Last but not least of the Fearsome Four is Mercury. Next to Plutonium it is the most toxic naturally occurring substance on the planet. It’s a potent neurotoxin that disrupts the development of the central nervous system, posing the biggest threat to pregnant women, children, and teenagers. Pregnant women should take particular care because Mercury easily crosses the blood brain barrier and placenta, and can remain in the body for up to a year –potentially harming a baby’s growing nervous system and brain. According to the EPA (Environmental Protection Agency), children exposed to Methylmercury in Utero have trouble with attention, cognitive thinking, memory, language, fine motor and visual spatial skills, Adults with high mercury levels have trouble with vision, motor function, and memory. Low-level symptoms include memory loss, fatigue, insomnia, joint pain, or headache.
That’s because Mercury competes with oxygen for space in red blood cells. When oxygen can’t get through, the body is deprived of energy. That’s why fatigue is a common symptom of mercury poisoning. Scientists are just beginning to understand how chronic, low-level exposure to Mercury can contribute to chronic health problems often seen in adults like heart disease and cataracts. And consumer advocacy groups like the Policy Project warn that the elderly and people with autoimmune diseases, high blood pressure and other heart-disease risk factors may also be vulnerable.
So how do we become exposed to Mercury? Coal-burning power plants are by far, the biggest producers of mercury pollution –spewing about 98,000 pounds of Mercury into the air. Remember the definition of heavy metal? Well from the air, Mercury seeps into the ground and rivers, lakes, and oceans, where it’s absorbed by small micro-organisms like algae. From there, it makes its way up the food chain to bigger and bigger fish –becoming more and more concentrated at each level. Sadly, once Mercury enters the environment, it never leaves.
Seafood remains the biggest source of exposure though there’s still some debate as to which fish to avoid. Shark, swordfish and tuna seem to be the worst offenders. The Environmental Working Group (EWG) recommends avoiding sea bass and halibut as well. See www.ewg.org/safefishlist/ for a more complete list.
Another common source of mercury exposure is the dental amalgam fillings in your teeth. Though the potential harm from this is also hotly debated. The FDA now says amalgam fillings, which contain 50% elemental mercury, may have neuro-toxic effects but doesn’t explicitly advise pregnant women and children against them.
To minimize exposure to this metal, be careful what fish you eat and how often you eat it. Aim low on the food chain and if you have to eat tuna stick to light canned tuna or fresh yellowfin tuna, which are likely to be less contaminated than other types. If you have mercury filings, find a holistic dentist experienced in the removal of mercury fillings and get them replaced with less toxic fillings.
As an added measure of protection, eat seaweed with your fish. It’s a natural “chelator” in the gut. If you hate seaweed then take a selenium supplement (at least 200 micrograms) instead.