Silver has low toxicity to vertebrate animals, is eliminated rapidly when ingested orally, and is not a cumulative toxin (Cooper and Jolly 1970). Since surface waters in Canada generally contain low levels of silver and there are few data on chronic silver toxicity to animals, no criteria seem to be justified at this time for wildlife, livestock or laboratory animal drinking water. Wildlife and free range livestock can safely drink water which meets the aquatic life criteria. Confined livestock and laboratory animals should drink water which meets human drinking water criteria.
The role of silver in animal metabolism is still unknown (Boyle 1968). Generally, the health effects on animals of short-term or long-term exposure to specific concentrations of silver in the air or the food are not known. Little information is available in the literature on the effects of chronic exposure of silver in farm animals. No studies were located documenting cancer in animals after exposure to silver or silver compounds (Anon. 1990).