The province of Alberta is considering legal action against Canadian National Railway for failing to warn that a derailment last week might have contaminated Wabamun Lake with a hazardous chemical.

"We hold parties that transport goods through Alberta responsible for knowing what's in their cargo," said Irwin Huberman, spokesman for Alberta's Environment Ministry.

The toxic substance suspected to be present in the spill of 700,000 liters of heavy Bunker C fuel oil is a polycyclic aromatic hydrocarbon used to treat utility poles. Health officials say such chemicals may cause skin cancer if touched or other cancers if inhaled.

"I think the fact that Alberta Environment put in an order meant there was significant dissatisfaction within their ranks about the responses. It's the first spill I've ever been at where an order has been enforced on someone in order for them to do something. I've been to six or seven spills in Canada. I've never seen them do an order yet." says Dr. Ron Goodman, who was involved in the Exxon-Valdez spill in 1989.

Wabamun Lake is a popular recreational site about 50 kilometers (30 miles) west of Edmonton, Alberta. Edmonton's health authority have ordered people not to swim, boat or rescue animals in the lake. They were also advised not to use the water for cooking, drinking, showering or brushing teeth. These warnings came only after many residents had entered the contaminated water to save wildlife injured by the spill and others had been routinely using the lakewater in their homes.

The 766-megawatt Keephills power generating plant, one of 3 in Wabamun, was shut down because the coal-fired plant uses water from the lake. Murky water near the ash pit of another TransAlta power plant on the lake in 2002 was found to have unacceptably high levels of aluminum, chromium, arsenic and copper, but water quality generally has been good.