Environmental Engineering Reference
In-Depth Information
• Moderate deiciency:
Slow growth, hypogonadism, skin alterations, poor appetite,
night blindness, slow healing of wounds, dysfunction of cell-mediated immunity,
and abnormal neuro-sensorial changes.
• Light deiciency:
Neuro-sensorial changes, oligospermia, hyperamonemia, reduc-
tion of the timuline serum activity, the production of interleukin-2 and the natural
killer cell activity, alterations in the T-cell subpopulation, and damage of the neu-
ropsychological functions.
In the past 10 years, there has been an increase in the volume of resources allocated to
the study of new materials capable of acting as zinc carriers and suppliers, as well as the
action mechanisms of this element in the biochemical processes, and also the zinc prod-
ucts that prevent the entry to the cells of such viruses as human immunodeiciency virus
(HIV), rotavirus, and poliovirus. Several government institutions and private foundations
in developing nations are working on projects to add zinc to the diet of segments of their
population, basically children and elders, to counteract malnutrition, diarrhea, and infec-
tious disease.
Humans should have a regular intake of zinc; however, in developing nations, extreme
zinc deiciency prevails associated to eating habits and famines. The recommended dos-
age for adults is 15 mg zinc/day, contained in beef, viscera, ish, and cheese; fruits and
vegetables are low in zinc. In general, human beings do not consume enough zinc, while
physical activity, alcohol consumption, smoking, and contraceptives tend to increase dei-
ciency. The recommended daily dosage of zinc is 11 mg for adults (70 kg of weight) and
from 11 to 13 mg for pregnant or lactating women, while the therapeutic dose for patients
with zinc deiciency is 220 mg of ZnSO
4
(USP quality) three times per day.
In summary, zinc is
• A micronutrient essential to humans and with a major role in reproduction,
growth and development, cell metabolism, gene expression, immune response,
and neurological function
• The catalytic cofactor of >300 enzymes that additionally stabilizes a great variety
of protein domains
• An element found in every organ of the human body—tissues, luids, and
secretions—in quantities of 1.5-2.5 g
Zinc reacts to pathogenic microorganisms by crossing the membranes of bacteria and
other microorganisms, interacting with functional groups of enzymes. Zinc ions replace
the metals acting as cofactors and modify their performance inhibiting the growth of
microorganisms and killing them; these are known as bacteriostatic and bactericidal
effects, respectively. This microbicidal effect has been conirmed in protozoans and their
cysts, and in fungi. Likewise, zinc interacts with the DNA, which accounts for its antiviral
effect.
Various studies have shown that zinc is effective against a wide variety of microorgan-
isms, especially those pathogens living in water that cause the gastrointestinal, pulmo-
nary, and skin infections that most commonly affect humans. That is why an increasing
amount of pharmaceuticals are formulated using zinc salts and compounds to combat
illnesses. Other chemical elements have a similar or higher microbicidal effect than zinc.
Such is the case of silver, which is more effective but highly toxic and less relevant to life.
