Download 110225-HazAlert

~dHazard Alert
~tMercury
~w2011-02-17
Mercury is a naturally occurring element (Hg on the periodic table) that is found in air, water
and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds,
and organic mercury compounds. Elemental or metallic mercury is a shiny, silver-white metal
and is liquid at room temperature. If heated, it is a colourless, odourless gas. [3]
Exposure to mercury can affect the human nervous system and harm the brain, heart, kidneys
lungs, and immune system. [3]
The most common way we are exposed to mercury is by eating fish or selfish that are
contaminated with mercury. [3]
Sources of Mercury
Mercury is an element in the earth’s crust. Humans cannot destroy or create mercury. Pure
mercury is a liquid metal, sometimes referred to as quicksilver that volatises readily.
Traditionally, it has been used to make products like thermometers, switches, and some light
bulbs. [3]
Mercury is found in many rocks including coal. When coal is burned, mercury is released into the
environment. Coal- burning power plants are the largest human-caused source of mercury
emissions to the air. [3]
Why is Mercury Harmful
* Mercury and most of its compounds are highly toxic. [2]
* The pure metal is absorbed easily by inhalation, ingestion or through the skin. [2]
* It is also a chronic pollutant and mercury concentrates in animal/fish tissues in increasing
amounts up the food chain. [2]
* Environmental Impacts: Mercury has been known to have harmful effects on fish birds, and
mammals. These effects include impaired growth and development, abnormal behaviour,
difficulties in reproduction, and even death. It enters the environment through a number of fuel
combustion, incineration, and industrial processes, as well as through some natural sources.
Atmospheric concentrations are, for the most part, very low. Mercury is deposited by way of wet
and dry processes to forest ecosystems. It then accumulates in highly toxic forms in the food
chain of aquatic ecosystems. This is detrimental to aquatic organisms, which in some cases leads
to problems in human health. Exposure from food occurs most often through consumption of
mercury contaminated seafood or plants, such as rice. [3]
* Health Impacts: Mercury is almost completely absorbed into the blood and distributed to all
tissues including the brain; it is also readily passes through the placenta to the foetus and the
foetal brain. The first symptoms of mercury poisoning are evident by numbness and tingling of
lips, toes, and finger; this is called paresthesia. Continued exposure results in stumbling, slurred
speech, constricted visual fields, and impaired hearing. In extreme cases tremors and jerks can
occur, followed by coma and death. Signs and symptoms associated with mercury intoxication
include tremor, ataxia, personality changes, loss of memory, insomnia, fatigue, depression,
headaches, irritability, slow nerve conduction, weight loss, psychological distress, and gingivitis.
Most of these signs of symptoms have been associated with people with long term occupational
exposure to air concentrations of mercury greater than 50µ g/m³ whose urinary mercury
concentrations are greater than100 µg/L. [3]
Uses [2]
* Mercury is used in barometers and manometers (instruments for measuring the pressure of
gases and liquids), because of its high density.
* In addition, the metal has a high rate of nearly linear thermal expansion, so it is used
extensively in thermometers.
* Its ease in amalgamating with metals is made use of in extracting gold, silver, and platinum
from their ores.
* Mercury is widely used in making advertising signs, mercury switches and other electrical
apparatus.
* It is also used in mercury-vapour lamps (which emit light rich in ultraviolet radiation). These
lamps are typically used for street lighting, as sun lamps, and as UV lights (black lights).
* Various compounds of mercury are used in medicine, dentistry, cosmetics (mascara) and also in
agriculture to make fungicides.
Toxicity and Safety [1]
Mercury and most of its compounds are extremely toxic and are generally handled with care; in
cases of spills involving mercury (such as from certain thermometers or fluorescent light bulbs)
specific cleaning procedures are used to avoid toxic exposure. Essentially, it is recommended to
physically merge smaller droplets on hard surfaces, combining them into a single larger pool for
easier removal by using an eyedropper, or by pushing it into a disposable container.
Mercury can be inhaled and absorbed through the skin and mucous membranes, so containers of
mercury are securely sealed to avoid spills and evaporation. Heating of mercury, or compounds of
mercury that may decompose when heated, is always carried out with adequate ventilation in
order to avoid exposure to mercury vapour. The most toxic forms of mercury are its organic
compounds, such as dimethylmercury and methylmercury. However, inorganic compounds, such
as cinnabar are also highly toxic by ingestion or inhalation of the dust. Mercury can cause both
chronic and acute poisoning.
[1] http://en.wikipedia.org/wiki/Mercury(element)
[2] http://www.chemicool.com/elements/mercury.html
[3] http://www.uvm.edu/~vlrs/doc/mercury.htm