out. Bio weapons maybe, chem weapons no way. You need a lot of chem stuff to make an effective WMD; a few cups aren't going to do it, and handling it is always dangerous. Bio weapons can be small, but if you really want to go large you need quite a bit (anthraxing New York would require hundreds of pounds of the stuff if you wanted to really Get It Right). A nuke can be very small, and with adequate shielding very difficult to detect. Also, you can use a nuke as a football (well, only if you like broken toes maybe;) when it's not armed with no fear that you're going to bake yourself into the earth. That's definitely not true for chem/bio weapons.

It's even easier if you can infiltrate a medical equipment company that deals with radiology; they're allowed to transport radioactive material.