Natural Path Silver Wings Silver Herbal Ointment 250 ppm offers pharmaceutical grade colloidal silver and pharmaceutical grade water. It is manufactured and filtered to the proper micron particle size for safety and immune support. Colloidal Silver ointment can be use for skin care and as moisturizing. Colloidal Silver is 99.9% silver and 0.1% casein. Natural Path/Silver Wings guarantees its colloidal silver to be colloid (0.01- 0.001 microns) with the highest percent of the silver particles at 0.002 microns. NP/SW tests for purity, particle size and concentration in both house and independent laboratories. The estimated amount of silver accumulation over a one-year period that is required to produce Argyria is 1 to 6 grams. This amount is very large compared to the 50 mcg typically recommended and consumed by people using OTC colloidal silver products. Using the most conservative figure, 1,000 mg (1 gram) of silver corresponds to the silver content in 100 liters of 10 ppm colloidal silver, 50 liters of 20 PPM colloidal silver, or 33.3 liters of 30 PPM colloidal silver.