Take a look at these links:

http://www.cc.nih.gov/ccc/supplements/selen.html

http://www.webelements.com/webelemen...xt/Se/key.html

What you should remember when handling Selenium, is that it is a non-soluble, rare Earth mineral. It should be handled only with protection: wear gloves, protective eye gear, and in a well-ventilated area.

Toxicity: At high doses (> 900 g/day), selenium produces a toxic syndrome consisting of dermatitis, loose hair, diseased nails, and peripheral neuropathy associated with plasma levels > 100 g/dL (> 12.7 mol/L).

I hope this helps.

ka