A leading radiation scientist for Canada's Department of National Defence says the country is not prepared to deal with a 'dirty bomb.'

The subject was discussed at an international conference on experimental hematology in Montreal.

Two months ago, a man was arrested in the United States on suspicion of trying to explode a so-called 'dirty bomb' in a large American city. That sparked fears that terrorists could get their hands on radioactive waste and build those weapons to attack Canadians and Americans.

Dirty bombs are created by attaching radioactive waste to a conventional bomb. When detonated, they disperse low-level radiation in limited areas.

Defence Research and Development Canada, an agency of the Department of National Defence, has been training first responders to treat potential victims.

But scientist, Dr. Robert Stodilka, says Canada is not prepared to handle a large scale dirty bomb attack, because of a "lack of equipment and a lack of co-ordination between the different experts that would be responding."

If a 'dirty bomb' went off in a large Canadian city today, Stodilka says authorities would have a hard time finding experts to help survey and clean up the damage. And he says it would be very expensive to decontaminate targetted areas.

Stodilka says the effects of a 'dirty bomb' would depend on the quality and quantity of the materials used. But many experts at the conference say the most harmful impact would be psychological and not physical.