MONTREAL - Tests conducted by an environmental group suggest last month's train disaster had a devastating impact on water quality and soil in Lac-Megantic, Quebec.

The group (Societe pour vaincre la pollution) says extremely high concentrations of carcinogenic polycyclic aromatic hydrocarbons and arsenic were detected in surface water.

The analysis, obtained by The Canadian Press, suggests the rate of carcinogenic polycyclic aromatic hydrocarbons is 394,444 times the standard acceptable for surface waters mandated by the provincial government.

As well, the concentration of arsenic detected on the water's surface is said to exceed the government's acceptable standard by 28 times.

The group, which worked with Greenpeace on the study, says there was also "an extremely high level of petroleum hydrocarbons" following the explosive derailment and oil spill.

The organization acknowledged that "because of its limited resources," it was unable to perform all chemical analysis required to identify all the toxins but said it hoped to carry out a second round of tests.

Greenpeace accused the Environment Department of underestimating the consequences of the July 6th derailment, which levelled part of the town and left 47 people dead.

Quebec governmment downplays pollution

Meanwhile, the Quebec government is downplaying concerns about environmental damage from the Lac-Megantic train disaster.

The province's environment department has released a series of charts listing the level of various pollutants in the water and air in the area.

It says the statistics show, in most cases, a return to the concentration levels present before the July 6 accident.

The government says only its own statistics will be released on the Environment Department website -- not those compiled by third parties.

That announcement came a day after the Societe pour vaincre la pollution's report.