Higher concentrations found in other brands (as much as 30ppm) can separate and settle at the bottom. Delivery to Europe via the website www.naturessunshine eu/europe/tigranius other countries? Any questions? Ask for email tigranius13()gmail com Moreover, prolonged use of higher concentrations may cause a gray discolouration of the skin and inner eyelid inflammation. Research indicates that colloidal silver deactivates the enzymes responsible for the metabolism and multiplication of bacteria, fungi and viruses. Nature’s Sunshine’s Silver Shield is safe and effective. Its fine particle size colloids ensure maximum efficiency. Just 1 teaspoon provides a full 90mcg (18ppm) of pure silver without heavy metal contamination. This product is completely non-toxic.