SELENATE ION is a compound containing an oxoanion with selenium in its highest oxidation state of VI. Selenates are analogous to sulfates and have similar chemistry, but unlike sulfate, selenate is a good oxidizer. Selenate is the form required by organisms that need selenium as a micronutrient. These organisms have the ability to acquire, metabolize and excrete selenium. The level at which selenium becomes toxic varies from species to species and is related to other environmental factors like pH and alkalinity that influence the concentration of selenite over selenate. Selenate and other forms of selenium are highest in areas where ancient seas have evaporated. These areas are enriched in selenium and over millennia, biologic adaptation has occurred.