
Why Is Mercury so Harmful?
Mercury is one of the toxic metals that can cross over the “blood-brain barrier”. The blood-brain barrier (BBB) is a “semipermeable membrane barrier”. The barrier is sophisticated and selectively “separates the circulating blood from the brain and extracellular fluid in the central nervous system (CNS).”
This barrier prevents neurotoxins from entering most of the brain, except for some regions (1).
When mercury trespasses this barrier, the brain can be damaged. This damage can take the form of:
- Immunological disorders, such as Parkinson’s or Alzheimer’s
- Chromosomal problems
- Neurological disorders
- Birth defects
- Psychological disorders
Most cases of mercury poisoning don’t occur overnight. The build-up of mercury in the human body takes time. This can vary from weeks to even years. This is also the same way that mercury builds up in fish and seafood.
How Does Mercury Get into Food?
Mercury can be released into the atmosphere during mining operations as well as chloralkali manufacturing plants that produce chlorine and sodium hydroxide, which is a lye/caustic soda (2).
Live Science explains how the mercury then falls into fresh water and sea water where it dissolves. The mercury (methylmercury) found in humans is 80%-90% the result of consuming shellfish and/or fish, especially tuna (3).
The Natural Resources Defense Council has compiled The Smart Seafood Buying Guide that rates fish according to least to highest mercury presence, along with recommendations for safe servings (4).
Other Sources of Mercury Exposure
There are many ways a person can be exposed to mercury. According to the National Center for Biotechnology Information (NCBI) of the US National Library of Medicine, National Institutes of Health, dental amalgam containing mercury can leech into the bloodstream. Aged fillings can expose humans to toxic amounts of mercury. The NCBI states that “the average American adult has seven mercury amalgam dental fillings.” (5)
Other ways humans are exposed to mercury include:
- Adhesives
- Batteries
- Cosmetics
- Fabric softeners
- Floor waxes/polishes
- Fungicides
- Hair dyes
- Laxatives
- Pesticides
- Plastics
Vaccines
World Mercury Project states that thimerosal, a mercury-based preservative used in vaccines is a “causative link to a suite of brain injuries, including autism.”
The link between vaccines and autism has been a highly charged and controversial argument. Robert F Kennedy, Jr writes, “Thimerosal is 50% ethylmercury” and is “far more toxic and persistent in the brain than the highly regulated methylmercury in fish.” Kennedy states that, “Hundreds of peer reviewed studies by leading government and university scientists” reveal how thimerosal is “a devastating brain poison linked to neurological disorders now epidemic in American children.” (6)
Latex Paints
Up until 1990, many latex paints contained mercury. In 1989, a 4-year old boy developed acrodynia that is caused by exposure to mercury. Upon investigating, doctors discovered the entire interior of the boy’s home had recently been painted with a latex paint.

The paint contained latex. A study of similar exposure to latex paints revealed mercury presence in test subjects. Subsequently, the EPA banned the use of mercury in latex paints (7).
Dental Fillings
According to the National Center for Biotechnology Information (NCBI) of the US National Library of Medicine, National Institutes of Health, dental amalgam containing mercury can leech into the bloodstream.
Aged fillings can expose humans to toxic amounts of mercury. The NCBI states that “the average American adult has seven mercury amalgam dental fillings.” (8)
Tattoos
Many tattoo inks contain mercury and other heavy metals. Forbes reports that a recent study conducted on four cadavers with tattoos found residue from several ink colors in lymph nodes.
This study provided evidence that the nanoparticles of ink can infiltrate the blood or the “lymph circulatory system” and carried by white blood cells to lymph nodes (9).
High Fructose Corn Syrups
SFGate reports that out of 20 high-fructose corn syrups (HFCS), nine tested positive for mercury. The amounts found in the samples were considerably small, such amounts might prove harmful to young children pregnant women and for those who have a high consumption rate of HFCS foods and drinks (9).
Mercury Poisoning Symptoms
There are many symptoms of mercury poisoning. Some of these include:
- Blindness
- Decreased cognitive abilities
- Deformities and/or severe nervous system disorders
- Double vision
- Headaches
- Increased risk of miscarriage
- Insomnia
- Interference in ability to walk normally
- Memory loss
- Muscle atrophy
- Muscle coordination and/or developmental problems in children
- Muscle twitching
- Numbness or pain in skin
- Seizures
- Uncontrollable tremors or shaking
- Various emotional changes, such as nervousness, mood swings, irritability, etc
- Weakness
Avoiding Mercury Exposure
Being aware of the sources of mercury can help you to avoid exposure. Blood, urine or hair tests can be used to determine different types of mercury poisoning (10).
References & Image Credits:
(1) Blood Brain Barrier
(2) Chloralkai Process
(3) Mercury Poisoning
(4) Smart Seafood Buying Guide
(5) NCBI
(6) Mercury Facts
(7) Acrodynia
(8) NCBI
(9) Potentially Toxic Tattoos
(10) Merury Lab Test