The element of arsenic has long been known to be acutely toxic. It is found in nature in low levels, mostly in compounds with oxygen, chlorine, and sulfur. Most of these compounds have no particular smell or taste. 

You can be exposed to harmful arsenic in the environment or through contact with contaminated consumer products such as pressure-treated wood and dietary supplements. Virtually all lumber sold for outdoor use in the U.S. is pressure-treated. Click here for more information.