In a surprise decision critics say could trigger widespread challenges to future construction projects, a group of city parents has halted construction of a school after arguing its proximity to high-voltage wires poses a health risk.

City politicians and school officials were assessing the implications Friday, a day after Lisa Amyotte and her neighbours successfully quashed a development permit for Archbishop Joseph MacNeil school, already under construction in the city's southwest.

While the parents hailed the development appeal board ruling as a victory for those seeking a safer school environment, Edmonton Catholic Schools board chairman Charlie Koester said the decision sets a far-reaching precedent.

The ruling could affect the development of every school, every business and the plans of every homeowner in Edmonton given a permit to build close to power lines. "The ramifications to this city are huge," said Koester.

"If this decision came down and all of a sudden your house is within that zone they're talking about, and they're telling you it's unsafe, wouldn't you go after the developers and after the city?"

The appeal was a last-ditch manoeuver, after a 10-month fight that included unsuccessfully lobbying city council twice to move the school being built 108 metres from overhead power lines.

The mothers who oppose the school agreed their victory could signal the start of more awareness about the issue of possible health effects of electric and magnetic radiation. "The members of the appeal board listened to the research and they made a judgment based on that," said parent Lisa Gelasco.

The subdivision and appeal board is a quasi-judicial panel that rules on disputes under zoning and subdivision bylaws. It won't release its legally binding written decision until Nov. 8, but board administrator Sheila McDonald confirmed the board upheld the appeal.

Gelasco, Amyotte, Nancy Manning and Patricia Tamman based their appeal on letters written by experts in electric and magnetic radiation. Edmonton Catholic Schools and its architect brought in their own expert, B.C. Cancer Agency epidemiologist Mary McBride, who told the panel she would send her own children to the school.

"I think it's a step for regulations and guidelines," said Gelasco, 28, who says for her the fight was fuelled by a brush with melanoma cancer last year. "I was really scared that this would be an increased risk for her."

The school for 400 students from kindergarten to Grade 9 was to open in September 2003. It was under construction at 23rd Avenue and Terwillegar Drive.

Amyotte cited an eight-year California study that reviewed existing research and was released Oct. 11. It concluded that electromagnetic fields produced by overhead power lines and household appliances create risks of childhood leukemia, adult brain cancer and more miscarriages.

Amyotte said the California study recommends electromagnetic field exposure at schools be similar to home exposure, between 0.7 milligauss and 1 milligauss -- the measure of the intensity of a magnetic field. Tests taken at the MacNeil school site measured between two and 2.2 milligauss, she said.

To be safe, the school should be built at least 400 metres from the power lines, the parents say.

But Koester insisted the site is safe. The board argued the school site is five times further away from power lines than many other schools, homes and businesses built in the city for the last quarter-century.

Citing the same California study, Koester said the researchers merely recommend constructing buildings a distance of 150 feet from power lines.

"The school site is over 350 feet from any power line," he added.

Koester said the board is looking at launching a court appeal or asking city council to intervene. He noted the board was given the land by the city, which approved the plan to build a school on it.

Coun. Bryan Anderson said he and Coun. Karen Leibovici are meeting with city planning and development staff to see if they can compile enough research to develop guidelines on development near power lines.

bmah@thejournal.southam.ca