Environmental contaminants are chemicals that accidentally or deliberately enter the environment, often, but not always, as a result of human activities. Some of these contaminants may have been manufactured for industrial use and because they are very stable, they do not break down easily. If released to the environment, these contaminants may enter the food chain. Other environmental contaminants are naturally-occurring chemicals, but industrial activity may increase their mobility or increase the amount available to circulate in the environment, allowing them to enter the food chain at higher levels than would otherwise occur. A wide variety of environmental contaminants have been detected in foods. These range from metals and “ionic” species like perchlorate to organic (carbon-based) substances, including the so-called “persistent organic pollutants” or POPs (named for their ability to exist in the environment for prolonged periods without breaking down). Legacy POPs such as PCBs have been banned for industrial or agricultural use, but remain in the food chain. Other POPs have been more recently identified, having been found in the environment and the food chain (for example, brominated flame retardants).