INTRODUCTION
A dust storm is one of many air pollutants known
to humans. About 800 trillion grams of dust particles
are spread in Asia. Particulate matter (PM) is usually
suspended in arid, semiarid, and desert areas [1].
Today, dust storms are one of environmental problems
that threaten the world [2]. The phenomenon of dust
in the atmosphere causes the spread of PM around the
globe [3]. Dust phenomena can be triggered by such
factors as environmental change, global drought, and
land cover [4]. The dry currents of the Saudi air and
lack of attention to the environment and desertification
in Iraq have dried up many of the marshes there and
created dusty areas. In the past, Iran, Iraq, and Saudi
Arabia jointly funded the mulching of these lands during
a particular season. The Iraq war obliterated this work,
resulting in a spike in western Iran, and eventually
almost throughout the whole country. According to
Harrington et al., the United States soldiers involved in
the Iraq war had respiratory problems due to the dust
phenomenon in that country [5].
Biological particles, salt sprays and, in particular,
dust phenomena have been reported to contain numerous
heavy metals [6]. Furthermore, these metals lead to
climate change in temperature and other seasonal
changes, such as the wind speed and patterns [7].
Although trace heavy metals are fundamental to living
organisms for a normal and healthy life, excessive levels
of heavy metal contamination in the environment could
cause harm [8, 9]. To reduce environmental pollution
and mitigate the resulting degradation of soil and water
resources, it is important to precisely determine heavy
metal concentrations [10, 11].
Some heavy metals, for example, chrome (Cr),
lead (Pb), cadmium (Cd), and mercury (Hg) in
the form of suspended particles in the air produce
significant toxicological effects on people and other
organisms by contaminating food and drinking water
in the environment [12]. Particulate matter, which
is contaminated with heavy metals, can pollute
groundwater. It has been indicated that contamination
is transmitted from the soil to the plant. As a result,
contaminated plants ingested by humans or animals can
cause a toxic effect. Consequently, the concentration
of heavy metals in animal products, such as raw milk,
also causes toxicity. The extent of toxicity depends on
different factors, such as plant processes and the amount
of raw materials used [13]. Moreover, heavy metals
such as lead, cadmium, chrome, nickel, and cobalt can
contaminate cows and their surroundings. Heavy metals
are absorbed by plant roots from the soil. As a result,
this pollution causes serious problems, changing the
amount and structure of milk [14].
The International Agency for Research on Cancer
(IARC, 2016) classifies arsenic (As) and chrome (Cr) as
carcinogenic metals and lead as a possible carcinogen.
Such metals can cause different types of cancer through
dermal contact, inhalation, and ingestion [15].
The western and southwestern climates of Iran
are influenced by environmental conditions and
markers such as geological, climatic, hydrological, and
geomorphological characteristics [3]. Among the factors
that cause dust storms are the development of deserts in
Iraq, a decrease in volume and flow of rivers, and the
Turkish dam on the rivers [16]. With a population of
172 000 people, the city of Ilam is located on the western
border of Iran (33°38′N, 46°25′E). Due to a small
population and a mountainous area, the city has low
traffic and also no air pollution industry.
With the onset of spring, the phenomenon of dust
comes to Iran from Iraq. This situation was aggravated
by the Iraq war. In this study, we investigated the
concentration of suspended particles in the environment
and evaluated the effect of heavy metals on cow raw
milk in the west of the country, Ilam province.
STUDY OBJECTS AND METHODS
PM concentration in dust. The dust samples were
collected from four districts of Ilam province: northern
and central, southern, western, and eastern (28 samples
in each). The sampling was performed on the roofs
of buildings seven meters above the ground and two
meters from the roof surface. During the sampling, we
complied with all the standards of the US Environmental
Protection Agency. In particular, we kept the required
distance from natural and artificial obstacles, pathways,
and sources of contamination. Suspended particles PM10
and PM2.5 were measured with the Enviro Check Laser
System using the Dust Monitor Check (Grimm). This
apparatus can directly and simultaneously measure the
particle count, PM10 and PM2.5. The system automatically
saves the values in its memory and calculates the
average on an hourly and a daily basis [17].
On normal days, the sampling was carried out
every six days and on days with dust (a concentration
above 150 μg/cm3), according to the Meteorological
Organization and satellite sites, on a daily basis. The
peak concentrations of PM10 and PM2.5 were recorded
and measured on average every hour. The data
obtained during a year were analyzed with the SPSS
software [18].
Heavy metals in dust. Teflon and fiberglass filters
were used to investigate heavy metals in the dust
phenomenon. A 100-cm section of a filter was cut and
transferred to a 100 mL beaker. Then, we added 50 mL
of Aqua Regia (HNO3+ 3 HCl) and heated it to 140°C
until the filter section was dry. Then, we removed it and
washed the beaker with 10% nitric acid. This work was
repeated three times. In the end, the prepared sample
was kept at room temperature until it was cooled. Then,
we transferred it into a 100-mL volumetric flask and
diluted to volume with 10% HNO3. The concentrations
of heavy metals (lead, arsenic, zinc, copper, and iron)
were determined by a Perkin-Elmer Analyst 800
atomic absorption spectrometer, including an AS-800
Autosampler equipped with Zeeman-effect background
correction. Each result was an average of three readings.
Blank filters were prepared by digesting clean glass
fiber filters with the same digestion method used for the
dust samples. Also, the dust samples were prepared in
different seasons [19].
Heavy metals in raw milk. A total of 112 samples
of cow raw milk were collected from four districts of
Ilam province: northern and central, southern, western,
and eastern (28 in each), at the same places as dust
samples. All the samples were collected in nitric acidwashed
polyethylene containers. They were immediately
transported to the laboratory in a cooler with ice packs
and stored at –20°C until analysis. The raw milk samples
were analyzed based on AOAC official methods. The
amounts of heavy metals (lead, arsenic, zinc, copper,
and iron) were measured by a Perkin-Elmer Analyst 800
atomic absorption spectrometer, including an AS-800
Autosampler equipped with Zeeman-effect background
correction. Each sample was studied three times [20].
The limit of detection and the limit of quantitation of the
atomic absorption device were 0.08 ppm and 0.15 ppm,
respectively.
Statistical analysis. The SPSS 21 software was
used to extract the data (P < 0.05). The results of three
repetitions were analyzed by ANOVA, using an SPSS
statistics package.
RESULTS AND DISCUSSION
Ilam is bordered by Iraq and close to the countries of
Saudi Arabia and Kuwait, which are the main sources of
dust events in the Middle East (Fig. 1).
According to Table 1, the sampling took 87 days.
The average PM10 and PM2.5 were about 105.6 ± 82.9 and
25.9 ± 15.4 μg/m3, respectively. The maximum particle
size of PM10 and PM2.5 was about 806.3 and 213.2 μg/m3,
respectively.
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Figure 1 Geographical location of Ilam province and Iraq (Google map)
Table 1 Concentrations of PM10 and PM2.5 in different months of sampling in Ilam province, μg/m3
Months Number of
sampling days
Average Maximum Minimum Median Standard deviation
PM10 PM2.5 PM10 PM2.5 PM10 PM2.5 PM10 PM2.5 PM10 PM2.5
March-April 12 178.3 42.7 725.1 171.1 31.7 8.3 179.1 31.2 185.2 41.7
April-May 9 142.4 31.3 562.3 210.4 62.7 12.5 142.3 37.1 127.5 32.4
May-June 16 210.3 56.6 806.3 213.2 91.8 17.7 181.3 35.8 197.3 30.1
June-July 7 112.7 27.2 351.7 98.2 51.2 10.3 125.2 29.6 110.2 12.5
July-August 9 139.9 37.5 393.4 99.1 57.4 12.1 139.1 28.8 123.1 13.1
August-September 6 79.8 25.1 185.2 55.3 26.6 8.7 76.6 12.5 31.5 9.2
September-October 4 56.7 12.7 100.1 21.1 18.7 6.2 43.9 8.7 26.7 6.7
October-November 5 58.7 13.3 110.7 20.7 19.2 6.0 45.2 8.4 27.1 7.3
November-December 4 62.7 14.1 211.2 18.7 30.1 11.8 52.2 9.7 30.7 10.9
December-January 4 48.4 12.2 89.6 12.9 15.2 4.4 38.3 3.5 20.3 5.2
January-February 4 39.6 11.5 75.3 12.1 13.3 4.1 35.2 4.1 18.7 4.9
February-March 7 137.5 26.9 300.8 121.6 41.3 9.6 127.5 11.2 97.3 10.4
Study period 87 105.6 25.9 325.9 87.8 38.3 9.3 98.8 18.4 82.9 15.4
Five heavy metals (lead, arsenic, zinc, copper, and
iron) were measured in all the samples. Fig. 2 shows the
range and mean concentrations (ng/m3) of the selected
heavy metals analyzed at the sampling stations. In
the spring and summer, the amounts of heavy metals
were higher than in the other seasons, especially iron.
Lead and copper levels were lower in all the seasons
compared to other metals.
Average values of ;ead content in the raw milk
samples are shown in Table 2. The highest average lead
level was determined in the western region (57.1 μg/kg).
The statistical analysis revealed a significant difference
in lead concentrations between the western and southern
regions compared to the east and north of Ilam province
(P-value < 0.05).
Average concentrations of arsenic in the milk
samples are shown in Table 3. Although arsenic was
higher in the south and west compared to the northern
and central region or the east of the province, we
found no significant difference. The highest average
*
**
** **
**
**
**
0
400
800
1200
1600
D Ph sp N Dph sp D Ph su N Dph su D Ph f N Dph f D Ph w N Dph w
Concentration, ng/m3
Seasons (with and without dust phenomenon)
Arsenic Zinc Copper Iron Lead
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arsenic level was observed in the west, amounting to
12.4 mg/kg.
Table 4 shows average zinc values in the raw
milk samples. The highest average amount of zinc
was determined in the western region (4582.8 μg/
kg). According to the statistical analysis, there was a
significant difference in zinc concentrations between the
western and southern regions compared to the east and
north of Ilam province (P-value < 0.05).
The concentrations of copper in different regions
are shown in Table 5. As we can see, the average level
of copper in the western and southern regions was
Figure 2 Seasonal average concentrations of heavy metals (lead, arsenic, zinc, copper, iron) in dust phenomena. Dust phenomenon
in spring (D Ph sp), non-dust phenomenon in spring (N Dph sp), dust phenomenon in summer (D Ph su), non-dust phenomenon in
summer (N Dph su), dust phenomenon in fall (D Ph f), non-dust phenomenon in fall (N Dph f), dust phenomenon in winter
(D Ph w), non-dust phenomenon in winter (N Dph w), * P-value < 0.05, ** P-value < 0.001 vs. the other group
*
**
** **
**
**
**
0
400
800
1200
1600
D Ph sp N Dph sp D Ph su N Dph su D Ph f N Dph f D Ph w N Dph w
Concentration, ng/m3
Seasons (with and without dust phenomenon)
Arsenic Zinc Copper Iron Lead
Table 2 Lead contents in raw milk samples
Northern and Central region Eastern region Southern region Western region
Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg
1 29 1 31 1 49 1 48
2 29 2 33 2 48 2 55
3 23 3 35 3 53 3 49
4 28 4 29 4 59 4 63
5 27 5 37 5 57 5 61
6 31 6 39 6 61 6 65
7 25 7 38 7 55 7 59
Average 27.4 Average 34.6 Average 54.6 Average 57.1
Max 31 Max 39 Max 61 Max 65
Min 23 Min 29 Min 48 Min 48
Table 3 Arsenic contents in raw milk samples
Northern and Central region Eastern region Southern region Western region
Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg
1 11 1 10 1 13 1 12
2 11 2 10 2 12 2 13
3 12 3 12 3 12 3 12
4 10 4 12 4 14 4 14
5 10 5 13 5 10 5 12
6 12 6 10 6 13 6 11
7 11 7 9 7 12 7 13
Average 11 Average 10.9 Average 12.3 Average 12.4
Max 12 Max 13 Max 14 Max 14
Min 10 Min 9 Min 10 Min 11
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Karimi E. et al. Foods and Raw Materials, 2020, vol. 8, no. 2, pp. 241–249
higher than in the eastern and northern regions. The
lowest average copper concentration (234.3 μg/kg) was
observed in the northern and central region.
According to Table 6, there was a significant
difference between the amounts of iron in the west and
south compared to the east and north of the province.
The highest average concentration of iron (3954 μg/kg)
was found in the southern region.
Typically, dust particles with a diameter of 616–
660 μm remain in their places of origin. Particles sized
31‒62 μm are dispersed over approximately 320 km
from their origin, while those sized 16‒30 μm, up to
1600 kilometers. Particles below 16 μm travel longer,
and particles ranging from 2‒50 μm have been reported
to mostly originate in deserts like Iraq, Saudi Arabia,
and Africa [21]. The main source of dust phenomenon in
the southwest of Iran is the deserts of Iraq [22].
In our study, the mean and standard deviations of
PM10 and PM2.5 were 105.69 ± 0.5 and 25.9 ± 15.4 μg/m3
at the time of sampling, and the maximum PM10 and
PM2.5 concentrations were 806.3 and 213.2 μg/m3 in June,
respectively. According to Draxler et al.,
the main sources of dust phenomenon in the
southwest and west of Iran are Kuwait, Iraq,
Table 4 Zinc contents in raw milk samples
Northern and Central region Eastern region Southern region Western region
Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg
1 3120 1 3210 1 4650 1 4740
2 3190 2 3460 2 4770 2 4400
3 2870 3 3110 3 4390 3 4810
4 3150 4 3060 4 3880 4 5030
5 3210 5 2930 5 4810 5 4560
6 3010 6 3420 6 4230 6 4330
7 2460 7 3250 7 4560 7 4210
Average 3001.4 Average 3205.7 Average 4470 Average 4582.8
Max 3210 Max 3460 Max 4810 Max 5030
Min 2460 Min 2930 Min 3880 Min 4210
Table 5 Copper contents in raw milk samples
Northern and Central region Eastern region Southern region Western region
Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg
1 210 1 200 1 230 1 170
2 300 2 320 2 690 2 480
3 190 3 170 3 410 3 550
4 180 4 350 4 520 4 400
5 250 5 420 5 450 5 670
6 310 6 300 6 360 6 510
7 200 7 380 7 590 7 430
Average 234.3 Average 305.7 Average 464.3 Average 458
Max 310 Max 420 Max 690 Max 670
Min 180 Min 170 Min 230 Min 170
Table 6 Iron contents in raw milk samples
Northern and Central region Eastern region Southern region Western region
Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg Sample Content, μg/kg
1 2554 1 2654 1 3865 1 3845
2 2129 2 2863 2 3978 2 3693
3 2763 3 2341 3 4762 3 4236
4 3327 4 3496 4 3687 4 4122
5 2645 5 2029 5 4831 5 3541
6 2431 6 2585 6 3573 6 3655
7 3504 7 3051 7 2985 7 4032
Average 2764 Average 2717 Average 3954 Average 3874
Max 3504 Max 3496 Max 4831 Max 4236
Min 2129 Min 2029 Min 2985 Min 3541
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and Saudi Arabia. The authors showed that
PM10 c oncentrations e xceeded 3 000 μ g/m3 [23].
In the study by Shahsavani et al., which agrees with
our results, the mean and standard deviations of
PM10 and PM2.5 in Ahwaz, southwest of Iran, were 407.07 ± 319.1
and 83.2 ± 69.5 μg/m3, while the maximum PM10
and PM2.5 c oncentrations w ere 5 337.6 a nd 9 10.9 μ g/
m3 in June, respectively [24]. In another study, in
the southwest of Iran, the mean and standard PM10
and PM2.5 deviations in the entire study period were 775.3 ± 598.9
and 129.5 ± 114.9 μg/m3, whereas their maximum
concentrations reached 4730.1 and 774.4 μg/m3 in
February, respectively [17]. The difference between the
maximum concentrations found by the authors and our
results may be due to differences in geographical and
atmospheric conditions and the distance from the dust
source in the period of particle measurement. Also, in
another study of 2007, the mean total concentration
of suspended particles was 282 μg/m3 and the PM10
and PM2.5 concentrations were 165 and 67 μg/m
3, respectively [25].
Finally, a 2010 study conducted in China reported
the mean concentrations of PM10 and PM2.5 to reach
322 ± 237.4 μg/m3 and 141.5 ± 108.8 μg/m3, respectively [26].
According to Jacobs et al., of 16.4 million homes in
the United States with more than one child below six,
25% still had significant amounts of lead-contaminated
deteriorated paint, dust, or adjacent bare soil [27].
Lu et al. detected the presence of heavy metals in soil
by spectroscopic methods [28]. In another study, the
voltammetric method found cadmium (0.06 μg/L)
and lead (0.65 μg/L) in soil [29]. However, the atomic
absorption technique is also very important for
analyzing heavy metals in air samples. Factors such
as high sensitivity, high performance, low cost, and
accuracy make this method a good choice. The amount
of heavy metals in the atmosphere depends on the origin
and the distance from the source of pollution. Seasonal
changes also affect concentrations of heavy metals in the
atmosphere [30]. Our results showed that the amounts
of arsenic, zinc, lead, and copper were higher during
the spring and summer. Zinc and iron had a higher
level compared to the others. Due to high temperatures
during the spring and summer, dust is denser than in the
fall or winter, and it is easier for animals and humans to
inhale them. In a study by Al-Dabbas et al., the X-ray
powder diffraction method was used to detect the
presence of heavy metals (Fe, Co, Ni, Cu, Zn, and Pb)
and dust particles in the streets of southern Iraq [31].
Also, in Ahwaz, southwest Iran, heavy metals (Cd, Cr,
Co, Ni, Pb, Zn, and Al) were identified in particles with
PM10 [32].
It has been well demonstrated that heavy metals
such as cadmium, chrome, nickel, and cobalt, which
contaminate the environment around animals, e.g. cows,
penetrate into cow milk and cause tissue problems.
Heavy metals can penetrate into plants through their
roots. Through contaminated drinking water and
water used in agriculture and food production, they
enter animal and human bodies [33]. As reported by
Razafsha et al., plants contaminated with particles
containing heavy metals increase the risk of raw milk
contamination [34].
Dairy products are a vital part of a healthy diet, and
milk is widely used in feeding infants and children.
Therefore, studying the presence of metals in milk
is especially important to ensure the safety of milk
production that is greatly reduced in a contaminated and
toxic environment [35, 36].
According to the FAO/WHO guidelines and the
Codex standard, the levels of lead, arsenic, zinc, and
iron in milk and dairy products are 2.0, 0.050, 0.9, and
0.6 μg/kg, respectively [37].
We examined the amounts of heavy metals in cow
milk in Ilam, west of Iran, and found that lead levels in
the western and southern regions were higher than in the
east, center, and north. This situation was also consistent
with arsenic, zinc, copper, and iron. The average
concentrations of arsenic and copper were generally
lower than those of zinc, lead, and iron. Farm animals,
which are used for milk and meat, tend to get polluted
with heavy metals through the environment. According
to recent observations, the concentrations of remaining
heavy metals in milk are significantly higher than those
approved by international authorities [38].
Consistent with our study, Konuspayeva et al.
reported that seasonal changes influenced the level of
lead in camel milk: it was lower in the spring compared
to other seasons [39]. They also found that the presence
of arsenic in camel milk and its contamination level
depended on the distance from the source of pollution,
wind and farm topography (soil type, vegetation type),
etc. [40]. Another study reported that the amount of iron
and copper in the milk collected in industrial areas was
higher than that of lead in traffic-intensive and industrial
regions [20]. This shows the effect of the environment
on the content of heavy metals in milk. Awasthi et al.
and Malhat et al. reported that the levels of cadmium,
iron, and zinc in cow milk were higher in industrial
areas compared to others [41,42]. A study in Egypt found
that the amount of cadmium in cow milk produced in
contaminated air was significantly higher [43].
It has been shown that all the milk samples collected
from different governorates contained lead and iron in
higher concentrations than those recommended for milk
by the IDF standard (1979). Lead is an environmental
pollutant that is toxic to humans and animals [44].
Similar to our study, Kabir et al. presented the
average concentrations of metals in 50 samples of cow
milk from contaminated environments in the following
order: Fe > Cr > Mn > Zn > Ni > PB > Hg > Sc > Cd >
As [45].
CONCLUSION
We analyzed the particle matter and the amounts
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Karimi E. et al. Foods and Raw Materials, 2020, vol. 8, no. 2, pp. 241–249
of heavy metals in the dust phenomenon in western
Iran (Ilam province) over one year and also studied
the presence of heavy metals in the raw milk samples
collected in its four regions. As a result, we can conclude
that the dust phenomenon that comes from Iraq to Iran
is probably one of the sources of milk contamination in
western Iran.
CONTRIBUTION
Naser Abbasi designed the work and took the lead in
writing the manuscript together with Elahe Karimi; Ali
Aidy performed the experiments; Monireh Yari and Hori
Ghaneialvar derived the models and analyzed the data;
Hamid Reza Kazemi and Reza Asadzadeh contributed to
the interpretation of the results.
CONFLICT OF INTEREST
The authors declare that they have no conflicts of
interest.
ACKNOWLEDGEMENTS
This work was supported by the Ilam University of
Medical Sciences.
ETHICAL STATEMENT
The authors confirm that they have adhered to
the journal’s ethical policies specified on its author
guidelines page, and received the approval of the
appropriate ethical review committee. The authors also
confirm that they have followed the EU standards for the
protection of animals used for scientific purposes and
feed legislation.

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