Background: Assessment of dairy products can identify the presence of heavy metals in them that poses a serious threat to human health and is a major concern on a global scale. Objective: The aim of this research was to evaluate the heavy metal concentrations in dairy products and their potential risks in urban areas in Bushehr city, Iran. Materials and Methods: A total of 71 dairy product samples (16 milk, 14 yoghurt, 15 cheeses, 13butter, 11 dough, and 12 creams) were collected randomly from dairy shops in Bushehr city, Iran and analyzed by using a flame atomic absorption spectrophotometer. Results: The results of this research showed that the concentrations of lead in cream and butter were significantly higher than in milk and yoghurt samples (P < 0.05). In addition, the levels of cadmium in cream and cheese were significantly higher than in milk samples (P < 0.05). Moreover, zinc contents in cheese and cream were significantly higher than in milk and butter (P < 0.05). The concentrations of Cu were significantly higher in butter and cream than in milk, cheese, and dough samples. Conclusion: The findings of the work obviously demonstrated that the daily intake of dairy products involved a tolerable amount of Pb and Cd. Therefore, the intake of dairy products in the study area is almost without potential risks.
Keywords: Dairy products, health risk, assessment, heavy metals
|How to cite this article:
Hashemi SE, Arfaeinia H, Ardashiri S, Karimyan K. Health risk assessment of exposure to heavy metals in dairy products collected from Bushehr, Iran. Ann Trop Med Public Health 2017;10:632-5
|How to cite this URL:
Hashemi SE, Arfaeinia H, Ardashiri S, Karimyan K. Health risk assessment of exposure to heavy metals in dairy products collected from Bushehr, Iran. Ann Trop Med Public Health [serial online] 2017 [cited 2020 Sep 22];10:632-5. Available from: https://www.atmph.org/text.asp?2017/10/3/632/213124
Dairy products are considered as the major components of the human diet, which contain almost all of the nutritional constituents, such as protein, essential fatty acids, vitamins, and minerals, which supply nutrition for the human body., However, milk and dairy products also can be easily contaminated with heavy metals in industrial areas that may adversely affect human health., Thus, exposure to the various heavy metals via consumption of dairy products as a main part of the daily diet is probable.
Toxic metals such as cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu) have been reported in dairy products., Cd and Pb are considered carcinogenic agents and are associated with causing some diseases in the cardiovascular, nervous, blood, and skeletal systems., Moreover, Cu and Zn which are essential micronutrients for many biological functions also have non-carcinogenic hazardous impacts on human health when their consumption rate is higher than tolerable reference dose level.,, Hence, there is a need to study the levels of heavy metals in dairy products and assess their health risks.
To the best of our knowledge, there is no study that analyzed the concentration of heavy metal and element in dairy products in Bushehr, Iran. Additionally, there is a need to have an insight into heavy metal uptake and evaluation of human health risks related to the consumption of dairy products.
This research was carried out to determine the levels of heavy metals in dairy products and to assess the human health risk of metals.
|Materials and Methods|
A total of 71 dairy products samples (16 milk, 14 yoghurt, 15 cheeses, 13 butter, 11 dough, and 12 creams) were collected randomly from dairy shops in Bushehr city, Iran. All samples were collected in polyethylene containers that were pre-washed with nitric acid. The samples were immediately kept in a cooler with ice pack and then carried to the laboratory at −20°C for analysis.
Approximately 2 mL or g of dairy product samples were taken and dissolved with a mixture of HNO3, H2 SO4, and HClO4 in the ratio of 5:1:1 at 110°C until the solution became transparent. The levels of Zn, Cu, Cd, and Pb were determined by using a flame atomic absorption spectrophotometer (Thermo Solaar M6 A.A. Spectrometer, Thermo Electron). All runs were carried out in duplicate and average values were selected for further analyses.
The following equation was used in calculating the estimated daily intake (EDI) (mg/kg bw/day) of metals:
In this formula, C element (mg/kg, on weight basis) represents the level of heavy metals in contaminated dairy products. WDairy Products stands for the average daily intake of dairy products and BW is the body weight. Adult body weight was assumed to be 65 kg in this study. The daily average intake per adult (65 kg BW) was considered to be 200,100, and 70 mL and 25, 7, and 4 g of milk, yoghurt, dough, cheese, butter and cream, respectively.
Target hazard quotient (THQ) was employed to assess the health risk of heavy metals due to the consumption of contaminated dairy products in the local inhabitant. Reference oral dose (RFDo) for each metal was used to measure this factor. The value of THQ when less than 1 is assumed to be safe for exposed population:
SPSS software version 18 was used to perform the statistical analysis. The obtained data from concentrations of dairy products were subjected to the analysis of variance to evaluate significant differences in the calculated variables at P < 0.05.
The levels of selected heavy metals (Pb, Cd, Cu, and Zn) in dairy product samples are given in [Table 1]. As shown in the table, the order of the heavy metal concentration is Zn > Pb > Cu > Cd in all kinds of dairy products. The mean concentrations of lead in milk, yoghurt, cheese, butter, dough, and cream samples were 0.2523, 0.2731, 0.5465, 0.6631, 0.1435, and 0.6123 ppm, respectively. In addition, the cadmium contents in milk, yoghurt, cheese, butter, dough, and cream samples were 0.0765, 0.0830, 0.1076, 0.0623, 0.0566, and 0.1324 ppm, respectively. Moreover, the values of copper contents in milk, yoghurt, cheese, butter, dough, and cream samples were 0.1038, 0.0830, 0.1076, 0.7309, 0.1106, and 0.4576 ppm, respectively. Finally, the mean concentrations of zinc in milk, yoghurt, cheese, butter, dough and cream samples were7.31, 7.67, 10.23, 6.01, 6.40, and 7.81 ppm, respectively. The highest values of Pb and Cu were found in butter, whereas the highest levels of Cd and Zn were found in cheese.
|Table 1: Concentrations of heavy metals (ppm) in dairy products samples of Bushehr
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The EDI for selected heavy metals (Pb, Cd, Cu, and Zn) in dairy product samples was calculated and is given in [Table 2]. As indicated in the table, the EDI of lead in milk, yoghurt, cheese, butter, dough, and cream samples was 1.4 × 10-3, 6.7 × 10-4, 8.9 × 10-4, 6.4 × 10-5, 5.4 × 10-4, and 3.1 × 10-5, respectively. In addition, the cadmium EDI in milk, yoghurt, cheese, butter, dough, and cream samples was 3.4 × 10-4, 1.2 × 10-4, 4.5 × 10-5, 9.8 × 10-6, 9.3 × 10-5, and 4.3 × 10-6, respectively. Moreover, the EDI values for copper in milk, yoghurt, cheese, butter, dough, and cream samples were 6.4 × 10-4, 2.6 × 10-4, 8.6 × 10-5, 3.6 × 10-5, 1.1 × 10-4, and 1.2 × 10-5, respectively. Finally, the EDI of zinc in milk, yoghurt, cheese, butter, dough, and cream samples was 4.2 × 10-2, 6.8 × 10-3, 8.8 × 10-3, 1.5 × 10-3, 3.2 × 10-3 and 8.8 × 10-4, respectively.
|Table 2: The estimated daily intake (EDI) (mg/kg bw/day) of metals via consumption of dairy products by adult person of Bushehr
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The THQ is a useful formula for the assessment of risks that are related to the intake of heavy metal- contaminated foods and is represented in [Table 3]. According to the table, the THQ values for Pb in milk, yoghurt, cheese, butter, dough and cream samples were 4.3 × 10-1, 1.3 × 10-1, 6.9 × 10-2, 7.6 × 10-2, 2 × 10-2, and 3.8 × 10-2, respectively. In addition, the THQ values for Cd in milk, yoghurt, cheese, butter, dough, and cream samples were 2.4 × 10-1, 8.8 × 10-2, 3.3 × 10-2, 5.8 × 10-3, 6.7 × 10-2, and 4.5 × 10-3, respectively. Moreover, the THQ values for Cu in milk, yoghurt, cheese, butter, dough and cream samples were 9.8 × 10-2, 6.7 × 10-2, 3.4 × 10-2, 3.4 × 10-3, 2.3 × 10-3, and 1.6 × 10-3, respectively. Finally, the THQ values of zinc in milk, yoghurt, cheese, butter, dough and cream samples were 1.7 × 10-2, 6.7 × 10-3, 1.1 × 10-2, 6.3 × 10-4, 4.4 × 10-3, and 7.5 × 10-4, respectively.
|Table 3: THQ for daily exposure to heavy metals through consumption of dairy products in Bushehr
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The results of this research showed that the concentrations of lead in cream and butter were significantly higher than in milk and yoghurt samples (P < 0.05). In addition, the levels of cadmium in cream and cheese were significantly higher than in milk samples (P < 0.05). These results can be attributed to the consequence of contamination caused by industrial procedures, use of polluted water, and selling of unpackaged butter and also lead and cadmium bind strongly to casein fraction. The main sources of presence of Pb in dairy products are environmental sources such as atmospheric deposition, automobile exhausts, E-waste, and industrial effluent. It must also be mentioned that the main sources of presence of cadmium are either natural or anthropogenic origins, such as fertilizers and atmospheric deposition in soil. Moreover, levels of zinc contents in cheese and cream were significantly higher in than in milk and butter (P < 0.05). Zinc is essential for the structure and the activity of enzymes that are responsible for some important function such as cellular differentiation and replication, nucleic acid and protein synthesis, insulin secretion, and sexual maturation, and it is also vital for the performance of the immune system and other processes of human bodies. The concentrations of Cu were significantly higher in butter and cream than in milk, cheese, and dough samples. This can ascribed to the consequence that it has affinity to bind to proteins and membrane lipoproteins of fat globules of milk. EDI has been calculated to deduce the health risk related to heavy metal contamination of dairy products. The EDI values for heavy metals in dairy products only account for a fraction of the contamination via daily dietary intake. If we take the total contaminants present in dietary products into consideration, the heavy metal contamination in the local population in the Bushehr would probably achieve unsound values. Thus, the analysis of the entire dietary intake of the population of this region is required for evaluating the real heavy metal risks.
The THQ a useful solution for the assessment of risks related to the intake of heavy metal-contaminated foods was calculated. The THQ is the ratio of quantified dose of a contaminant to an RFDo for that toxic material. The RFDos for cadmium, lead, zinc, and copper were 3.5 × 10-3, 1 × 10-3, 3 × 10-1, and 4 × 10-2 mg/kg bw/day, respectively. The THQ values for the intake of all heavy metals (Pb, Cd, Cu, and Zn) through dairy products were less than 1 [Table 3], proposing that the local residents in Bushehr were not exposed to a dangerous health risk from the intake of dairy products; however, there are also other ways of heavy metal exposures including skin contact, dust respiration, and ingestion of other foodstuff and water that were not included in this research.
The current research gave some good information about the concentrations of heavy metals (Pb, Cd, Cu, and Zn) in dairy product samples collected from Bushehr city, Iran. The results showed that the heavy concentration of Pb content was found in butter and cream samples, whereas the concentration of zinc was the maximum in cheese samples. Considerably more Pb and Zn concentrations were found in cheese than in milk samples. The findings of the research showed that daily intake of dairy products included a tolerable amount of Pb and Cd. Intake of dairy products in the studied area is without potential risks; however, the accumulation of Pb and Cd via the food consumption of other stuff should also be the matter of further investigation.
This work is supported by a project founded by Bushehr University of Medical Sciences (Grant No. 2638). The authors wish to thank Mr. Mohammad Eshaghi Gorji for kindly preparing the milk and other dairy product samples.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3]