Silver is a potent nerve cell toxicant.

Silver is a potent nerve cell toxicant.
http://www.environmentalhealthnews.org/ehs/newscience/silver-is-potent-neurotoxicant/

"A study finds that silver has the potential to cause problems with nerve cell development at concentrations five times less than that of the pesticide chlorpyrifos, a known nerve cell toxicant."