Union leaders renewed calls for more protection for farm workers in Alberta at an annual Labour Day barbecue in downtown Calgary.

Alberta is the only the province where farm workers are not protected by occupational health and safety laws. They have no right to refuse unsafe work, do not get a minimum wage and don't qualify for workers’ compensation benefits.

The Alberta Federation of Labour has been fighting for years for better protection for agriculture workers, but president Gil McGowan says nothing has changed.

“Agricultural workers don't have any of the same protections in the workplace that other Canadians take for granted."

Provincial data shows 447 Alberta farmers died on the job between 1985 and 2010.

"If a farm worker is killed or injured on the job they may not receive any kind of compensation for their injuries, or their family may receive nothing, so we think they're putting farm workers in a really vulnerable position," said Alexander Shevalier of the Calgary and District Labour Council.

Former premier never made changes

Most health and safety regulations for farm workers are strictly voluntary. Former premier Alison Redford said she would change that — a promise that went unfulfilled.

Alberta Liberal agriculture critic David Swann doesn't expect any of the three Alberta Progressive Conservative leadership candidates vying to replace her to follow through.

"I'm disappointed but this is the ‘same old, same old’ in Alberta — kowtowing to very narrow interests in rural Alberta that do not protect the very people that feed us every day," he said.

CBC News asked the three leadership contenders for their positions on farm workers' rights.

Thomas Lukaszuk says he supports extending health and safety laws to farm workers, but he says the province needs to develop industry safety standards first. 

Jim Prentice says the answer is more education, not changes to workplace laws. Ric McIver wouldn't say what his position is on farm workers' rights. He says he has other priorities.