Mercury is one of the most toxic heavy metals. There are numerous natural and man-made sources of mercury, but the most concerning are the ones we are exposed to daily. Mercury is known to affect the nervous, circulatory, immune, reproductive, and digestive systems, along with organs such as the kidneys, lungs, and gastrointestinal tract. Mercury primarily targets sulfhydryl groups (sulfur) and selenium, for which it has a high affinity. Later in this blog is a list of the most common sources of mercury exposure, but before we get into that, it is important to distinguish the three different types of mercury and their common exposure routes.