Learn More About Mercury
Mercury Speciation Analysis
Today’s scientists know that mercury is no friend of mankind. In fact, mercury is extremely toxic in most forms and can be absorbed through the skin and mucous membranes, and its vapors can be inhaled. Yet, over the millennia it has been misused to treat syphilis, typhus, skin conditions, constipation, intestinal parasites, and many more chronic and acute conditions. In more recent times, it has been misused in infant teething powders, dental amalgam fillings, and vaccines as a preservative. These modern-day medicinal applications have caused dangerous levels of mercury in children and adults. Furthermore, mercury can enter the human body through the consumption of contaminated fish that swim in mercury-polluted waters. Without a doubt, mercury is no friend to humans or the environment.
But mercury is considered a global pollutant, as it's capable of spreading far beyond its source area. The arctic, for example, has no known sources of mercury, but it harbors mercury-contaminated fish, and recent studies indicate that whales feeding in the arctic have high levels of mercury in their tissue.
What is Methylmercury? Methylmercury is an extremely toxic form of mercury that biomagnifies in aquatic food chains. It is a potent neurotoxin and the easiest form for animals to store in their tissue. It harms the brain, affecting memory, understanding and movement. Studies have shown that mercury exposure in humans can result in developmental delays in children, motor impairment, cardiovascular effects and, in acute cases, death. Its effects have been studied in fish, whales, seals and seabirds. Methylmercury binds to proteins and easily crosses cell membranes, including the blood-brain barrier and the placenta. Affected wildlife, such as loons, develop behaviors that ultimately reduce their chances for survival and reproduction. Studies conducted on human populations have estimated that between 200,000 and 400,000 children in the United States alone are born each year with pre-natal exposure to methylmercury sufficient to put them at risk of neurologic impairment.
People are exposed to mercury mainly by eating fish and shellfish—and 95 percent or more of the mercury in fish is the more toxic methylmercury. According to the EPA, fish filets containing more than .3 parts per million (ppm) of methylmercury should not be eaten (Canada and the states of Maine and Minnesota suggest you avoid fish with .2 ppm). Fish caught in water with very low concentrations of mercury (less than 1 part per trillion) can nonetheless contain harmful levels of methylmercury. In some marine ecosystems, the concentration of methylmercury increases 10 million times as it makes its way up through the food web from microscopic algae to whales, dolphins, shark and tuna.
Mercury concentrations in fish found in lakes and rivers throughout the United States now exceed the mercury levels that cause concern for human and wildlife health. As of 2008, all 50 states and one U.S. territory have fish-consumption advisories for mercury. In addition, all states on the Atlantic and Gulf of Mexico have coastal fish advisories. Although much of the scientific research on mercury in fish has focused on freshwater ecosystems, most Americans are exposed to mercury through seafood consumption. There are many questions to be answered about where the mercury in the fish that we eat comes from and what fish are safe to eat. Solutions to the complex problem of mercury pollution have been impeded by conflicting information on the sources, transport and accumulation of mercury in the environment. Our program hopes to address these questions and, therefore, provide the scientific basis for solutions to this pressing environmental and human health issue.
There are three main forms of mercury measurable in the human body. They are all toxic. Which is why you need our mercury level test.
Methylmercury (MeHg), also known as monomethylmercury, is the most researched form of mercury present in nature. It is an organic mercury species commonly found in fish and other animal tissues. Although methylmercury is mobile and easily absorbed, it is difficult for organisms to eliminate. Instead, the methylmercury accumulates in biological tissues. For example, while digesting its prey, the predator absorbs the methylmercury contained in its victim. As a result, animals higher on the food chain tend to have more methylmercury in their tissues than those lower on the food chain. This process of methylmercury exposure is known as bioaccumulation. Bioaccumulation can result in fish having over 1 million times higher methylmercury concentrations than the water in which they swim.
Inorganic mercury is the term used to refer to mercuric ion (HgII). Inorganic mercury is highly toxic but not very mobile. Inorganic mercury in sediments, soils and food sources does not pass easily into biological tissues. However, once inside of the tissue, inorganic mercury is very difficult to remove. Inorganic mercury accumulates in tissues when a more mobile form of mercury such as elemental mercury vapor, methylmercury or ethylmercury enters the tissue and breaks down into inorganic mercury. In biological tissues, most organic forms of mercury will eventually break down into inorganic mercury.
Like methylmercury, ethylmercury is an organic form of mercury. Ethylmercury can be present in sediments or petroleum hydrocarbons. Ethylmercury is also used as a component in vaccine preservatives (thimerosal). Vaccination is the most common exposure route for this organic form of mercury. Like methylmercury, ethylmercury can move easily into biological tissues. However, ethylmercury tends to break down into inorganic mercury more rapidly than methylmercury.
Total mercury analysis alone cannot provide an adequate representation of the mercury chemistry present in a test sample. As demonstrated in a study published in Science, knowing the distribution of different mercury species can create clearer data relationships and enable more accurate conclusions. For this reason, all current research recommends mercury speciation rather than total mercury analysis. Quicksilver Scientific's mercury speciation provides much more insightful data and has the following key advantages over total mercury analysis:
The distribution of different mercury species in a test sample varies widely. Simply measuring total mercury and using a conversion factor to determine the mercury species distribution can produce wildly inaccurate data. Ratios of methylmercury to inorganic mercury are both sample and site specific. The only accurate method for determining the distribution of mercury species in a test sample is through direct measurement with speciation analysis.
For example, methylmercury (MeHg) in sediment samples may range from <0.001% to >>1% of the total mercury present. The remaining mercury will include inorganic mercury (HgII) with the possible presence of other species. In speciation testing performed on insects and macroinvertebrates, Quicksilver Scientific determined that methylmercury levels (as a percentage of total mercury) could vary more than 80 percentage points. It is clear that bioaccumulation studies cannot rely on total mercury analysis for accurate results.
The various forms of mercury move through biological systems and tissues in different ways. They also express different modes of toxicity. Only speciation analysis can determine which types of mercury are in a sample. Only Quicksilver Scientific can provide this data with a single test.
Methylmercury is highly mobile and can pass through tissues with much more ease than inorganic mercury, which tends to stick to cell walls. The mobility of methylmercury plays a major role in its ability to bioaccumulate. In the environment, methylmercury moves from sediments and water into living things, such as bacteria and plankton. Inorganic mercury, however, sticks to the cell walls of bacteria and to the carapaces of plankton. As predators consume smaller organisms, the inorganic mercury contained in the cell walls and carapaces gets excreted. However, the methylmercury contained in the inner organs and tissues is assimilated into the predator organism. This process continues along the entire food chain. The larger the predatory species, the more methylmercury it contains. This process is known as bioaccumulation. The dramatic effect of bioaccumulation is often demonstrated by methylmercury levels in fish. Fish can have methylmercury concentrations 1 to 10 million times higher than the water in which they swim.
Methylmercury is equally mobile in the human organism. In fact, human intestines absorb about 95% of the methylmercury that enters the digestive tract. During the digestive process, methylmercury binds to an amino acid known as cysteine. The resulting mercury compound (methylmercury cysteine) is mistaken for methionine by the transport proteins which bind amino acids. Once in the circulatory system, methylmercury can easily cross the placental and blood-brain barriers. This methylmercury exposure can result in debilitating neurological effects.
Eventually, the human organism identifies the presence of methylmercury and binds it to glutathione, a tripeptide compound that is also an important antioxidant. The human detoxification system attempts to remove the methylmercury through the small intestine via the bile. However, the glutathione is broken down into cysteine while in the intestinal tract, which again results in the production of methylmercury cysteine. The resulting methylmercury cysteine is then “recycled” by enterohepatic circulation. Enterohepatic circulation is the cycle by which bile salts and other substances excreted by the liver are absorbed by the intestinal mucosa and returned to the liver via the portal circulation. Methylmercury remains in enterohepatic circulation for an extended period. Without proper therapeutic detoxification, the removal of methylmercury from the human body is a very inefficient process.
Biological organisms do not absorb inorganic mercury as easily as methylmercury. As a result, inorganic mercury does not bioaccumulate to the same degree. However, when inorganic mercury is absorbed into biological tissues, the toxic effects pose an immediate threat. For example, high levels of inorganic mercury in prey animals (insects, etc.) can cause toxic effects in the predators that consume them. The potential effects of this mercury toxicity include nerve impulse and reproductive disruptions, as well as thyroid dysregulation. In addition to this, recent studies provide evidence that fish with high inorganic mercury loads suffer from liver toxicity.