In 2022, Qatar will host the World Cup. The host city has already made some waves with its stadium shaped like a certain body part. But what you might not know is that, since 2012, about 900 workers have died while working on infrastructure in Qatar, in a building boom anticipating the World Cup.*

Last month, the Guardian reported that over 400 Nepalese migrant workers had already died at building sites. Between 2010 and 2012 more than 700 workers from India lost their lives working on construction sites in Qatar, too. A report by the International Trade Union Confederation (ITUC) says that if conditions don’t get any better, by the time the World Cup kicks off, at least 4,000 migrant workers will have died on the job.

For comparison, 25 construction workers died during the preparations for Sochi. Only six workers have died during construction for the 2014 World Cup in Brazil that starts this summer. Only eleven men died during the construction of the Golden Gate Bridge in the 1930s. By all measures, the death count in Qatar is extreme.

Robert Booth at the Guardian explains why Qatar is so unusual:

Workers described forced labour in 50C (122F) heat, employers who retain salaries for several months and passports making it impossible for them to leave and being denied free drinking water. The investigation found sickness is endemic among workers living in overcrowded and insanitary conditions and hunger has been reported. Thirty Nepalese construction workers took refuge in the their country's embassy and subsequently left the country, after they claimed they received no pay.

According to the ITUC, there are already 1.2 million migrant workers in Qatar, and about a million more will probably pour into the country to help with construction. These are essentially slaves, Sharan Burrow from the ITUC told Booth. “Fifa needs to send a very strong and clear message to Qatar that it will not allow the World Cup to be delivered on the back of a system of modern slavery that is the reality for hundreds of thousands of migrant workers there today," she said.

When presented with the results of the Guardian investigation, a spokesman from Qatar told Booth: “The health, safety, wellbeing and dignity of every worker that contributes to staging the 2022 Fifa World Cup is of the utmost importance to our committee and we are committed to ensuring that the event serves as a catalyst toward creating sustainable improvements to the lives of all workers in Qatar.”

Even 900 deaths during construction is unusual, and Qatar is years away from finishing their work. Chances are more people will die, and, if the ITUC is right, it could be thousands.

*We've updated this sentence and the headline to reflect more clearly a change made to one of the Guardian stories cited in the post.