"We trust the organizers and (the) ISAF will carry out the necessary research and analysis that will be carefully considered in order to ensure the safety of the athletes," the IOC said in a statement.
The IOC did not respond to repeated requests to interview IOC Medical Director Dr. Richard Budgett about potential health risks to athletes. In March, Nawal El Moutawakel, head of the IOC inspection team in charge of preparing Rio, said she had been assured the bay could be "clean from garbage."
"I don't think we will forgive ourselves if we let the athletes compete in an environment that is not safe and secure," she said.
Malcolm Page, a two-time Olympic gold medalist and chairman of the sailing federation's Athletes' Commission, said he trusted state tests, but welcomed independent testing.
"If the Brazilians are happy to receive any of that independent help, it only makes dealing with the problem easier and removes any sugar-coating," he said. "The sailors are certainly worried about it."
An analysis last year of a decade's worth of government data on Guanabara and other waterways showed that sewage pollution indicators consistently spiked far above acceptable limits, even under Brazilian laws that are far more lenient on pollution than those in the United States or Europe.
Fox said at least five courses — three inside the bay and two in the open Atlantic — would be used at the test event beginning Aug. 2. He said courses outside the bay had always been planned, not driven by the pollution problems.
Fox said plans call for the medal race — the final race where the gold, silver and bronze medals are decided — to be held in Guanabara near Flamengo Beach, a venue convenient for fans.
Signs around that beach warn against swimming.
Mario Moscatelli, a biologist and outspoken environmentalist, said retrieving the floating garbage in the bay was fine, but did not address the problem of untreated sewage.
In an open letter to Brazilian President Dilma Rousseff, he asked for the "release of the funds needed to recover the environmental assets, which are being used in Rio as garbage dumps and latrines."
Associated Press writer Jenny Barchfield contributed to this report.
Stephen Wade on Twitter: http://twitter.com/StephenWadeAP