This is the fifth article in a series reviewing the metals present in personal care products.
Earlier installments appeared in January 1998, Toxic Potential from Metals Absorbed through the Skin (pages 33-42); March 1999, Metals in Personal Care Products, (pages 47-56); August 2000, Chromium, Cobalt, Copper and Iron: Metals in Personal Care Products, (pages 52-65); and August 2001, Lead, Manganese and Mercury: Metals in Personal Care Products, (pages 26-36).
Toxicity: Silver and its salts pose no notable hazard upon contact with healthy, intact skin. Binding to keratin-rich, superficial layers of the skin appears to prevent absorption of the silver ion into the deeper layers, and penetration rates of water soluble salts are considered to be toxicologically insignificant. No data are available which would allow calculation of flux or permeability coefficients. Reports of allergic reactions of the immediate and delayed type due to contact with the metal or its salts are rare.
The only toxicological hazard is presented by concentrated silver salt solutions, due to their caustic action on live tissue. Similar to other heavy metals, the highly electrophilic silver ion reacts with nucleophilic amino acid residues in proteins, attaching to sulfhydryl, amino, imidazole, phosphate and carboxyl groups of membrane or enzyme proteins, leading to protein denaturation...