Wooden pallets are originally used to support large packages for shipment, but over time become less sturdy and therefore less useful to businesses. Pallets are then often discarded or sold cheaply by businesses to hobbyists and DIY enthusiasts looking for an inexpensive material with which to build furniture or garden projects. Some of these pallets are chemically treated, which can be harmful to your health; some are heat-treated, which poses little threat to your well-being.
Put on the gloves. In case the pallet is treated, you don't want to be touching it with bare hands.
Find the stamp on the pallet. It's usually in black ink, and often enclosed in a square or oval shape.
Examine the code stamped on the pallet. If the code includes the letters HT, then the pallet has only been heat-treated and should be safe to use however you wish. However, if the code includes the letters MB, then it has been fumigated with methyl bromide and should not be used anywhere that bare skin could come into contact with it or near food.