WHY OUR MERCURY TEST IS BETTER THAN ANY OTHER MERCURY TEST?
WHY MERCURY SPECIATION ANALYSIS?
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:
- Quicksilver mercury speciation analysis measures the biologically active forms of mercury with a single test procedure.
- Mercury speciation provides clear data on the distribution (proportion) of methylmercury to inorganic mercury and total mercury present in a test sample.
- Mercury speciation analysis can also predict the mobility and toxicity of mercury within the food chain of a specific ecosystem.
Different Forms, Inconsistent Proportions
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.
Differences in Mobility, Differences in Toxicity
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.