Beryllium
Beryllium is a toxic bivalent
element, steel gray, strong, light-weight, primarily used as hardening agent in
alloys. Beryllium has one of the highest melting points of the light metals. It
has excellent thermal conductivity, is nonmagnetic, it resists attack by
concentrated nitric acid and at standard temperature and pressures beryllium
resist oxidation when exposts to air.
Applications
Beryllium is used as an alloying
agent in the production of beryllium-copper. Thanks to their electrical and
thermal conductivity, high strength and hardness, non magnetic properties, good
resistance, dimensional stability over a wide temperature range
beryllium-copper alloys are used in many applications. A typical application of
beryllium-copper alloys is in the defense and aerospace industries.
Beryllium is also used in the field of X-ray detection diagnostic (it is
transparent to X-rays) and in the making of various computer equipment.
Beryllium
in the environment
The beryllium content on Earth
crust is 2.6 ppm, in soil 6 ppm.
Beryllium in soil can pass into the plants grown on it, provided it in a
soluble form. Typical levels in plants vary between 1 and 40 ppb, too low to
affect animals which eat these plants.
Beryllium is found in 30 different minerals, the most important of which are bertrandite, beryl, chrysoberyl,
and phenacite. Precious forms of beryl are aquamarine
and emerald.
Health
effects of beryllium
Beryllium is not an element that is crucial for humans; in fact it is
one of the most toxic chemicals we know. It is a metal that can be very harmful
when humans breathe it in, because it can damage the lungs and cause pneumonia.
The most commonly known
effect of beryllium is called berylliosis, a
dangerous and persistent lung disorder that can also damage other organs, such
as the heart. In about 20% of all cases people die of this disease. Breathing
in beryllium in the workplace is what causes berylliosis.
People that have weakened immune systems are most susceptible to this disease.
Beryllium can also cause
allergic reactions with people that are hypersensitive to this chemical. These
reactions can be very heavy and they can even cause a person to be seriously
ill, a condition known as Chronic Beryllium Disease (CBD). The symptoms are
weakness, tiredness and breathing problems. Some people that suffer from CBD
will develop anorexia and blueness of hands and feet. Sometimes people can even
be in such a serious condition that CBD can cause their death.
Next to causing berylliosis and CBD, beryllium can also increase the
chances of cancer development and DNA damage.
Environmental
effects of beryllium
Beryllium enters the air, water
and soil as a result of natural processes and human activities. It occurs
naturally in the environment in small amounts. Humans add beryllium through
production of metal and combustion of coal and oil.
Beryllium exists in air as very small dust particles. It enters waterways
during weathering of soils and rocks. Industrial emissions will add beryllium
to air and wastewater disposals will add beryllium
to water. It usually
settles in sediment. Beryllium
as a chemical element occurs naturally in soils in small amounts, but human
activities have also increased these beryllium levels. Beryllium is not likely
to move deeper into the soil and dissolve within
groundwater.
In water, chemicals will react with beryllium, causing it to become insoluble.
This is a good thing, because the water-insoluble form of beryllium can cause
much less harm to organisms than the water-soluble form.
Beryllium will not be accumulated in the bodies of fish. However, some fruits
and vegetables such as kidney beans and pears may contain significant levels of
beryllium. These levels can enter animals that eat them, but luckily most
animals excrete beryllium quickly through urine and feces.
The uptake of beryllium has consequences mainly for human health. However,
laboratory tests have indicated that it is possible for beryllium to cause
cancer and changes of DNA with animals. So far there is no field evidence to
support these findings.