Microsoft Word - A_11_Kodrik_R.doc HUNGARIAN JOURNAL OF INDUSTRIAL CHEMISTRY VESZPRÉM Vol. 39(1) pp. 15-19 (2011) THE EFFECT OF HIGHWAY TRAFFIC ON HEAVY METAL CONTENT OF COW MILK AND CHEESE L. KODRIK1 , L. WAGNER1, K. IMRE2, K. F. POLYAK2, F. BESENYEI3, F. HUSVETH1 1University of Pannonia, Department of Animal Sciences and Animal Husbandry 8360 Keszthely, Deak Ferenc u.16, HUNGARY E-mail: kodriklaszlo@gmail.com 2University of Pannonia, Department of Earth and Environmental Sciences, 8200 Veszprem Egyetem u. 10, HUNGARY 3Pannontej Zrt., 8900 Zalaegerszeg Platan sor 6, HUNGARY Human exposure to heavy metal elements through milk and dairy products may have influences on food safety. Although certain elements such as zinc, chromium are essential in small quantities, in high amount they can result in toxic effects on animal and human health. In this experiment samples of raw cow milk were collected from dairy farms close to highways in the central region of Hungary, and in rural green regions in West Hungary. Concentrations of selected heavy metals such as As, Cd, Cr, Cu, Fe, Mn, V, Ni, Pb and Zn in cow milk and cheese were determined using inductively coupled plasma mass spectrometry and inductively coupled plasma-optical emission (spectrometry). Chrome, copper, iron, vanadium, manganese, cadmium, arsenic, and lead content showed higher concentrations in the milk from intensive traffic areas than those in the milk from non-polluted green areas. However, in the cheese only copper, chrome, iron and lead concentrations were found significantly higher in the highway samples than those in non-polluted green samples. Keywords: food safety, dairy products, heavy metal pollution Introduction The rapid development of industrial production and traffic system may result in the contamination of food sources. Pesticides, industrial by-products, fertilizers and the increasing number of vehicles using highways, roads are important sources of heavy metals. The potential environmental factors affecting animal production (soil, water and air) are polluted with toxic metals [8] as well. Different levels of these elements have been measured in many countries in soil, vegetation, and the atmosphere. Lead, cadmium, nickel, and zinc concentrations in earthworms were found high by Scanlon [16], mushrooms tended to accumulate some metals [12]. Transport of heavy metal contaminants in the air has been also observed [17]. According to Coni et al. [3] different environmental conditions, rather than animal species, tend to affect the concentration of certain elements in three types of milk (sheep, goat and cow). Heavy metals are well known, mostly because of potential hazards to the health of living organisms. They can accumulate in tissues of the body, can be toxic even at low level of exposure [11] and can be transferred through food chains. Interest in this subject has led some scientists to the use of plants to clean up contaminated soil and water [15, 19] or to the use of zeolites to remove metals from wastewater [10]. Milk and milk products are important as human foodstuffs; they are essential sources of protein, fat and minerals. The principal type of milk used throughout the world is cow milk. Dairy cattle are fed mostly locally grown forages and preserved feedstuffs and therefore they are exposed to metal contamination if the field is located nearby an industrial area or highway. This is the reason why the concentrations of certain metals in dairy cattle products have been measured from in several countries [18, 4, 6, 5]. The objective of this study was to study the toxic metal concentrations in cow milk and cheese from two different environmental regions in Hungary. The studied regions included polluted industrial and traffic intensive areas as well as in green non-polluted areas. Materials and methods Sample collection and preparation Cow milk was collected at different dairy farms during the summer of 2011. Two farms were located in polluted areas (near highways M6 and M7; central Hungarian region), where density of the road traffic was high. The other two sampling areas were located in non-polluted green areas (Őrség and Hetés, West Hungary), where the number of roads and traffic density were very low. Mixed milk samples starting from morning milking were taken from each cow. 16 Cows were fed twice daily with a total mix ratio (TMR) diet formulated to meet the requirements of lactating cows [14]. TMR consisted of corn silage, grass hay, and cereals produced in the indicated areas respectively as main components. Heavy metal contents of the ingredients were measured by the methods indicated later. The concentrations of the metals in the feed ingredients are shown in Table 1. Table 1: Heavy metal contents (mg kg-1) in the ingredients of the diet fed with lactating cows kept in non-polluted green or highway conditions Non-polluted green area Elements Corn silage Grass hay Cereals Zn 9.33 6.31 13.11 V 0.09 0.07 ND Cd ND ND 0.02 Cr 0.10 0.09 0.10 Pb 0.12 0.10 0.01 Ni 0.42 0.62 0.21 Highway area Elements Corn silage Grass hay Cereals Zn 14.61 6.82 13.81 V 0.15 0.09 0.09 Cd 0.02 0.02 0.02 Cr 0.23 0.23 0.01 Pb 0.22 0.20 0.14 Ni 0.42 0.81 0.22 ND: not detectable Milk of ten cows was collected at each farm (a total of 40 samples) into plastic tubes. Aliquot volumes of milk were carried separately from each farm to a milk processing factory (Pannontej Zrt.) where a popular Hungarian cheese type (Trappista) was produced from the cow milk according to the technology of the factory. After the second month of cheese processing, 400 g samples were collected from each cheese roll respectively and the samples were packed in polyethylene bags. Both milk and cheese samples were stored refrigerated until chemical analyses. Analytical measurements All sample treatment and analytical processes were performed in clean conditions to avoid exogenous contamination. Milk, cheese and dietary ingredients were digested by acidic digestion in microwave oven (Ethos 1, Milestone). Approximately 0.5 g of both cheese and feed, and 5 mL of milk samples were transferred into teflon vessels and 8 mL of nitric acid (HNO3, 65% Suprapur®, Merck) and 2 mL of hydrogen peroxide (H2O2, TraceSELECT ® Ultra) were mixed. Details of the microwave degradation conditions are shown in Table 2. Table 2: Microwave digestion program of the milk, cheese and feed samples Program step Time (min) Power (W) Temp. (°C) 1 03:00 800 85 2 05:00 800 145 3 05:00 800 180 M ilk , c he es e 4 12:00 800 200 Program step Time (min) Power (W) Temp. (°C) 1 03:00 800 85 2 04:00 800 145 3 07:00 800 200 Fe ed 4 11:00 800 200 Microwave degradation was followed by a cooling period at room temperature, and then the sample solutions were transferred into volumetric flasks and adjusted to 25 mL up with high purity, double deionised water. The digested solutions were then stored at room temperature until analyses. Blank digest was made in the same way without milk, cheese or feed samples. Analyses of the elements were carried out by inductively coupled plasma-optical emission spectrophotometer (PerkinElmer Elan DRC II) and inductively coupled plasma mass spectrometer (Perkin Elmer Optima 2000 DV). At lower levels of contamination, ICP-MS provided lower detection limits for measurement (As, Cd, Cr, Cu, Mn, V, Ni and Pb), while ICP-OES was used for measuring higher concentrations of metals such as Fe and Zn. The instrumental conditions and operating variables of the instruments are summarized in Table 3. Table 3: Variables and conditions of ICP-MS and ICP-OES PerkinElmer Optima 2000™ DV RF Power 1450 W Plasma Flow 15 L/min Nebulizer Flow 0.65 L/min Auxilliary Flow 0.5 L/min Sample Pump Flow 1.5 mL/min Neb. GemCone™ Low-flow Nebulizer Chamber Cyclonic Injector Alumina, 2 mm Processing Mode Area PerkinElmer Optima 2000™ DV RF Power 1550 W Plasma Gas 15 L/min Nebulizer Gas 0.54 L/min Auxilliary Gas 0.975 L/min Sample Uptake 0.7 mL/min Nebulizer Meinhard Type K3 Sampler and Skinner Platinum Injector Alumina, 0.85 mm Reaction Gas NH3 17 Statistical analysis All statistical analyses were carried out with the computer software SPSS Statistics 17.0. The data were statistically analyzed using one-way analysis of variance (ANOVA) and t-test to examine statistical significance of differences in the mean concentration of heavy metals obtained in milk and cheese samples. The levels were found significantly different at P < 0.05. Results and Discussion Metal concentrations in milk samples Ten heavy metals were detected in the cow milk: As, Cd, Cr, Cu, Fe, Mn, V, Ni, Pb and Zn. Total concentrations of elements in the 40 samples analysed (20 from highway, and 20 from non-polluted green areas) are shown in Table 4. The content of lead, copper, vanadium, arsenic in milk collected from traffic intensive areas was significantly high, almost twice to three times as much as in that collected from green rural areas. Lower, but significant difference was detected in the concentrations of iron, however, milk from highway areas showed similar Ni concentrations to those observed in milk collected from non-polluted green areas. The contents of Zn reached the highest value of all the elements tested in both groups. In cow milk, about the same concentrations of this element have previously been observed by some authors [7]. The higher concentrations of zinc in milk results mainly from metal pesticides according to Watson [1], or zinc can be transferred from machines and tools used in milk collection procedure. No cadmium pollution could be detected in the milk from the green areas, however, 5.18 µg kg–1 Cd content was measured in the milk of highway areas. In the milk collected from the highway areas, the concentrations of vanadium were measured three times higher than in the milk from non-polluted green areas. The concentrations of Cr and Fe detected in this study were quite similar to those measured under similar conditions in Poland [9], however As and Pb contents were detected higher in our study. Metal concentrations in cheese samples The concentrations of metal elements measured in semi- hard cheese (Trappista) are shown in Table 5. The sequence of heavy metals in the cheeses made from milk collected in non-polluted green or highway areas were as follows: As, Cd < V < Pb < Cr < Mn > /ColorImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000ColorACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000ColorImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasGrayImages false /CropGrayImages true /GrayImageMinResolution 300 /GrayImageMinResolutionPolicy /OK /DownsampleGrayImages true /GrayImageDownsampleType /Bicubic /GrayImageResolution 300 /GrayImageDepth -1 /GrayImageMinDownsampleDepth 2 /GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages true /GrayImageFilter /DCTEncode /AutoFilterGrayImages true /GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /GrayImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000GrayACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000GrayImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasMonoImages false /CropMonoImages true /MonoImageMinResolution 1200 /MonoImageMinResolutionPolicy /OK /DownsampleMonoImages true /MonoImageDownsampleType /Bicubic /MonoImageResolution 1200 /MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000 /EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode /MonoImageDict << /K -1 >> /AllowPSXObjects false /CheckCompliance [ /None ] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false /PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true /PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXOutputIntentProfile () /PDFXOutputConditionIdentifier () /PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped /False /CreateJDFFile false /Description << /ARA /BGR /CHS /CHT /CZE /DAN /DEU /ESP /ETI /FRA /GRE /HEB /HRV (Za stvaranje Adobe PDF dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. 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