The Supreme Court of Canada has ruled in favour of three British Columbia medical workers who argued they developed breast cancer as a result of their jobs, where they used known carcinogenic chemicals.
Katrina Hammer, Patricia Schmidt and Anne MacFarlane, who worked at Mission Memorial Hospital, were among seven women at the lab who developed breast cancer.
The Workers' Compensation Board originally denied their applications for compensation benefits on the grounds their breast cancers were not occupational diseases.
But rulings by the Workers Compensation Administrative Tribunal in 2010 and 2011 overturned those decisions and linked the cancers to the workplace.
The British Columbia Court of Appeal, however, said the tribunal's decisions were "patently unreasonable" because there was no evidence that the women's cancer was caused by their work environment and the tribunal ignored expert advice to the contrary. The court suggested the cases were a statistical anomaly.
On Friday, the Supreme Court ruled 6-1 in favour of women.
Justice Russell Brown, writing for the majority, said the tribunal's finding was not patently unreasonable.
"While the record on which that decision was based did not include confirmatory expert evidence, the tribunal nonetheless relied upon other evidence which, viewed reasonably, was capable of supporting its finding of a causal link between the workers’ breast cancers and workplace conditions," he wrote.
He said the law sets a lower burden of proof in such cases and must favour the women.
"The applicable burden of proof is not the civil burden of 'balance of probabilities,' " he wrote.
"Where the evidence leads to a draw, the finding must favour the worker."
Justice Suzanne Cote disagreed sharply with the majority.
"In my view, the original decision of the Workers’ Compensation Appeal Tribunal is patently unreasonable," she wrote in her dissent.
"On my reading, there is no evidence — and certainly no positive evidence — capable of supporting a causal link between the workers’ employment and the development of their respective disease."
Tonie Beharrell, a lawyer representing the Health Sciences Association and members Hammer and MacFarlane, said the decision empowers the Workers' Compensation Appeal Tribunal to decide causation of disease based on occupational factors without strict scientific evidence or intervention by the courts.
"There was evidence that said there's a statistically significant cancer cluster, an increase rate of breast cancer, which is about eight times that of what you would expect in the general B.C. population, but we don't know what caused it."
Beharrell said some of the women tested blood and other bodily samples in their jobs using chemical carcinogens including ortho-toluidine and falmalin, a component of formaldehyde.
Several breast cancer cases of workers at the lab were diagnosed dating back to at least 1990, and there were six cases between 2000 and 2005, she said.
"It made them wonder: Why are we all getting breast cancer?"
The three women, who are now in their 50s, are in remission, Beharrell said.
None of the women could be reached for comment.
Beharrell said the use of carcinogenic substances and the degree of exposure was significantly higher in the past and that a variety of new processes have been introduced.
Val Avery, president of the Health Sciences Association, thanked the three workers for their perseverance.
"Today, they are responsible for setting an important precedent for all workers," she said.
Fraser Health, the authority responsible for the hospital, could not immediately be reached for comment.