Silver is a potent nerve cell toxicant.

Jan 21, 2010

Powers, CM, N Wrench, IT Ryde, AM Smith, FJ Seidler and TA Slotkin. 2009. Silver impairs neurodevelopment: studies in PC12 cells. Environmental Health Perspectives doi:10.1289/ehp.0901149.

Synopsis by Heather Hamlin

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.

Results of a new cell study provide evidence that silver has the potential to kill developing nerve cells and is even more potent than currently known neurotoxicants. A neurotoxicant is a substance that can harm or kill nerve and/or brain cells.

The findings call into question the widespread and increasing use of silver in consumer products. Silver is a good antiseptic agent and is added to some products to reduce the growth of disease-causing microbes. The silver is found in the items primarily as very tiny silver nanoparticles.

The recent and tremendous increases in the use of silver means there is a higher risk of human exposure to the metal.

It takes a relatively high amount of silver to cause illness or death in adults. However, silver can pass from a mother to her fetus, creating concern that developing cells may be particularly vulnerable to silver's effects and that exposure at such an early stage may lead to neural development disorders in the children.

Researchers exposed rat nerve cells to various concentrations of silver and observed its effects on DNA synthesis, protein synthesis, cell growth and other parameters. Researchers compared the cells’ responses to the silver to cells exposed to chlorpyrifos, a pesticide known to cause neurodevelopmental disorders.

Cells exposed to silver at a concentration five times less than chlorpyrifos had inhibited DNA synthesis, reduced protein synthesis, fewer numbers and poorer health. These effects were significantly greater than those of the known neurotoxicant. 

Effects were also seen at doses less than 10 times those historically found in fetal tissue. This is a concern as silver use climbs and possibly increases prenatal exposures.

In addition, the cells’ responses to silver varied dramatically – from subtle effects to death – across doses and developmental stages of the cells, making conclusions of what dose is “safe” very difficult to ascertain.