Seasonal agricultural work has been placed under renewed scrutiny after 10 migrant farm labourers were killed in a collision in southwestern Ontario.

Police said the workers and one truck driver died Monday evening when their passenger van was hit by a flatbed truck northeast of Stratford, Ont.

Various media reports indicate the van may have run a stop sign.

Now, as investigators try to piece together what happened, many in the agricultural sector are decrying the conditions that Canada's migrant workers face.

Stan Raper of the Agriculture Workers Alliance says long hours, lack of protection and little to no representation leaves temporary labourers vulnerable.

"We call it the three Ds: dangerous, dirty and deadly," he told CTV Toronto. "A lot of Canadians don't want to do this work."

He points out that exhaustion may have contributed to Monday's collision. The workers, most of whom are believed to be from Peru, had just wrapped up a day of work at a nearby poultry farm.

"These workers in particular worked in the poultry sector as chicken catchers and inoculators," he said. "It's long hours and very difficult work."

According to Raper, the workers would have been responsible for entering barns filled with thousands of chickens to catch and vaccinate the birds.

Deena Ladd, co-ordinator of the Workers' Action Centre, said migrant workers often don't receive the same protections as other workers, and have little means to complain about their treatment.

"Migrant workers have little power in the workplace. Brought into Ontario under temporary foreign work permits or the seasonal agricultural program, workers are tied to one employer and can be sent back to home countries if they raise concerns about health and safety or wages and working conditions," Ladd said in a statement.

The WAC called on the Ministry of Labour to investigate the transportation of migrant workers, who are often shipped "from barn to barn, farm to farm," according to the statement.

For decades, farmers across the country have used temporary labourers to meet their seasonal work needs.

Each year, migrants perform manual work on 1,800 farms in nine provinces, according to a North-South Institute report. Nearly 1,600 of these farms are in Ontario.

The North-South Institute says the majority of Canada's migrant workers come from Caribbean countries and Mexico, the result of a joint program between these nations and Canada.

Chris Ramsaroop of Justice for Farm Workers said all levels of government need to work together to protect migrant workers who have little representation.

In an interview with CTV News Channel Tuesday, he said that many workers have complained of abuse or have been sent back to their home countries with untreated injuries.

"With both levels of government we want to ensure they take the time and responsibility to enforce the rights of migrant workers," he told CTV News Channel.

The incident is Ontario's deadliest multi-vehicle crash in more than a decade.