You should be very cautious of using extract on $_REQUEST, $_GET, $_POST, ext. Make sure you know what you're doing and use the proper flags to avoid overwriting variables.

... which is really not a good idea.

Just leave variables where they are, and then, 300 lines into your code, you'll actually know where each variable comes from. You can sanitise the values without putting them in different variables so there's really no point.

I found extract to be a handy function for really small utility scripts though