Silver is a toxic heavy metal?

The silver ion is among the most toxic of heavy metal ions, particularly to microorganisms and to fish. The ease with which Ag forms insoluble compounds, however, reduces its importance as an environmental contaminant. Ag is not likely to concentrate to harmful levels through either terrestrial or aquatic food chains. There is some possibility that Ag from cloud seeding will retard growth of algae, fungi, bacteria, and fish in fresh water; additional laboratory investigations are needed. Inhibition of aquatic microorganisms would interfere with the cycle that returns essential nutrients to the water. Ag in air and water should be regularly monitored. Iodine in AgI poses no environmental danger. Organic seeding agents currently being proposed are not likely to be toxic in either the short or the long run, but dispersal of proprietary organic compounds should be prohibited unless their composition is fully revealed.