DETERMINATION OF METALS IN COW MILK COLLECTED FROM MUMBAI CITY, INDIA. ZODAPE G. V.1; DHAWAN V. L.2; WAGH R. R.3 Departments of Zoology and Chemistry2,3 S.S. & L.S. Patkar College of Arts and Science & V.P. Varde College of Commerce and Economics, S.V. Road, Goregaon (West), Mumbai- 400 062, India Email:
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ABSTRACT : In the present study, the levels of certain metals, present in 15 samples of cow milk of different brands collected from various locations of Mumbai city and were analyzed on Inductively Coupled Plasma Atomic Emissions Spectroscopy (ICP-AES) for the determination of the five heavy metals, namely Copper, Zinc, Chromium, Lead and Mercury. In the present work, the mean concentrations of copper, in said samples, were found by us to be between 37.290 ppm and 0.039 ppm. These values are higher than those prescribed by IDF (1997) which has recommended the MRL for copper in milk as 0.01 ppm. The mean concentrations of zinc were found by us to be between 0.496 ppm and 0.786 ppm. These values are lower than the tolerable limits set by Food and Nutrition Board (1980). The mean higher and lower concentrations of chromium were found by us to be 0.175 ppm and 0.013 ppm respectively and these values are higher than those reported in the literature, except than those reported by Martino et al., 2000 and Ogabiela et al., 2011. The mean concentrations of lead were found by us to be between 5.904 ppm and 0.139 ppm and these values are higher than those reported by researchers from other countries. In only two samples out of fifteen samples, we detected the presence of mercury. The mean concentrations of mercury in said samples were found by us to be between 0.015 ppm and 0.023 ppm, and these values are below the tolerable limits. Key Words: Assessment, Metals, Milk, Spectroscopy,
The measurement of the levels of metals in cow milk will depend not only in ascertaining risk to human health but also in the assessment of environmental quality. It is therefore necessary to determine the extent of contaminants in cow milk so that the warning signals, wherever required, can be given to the society. Even otherwise it has become very important to educate the society of the social evils of these contaminants.
INTRODUCTION: It is well known that increase in industrial and agricultural processes has resulted in increased concentration of metals such as Cu, Zn, Mn, Fe, Cr, Ni, Pb, Cd, Al, Se and Hg in air, water and soil. Such metals are taken in by plants and subsequently get accumulated in their tissues. Thereafter such metals get accumulated in the animals that graze on such contaminated plants and/or in the animals that drink polluted waters and/or inhale polluted air. Metals enter the human body through inhalation of polluted air, ingestion of polluted food and water or absorption through the skin Ogabiela et al., 2010; Ahmed, 2002. Thus, large amount of these metals that are taken up by plants and animals subsequently find their way into the food chain. The scientific community is greatly concerned about the ever increasing pollution of the environment, especially about the intake of harmful metals by human beings, plants and animals. The consumption of milk and milk-products has increased in recent years as they have become the main requirement of daily diet, especially for the vulnerable groups such as infants, schoolgoing children and old persons (Enb et al., 2009; Li-Qiang et al., 2009). In recent times, the amount of metals in cow milk is widely studied, particularly in industrialized and polluted areas of the developed and the developing countries of the world, since animals grazing freely on open fields are considered as bio-indicators of environmental pollution Korenekovg and Nai, 2002; . LI- Quang et al., 2009. Many reports indicate the presence of heavy metals in milk, and often it is needed to assess the levels of heavy metals in food (Licata et al., 2004; Tajkarimi et al., 2008; Patra et al., 2008). However, in India, and particularly in Maharashtra the contamination of cow's milk and milk products has not been seriously attended to so far. Few reports are available on this topic. The study of toxicity levels in milk and milk products and their relation with various symptoms have not been reportedly carried out in India.
MATERIALS AND METHODS : a) Sample Collection: The 15 samples of cow milk of different brands were collected from various locations of Mumbai city. The cow milk samples, packed in propylene bags, were stored at 20 0C in deep freezer in the Department of Zoology, S.S & L.S. Patkar College, Goregaon (West) Mumbai for further analysis. b) Sample Digestion: The method was followed with some modifications as prescribed by Ogabiela et al.,(2011). To 1 ml of the milk sample taken in a Kjeldal flask was added 5 ml of concentrated hydrochloric acid (HCl) and 5 ml of concentrated perchloric acid (HClO4) acid. This mixture was digested by heating the flask in a heating mantel, and 30 % hydrogen peroxide was added to it intermittently till a pale yellowcolored solution was obtained. The digestion flask was further heated gently until frothing subsided and the sample was then heated to dryness. The residue so obtained was dissolved in 30 ml of deionized water and the solution was filtered using Whatman filter paper No. 42. The digested sample was quantitatively transferred into 50 ml flask, and then diluted with distilled water up to the mark and stored in a polypropylene bottle. The above procedure was repeated for all the other samples. All above chemicals used were of analytical grade. c) Preparation of standard metal ion solutions: Stock solutions (1μg / ml) of each of the metal ions were prepared using appropriate metal salt of AR grade quality in dilute hydrochloric acid. The working standards of these solutions were prepared by appropriate dilutions in distilled water. 270
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d) Instrumentation:The samples were analyzed on Inductively Coupled Plasma Atomic Emissions Spectroscopy (ICP-AES, Model ARCOS from M/s. Spectro, Germany) at the Sophisticated Analytical Instrument Facility (RSIC), Indian Institute of Technology (IIT) Powai, Mumbai-400076, India.
found below the tolerable limits in all the remaining branded milk products collected from different areas of Mumbai city. These values are lower than those reported by Tripathi et al., (1997) and Krishnamoorty and Tripathi, (1998) (113 g of fresh cow milk contained 5.9 ppm/ day) The low concentrations of copper obtained in our study are in the line with those reported by other authors (0.10.3 ppm/mL in cow milk) (Kira et al., 2007; Kondyli et al., 2007; Tripathi et al., 1999). The low concentrations of copper could be due to zinc contained in food that interferes with the copper absorption system, explaining the presence of low levels of this metal in milk (Doull's, 2000). The mean concentration of copper was 0.110 ppm, as reported b Favretto & Marletta (1984) and Garcia et al. (1999). This result is comparable with the results obtained by us. But our results show higher concentrations of copper in all the branded samples of cow milk collected from Mumbai city, in comparison with those prescribed by IDF (1997) which recommends the MRL for copper in milk as 0.01ppm.
RESULTS AND DISCUSSION: Table No. 1. Samples showing Metal Ion Concentration in ppm in cow milk of different brands collected from various locations of Mumbai city
Zinc :Both acute and chronic toxicity syndromes occur with large overdoses of zinc and the principal features are epigastric pain, diarrhea, nausea and vomiting. In addition to the gastrointestinal effects, the central nervous system may be affected, showing symptoms such as irritability, headache and lethargy (Hambidge et al., 1986). Prolonged intake of a relatively modest excess of zinc may depress serum high density lipoprotein cholesterol levels Hooper et al., (1980). Chronic ingestion of excess supplemental zinc (Zn) can produce anemia and leucopenia consequent to induced copper deficiency Hoffman et al. (1988). Zinc toxicity in humans from excessive dietary ingestion is uncommon, but gastrointestinal distress and diarrhea have been reported Reddy & Hayes (1989); Walshe et al. (1994); Casarett & Doull's (1996). The mean Zn concentration in the analyzed fresh cow milk samples (0.98 ppm) was lower than that reported in raw bovine milk (0.29-4.96 ppm) (Licata et al., 2004). The mean Zn concentration in powdered milk is reported as 3.24 ppm and the Zn concentrations in the commercial cow milk samples are in the range of 0.48-1.54 ppm. These concentrations are lower then those determined in powdered and commercial goat milk (32.10 ppm and 3.10 ppm respectively) (Park, 2000) and this value is comparable with 3.661 ppm. Gartrell et al,. (1986). Higher values of zinc contaminant in milk have been reported by Mazzotta et al. (1993), whereas lower values have been reported by Garcia et al. (1999). In our present study, the mean concentrations of zinc are found to be between 0.496 ppm and 0.786 ppm and these values are lower than the values reported by above-said researchers. From the above-stated results, it is confirmed that the level of zinc, in branded milk samples collected from different locations of Mumbai city, is below the tolerable limits as set by Food and Nutrition Board (1980).
NB:N = Average reading = 6 = Total number of readings taken ND = Metal ion is Not Detected or, when detected, it's concentration is less than 0.001ppm . Copper :The possible contamination of milk with copper can occur from animal feed, higher copper content in water and also from copper bearing and copper alloys used in equipment (Mitchell, 1981). Contamination of cow's milk with copper from brass containers has been cited as the major environmental factor in the etiology of Indian childhood cirrhosis (Tanner et al., 1983; Bhave et al., 1987). It has been reported that cow's milk stored in brass utensils would supply 400 mg Cu/kg to an infant and that more data are needed on the role of excess copper intake in the etiology of this disease and of the actual levels of intake associated with hepatic toxicity in Indian childhood cirrhosis. Excess hepatic copper accumulates in cholestatic which causes liver diseases Walshe, J. M. (1984) Studies relating to the concentration of copper as one of the contaminants showed that there was a wide variation in mean concentrations of copper among different branded cow milk products. The mean concentration of copper was recorded highest in M-03 (37.290 ppm) whereas the lowest concentration of copper was found in M-05 and M-07 milk (0.039 ppm). The level of copper was found above the tolerable limits in M-03 (37.290 ppm); M-13 (31.384 ppm); M-11 (19.220 ppm) and M-09 (16.390 ppm). The level of copper was
Chromium :The particulates of chromium enter the aquatic medium through effluents discharged from tanneries, textiles, electroplating, and mining, dyeing and printing industries (Mertz, 1992, 1993; Burton et. al 1993; Burton, 1995). In the environment, chromium exists primarily in the tetravalent and hexavalent forms, predominantly as the trivalent form in natural waters. Chromium compounds have been found to be 271
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mutagenic and carcinogenic in a variety of test systems. Chromium is also a compound of biological interest, probably having a role in glucose and lipid metabolism as an essential nutrient (Lingard et. al 1979). Death in acute chromium poisoning is usually due to uraemia. Chronic intoxication by inhalation or skin contact leads to incapacitating eczematous dermatitis, with oedema and ulceration (Upreti et al., 2004). The average higher and lower values of concentrations of chromium in samples of cow milk were found by Lante et al. 2004 as 0.005ppm and 0.030 ppm. Results of other researchers in respect of concentrations of chromium in samples of cow milk are reported by Caggiano et al. 2005 (0.004 ppm), Tajkarimi et al. 2008 (0.20 ppm), and Martino et al., 2000 (0.21 ppm). Birghila et al. (2008) have reported the average concentrations of chromium in powder milk (0.18 ppm), in fresh cow milk (0.04 ppm) and in three different samples of pasteurized milk from three different places in Nijeria (Brenac: 0.10 ppm; Dorna: 0.04 ppm and Diami: 0.06 ppm). The average concentrations of chromium in cow milk samples from Kano and Zaria are reported by Ogabiela et al.,( 2011) as 1.756694 ppm and 1.5683 ppm respectively. In the present work, the average higher and lower concentrations of chromium were found to be 0.175 ppm and 0.013 ppm respectively in branded milk samples collected from different locations of Mumbai city. It was also observed by us that the average higher concentration of chromium found by us was higher than that reported by various researchers mentioned hereinabove, except that reported by Martino et al., 2000 and Ogabiela et al., 2011. Lead:The main sources of lead pollution in the environment include effluents & emissions from industries, emissions from vehicles running on leaded petrol, the smoke and dust emissions of coal and gas-fired power stations, use of lead sheets by roofers as well as the use of paints and anti-rust agents. Contamination by lead of foodstuffs is caused by the soldered seams of cans and the soldered closures of condensed milk cans, the metal caps of wine bottles and, also by lead pipes used in drinking water systems. Lead can trigger both acute and chronic symptoms of poisoning. Acute intoxications only occur through the consumption of relatively large single doses of soluble lead salts. Chronic intoxications can arise through the regular consumption of foodstuffs only slightly contaminated with lead. Lead is a typical cumulative poison. The danger of chronic intoxications is the greater problem. The mean concentrations of lead (0.139- 5.904 ppm ) in all examined milk samples were found by Lithuanian Hygiene Norm Hygiene Norm, 2001, to be higher than the maximum allowed levels (MAL) which allows concentrations up to (0.020 ppm). There are no specific MAL for other heavy metals in milk - both in Lithuanian Hygiene Norm and Commission Regulation (EC) No 466/2001. The lead levels were detected in milk in Lithuania 20 years ago. In 1991 lead concentrations of 0.0600.080 ppm were determined in some samples though concentrations of less than 0.010 ppm have also been reported (Urbiene· & Ciuckinas ,1993). Lead levels of (0.0200.030 ppm) were detected in 19901993 (Ciuckinas & Urbiene·, 1994). Licata et al. (2004) analysed 40 samples of cow milk in Calabria, Italy. The highest mean lead concentrations amounted to 0.992 ppm. Also, mean value of lead was below the general statutory limit of 1.000 ppm set by
Food Regulations, 1979, but above the proposed European maximum limit of 0.020 ppm (European Commission, 1997). At present, the CE Regulation no. 2001/466 (CE Regulation, 2001) establishes a limit for lead in milk (MRL = 0.02 ppm). The results obtained in our present study to be between 5.904 ppm and 0.139 ppm show that the highest mean lead concentrations in some samples of cow milk are higher than those reported by researchers from other countries and also higher than the reported MRLs. Therefore, the lead concentrations above MRLs found in the samples of cow milk collected by us from different locations of Mumbai city indicate that the cow milk is unsafe for human consumption. . Mercury :Mercury in the form of its methyl compounds is specifically the most toxic of the heavy metals. When consumed orally, it first passes into the liver and then into the kidneys and the brain. Accumulation of mercury only takes place temporarily and a large part of it is excreted with the faeces. The salts of bivalent mercury, in the case of chronic consumption, first cause tiredness, loss of appetite and weight loss and finally cause the failure of kidneys. Muscular weakness and paralysis are typical. The methylmercury from animal foodstuffs also damages the central nervous system and the immune system. Teratogenic effects have also been observed. It has been reported that the concentrations of mercury contaminants in human milk vary from
