Scientists weigh change to dusty old kilogram

LONDON - After years of nursing a sometimes dusty cylinder of metal in a vault outside Paris as the global reference for modern mass, scientists are updating the definition of the kilogram.

Just as the redefinition of the second in 1967 helped to ease communication across the world via technologies like GPS and the internet, experts said the change in the kilogram will be better for technology, retail and health - though it probably won't change the price of fish much.

The kilogram has been defined since 1889 by a shiny piece of platinum-iridium held in Paris. All modern mass measurements are traceable back to it - from micrograms of pharmaceutical medicines to kilos of apples and pears and tons of steel or cement.