Catalytic pollution fear

April 24, 1998

Julia Hinde at the Geoscience 98 conference at Keele University

Catalytic converters fitted to modern cars to reduce dangerous gas emissions may be polluting the environment with metals whose effects on human health are not fully known, researchers told the Geoscience 98 conference.

Concentrations of platinum up to 1,000 times higher than is naturally found in rocks have been measured next to the M6 motorway by researchers from the University of Wales, Aberystwyth. This, they say, is the direct result of catalytic converters.

Quantities of the metal drop off away from the roadside, but higher than normal concentrations can still be measured up to one km from the road.

Actual quantities may still be low overall - not exceeding 330 parts per billion, says Nick Pearce, who is leading the research. But it remains unclear what the effects could be on human health.

Catalytic converters contain a mixture of metals such as platinum, rodium and paladium, each of which is only present in small quantities in rocks and in the natural environment.

The converter causes the chemical reaction in the exhaust which converts poisonous carbon monoxide into carbon dioxide.

Gradually, says Dr Pearce, over the lifetime of a car, the metals in the catalyst wear away.

He explained: "People know that catalytic converters don't survive forever. But what they don't know is just how much of this platinum and other metals are being thrown out into the environment. It may be up to 1,000 times more than in rocks.

These are metals which have never been released into the environment before. They are probably inert but there is a disease called platinosis which affected those who used to work in the platinum industry, while the metal is also used in cancer treatments. It may well have a medical effect. It may be a worry."

With Sue Brothwood and Ron Fuge, Dr Pearce is attempting to measure the extent of the metals being released.

Even though platinum is an unreactive metal, Dr Pearce says it may become mobile in the presence of chlorine.

Therefore when road salt - which is sodium chloride - is spread on the roads, it may lead to the platinum becoming mobile and being taken up by nearby plants.

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