"The IOM has set the RDAs for selenium based on the amount required to maximize the activity of glutathione peroxidases found in blood plasma. The RDAs for different age groups are listed in Table 11.6 “Dietary Reference Intakes for Selenium”. Infants ages 0–6 months have an adequate intake of 15 micrograms per day and a UL of 45 micrograms per day; infants ages 7–12 months have an adequate intake of 20 micrograms per day and a UL of 65 micrograms per day; children ages 1–3 years have an RDA of 20 micrograms per day and a UL of 90 micrograms per day; children ages 4–8 years have an RDA of 30 micrograms per day and a UL of 150 micrograms per day; children ages 9–13 years have an RDA of 40 micrograms per day and a UL of 280 micrograms per day; adolescents ages 14–18 years have an RDA of 55 micrograms per day and a UL of 400 micrograms per day; and adults older than 19 years have an RDA of 55 micrograms per day and a UL of 400 micrograms per day. Selenium at doses several thousand times the RDA can cause acute toxicity, and when ingested in gram quantities can be fatal. Chronic exposure to foods grown in soils containing high levels of selenium, significantly above the UL, can cause brittle hair and nails, gastrointestinal discomfort, skin rashes, halitosis, fatigue, and irritability. The IOM has set the UL for selenium for adults at 400 micrograms per day."