Since the tips of applicators and pencils are small and standardised, there is less of a risk of excess being applied accidentally. Silver nitrate is a hazard due to its causticity, and is toxic when taken by mouth. However, absorption of silver nitrate through intact skin is negligible. Due to its chemical reactivity and the fact that it is metabolically highly refractory, there is a low risk of systemic toxicity if applied externally.
There is no defined maximum recommended dose since the circumstances of individual cases vary considerably but undesirable effects generally only result when the substance is applied chronically in much larger quantities than available from a pencil or applicator. The condition known as argyria, caused by an accumulation of silver metal and compounds in connective tissues and thought to be harmless may result in cases of extreme excess, but this is very rare.
Methaemoglobinaemia, due to absorption of nitrite by the action of local nitrate-reducing bacteria in burns and open wounds, is a potentially serious condition which can arise from repeated application of sizeable dosages of silver nitrate, when used as an antiseptic on these areas.
Silver nitrate should not be released into the environment. Small amounts can be dissolved in a salt and water solution, which changes its chemical composition, and then safely disposed in normal waste, see Waste Disposal.
Studies of the ecotoxicological effects of silver nanoparticles, silver nitrate and colloidal silver have reported harmful effects on small organisms such as daphnia.
Water containing silver nitrate looks like tap water but will permanently stain most absorbent surfaces. Stains on skin are harmless and will disappear through the normal process of exfoliation.