Sailors are gathering for the first test event of the 2016 Olympics in Rio de Janeiro, concerned about water pollution in Guanabara Bay that some liken to a sewer.

Rio dumps almost 70 percent of its untreated sewage into surrounding waters, which fouls the bay with human waste and floating debris. A fleet of special rubbish boats has been working the bay for months, and organizers are allowing teams to test the water, hoping to allay health concerns.

The regatta starts this weekend.

In landing the Olympics, Rio pledged to cut pollution in the bay by 80 percent. State environmental official acknowledge they will miss the target, but argue the water meets international standards.

After hosting the World Cup, Brazil now faces scrutiny over its delayed preparations for the Olympics.

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