Pollution of chicken meat and its products by heavy metals
is important for human diet in all over the world because they
contribute to solve the global food problems and provide the well-
known protein, fat, essential amino acids, minerals, vitamins and
other nutrients and they also have a milder flavor which is more
readily complemented with flavoring and sauces. Environmental
pollution by heavy metals is considered as one of the most serious
problems in the world over the last few decades. Emissions of heavy
metals to the environment occur via a wide range of pathways,
including air, water and soil, threatening the animal and human
health and quality of the environment. Heavy metal toxicity could
be present in different ways depending on its route of ingestion,
its chemical form, dose, tissue affinity, age and sex, as well as
whether exposure is acute or chronic. Nowadays, poultry feed
is produced from various raw materials such as fish by-products
that can transfer heavy metals to poultry feed in undesirable levels
following collecting them from contaminated waters, that may
lead to increase of trace metals in chicken and chicken products
with a serious threat because of their toxicity, bioaccumulation
and biomagnifications in the food chain. The main heavy metals of
concern are lead, cadmium, copper, mercury and arsenic which at
even low concentrations pose serious health hazard to primary and
secondary consumers due to bio magnifications (Munoz-Olives and
Camera and Demirezen et al. The effects of metals and metalloids
are partly due to the direct inhibition of enzymatic systems and
also to the indirect alteration of the essential metal ion equilibrium.
Majority of the known metals and metalloids are very toxic to living
organisms and even those considered as essential can be toxic if
present in excess. Moreover, owing to their toxicity persistence
and tendency to accumulate, heavy metals when occurring in
higher concentrations, become severe toxic for human being and all
living organisms through alteration of physiological activities and
biochemical parameters in blood and tissues, and through defects
in cellular uptake mechanisms in the mammalian liver and kidney,
inhibiting hepatic and renal sulfate / bicarbonate transporter
causing sulfaturia.
Lead is an accumulative poison; it has hematological effect due
to the inhibition of hemoglobin synthesis and shortening life span
of circulating erythrocytes resulting in anemia. It has a toxic and
damage effects leading to reduction of the cognitive development
and intellectual performance in children; increase blood pressure;
damage of the brain and kidneys; cardiovascular and reproductive
diseases in adults. Cadmium is used extensively in the mining and
electroplating industries and found in fertilizes and fungicides.
It is a very toxic heavy metal, which accumulates inside the body
particularly kidneys and chronic exposure may induce heart
diseases, anemia, skeletal weakness, depressed immune system
response, kidney and liver diseases; cancer and death. Copper is an
essential element for man and animals. It is required for normal
biological activity of several enzymes and it added to poultry diets
with manganese and zinc (premix) to enhance their weight gain
and disease prevention. Meanwhile, ingestion of excessive doses of
copper may lead to adverse health problems, such as severe nausea,
bloody diarrhea, hypotension, liver and kidney damage. Arsenic is
a metalloid that occurs in inorganic and organic forms and is found
in the environment, both naturally occurring and as a result of
human activity. The inorganic forms of arsenic are more toxic than
organic ones. However, so far, most of the data regarding arsenic
occurrence in food, gathered under the official control of foodstuff,
is still reported as total arsenic, without differentiating the various
types of arsenic in the diet. It has a toxic effect includes decrease
in hemoglobin, packed cell volume, erythrocytic count and total
leukocytic counts, heterophils and lymphocytes. The presence of
the residual agro-chemicals in foods is detrimental to human health
and the accumulation of foreign chemicals such as lead, arsenic,
cadmium, copper and mercury in human system has been linked to
immune-suppression, hypersensitivity to chemical agents, liver and
kidney damage, breast cancer, reduce sperm count and infertility,
respiratory distress DNA alteration and death in extreme cases.
Considering the fact that chicken meat and its products can contain
some toxic heavy metals and therefore exposure to the toxic trace
metals will be gained through consumption of these products, the
accurate determination of them has been focused by researchers in
last decades, worldwide.
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