Agriculture Reference
In-Depth Information
ensure that substances banned in food production within the EU are not used
in animals intended for the EU market [21].
As a direct consequence of the crisis, the entire production process for
chicken meat and shellfish has come under close scrutiny in an effort to ensure
the removal of nitrofurans as contaminants. Extensive efforts have been made
to eliminate the possibility of nitrofuran residues entering the human food
chain from any point in the production process. One frequent cause of
unwanted and unintended residues in food of animal origin is contamination of
animal feedingstuffs with drugs at subtherapeutic doses, as a result of carry-
over of medication during the animal feedingstuff manufacturing process. This
has been investigated in both poultry [24-25] and pig production systems [26].
The electrostatic nature of some drugs such as FZD and FTD leads to their
having the potential to become trapped in feed mills, carrying over from one
batch of feed to another [27].
Concentrations in feeds ranging from 8 to 400 mg kg
−1
were considered to
be appropriate to have a zootechnic effect depending of the intended use.
However, it has been confirmed the possibility for the detection of very low
concentrations of nitrofuran metabolites in animal tissues exposed to a diet of
contaminated feeds with furazolidone and furaltadone at levels as low as 30 µg
kg
−1
[8]. As such, animal feedingstuffs must be analyzed with analytical
procedures capable of measuring very low concentrations of nitrofurans in
order to assure its ―fit-for-purpose‖ [15].
Concerning contamination, it has also been reported previously [28] that
veterinary drug residues can be detected in the tissues of un-medicated animals
that have been exposed to an environment where animals, previously
undergoing medication, have been housed. A pilot study was also performed
to see if unmedicated poultry, in contact with the litter from a flock that had
previously been exposed to contaminating concentrations of furazolidone,
could pick up sufficient AOZ from the litter to result in detectable residues in
tissue. This may be of importance in those poultry production systems that do
not change litter between crops. Furthermore, birds are at risk of accumulating
residues simply through exposure to a pen, which previously housed birds fed
on a diet containing a very low concentration of nitrofuran. All these aspects
have implications for the poultry industries trying to eliminate nitrofurans
from their production system and for regulatory analysts attempting to
measure nitrofurans in animal feedingstuffs [21].
It should be added that food to be consumed in Europe may, despite all
measures taken, have been derived from animals fed with nitrofuran-
contaminated feeds. This circumstance highlights the necessity of an effective
