Excess heavy metal accumulation in soils is toxic to humans and other animals. Exposure to heavy metals is normally chronic, due to food chain transfer. Acute poisoning from heavy metals is rare through ingestion or dermal contact, but is possible. Chronic problems associated with long-term heavy metal exposures are: Arsenic – skin poisoning, affects kidneys and central nervous system, Lead – mental lapse and neurotoxicity, and Cadmium – affects kidney, liver, and gastrointestinal tract. All of these heavy metals are possibly carcinogenic to human (ATSDR, 2007).