researchers in Canada have proved that persistent toxic fluorochemicals used in industrialised parts of the world land up in the blood of humans and animals in pristine areas far away, such as the Arctic region.

The chance detection of the derivatives of fluorotelomer alcohols, which are carcinogenic, in the cells of people and wildlife inhabiting the polar region in the year 2000 had kicked off a major controversy.

Used in products that include stain protectors, popcorn bags for microwave ovens, fast-food wrappers, polishes and paints, fluorotelomer alcohols are volatile compounds made up primarily of carbon, fluorine and hydrogen atoms. The best known derivative of fluorotelomer alcohol is perfluorooctanoic acid (pfoa) which is used by us chemical giant DuPont to make its proprietary Teflon. This material is used to make non-stick utensils and stove hoods.

The scientists, led by University of Toronto chemist Scott Mabury, used the latest 3-dimensional modelling techniques to explain how air currents carry the bioaccumulative fluorotelomer alcohols to the Arctic.

They proposed that as the air currents transport fluorotelomer alcohols from densely populated, industrialised regions such as the northeastern us to remote regions, they react with other chemicals present in the atmosphere and transform themselves into pfoa and other perfluorocarboxylic acids (pfcas). Their paper was published in the online version of Environmental Science and Technology on December 28, 2005.

The model indicates that roughly 5 per cent of atmospheric fluorotelomer alcohols are converted into pfcas, which are distributed throughout the northern hemisphere, with highest levels prevailing in the Arctic and the mid-Atlantic Ocean. The model predicts that the levels of the chemicals reach a peak in the Arctic during the summer, when their concentration becomes roughly twice as high as the concentrations in eastern us. The scientists are now trying to conduct experiments that will test the validity of these predictions.