Toxic substances capable of producing depression include lead, cadmium, mercury, and a wide variety of organic and inorganic chemicals. Overloads of this type can produce a sudden, prolonged bout of depression without apparent reason even in those without a prior history of depression. Treatments vary according to the toxic substance involved. Heavy-metal overloads can be corrected quickly by in-hospital chelation, though care must be exercised to avoid flooding the kidneys with toxins during the early stages of treatment. A long-term ‘cure’ of a toxic overload often requires high-dose antioxidants as well as lifestyle adjustments to help the individual avoid toxic triggers.