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.
1 Asthma. 2  Research suggests that there is no link between selenium blood levels and asthma. 3  Additionally, research suggests that taking 100 mcg of selenium daily for up to 24 weeks does not improve quality of life, lung function, asthma symptoms, or inhaler use in people with asthma.