Mercury is a
natural substance present in the earth, but it is also produced in
various industrial and medical uses. In our environment, the three
forms of mercury present are:
* elemental metal – such as in mercury thermometers and dental
fillings
* organic compound – mercury is converted by bacteria in the water
into methylmercury and this enters the fish food chain
* inorganic compound – naturally present in coal, mercury is
released into the air when coal is burned to generate power. mercury
is also produced as a waste product in various industrial processes.
The majority of exposure to humans is through organic methylmercury
that has entered the food chain and accumulates at higher levels in
larger species of fish. The major threat to human health from
mercury poisoning is from inhaling mercury as a vapour.
Preventing or minimising exposure to mercury in your environment is
the best way to reduce your risk of mercury poisoning.
Mercury in the environment
There are a number of common sources of mercury in our environment
including:
* larger fish species – if eaten in large quantities, these can
increase the amount of mercury in your body
* fluorescent and low-energy light bulbs – if broken, there is some
risk from inhaling mercury vapour and skin contact with mercury
* mercury thermometers – the pure mercury (or ‘quicksilver’) from
broken thermometers could pose some risk to people if they inhale
mercury vapour or have skin contact with mercury
* dental fillings – modern amalgam fillings have a low level of
mercury, which is considered safe for most people
* batteries – some batteries contain mercury that can enter the
environment if they end up in landfill.
Reducing exposure to mercury
There are a number of precautions that you can take to minimise your
exposure to mercury while also reducing the amount of mercury in our
environment.
Reducing exposure to mercury from fish
Educate yourself about the types of fish that are more likely to
contain higher levels of mercury. These include:
Some freshwater species of fish in Victoria can have high levels of
mercury. This is because of Victoria’s goldmining history.
Goldmining has increased the level of mercury in the sediment of
riverbeds, and this means that large brown trout and redfin in the
Upper Goulburn and Lake Eildon (and surrounding rivers) may have
high levels of mercury.
Most people can still eat fish with higher levels of mercury, but
Food Standards Australia New Zealand recommend that they should be
eaten less often than fish species with lower levels of mercury.
People in high-risk groups (such as pregnant women, children and
people with kidney disease) should check the recommendations before
eating these fish.
The recommendations for the quantities of fish that can be eaten are
different for pregnant women and children compared with the rest of
the adult population. Pregnant women, nursing mothers, women
planning pregnancy and children up to six years old should avoid
fish high in mercury.
Many people take supplements of fish oil to increase their intake of
omega-3 fats. While it is better to get your omega-3 fats from fish
rather than supplements, if you do use fish oil capsules, check to
see if the product has been tested for mercury levels.
Reducing exposure to mercury from fluorescent bulbs and lamps
In 2010, new standards were introduced for low-energy bulbs in
Australia. This means that the number of low-energy bulbs has
greatly increased and these bulbs contain small levels of mercury.
The mercury-containing bulbs include fluorescent tube lamps and the
compact low-energy bulbs mostly used in homes.
The amount of mercury in a single bulb or lamp is very small and
unlikely to harm people. Commercial and public lighting uses many
more lamps and FluoroCycle is a voluntary national scheme to recycle
mercury-containing lamps for industrial and public lighting.
For information on lamps used at home, you can contact your local
council to find out how best to dispose of light bulbs and lamps.
Broken tubes, bulbs or lamps can be cleaned up as follows:
* Air (ventilate) the room.
* Wear gloves and scoop up all the glass fragments and powder.
* Put all the broken globe or tube into a rigid, sealed container.
* Use sticky tape to pick up any remaining small glass fragments and
powder.
* Wipe the area clean with damp paper towels or disposable wet wipes
and place them in a glass jar or plastic bag.
* Continue to air the room for 12 to 24 hours.
* Dispose of the mercury and any contaminated items in the rubbish,
not in the recycling bin.
Reducing exposure to mercury from thermometers and other devices
Spirit-containing thermometers are now widely available, but some
people still use thermometers containing silver mercury. Intact,
these are not dangerous, but when broken there is the possibility of
inhaling mercury vapour and of skin contact. These spills should be
cleaned up carefully.
The procedure includes the following steps:
* Clear the room of people and pets.
* Air (ventilate) the room for 15 minutes (turn off ducted heating
or cooling) before cleaning up.
* Do not use a vacuum cleaner or broom.
* Remove jewellery, wear gloves and wear old clothing that you can
throw away.
* Clean up using an eyedropper or syringe to pick up droplets of
mercury or use a pen or card to guide the droplets onto a piece of
card.
* Use sticky tape to pick up small droplets.
* Place mercury droplets into a strong plastic container with a lid.
* Keep the room ventilated for 24 hours.
* Place any item (including clothes) that came into contact with the
mercury into a sealed plastic bag and place in the rubbish.
* Contaminated carpet and other absorbent items will need to be cut
out or removed and disposed of carefully.
* More detailed information is available for cleaning procedures.
Other devices around the home can contain more than two tablespoons
of mercury. These include thermostats and some medical equipment
(such as a sphygmomanometer – to measure blood pressure). Large
mercury spills need to be professionally cleaned up. The following
steps should be taken:
* Evacuate the area.
* Air (ventilate) the area.
* Contain the spill – call triple zero (000) and ask for fire
services.
* Clean up the spill – this should be performed by experienced
professionals who specialise in hazardous chemicals.
Reducing exposure to mercury from dental fillings
Dental fillings are used to treat damaged or worn teeth and can be
made of amalgam that contains mercury, silver and tin. This
substance is used because of its strength, especially in the back
teeth that are under a lot of pressure during chewing. Modern
amalgam has low levels of mercury and is considered safe for most
people.
Alternate materials for fillings that are similar in colour to teeth
do not contain mercury but these are not as strong as amalgam. You
can replace your amalgam fillings with this material, but it might
not last as long, especially in your back teeth. Replacing fillings
can also be expensive. Speak with your dentist about your options.
Some people are advised to avoid getting new amalgam fillings and to
avoid having existing amalgam removed or replaced if possible
including:
* pregnant women – mercury may cross the placenta and enter the
bloodstream of the unborn baby
* women who are breastfeeding – mercury may be passed to the baby
through breastmilk
* children – growing and developing teeth are more sensitive to the
effects of any chemical substances in the environment, including
mercury
* people with kidney disease – high levels of mercury exposure can
affect the kidneys, so exposure to mercury should be minimised.
While there is currently no scientific evidence directly linking
amalgam with either ill health or birth defects, these
recommendations have been made for precautionary reasons.
Reducing exposure to mercury from batteries
Not all batteries contain mercury, but those that do can damage the
environment if they end up in landfill. Your local council can give
you advice about safe disposal of batteries.
People at risk of exposure to mercury
The effect of mercury exposure depends on the type of mercury. In
general, mercury tends to affect the nervous system. This means that
unborn babies and children are at more risk because their nervous
systems are developing.
People at higher risk from mercury exposure include:
* unborn babies
* infants
* children up to six years of age
* workers in industrial settings where mercury is used or produced
* people with kidney disease
* people born before the 1950s who were exposed to mercury in baby
products and contracted pink disease.
* Pregnant women should avoid mercury so that it is not transmitted
to their unborn baby via the bloodstream. Levels of mercury in
breastmilk are normally not high enough to be a risk for babies.
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