Silver Safety

Like any other substances, silver and silver-based products can have undesirable effects with excessive intake. You can safely limit your intake using the EPA’s Reference Dose for oral intake of silver, which is 0.005 mg per kilogram of body weight. This means a daily intake limit of 0.31 mg for a person weighing 140 pounds, or up to 0.4 mg for a person weighing 180 pounds.

Understanding the Reference Dose

The Reference Dose (RfD) is an estimate of daily intake that is likely to be without a significant risk of harmful effects during a lifetime. It is defined based on the “critical effect” for a given substance, which is the first adverse effect that occurs as the dose rate increases. The underlying assumption is that if this critical effect is prevented, then all adverse effects observed at subsequent doses are also prevented.

The critical effect used to determine the RfD for silver is argyria, a benign, but permanent, bluish-gray discoloration of the skin. Although creating an undesirable cosmetic effect, argyria is not associated with other adverse health effects. In summary, the RfD for lifetime silver intake has been set to prevent argyria or other adverse health effects from occurring.

It is important to note that the rare reported cases of argyria were caused by the intake of silver in the form of salts, not colloidal or nanoparticle silver. Nanoparticle silver pruduced in a tightly controlled process, or even properly prepared home-made colloidal silver, is safe for limited intake and will not cause argyria.