Arsenic is a chemical element with symbol As and atomic number 33. It is a metalloid that is a member of the same family as metals, but has properties more like non-metals. Arsenic is known for its various forms and compounds which have been used in agriculture, medicine, and as a poison. In nature, arsenic can be found in ores such as arsenopyrite, and it is also released through human activities such as mining, smelting, and burning of fossil fuels. Arsenic is toxic in high concentrations and can cause various health problems including skin lesions, cancer, cardiovascular diseases, neurological effects, and diabetes.