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Trace Elements in Abiotic and Biotic Environments
General population can be exposed to trace amounts of Be through inhalation of air, consumption of food and water, and skin contact with air, water, or
soil that contain Be. Beryllium and its compounds are not biotransformated, but
soluble Be salts are partially converted to less soluble forms in the lungs (ATSDR
2002a).
Exposure to Be and its compounds is much more hazardous by inhalation than
by ingestion, because they are poorly absorbed after oral and dermal exposure.
The respiratory tract in humans and animals is the primary target of Be toxicity
following inhalation exposure. Occupational exposure to high concentrations of
soluble Be compounds can result in acute Be disease, whereas exposure to relatively low concentrations (0.5 μg/m 3 ) of soluble or insoluble Be compounds can
result in chronic Be disease. Acute Be disease is characterized by an inflammation of the respiratory tract tissues and is usually resolved within several months
of exposure termination. In contrast, chronic beryllium disease or berylliosis is
immune response to Be, and is only observed in individuals who are sensitive to
Be (usually <15% of exposed population). Other systemic effects, that have been
observed in individuals with severe cases of chronic Be disease include damage to
the right heart ventricle, hepatic necrosis, kidney stones, and weight loss. Dermal
contact with Be can result in an allergic response, especially skin granulomas, in
certain individuals. Dermatitis, which may be due to direct irritation rather than
an immune response, has also been observed in workers exposed to high concentrations of airborne Be. Tobacco smoke is another potential source of exposure to
Be in the general population. Beryllium levels of 0.47, 0.68, and 0.74 μg/cigarette
were found in three brands of cigarettes. Between 1.6% and 10% of the Be content,
or 0.011–0.074 μg/cigarette, was reported to pass into the smoke during smoking
(WHO 2001a).
Inhaled and parenterally administered Be salts lead to its accumulation in the
skeletal system. Following oral exposure, Be accumulates mainly in bones, but is also
found in several other organs and soft tissues. Systemic distribution of the more soluble Be compounds is greater than that of the insoluble compounds. Transportation
of Be across the placenta has been shown in rats and mice treated by intravenous
injection (ATSDR 2002a).
Soluble Be compounds are absorbed to a greater degree (~20% of the initial lung
burden) than sparingly soluble compounds (e.g., Be oxide). Ingested Be is poorly
absorbed (<1%) from the gastrointestinal tract. Dermal exposure of Be and its compounds in humans can result in a delayed-type (cell-mediated) hypersensitivity skin
response.
Beryllium is chemically similar to Mg and therefore can displace it from enzymes,
which causes them to malfunction. It can deplete the store of Mg in the body, lodge
in vital organs, and prevent them from performing their functions, and interfere
with a number of enzyme systems of the body. IARC (1993) designates Be and its
compounds as carcinogenic to humans (Group 1). Tolerable daily intake of 2  μg/kg
bw was estimated (WHO 2011a). The content of Be in food is small (Table 5.2).
There is a surprising lack of information on levels of Be in foods and beverages, in
spite of the considerable interest in its environmental and toxicological importance
(Reilly 2002).