Yellowknife (Apr 26/02) - Though they have operated for half a century, the two gold mines flanking the city have not increased city residents' risk of illness due to exposure to arsenic, said the consultant hired to develop standards for the cleanup of the mines.

The Northwest Territories' chief medical health officer, Andre Corriveau, said people are 10 times more likely to get skin cancer from exposure to sun than they are from exposure to arsenic in city soils.

The statements were made Tuesday night at a carefully managed presentation of three reports Richardson prepared dealing with arsenic contamination in the Yellowknife area and the risks associated with it.

"(Yellowknife) has among the highest levels of arsenic I have seen anywhere," Richardson told an audience of about 50 people at a public meeting Tuesday night.

The founder and director of Ontario-based Risklogic Scientific Services wrote in one of three reports presented, "the soil arsenic levels within the city are within typical background levels for the area and, as such, represent those posed by natural background."

Richardson distinguishes between city residents and Con mine trailer park residents.

Arsenic levels in the trailer park were significantly higher than in the rest of the city.

Using accepted scientific calculations, Richardson concluded arsenic in the soil around the trailer courts would result in seven times the tolerable daily intake recommended by the U.S. Environmental Protection Agency.

Richardson's conclusion appear to be at odds with some previous studies of surface contamination at the two mines.

In its proposed abandonment and restoration plan for Con mine, Miramar states, "soil within the property contains arsenic in forms originating from earlier stack emissions."

Richardson said the thousands of tonnes of arsenic trioxide particles emitted from refinery stacks of the mine amount to only about 10 per cent of the arsenic produced by the mines.

Because the highly toxic particles dissolve in water they would be dispersed into the environment during the decades of spring melts and summer rains, he said.

A 1998 EBA Engineering study of surface contamination at Giant stated: "It is felt that the most significant (human produced) arsenic in the Yellowknife area in particular and the Royal Oak mine site in particular is the arsenic trioxide which was deposited onto surface waters and soils from stack emissions."

Several tonnes of arsenic were emitted daily from the Giant roaster stack during the early to mid-1950s.

With the gradual introduction of pollution reduction technology, the emission had dropped to kilograms per day by the time the roaster was shut down, in 1999.

Con mine switched from a gold roaster to an autoclave, which emits almost no arsenic, in 1970.