And, there aren't too many poisons out there that start with the letter 'U'... I had thought of creating an "Unknown" post--- but, it's rather difficult to describe something that is unknown. I mean, what do you say regarding something you have no clue about? So, I've stretched the 'poison' definition here to add uranium, in its natural state and not as an intentional bomb/weapon component... it is mildly toxic and radioactive (though it is on the weaker end of radioactive scale). Though there have been a few deaths resulting from the inhalation of uranium hexafluoride (used in nuclear reactors), the deaths have generally been attributed to a concentration of hydrofluoric acid rather than the uranium itself. Even though uranium is a radioactive metal, the precautionary measure of wearing a simple pair of gloves before handling it is enough to keep you protected. What uranium is very good at, in large doses--not the everyday minimum exposure...