Health Hazards of selenium

Selenium, a trace element, is important in the diet and health of both plants and animals, but can be only taken in very small amounts.  Exposure to an excess amount of selenium is known to be toxic and cause health problems.  With a tolerable upper intake level of 400 micrograms per day, too much selenium can lead to selenosis and may result in health problems and even death.  Compounds of selenium are also known to be carcinogenic.