Pollution worries in Rio days before athletes take to the water

Professor Renata Picao doesn’t want to be a party pooper - not when the party that is the Olympic Games are about to open in her home city.

But she’s a worried woman.

"I won’t go in the sea, and I don’t let my children either. We just don’t know the risks."

She’s speaking to me on a beach close to the Federal University of Rio, where she’s been conducting some alarming research.

The clues are all around us.

A thick slick of filth washed up across the sand. A used syringe here, a teddy bear there; a mattress and piles of nappies.

Follow the stench and you discover the source of these ills.

A sewage outfall flows untreated waste directly in the bay where rowers, sailors and open water swimmers begin competition this weekend.

"I didn’t know this was here," she says, genuinely shocked, because this is so close to where she works.

"It’s part of the problem. We have no record of this. It’s all so unregulated."

More than half of Rio sewage flushes directly into the sea. So too, industrial and hospital waste. And that last source is her greatest concern.

Professor Picao and her team have found antibiotic resistant superbugs in the sands and in the sea, linked to an alarming list of ailments like meningitis and pneumonia, and by their nature, hard to treat.

She says more research is needed before they can assess the dangers.

The International Olympic Committee has insisted that the water is, if not clean, then safe, and that it meets World Health Organisation standards.

But they've not tested for the kind of bacteria that Professor Picao has found here.

"It would be premature to halt the games," she says carefully. "But I think there should be greater concern for the athletes."

And before we leave the beach, she makes me promise I’ll wash the sand and God knows what else off my boots as soon as I can.