5 Reasons To Test Your Mercury Levels Mercury is a heavy metal that can be extremely toxic to humans, affecting various organs and systems, particularly the nervous system. High levels of mercury in the blood can result from: Environmental Exposure, Dietary Intake: especially from large fish like tuna and swordfish, Dental Amalgams, or Occupational Exposure. 5 reasons to test for mercury include: 1️⃣ Neurological Symptoms: Mercury exposure can cause a range of neurological issues, including memo