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Food Additives and Contaminants: Part B: Surveillance Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfab20
Heavy metals in raw cow and ewe milk from north-east Iran a
Vahid Najarnezhad & Masoome Akbarabadi
b
a
Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran b
Veterinary Office of Korasan-Razavi, Mashhad, Iran Accepted author version posted online: 26 Feb 2013.Published online: 28 Mar 2013.
To cite this article: Vahid Najarnezhad & Masoome Akbarabadi (2013): Heavy metals in raw cow and ewe milk from northeast Iran, Food Additives and Contaminants: Part B: Surveillance, DOI:10.1080/19393210.2013.777799 To link to this article: http://dx.doi.org/10.1080/19393210.2013.777799
PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Food Additives & Contaminants: Part B, 2013 http://dx.doi.org/10.1080/19393210.2013.777799
Heavy metals in raw cow and ewe milk from north-east Iran Vahid Najarnezhada* and Masoome Akbarabadib a Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran; bVeterinary Office of Korasan-Razavi, Mashhad, Iran
Downloaded by [Brandon University GST] at 03:56 29 April 2013
(Received 5 June 2012; final version received 15 February 2013) The presence of toxic metals in milk may create significant health problems for the population. In this study, 1440 raw cow and ewe milk samples from 18 townships in north-east Iran were analysed in four different seasons. Lead, cadmium and mercury levels were determined using atomic absorption spectrophotometry. Mean concentration of lead, cadmium and mercury in cow milk samples was 12.9 ± 6.0, 0.3 ± 0.3 and 3.1 ± 0.3 ng g−1, respectively, and in ewe milk samples, these mean values were 14.9 ± 7.8, 1.6 ± 1.2 and 3.1 ± 0.3 ng g−1, respectively. Statistical analyses showed that lead and cadmium concentrations in ewe milk were significantly higher than in cow milk. Concentrations of these metals in ewe milk varied significantly with different seasons. As the concentrations did not exceed the safety limits, they could not pose a serious danger to public health. Keywords: lead; cadmium; mercury; milk; cow; ewe; season; Iran; heavy metal
Introduction Lead (Pb), Cadmium (Cd) and Mercury (Hg) in milk draw public attention because of food safety issues and potential health risk, as they are widely dispersed in the environment. Accumulation of these heavy metals in food represents a severe risk for their long-term toxicological effects (Llobet et al. 2003). The toxic metal content of milk and dairy products is due to several factors, in particular, environmental conditions and possible contamination during several steps of the manufacturing processes (Pavlovic et al. 2004; Anastasio et al. 2006). North-east Iran with more than 8,000,000 sheep and 500,000 cows represents an important source of income for rural areas. The milk from sheep and cow are almost entirely used to produce cheese and yoghurt. At present, no data are available concerning levels of heavy metal contamination in milk from sheep and cattle in Khorasan-Razavi, the region that corresponds to the north-east of Iran. The aim of this work was to determine the concentration of some heavy metals in cow and ewe milk collected from the farms of Khorasan-Razavi province and to evaluate to which extent these metals in dairy products have an effect on human health. Material and methods Sampling strategy A total of 1440 milk samples (720 cow and 720 ewe milk samples) were collected from 18 townships in Khorasan-Razavi during four different seasons (n = 10 *Corresponding author. Email: [email protected] © 2013 Taylor & Francis
per season). All samples were frozen immediately after collection and were transported frozen to the National Food Quality Control Laboratory of the Veterinary Council of Khorasan-Razavi. Milk samples were stored at a temperature of –20°C until analysis. Clean polyethylene bottles were used to collect the raw milk. The samples were allowed to thaw at room temperature just before analysis.
Analytical procedure Milk sample portions of 2 ml were placed in digestion vessels and mixed with 4 ml of concentrated HNO3 (Suprapur®, 65.3%, Merck, Bremen, Germany). The mixtures were incubated at 85°C for 24 h, where after 4 ml of 30% H2O2 was added to each mixture and incubated at 120°C for 1 h. Finally, the mixture was diluted to 10 ml with 1% HNO3.
Instrumentation Lead and cadmium concentrations were determined by an atomic absorption spectrophotometer (AS800, PerkinElmer, Waltham, MA, USA) at 283.3 and 228.8 nm, respectively, using a graphite furnace. The instrumental conditions are shown in Table 1. Mercury concentrations were determined using an Automated Mercury Analyzer (AULA254, Mercury Instruments, Karlsfeld, Germany) at 253.7 nm. All heavy metal concentrations are expressed as nanograms per gram dry weight.
2
V. Najarnezhad and M. Akbarabadi
Table 1. Instrumental conditions for determination of lead and cadmium in milk. Parameter Wavelength, nm Slit width, nm Atomisation system Drying, °C Ashing temperature, °C Atomisation temperature, °C Injection volume, µl Cleaning, °C Matrix modifier Signal mode
Lead
Cadmium
283.3 0.7 Platform 120–400 850 1800 20 2450 NH4H2PO4 + Mg(NO3)2 Peak area
228.8 0.7 Platform 110–130 500 1550 20 2450 NH4H2PO4 + Mg(NO3)2 Peak area
Downloaded by [Brandon University GST] at 03:56 29 April 2013
Statistical analysis The statistical analyses were carried out using the SPSS 11.5 program (SPSS Inc., Chicago, IL, USA). One-way analysis of variance (ANOVA) and t tests were carried out for all the variables studied, to compare mean values among different populations. Results were displayed as mean ± standard deviation and significance was defined as P < 0.05.
times the standard deviation of an average of procedural blanks. The corresponding values for lead, cadmium and mercury were 0.03, 0.01 and 0.02 ng g−1. The repeatability of the measurements was not worse than 1%. To control the stability of the analytical signals, the measurements for the standard solutions were repeated before and after the measurements of the samples. Comparison of measured and certified reference material values is given in Table 2.
Quality control Certified reference materials BCR-063R and BCR-150, skim milk powders (IRMM, Geel, Belgium) were used for validation purposes. The limit of detection was defined as three
Results and discussion Mean concentrations of lead, cadmium and mercury in all milk samples are listed in Tables 3 and 4. The results
Table 2. Comparison of measured and certified reference material values (ng g−1) of lead, cadmium and mercury. Lead (n = 5) Certified material Skim milk powder BCR-063R Skim milk powder BCR-150
Cadmium (n = 13)
Mercury (n = 7)
Certified
Found
Certified
Found
Certified
Found
18.5 ± 2.7 –
18.5 ± 0.1 –
– 21.8 ± 1.4
– 21.8 ± 0.1
– 9.4 ± 1.7
– 9.4 ± 0.1
Table 3. Mean lead, cadmium and mercury concentrations in cow milk from different townships (ng g−1). Township Kalat Kashmar Khaf Mashhad Ghuchan Mahvelat Jovein Roshtkhar Sarakhs Taybad Torbat-Heydarie Bardaskan Chenaran Sabzevar Fariman Nishaboor Joghatay Gonabad
Lead 8.9 15.2 9.1 18.3 17.4 25.4 4.0 6.0 11.8 9.3 13.1 6.5 15.1 17.2 16.6 12.7 13.6 12.4
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
4.8 3.4 3.3 2.5 2.6 3.3 1.6 1.4 3.8 2.5 1.6 3.0 2.9 4.8 6.6 1.5 1.1 3.9
Cadmium
Mercury
Food Additives and Contaminants: Part B: Surveillance Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tfab20
Heavy metals in raw cow and ewe milk from north-east Iran a
Vahid Najarnezhad & Masoome Akbarabadi
b
a
Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran b
Veterinary Office of Korasan-Razavi, Mashhad, Iran Accepted author version posted online: 26 Feb 2013.Published online: 28 Mar 2013.
To cite this article: Vahid Najarnezhad & Masoome Akbarabadi (2013): Heavy metals in raw cow and ewe milk from northeast Iran, Food Additives and Contaminants: Part B: Surveillance, DOI:10.1080/19393210.2013.777799 To link to this article: http://dx.doi.org/10.1080/19393210.2013.777799
PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Food Additives & Contaminants: Part B, 2013 http://dx.doi.org/10.1080/19393210.2013.777799
Heavy metals in raw cow and ewe milk from north-east Iran Vahid Najarnezhada* and Masoome Akbarabadib a Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran; bVeterinary Office of Korasan-Razavi, Mashhad, Iran
Downloaded by [Brandon University GST] at 03:56 29 April 2013
(Received 5 June 2012; final version received 15 February 2013) The presence of toxic metals in milk may create significant health problems for the population. In this study, 1440 raw cow and ewe milk samples from 18 townships in north-east Iran were analysed in four different seasons. Lead, cadmium and mercury levels were determined using atomic absorption spectrophotometry. Mean concentration of lead, cadmium and mercury in cow milk samples was 12.9 ± 6.0, 0.3 ± 0.3 and 3.1 ± 0.3 ng g−1, respectively, and in ewe milk samples, these mean values were 14.9 ± 7.8, 1.6 ± 1.2 and 3.1 ± 0.3 ng g−1, respectively. Statistical analyses showed that lead and cadmium concentrations in ewe milk were significantly higher than in cow milk. Concentrations of these metals in ewe milk varied significantly with different seasons. As the concentrations did not exceed the safety limits, they could not pose a serious danger to public health. Keywords: lead; cadmium; mercury; milk; cow; ewe; season; Iran; heavy metal
Introduction Lead (Pb), Cadmium (Cd) and Mercury (Hg) in milk draw public attention because of food safety issues and potential health risk, as they are widely dispersed in the environment. Accumulation of these heavy metals in food represents a severe risk for their long-term toxicological effects (Llobet et al. 2003). The toxic metal content of milk and dairy products is due to several factors, in particular, environmental conditions and possible contamination during several steps of the manufacturing processes (Pavlovic et al. 2004; Anastasio et al. 2006). North-east Iran with more than 8,000,000 sheep and 500,000 cows represents an important source of income for rural areas. The milk from sheep and cow are almost entirely used to produce cheese and yoghurt. At present, no data are available concerning levels of heavy metal contamination in milk from sheep and cattle in Khorasan-Razavi, the region that corresponds to the north-east of Iran. The aim of this work was to determine the concentration of some heavy metals in cow and ewe milk collected from the farms of Khorasan-Razavi province and to evaluate to which extent these metals in dairy products have an effect on human health. Material and methods Sampling strategy A total of 1440 milk samples (720 cow and 720 ewe milk samples) were collected from 18 townships in Khorasan-Razavi during four different seasons (n = 10 *Corresponding author. Email: [email protected] © 2013 Taylor & Francis
per season). All samples were frozen immediately after collection and were transported frozen to the National Food Quality Control Laboratory of the Veterinary Council of Khorasan-Razavi. Milk samples were stored at a temperature of –20°C until analysis. Clean polyethylene bottles were used to collect the raw milk. The samples were allowed to thaw at room temperature just before analysis.
Analytical procedure Milk sample portions of 2 ml were placed in digestion vessels and mixed with 4 ml of concentrated HNO3 (Suprapur®, 65.3%, Merck, Bremen, Germany). The mixtures were incubated at 85°C for 24 h, where after 4 ml of 30% H2O2 was added to each mixture and incubated at 120°C for 1 h. Finally, the mixture was diluted to 10 ml with 1% HNO3.
Instrumentation Lead and cadmium concentrations were determined by an atomic absorption spectrophotometer (AS800, PerkinElmer, Waltham, MA, USA) at 283.3 and 228.8 nm, respectively, using a graphite furnace. The instrumental conditions are shown in Table 1. Mercury concentrations were determined using an Automated Mercury Analyzer (AULA254, Mercury Instruments, Karlsfeld, Germany) at 253.7 nm. All heavy metal concentrations are expressed as nanograms per gram dry weight.
2
V. Najarnezhad and M. Akbarabadi
Table 1. Instrumental conditions for determination of lead and cadmium in milk. Parameter Wavelength, nm Slit width, nm Atomisation system Drying, °C Ashing temperature, °C Atomisation temperature, °C Injection volume, µl Cleaning, °C Matrix modifier Signal mode
Lead
Cadmium
283.3 0.7 Platform 120–400 850 1800 20 2450 NH4H2PO4 + Mg(NO3)2 Peak area
228.8 0.7 Platform 110–130 500 1550 20 2450 NH4H2PO4 + Mg(NO3)2 Peak area
Downloaded by [Brandon University GST] at 03:56 29 April 2013
Statistical analysis The statistical analyses were carried out using the SPSS 11.5 program (SPSS Inc., Chicago, IL, USA). One-way analysis of variance (ANOVA) and t tests were carried out for all the variables studied, to compare mean values among different populations. Results were displayed as mean ± standard deviation and significance was defined as P < 0.05.
times the standard deviation of an average of procedural blanks. The corresponding values for lead, cadmium and mercury were 0.03, 0.01 and 0.02 ng g−1. The repeatability of the measurements was not worse than 1%. To control the stability of the analytical signals, the measurements for the standard solutions were repeated before and after the measurements of the samples. Comparison of measured and certified reference material values is given in Table 2.
Quality control Certified reference materials BCR-063R and BCR-150, skim milk powders (IRMM, Geel, Belgium) were used for validation purposes. The limit of detection was defined as three
Results and discussion Mean concentrations of lead, cadmium and mercury in all milk samples are listed in Tables 3 and 4. The results
Table 2. Comparison of measured and certified reference material values (ng g−1) of lead, cadmium and mercury. Lead (n = 5) Certified material Skim milk powder BCR-063R Skim milk powder BCR-150
Cadmium (n = 13)
Mercury (n = 7)
Certified
Found
Certified
Found
Certified
Found
18.5 ± 2.7 –
18.5 ± 0.1 –
– 21.8 ± 1.4
– 21.8 ± 0.1
– 9.4 ± 1.7
– 9.4 ± 0.1
Table 3. Mean lead, cadmium and mercury concentrations in cow milk from different townships (ng g−1). Township Kalat Kashmar Khaf Mashhad Ghuchan Mahvelat Jovein Roshtkhar Sarakhs Taybad Torbat-Heydarie Bardaskan Chenaran Sabzevar Fariman Nishaboor Joghatay Gonabad
Lead 8.9 15.2 9.1 18.3 17.4 25.4 4.0 6.0 11.8 9.3 13.1 6.5 15.1 17.2 16.6 12.7 13.6 12.4
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
4.8 3.4 3.3 2.5 2.6 3.3 1.6 1.4 3.8 2.5 1.6 3.0 2.9 4.8 6.6 1.5 1.1 3.9
Cadmium
Mercury
