METHYL MERCURY POISONING

Methyl Mercury Poisoning



Methyl Mercury Poisoning

Introduction

Methyl mercury is form when elemental mercury are releasing into the environment through either industrial processes or natural occurrences such as volcanoes. Once this mercury is discharge into the environment, it finds its way into rivers, lakes and oceans where it eventually settles to the sediments on the bottoms of these waterways. There bacteria and other microorganisms that contain unique enzymes, which enable to add a methyl group to the metallic mercury to form methyl mercury, ingest it. Since methyl mercury is a persistent pollutant, as creatures on each level of the food chain eat the creatures below them, they ingest the mercury that has accumulated in those creatures' bodies. The result is that methyl mercury can accumulate to reach very high concentrations in predatory fish at the top of the food chain. This also means that fish and shellfish, which are towards the bottom of the aquatic food chain, have lower concentrations of mercury in their flesh and are safer to eat. For a list of which popular fish and shellfish are high and low in mercury, please see table 1 in “Ways to avoid mercury exposure” (Tsuchiya, 2009) (Al-Shahristani, 1974).

What is mercury?

Mercury is a chemical element, a heavy metal. Mercury exists in nature in three different forms; metallic (elemental) mercury - the dense silvery liquid metal we all know from thermometers and our high school chemistry labs; inorganic salts of mercury; and organic mercury compounds, most notably methyl mercury and ethyl mercury. Each form of mercury found in different environmental locations and, each poses individual risks to human health (Al-Shahristani, 1974).

Metallic Mercury: Metallic mercury is the most recognizable form of mercury. Often known as “quicksilver”, it is distinguishing by its silver-liquid consistency. Metallic mercury used in Thermometers and mercury switches for a wide variety of industrial and commercial purposes, as well as in assorted batteries. For example, those popular children's sneakers that Light up as they walk contain mercury switches (Clarkson, 2009).

Inorganic Mercury: Inorganic mercury, which takes the form of a white solid, infrequently used in Chinese, Spanish and, homeopathic medicines for stomach disorders and, may be present in skin lightening creams. In the past, inorganic mercury was use in the US as a treatment for worms and as a teething powder. Most uses of inorganic mercury in the US have stop (Clarkson, 2009).

Organic Mercury: There are two significant forms of organic mercury - methyl mercury and ethyl mercury. While ethyl mercury and methyl mercury are both forms of organic mercury (meaning they have carbon-based structures), both have very different properties. The difference between the two is like the difference between ethyl alcohol (found in alcoholic beverages) and methyl alcohol, a highly toxic form of alcohol, which causes blindness and death (Trasande, 2005).

How does mercury exposure occur?

Exposure to the different forms of mercury (organic, metallic, and inorganic) comes from different, unique sources and via different routes.

Metallic Mercury: Metallic (elemental) mercury exposure occurs through inhalation of mercury ...