A chemical burn occurs when living tissue is exposed to a corrosive substance (such as a strong acid, base or oxidizer) or a cytotoxic agent (such as mustard gas, lewisite or arsine). Chemical burns follow standard burn classification and may cause extensive tissue damage. The main types of irritant and/or corrosive products are: acids, bases, oxidizers / reducing agents, solvents, and alkylants. Additionally, chemical burns can be caused by biological toxins (such as anthrax toxin) and by some types of cytotoxic chemical weapons, e.g., vesicants such as mustard gas and Lewisite, or urticants such as phosgene oxime. Chemical burns may: need no source of heat occur immediately on contact not be immediately evident or noticeable be extremely painful diffuse into tissue and damage cellular structures under skin without immediately apparent damage to skin surface From Wikipedia
