That's a DNA test and has nothng to do with a drug screen.
You should have the right to refuse a test and you should check the various legal ramifications of them taking DNA tests.

Man... if I was subjected to that kinda crap I'd tell em to go f#** themselves.

Especially for a low pay job like Safeway.

Personally, I'd contact a lawyer and have him look into it. Something's awful weird about taking DNA swabs from low level employees at a supermarket.