There are three types of mercury that can affect the body: elemental mercury, inorganic mercury, and organic mercury. Though all three forms cause health problems, organic mercury is the most common form to affect humans. Very small amounts of these organic mercury compounds, such as methyl mercury, can cause central nervous system (CNS) damage and even death.
Methyl mercury is not a natural state of mercury. The process in which it is created is as follows:
- Elemental mercury is found naturally in resources we use as fuel such as, coal, oil, and wood. When we burn this fuel, especially coal, we release the mercury into the atmosphere. In outdoor air the mercury concentrations are low and usually not a direct concern to humans. The problem arises when the mercury falls to the earth in rain or snow.
- When the mercury in the precipitation comes in contact with the ground or bodies of water a biological process called, methylation, occurs. It has now become methyl mercury, a highly toxic and bioaccumulative form of mercury.
How does this methyl mercury come into contact with humans?
- Methyl mercury in the sediment and water is absorbed or eaten by plankton.
- Smaller fish species and juvenile fish eat large amounts of plankton over time; however, the methyl mercury is bioaccumulative which means it forms a strong bond with proteins and can not be processed out. This means that all of the mercury consumed by these small fish did not leave their bodies.
- Those smaller fish filled with mercury are then eaten by larger predatory fish. The larger and older the fish the more mercury it has in its body.
- These fish are caught privately and commercially by humans for consumption. Thus causing the methyl mercury in human tissue to accumulate.
What does this mean for human health?
- When a fetus is exposed to mercury in the womb the negative effects to its health can be devastating. The fetus is exposed to mercury through consumption of fish by its mother. Even a small level of exposure by the fetus can cause serious brain and CNS disorders. In fetuses, infants, and children this exposure means that they could experience serious impacts on memory, attention, language, motor development, and other skills vital to their development and their life. They may also be born with mental retardation, ataxia, deafness, constricted visual field, blindness, and cerebral palsy.
- Acute exposure to high levels of methyl mercury cause CNS problems such as: blindness, deafness, impaired level of consciousness, and death.
- CNS damage is the biggest effect of chronic exposure to methyl mercury. Early effects present as paresthesia, blurred vision, and malaise. Higher doses cause deafness, speech difficulties, and constriction of visual field.
- The EPA classifies methyl mercury as Group C, possible human carcinogens.
Can mercury be purged from our bodies?
- Mercury accumulation can only be treated with medication. The process is slow and can take months or years. In some cases mercury permanently damages some of the internal enzymes and there is no known way to bring them back