Arsenic is a naturally occurring element found in the crust of the Earth. It is distributed in the air, water, and land. In its inorganic form, it is extremely poisonous to plants, animals and human; while organic arsenic compounds (such as those found in seafood) are less harmful to health. Arsenic poisoning can result from long-term exposure to inorganic arsenic, typically through food and drinking water. People are exposed to high levels of inorganic arsenic through tobacco use, eating contaminated food, drinking polluted water, using contaminated water to prepare food and irrigate food crops, and industrial operations. The most prevalent side effects are skin blemishes and cancers of the skin, bladder and lungs. Other effects include developmental effects, diabetes, pulmonary disease, and cardiovascular disease.