Cosmic Rays and bacteria?

I was listening to a story on NPR where they said that kim chee on a space station exposed to cosmic rays could become toxic.

Wha???

Apparently it has something to do with bacteria? Once the bacteria were neutralized by irradiation (but cosmic rays make it toxic??) it was safe to bring onto the space station.

Any of you biologically inclined folks have any idea what the heck they're talking about?