Thanks to a legal challenge by a Smithers, B.C.-based woman, Health Canada must now undertake a formal safety review of an herbicide widely used in forestry and agriculture.

Josette Wier, an environmental activist, says that around 2006, she noticed a pesticide permit application in the local newspaper for the aerial spraying of the Monsanto herbicide Vision in the forests near Smithers.

Glyphosate is the key ingredient in Vision, Roundup and other herbicides, and has become the top-selling weed-killer worldwide since Monsanto introduced it in 1974, according to Reuters.

Wier argued that since glyphosate was first approved for use in Canada, there had been new scientific evidence indicating glyphosate herbicides pose unacceptable health risks to human health and the environment. Specifically, those that contain certain additives, known as POEA, which help the chemical stick to leaves.

Health Canada is required to address requests by the public for pesticide safety reviews when there is scientific uncertainty about its risks. Wier's first request was turned down, but in 2009 she appealed the decision, and on Monday Justice Michael Kelen of the Federal Court of Canada ordered Health Canada to conduct the review. (The full decision can be found here.)

Wier said she could not have done it without the help of West Coast Environmental Law and her lawyer, Jason Gratl.

Andrew Gage, staff counsel for West Coast Environmental Law said Health Canada is now required to look specifically at the pesticide's impact on amphibians. Currently, he says, it cannot be sprayed over water surfaces but can be sprayed on wetlands or creek beds that are dry some of the year. Gage says the decision could have "fairly significant implications" therefore, on how it is used by logging companies.

Glyphosate-based herbicides have come under fire recently by environmentalists, consumer groups and scientists who are concerned the chemical could cause infertility or cancer amongst humans -- as well as by the agricultural industry which claims weeds are becoming resistant to the herbicide. This year the U.S. Environmental Protection Agency decided to re-evaluate the risks from glyphosate and set a deadline of 2015 to determine if sales of the chemical should be limited or stopped.

Wier says she is "ecstatic" about the decision but wonders "why does the public have to do the work for government?"

"These agencies, these bureaucracies, they really try to discourage you," she said, referring to the fact that she had to go to court to force Health Canada to do a review. "I don't know what's wrong with me but I'm extremely stubborn. It's a curse but in some cases it's useful."

Colleen Kimmett reports for The Tyee.