Happy Monday listeners. This is Rachel Feltman and you're listening to Scientific Americans

science quickly. Let's kick off the week by catching up on the latest science news.

First let's check in on a couple of stories we've been following recently.

A few weeks ago, Siam's own Allison Partial joined us to explain how and why Paris was trying to make the

said clean enough for Olympians to swim in. Now the river did indeed host

individual triathlon swimmers for their event on July 31st, but since then

there's been a lot of trash talk about the river's bacteria levels. On August 4th

Belgium's Olympic Committee actually said it was pulling its team from the mixed

relay triathlon because one of its swimmers had gotten sick after competing in the

Cen. Now Belgium's athlete, Claire McEl, did indeed get quite ill with gastrointestinal symptoms,

but she clarified on Instagram last week that she was sick with a virus, not an E. coli infection,

as many folks had speculated.

As Allison explained for us on the pod a few weeks ago,

the safety of the Senn changes from day to day.

So it's not really a question of whether or not the Sen might be dangerous to swim in.

It's a question of what days the Sen is too dangerous to swim in and what days it's safe enough

to swim in.

And this is something that the Olympic Committee has been very upfront about.

Last week, swimmers actually had to skip a planned practice day because of high bacterial counts.

They did get cleared to swim the following day, but some swimmers actually used paddleboards so that they could get a feel for the course without putting their heads under the water.

They just said it wasn't worth the risk if it wasn't really competition day.

To learn more about this massive ecological undertaking and why Paris put such a big seemingly

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