Formic Acid

The smell from blue cheese dressing. It's the same smell you get from lots of crushed ants. And now, a menace to the Salton Sea as well:

A train derailment in the Southern California desert spilled litres of blue cheese dressing into a canal leading to the Salton Sea.

...The spilled dressing and other materials flowed into the Coachella Canal about two kilometres from the north shore of the Salton Sea, hazardous materials specialist Robert Becker said.

"There was blue cheese - a lot of it," Becker said.

The canal was dammed and there was no threat to the salty Salton Sea, Becker said.