Hazards of mercury contamination on health and environment
Mercury is a naturally occurring metal which is toxic. It is a silvery-white liquid which quickly alters into a vapor. When vaporized, it enters the atmosphere and remain there for a long time, and is cultured globally.
Researchers have revealed that mercury can be a danger to the health of people and wildlife in many environments that are not obviously polluted. The breathing of mercury vapor can produce adverse effects on the nervous, digestive and immune systems, lungs and kidneys which can be fatal.
Mercury exists in the following main states under natural conditions
• As metallic vapor and liquid /elemental mercury
• Bound in mercury-containing minerals
• As ion in solution or bound in ionic compounds(inorganic and organic salts)
• As soluble ion complexes
• As gaseous or dissolved non-ionic organic compounds
• Bound to organic or inorganic particles /matter by ionic,
• Electrophilic or lipophilic adsorption
Potential health effects of mercury:
The toxicity of mercury depends on its chemical form. The sources of exposure are also markedly different.
For alkyl mercury compounds, among which methylmercury is by far the most important, the major source of exposure is diet, especially fish and other seafood.
For elemental mercury vapor, the most important source for the general population in dental amalgam, use of skin-lightening creams and soaps that contain mercury and use of mercury for cultural/ritualistic purposes or in traditional medicine, can also result in substantial exposures to inorganic or elemental mercury.
Almost all people have at least small amounts of methylmercury in their bodies, reflecting the widespread presence of methylmercury in the environment, and people exposed to high levels may experience adverse health effects.
Possible symptoms of methylmercury poisoning may include:
• Loss of peripheral vision
• Pins and needles feelings, usually in the hand, feet and around the mouth
• Lack of coordination of movements
• Impairment of speech, hearing, walking
• Muscle weakness
Effects on Infants and Children
It is a well-documented neurotoxicant, causes adverse effects on the developing brain. Moreover, this compound readily passes both the placental barrier and the blood-brain barrier, therefore exposure during pregnancy are of highest concern. Also, some studies suggest that even a small increase in methylmercury exposures may cause adverse effects on the cardiovascular system, thereby leading to increased mortality.
Children exposed to methylmercury while they are in the womb can have impacts on their, Cognitive thinking, Memory, Attention, Language, Fine motor skills, and visual-spatial skills.
Elemental mercury effects
Elemental mercury is a shiny, silver-white metal that is a liquid at room temperature and is traditionally used in thermometers and some electric switches. If not enclosed at room temperature some of the metallic mercury will evaporate and form mercury vapors. Mercury vapors are colorless and odorless. The higher the temperature, the more vapors will be released from metallic mercury. Some people who have breathed mercury vapors report a metallic taste in their mouths. Metallic mercury mainly causes health effects when inhaled as a vapor where it can be absorbed through the lungs.
Symptoms of prolonged and/or acute exposures include,
• Emotional changes (such as mood swings, irritability, nervousness, excessive shyness)
• Neuromuscular changes (such as weakness, muscle atrophy, twitching)
• Disturbances in sensations
• Changes in nerve responses
• Poor performance on tests of mental function
• Higher exposures may also cause kidney effects, respiratory failure, and death.
Effects of Other Mercury Compounds
High exposure to inorganic mercury may result in damage to the gastrointestinal tract, the nervous system, and the kidneys. Both inorganic and organic mercury is absorbed through the gastrointestinal tract and affect other systems through this route.
Symptoms of high exposures to inorganic mercury include:
• Skin rashes and dermatitis
• Mood swings
• Memory loss
• Mental disturbances
• Muscle weakness.
People concerned about their exposure to inorganic mercury should consult their physician.
Hazards of mercury contamination on the environment
There are a number of natural and industrial sources of mercury emissions. Mercury is released into the environment as a result of volcanic eruptions, forest fires, and volatilization from the ocean and melting of icecaps. Intentional use of mercury in artisanal and small-scale gold mining, chloralkali processing and the production of mercury-containing products in one of the main anthropogenic sources of mercury.
Mercury is also released as a by-product of processes such as coal combustion, metal smelting, and waste incineration.
In general, mercury and its compounds can be found in all environmental and other media including ambient and indoor air, surface and drinking waters, soil and sediments, biota, food and the occupational environment.
Concentrations of mercury in waters do not usually create risks for health. Direct spills into aquatic environments can, however, cause significant local contamination that potentially leads to elevated population exposures and, therefore, likely to be of greater local concern.
Rising water levels associated with global climate change have implications for methylation of mercury and its accumulation in fish. For example, there are indicators of increased formation of methylmercury in small, warm lakes and in many newly flooded areas.
Few land management options exist to address elevated methylmercury (MeHg) levels in fish and wildlife.
However, Sams (2009) provides the subsequent recommendation that ought to be thought of for implementation by land management agencies:
Monitor mercury levels in water and life, as coupled to implementation, effectiveness, and validation observation related to numerous forest land management activities (e.g., management of alluviation related to timber harvest).
Rank wetlands and lakes on their potential for elevated MeHg production rates.
Minimize water level manipulations of lakes and wetlands to attenuate mercury methylation rates at intervals aquatic sediments.
Minimize alluviation related to land disturbance activities.
Manage fish species relative to risk factors related to proximity of mining operations, lake morphology, and landscape ecology (e.g., avoid managing for high predators in areas of high risk).
Comment to state and federal air restrictive officers to maximize controls on industrial mercury and Sulphur dioxide emission rates close to sensitive ecosystems.
Hazards of mercury contamination on health and environment