Yellowknife (July 12/06) - If tonnes of arsenic trioxide from Giant Mine were to escape into Great Slave Lake, it's unclear what would happen or how dangerous it would be, says the territorial government's top environmental protection official.

"In all honesty, I can't answer your question," said Emery Paquin, with Environment and Natural Resources.

"I can't make that call because I don't know what would happen."

Arsenic trioxide dissolves in water but not as readily as say, table salt, said Paquin. The colder the water temperature, the less able it is to dissolve.Yellowknife's drinking water supply is protected by virtue of its location on the Yellowknife River - some 5 km upstream from Yellowknife Bay.

Regardless, a large release of arsenic is not going to happen, said Paquin.

"We're not looking at a catastrophic release, we're looking at, at worst, the slow release of arsenic into the groundwater," said Paquin.

"You may be able to pick it up with modern scientific monitoring, but it's not like somebody is going to drop 237,000 tonnes of arsenic trioxide into the middle of Yellowknife Bay," said Paquin.

Arsenic trioxide:

- Is a white or transparent solid in glassy, shapeless lumps or a crystalline powder that resembles sugar.

- Produced mainly from smelting of metals at high temperatures.

- It has no odour or taste.

- Solubility in water at 20C: 37 grams per litre; 115 grams per litre at 100C.

- Inhalation or skin contact can cause irritation but unlikely to have toxic effects, although ingesting as little as 1 to 2.5mg can be deadly. It produces highly toxic fumes when burned.

- Primarily targets the gastro-intestinal tract, heart, brain and kidneys. It binds with certain cellular proteins, which inhibits energy production needed to maintain body tissues. Long-term exposure can cause cancers, brain lesions, and nervous disorders.

Source: U.S. Agency for Toxic Substances and Disease Registry