Mercury in the environment and human health risks associated with mercury exposure and consumption.

Thermometers are very common tools, used almost everywhere we look, to check temperatures. Thermometers used to measure body temperature are one of the most essential tools used in the health field. The most common  thermometers used in homes are mercury thermometers. As a result of the unique ability of mercury to change at a fixed volume for every degree rise in temperature, this element has been used in thermometers for centuries. As much as mercury thermometers benefit us, the mercury itself is one of the most dangerous elements that exist.
Mercury in its standard state is a liquid at room temperature and has a very strong surface tension. As a result, it doesn't flow readily like any other liquid. When liquid mercury is exposed to the atmosphere, it releases a colorless, odorless, tasteless, toxic gas. This gas, if inhaled can cause health problems such as gingivitis, gastrointestinal problems, anxiety, and other nervous system problems.
Although some of these problems are not so severe, mercury can be deadly in its other forms.
One of teh most harmful forms of mercury is methylmercury.
Methylmercury is a carcinogen as well as a neurotoxin. It is produced when marine bacteria consume mercury and metabolize it into a methyl-mercury compound. This compound is concentrated in the tissue of any organism that consumes the bacteria. when larger organisms consume the smaller ones, the methylmercury concentration in their tissues builds up to a level higher than the lower trophic organisms. This process, known as biomagnification causes the methylmercury concentration to increase with progressively larger marine animals. When large predator fish are consumed by humans, they already have significantly high concentrations of methylemrcury. The compound is then concentrated in the human system, and thats where the damage begins.
Methylmercury in humans can lead to major birth defects, severe neurological damage, severe dental and gastrointestinal problems, and sometimes, major cardiovascular problems.
Although mercury has its benefits, the damage it can cause on the human body is too extreme to risk. As a result, thermometers and other tools and porcesses that require the use of mercury are being re-developed to use other alternatives. an example is the computerized thermometer that does not require mercury to function.

The image below shows how mercury is cycled in the environment and how the process of biomagnification affects its concentrations in animals.

The link below shows a fact sheet that shows a summary of some basic information about mercury.
http://www.mercer.edu/enp/Hg_Gamra.pdf