The group, the Peace Environment and Safety Trustees Society, says Calgary-based Intrinsik Environmental Sciences Inc. has previous involvement with the oil and gas industry.
Society spokesman Tim Ewert said Intrinsik was hired by EnCana Corporation after a sour gas leak in 2009 and spoke with residents about how sour gas was affecting their health.
"We felt during their presentation that they down-played the dangers of [sour gas] extremely well," Ewert said.
Ewert worries the study will downplay residents' concerns once again.
Intrinsik spokesman Bart Koppe insists that won't happen.
"You know, our work is strictly dictated by science and our interpretation of science cannot and never be influenced by our client," Koppe said.
Koppe said an advisory panel made up of health professionals, industry and government will ensure that the study is balanced.
The company recently released a report on the air quality in the mining town of Labrador City commissioned by the Iron Ore Company of Canada.