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Iraqi Journal of Agricultural Sciences –9:50(3):879-885 Abu-Almaaly
STUDY THE CONTAMINATION OF SOME CHEMICAL POLLUTANTS IN
HOT FOODS STORED IN PLASTIC BAGS AND CONTAINERS
R. A. Abu-Almaaly
Market Researches and Consumer Protection Center/ University of Baghdad/ Baghdad/ Iraq r12maaly@gmail.com
ABSTRACT
Plastic food containers and bags are classified as the most dangerous food and water
contaminants around the world, because of the possibility to transfer the chemicals from it to
food as a result of heating. Therefore this study was aimed to estimate the chemical pollutants
(heavy metals included lead, cadmium, arsenic, mercury and zinc) that transfer from plastic
food containers and bags to food. Thirty food containers (15 packages and 15 bags)
synthesized from Polyethylene Terephthalate (PET) were purchased from the local market in
Baghdad. Cut each into small equal pieces (0.5×0.5) cm and placed in a thermo glass
containers then submerged 3 food solution (D.W, 3%, acetic acid, and olive oil). Two thermal
treatments were done on it; the first one was carried out by boiling on a hot plate surface for
10 and 15 minutes, and the second by heating in microwave for 5 and 10 minutes, heavy
metals were estimated by using Atomic Absorption technique. The results showed the
significant difference between the concentration of the elements at level (p<o.o5) in these
treatment. Also transfer of heavy elements at zero time was very small percentage and
insignificant, and the concentration of heavy metals in three solutions were increased as
C>B>A after treated with two thermal treatment. The concentration of all heavy elements in
this solution after heating for 10 minutes and heating in microwave for 5 and 10 minutes.
Were higher than the acceptable limits by the Food and Drug Administration (FDA) and
European Commission (EU).
Key words: Food pollution, heavy metals, atomic absorption technique.
- )
r12maaly@gmail.com
Polyethylene Terephthalate (PET))
P<0.05
C > B > A
(FDA) EU Commission
*Received:13/1/2019, Accepted:17/4/2019
Iraqi Journal of Agricultural Sciences –9:50(3):879-885 Abu-Almaaly
INTRODUCTION
Food safety from different toxins is a major
source of concern for food manufacturers,
regulators, consumers and consumers around
the world, food contamination refers to the
presence of toxic chemicals or microbial
pathogens that can have adverse health effects
on humans (5, 18), the effect of chemicals on
consumer health is often apparent after long
exposure and at low levels, usually, chemical
pollutants present in foods are not affected by
the temperature used in cooking, but they
remain in them and do not break down because
they are often resistant to high temperatures
(7). The packaging process protects packaged
food from damage by external factors such as
pests, unwanted odors, microorganisms, light
and oxygen, so, food packaging factories seeks
to produce and develop high quality,
multilayer carton, mineral and polymer
packaging systems which are supposed to be
non-perishable, decomposing, interaction and
interfering with food to allow the marketing of
pre-cooked foods while retaining most of its
desirable characteristics to the consumer, such
as prolonging life of the product, while
keeping it as fresh as possible, preserving the
taste, flavor, color and smell desired and
characteristic of that food, it provides a
appropriate mechanism for serving the
consumer in a single meal that can be prepared
in a few minutes either by immersing and
boiling the food bag in water or heating in the
normal oven or microwave (3, 12, 20). Food
and beverage products may be highly reactive
with the substances they touch, they are good
as many solvents used in chemistry lab, for
example, food acids can cause corrosion of
metals, and can decompose fats, oils and the
plastic material leakage, reacts with it, drinks
can break up paper and unprotected cardboard,
in practice, there are no fully functional
nutrients, so their chemical components may
migrate to packaged food, glass, ceramics,
plastics, rubber and paper can release accurate
amounts of their chemical components when
they touch certain foods (2,7). The
transmission of chemical contaminants from
food contact materials is called migration, a
source of significant contamination of food,
the transfer of chemical pollutants from the
packaging to the food depends on various
factors such as the physiochemical
characteristics of the transfer process, the type
of packaging material and the type of food
(fat, acidic, salt, etc.), temperature, storage
time, and the size of the package is
proportional to the size of the food stored in it,
and the types of chemical pollutants that can
be transported from the package to food are
very numerous and varied [19,8]. The
chemical contaminants that move from the
packaging to the food are divided into two
categories, the first category includes
polymeric and chemical materials that are
intentionally added to the plastic packaging's
in operation to ensure certain characteristics
are required in the package, These include
antiperspirants, antioxidants, UV stabilizers,
paints, printing inks, etc. which can migrate or
migrate from the packaging to food, in
addition, residues of the polymeric materials
from which the packaging is made may be
transported mainly to food, the target category
also includes intentionally added chemicals
such as food additives for flavor, taste, bleach,
antioxidants, etc., added to food when
manufactured, the second category could come
from unintentional chemical pollutants during
production, processing, packaging, transport
and storage operations (9, 18). Food packaging
materials are sources of pollution with heavy
metals that can migrate from the packaging to
the food product, these heavy metal elements
and metal compounds may be hazardous to
human health such as arsenic, barium,
cadmium, lead, mercury and other elements,
that may be present in small concentrations,
but some of them very dangerous to health
even those concentrations (22), these heavy
metal may exist in the food within the
permissible limits, but because of their ability
to accumulate in the human body occur
diseases and symptoms of serious damage to
the nervous system and problems in the
process of digestion and representation of food
and is a factor in the incidence of tumors and
cancers, may disrupt metabolic functions
inside the human body in two ways, either
accumulate in organs such as the heart, brain,
liver, kidneys and bones and thus disrupt the
function of those members, or substituting
useful biological food minerals, thus inhibiting
or chelating them in their biological function
Iraqi Journal of Agricultural Sciences –9:50(3):879-885 Abu-Almaaly
in metabolism of nutrients within the body (4).
Due to the multiplicity and spread of
packaging materials from various local and
foreign producers in the Iraqi markets and
their use in packing various kinds of
foodstuffs, and because of the lack of health
culture by most owners of packaged and
ready-made food factories, restaurant owners
and consumers the great risks caused by
misuse of these materials during the process of
heating food or save and sell it is hot in plastic
packaging, or through the use of some plastic
containers in the preservation of acidic and
fatty foods, the aim of this study was to
investigate chemical contamination of heavy
metal elements that may be transferred from
plastic containers and packages to food and
hot beverages.
MATERIALS AND METHODS
The transfer of heavy metal elements from
bags and plastic containers to the foods stored
there was studied based on recommendations
adopted by the US Food and Drug
Administration and the European Food
Commission (11, 13) Which classified foods
depending on their type, grade of fat content,
sugar and alcohol content, Accordingly, the
liquids in the food to be studied were divided
into groups to simulate natural food solutions,
which could measure the extent of migration
between food and packaging materials based
on a study (6) as in Table 1.
Table 1. FDA and EU recommended for alternative food simulants:
alternative food simulants
simulants
Water for aqueous foods
Simulant A
3% w/v acetic acid for acidic foods
Simulant B
Rectified olive oil for fatty/oily foods
Simulant C
Samples collection
Disposable plastic bags and containers that
purchased from the local markets of Baghdad
from polyethylene terephthalate (PET), were
transferred to the laboratories of the Market
Research and Consumer Protection Center /
University of Baghdad, after stored in clean
containers until laboratory tests
Experience design
The experiment of this study was designed
according to a study (17) with some
modification; three experimental solutions
were prepared (D.W. only, D.W. + 3% acetic
acid, olive oil). The plastic bags and packages
were cut into regular pieces (0.5 cm x 0.5 cm)
each type were placed separately in tight
closed thermocouple containers of suitable
size, then added 15 ml of each experimental
solution to each type of plastic (bag and
package), the last separately samples of some
samples were treated with heat by hotplate
surface until boiling for10 and 15 minutes, the
others treated by putting inside the microwave
oven and heat for 5 and 10 minutes separately
as shown in (Table 2). All samples were left to
cool and analyze to estimate the transfer of
chemical contaminants from packaging to
food.
Table 2. Design of the experiment in terms of types of plastic polymers, types of food
simulants solutions and standard thermal transactions
Microwave
for 10 min.
Microwave
for 5 min.
Boiling for
15 min.
Boiling for
10 min.
zero time
food
simulants
package-food
some
samples
some
samples
some
samples
some
samples
some
samples
Distilled
Water
polyethylene
terephthalate
(PET)
3% w/v acetic
acid
Rectified
olive oil
Samples preparation
One to two ml of cooled solutions were
transferred to a glass bottle and sealed with a
silicone seal, placed in the helium vaporizer at
room temperature.
Preparation of solutions and glass
All the standard solutions were prepared for
the experiment, deionized water used for
dilutions; HClO4 acid was supplied by
E.Merck, Germany, and dilution 10% with
deionized water. All glass tools and bottles
were cleaned with nitric acid (10%) then
Iraqi Journal of Agricultural Sciences –9:50(3):879-885 Abu-Almaaly
washed with non-ionic water twice and dried
well.
Calibration standards preparation
Standard calibration solutions for heavy metals
(lead, cadmium, arsenic, mercury and zinc )
were prepared at the same time it was prepared
with 5% nitrates at concentrations 0, 0.1, 0.2,
0.4, 0.6, 0.8, 1 mg /dcm3.
Determination of heavy elements in samples
Heavy metal elements lead Pb, cadmium Cd,
arsenic As, mercury Hg and zinc Zn were
estimated filtration the samples using
Shimadzu AA-6200 supplied with ASC 6100
auto sampler atomic absorption spectrometer
provided according to the method mentioned
(16) and by using acetylene gas then compared
with standard solutions. The concentrations of
mg /dcm3 were converted to mg / kg.
Statistical analysis
The Statistical Analysis System- SAS (2012)
program was used to explain the effect of
difference factors in study parameters. Least
significant difference –LSD test were used to
significant comparing between means in this
study (24).
RESULTS AND DISCUSSION
The results shows in Table (3) that amount of
heavy metal elements in the PET plastic
samples were treated with the simulant
solution (water only), There were significant
differences between the levels of the elements
in the treatments at the level of significance (P
<0.05).
Table 3. Concentration of heavy metals in plastic samples treated with a distilled water
solution (Simulant A), estimated at mg / kg
Microwave
for 10 min.
Microwave
for 5 min.
Boiling for
15 min.
Boiling for
10 min.
zero time
food
simulants
package-food
some
samples
some
samples
some
samples
some
samples
some
samples
Distilled
Water
polyethylene
terephthalate
(PET)
3% w/v acetic
acid
Rectified
olive oil
The results in Table 3 show that
concentrations of all heavy metals at zero time
before the treatment were very small and
almost insignificant, but after heating for 10
minutes it seems that the migration of heavy
elements became slightly higher
concentrations while within the acceptable
limits approved by the legislative
organizations (15,25), arsenic, mercury and
lead concentrations were 0.0011, 0.0010 and
0.0011 mg / kg, respectively, this corresponds
to the findings of (23,28) which indicated that
migration is virtually zero at zero time of
thermal treatment, however, concentrations of
heavy elements soon begin to increase with
heat treatment in boiling and in microwave
after treatment for 10 minutes. At boiling point
for 15 min it became clear that concentrations
of most elements exceeded the acceptable
limits to 0.0212, 0.0067, 0.0054, 0.1023 and
0.3102 mg / kg respectively except of
cadmium, which did not exceed the acceptable
limit, with a concentration of 0.0438 mg/ kg,
this was confirmed by (21) when they mention
that the transfer of mineral pollutants from
plastic food containers to food during cooking
with water only, and they find that the
concentrations of lead and cadmium reached
0.8790 and 0.6751 mg / kg, respectively. After
15 minutes of cooking, all heavy element
concentrations were significantly increased.
After 10 minutes of microwave treatment the
results were similar to (7) when they heated
plastic cans in distilled water, and found the
concentrations of lead, mercury, cadmium and
antimony compounds were reached to 0.1213,
1.1042, 1.7211 and 2.4532 mg / kg,
respectively, while (23) indicated a significant
increase in heavy metals concentrations due to
migration during microwave heating for 15
minutes to 0.7630, 4.7612 and 6.8761 mg / kg
for elements of mercury, cadmium and
antimony, respectively. Table 4. shows the
concentration of heavy metal elements in
plastic samples treated with 3% acetic acid
(Simulant B). Significant differences between
element levels were observed at (P<0.05).
Iraqi Journal of Agricultural Sciences –9:50(3):879-885 Abu-Almaaly
Table 4. Concentration of heavy metals in plastic samples (PET) treated with 3% acetic acid
(Simulant B), estimated at mg / kg
Permissible
limits
LSD
value
Microwave
for 10 min.
Microwave
for 5 min.
Boiling for
15 min.
Boiling for
10 min
Control
Zero time
Heavy
Metals
0.739 *
Pb
0.074 *
As
0.825 *
Cd
0.306 *
Hg
0.655 *
Sb
0.609 *
Zn
* (P<0.05).
At time zero before treatment, the levels of the
elements were very small and insignificant
except for the antimony and zinc, which
appeared at 0.0134 and 0.0612 mg / kg,
although there are within acceptable limits, but
it indicates the sensitivity of this element to
acid solutions, which causes the migration of
packaging materials to food, this is confirmed
by (26) when they mention to sensitivity of
this element in the plastic bottles of beverages
and juices. The concentrations of migratory
heavy metals from the food packages and
containers treated with the Simulant B solution
increased after 10 minutes of boiling, all of
which exceeded the acceptable limits,
especially in cadmium 1.1072 mg / kg ,
antimony 2.3153 mg / kg and zinc 1.1724 mg /
kg, these results were similar to those of (9,21)
when found that the transmission of these
elements was 2.5431, 2.9754 and 2.0891 mg /
kg respectively in the first study, and 2.1102,
1.9231 and 1.6754 mg / kg for the same
elements in the second study, also after the
boiling for 15 minutes, the concentration of all
elements increased significantly, that
indicating the significant effect of boiling for
medium period on the transport of heavy
elements from the covers to the acidic fluids,
this was confirmed by (21) when obtain the
concentrations of lead, mercury, and antimony
compounds were 2.6541, 0.6511 and 3.5422
mg / kg in cooking plastic containers in acidic
medium for 15 minutes. The concentrations of
heavy metals migrated from food packages to
the acid solution by heated in microwave oven
for 5 and 10 minutes record of the high levels
in lead elements 2.9723, 4.1023 mg / kg,
cadmium 3.4265, 4.1145 mg / kg, antimony
3.3892, 4.1037 mg / kg, zinc 4.1022 and
5.9832 mg / kg, respectively. The studies of (1,
27) indicated a significant increase in the
concentrations of lead, mercury and antimony
elements from the acceptable limits when
treated with a 10-minute acidic acid solution to
5.1233, 1,0123 and 4.7651 mg / kg
respectively in the first study and 4.9102,
1.3661, and 5.0982 mg / kg respectively in the
second study. Therefore the results indicated
that great effect of transfer or migration of
heavy element from packing materials to food
when heating by microwave.
Table 5. Concentration of heavy metals in plastic samples treated with olive oil (Simulant C),
estimated at mg / kg
Permissible
limits
LSD
value
Microwave for
10 min.
Microwave for
5 min.
Boiling for 15
min.
Boiling for 10
min
Control Zero time
Heavy
Metals
0.508 *
Pb
0.259 *
As
1.019 *
Cd
0.357 *
Hg
0.926 *
Sb
1.192 *
Zn
* (P<0.05).
Table 5 shows the concentration of heavy
metals in the plastic samples (PET) treated
with olive oil (Simulant C). The results
showed significant differences between the
levels of elements at the level of significance
(P <0.05) in treatment, the concentrations at
zero time before thermal treatment were very
small and almost insignificant in most
treatments except lead (0.0118 mg / kg), which
was clearly affected by the oil solution, that
Iraqi Journal of Agricultural Sciences –9:50(3):879-885 Abu-Almaaly
mean it was on the edge of the acceptable
limits of 0.01mg / kg, while after 10 minutes
of boiling, the concentrations of all heavy
metals increased from acceptable limits to
0.0392, 1.8326, 1.6521, 0.1078 and 1.8722 mg
/ kg in arsenic, cadmium, antimony mercury
and zinc, respectively. And after 15-minute of
boiling a stronger effect than its predecessor
on heavy element concentrations, these results
were consistent with (9) when they study the
treatment of plastic containers at boiling
temperature in an oil medium for 10 to 20
minutes, the heavy metals migration recorded
high levels of 3.7621, 1.0032, 5.7102 and
1.0923 mg / kg for lead, arsenic, antimony and
zinc respectively, Kigozi, et al. (17) pointed
out that the migration of heavy metal elements
from plastic to food at boiling temperatures in
oil solution for 20 minutes was 6.0924 and
2.9871 mg / kg for the antimony and lead
elements, respectively. The concentration of
heavy metals transported from the plastic
containers to the oil medium recorded very
high levels when heated with microwaves for
5 and 10 minutes. The concentration of lead
was 3.6532 and 5.0137 mg / kg, cadmium
4.9065, 6.1092 mg / kg, and antimony 5.0133
and 7.2092 mg / kg Respectively, zinc 4.9323
and 7.3102 mg / kg respectively, and the
concentrations of all elements were well above
the acceptable limits established by the
legislative organizations concerned with food
contamination (11,27)، while Galotto and
Guarda (14) reported the removal of heavy
metals and high concentration of plastic
containers into fatty solutions of foods when
treated with high temperatures such as boiling
and heating with microwaves for 25 minutes,
the concentrations of lead, mercury and
antimony compounds reach to 6.9102, 1.9821
and 8.7234 mg / kg, respectively.
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