Balancing chemical equations is a key chemistry skill. Use these step by step instructions to write and balance chemical equations. Balancing chemical equations is a key chemistry skill. Use these step by step instructions to write and balance chemical equations.
So, there are many signs and symptoms of Selenium Overdose- some occur very early and some occur much later. 1  Early Signs: Some of the early signs of Selenium Toxicity are endocrine hormone disturbances- particularly thyroid issues. Poor hair and nail growth are early signs that are probably the easiest to notice.
Symptoms of overdose may include the following: 1  nausea. 2  inability to urinate. 3  fainting. 4  fast, pounding, or irregular heartbeat. 5  unresponsiveness.