Periodically, questions arise from pet owners regarding mercury in pet foods. They are curious why mercury is put in their pets’ diets or, more emphatically, why poisons are being added to their food. Nothing could be further from the truth. No pet food company is adding mercury as an ingredient to their foods and none would want to cause harm to their pet customers. Many times, these questions come after the publication of a report or website proclaiming their analytical results from samples of pet foods which supposedly contain non-nutritional metals, like mercury. So, how is mercury finding its way into our pet foods and do we need to be alarmed?
First, a bit of background on this element. In the earth’s crust, mercury is actually quite rare with an average of only 0.08 ppm, though it is concentrated at higher levels in some ores such as cinnabar. Mercury use dates back to ancient times where it was imbued with all sorts of magical properties. In more recent times it has been used in a host of industrial and pharmaceutical applications, such as batteries, compact fluorescent light bulbs, thermometers, dental fillings and thimerosal in vaccines to name a few. That is in small part why we see it appear in environmental samples. But the bulk of mercury in water and food occurs as a result of volcanic eruptions which lead to sedimentation onto the ocean floor. It is here that it begins to enter the food chain.
