of smell may be unique.

The paper was published in the journal Proceedings of the National Academy of Sciences (PNAS).