|Year : 2012 | Volume
| Issue : 2 | Page : 64-68
Milk minerals in cow milk with special reference to elevated calcium and its radiological implications
Edison Mahiban Ross1, Mamkuptipadapth Pisharath Rajan2, Samuel Godwin Wesley3
1 Department of Zoology, Scott Christian College (Autonomous), Nagercoil, Tamil Nadu; Sam Higginbottom Institute of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India
2 Environmental Survey Laboratory, Kudankulam Nuclear Power Project, Anu Vijay Town Ship, Chettikulam Post, Tirunelveli District, Tamil Nadu, India
3 Department of Zoology, Scott Christian College (Autonomous), Nagercoil, Tamil Nadu, India
|Date of Web Publication||21-May-2013|
Edison Mahiban Ross
Department of Biological Sciences, Sam Higginbottom Institute of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh
Source of Support: This work was funded by Department of Atomic Energy-Board of Research in Nuclear Sciences, India., Conflict of Interest: None
Context: In Kudankulam, the South Eastern tip of India, a nuclear power station is under construction. Various studies have been carried out around this project site; however, there is no literature pertaining to the minerals in cow milk samples in this region. Further, various minerals in cow milk are analogs of natural and anthropogenic radionuclides and a study on stable elements would help to assess the behavior of their radioactive counterparts. Materials and Methods: Milk samples (n = 25) from the study area were analyzed for macro-minerals (potassium [K], magnesium [Mg] and calcium [Ca]) and micro-minerals (zinc [Zn], copper [Cu] and manganese [Mn]) using a Z5000 series Hitachi atomic absorption spectrophotometer. The performance of the method was evaluated by using an International Atomic Energy Agency (IAEA) reference material, i.e., the fish tissue homogenate (IAEA-407). Results: The concentration values of major and trace minerals in the milk samples were in the order Ca > K > Mg and Zn > Cu > Mn, respectively. Conclusion: The high-water Ca levels and the prevailing tropical semi-arid climatic conditions seem to be the reasons for the high-Ca levels observed in the investigated milk samples. A CaCO3 bed is present in this area and lime is being excavated by cement industries and it is also evident from the literature that elevated Ca levels would have an immense impact on the levels of natural and fall out radionuclides in cow milk.
Keywords: Kudankulam, radium, strontium, milk minerals, tropical region
|How to cite this article:|
Ross EM, Rajan MP, Wesley SG. Milk minerals in cow milk with special reference to elevated calcium and its radiological implications. Radiat Prot Environ 2012;35:64-8
|How to cite this URL:|
Ross EM, Rajan MP, Wesley SG. Milk minerals in cow milk with special reference to elevated calcium and its radiological implications. Radiat Prot Environ [serial online] 2012 [cited 2022 Jun 28];35:64-8. Available from: https://www.rpe.org.in/text.asp?2012/35/2/64/112340
| Introduction|| |
The study of minerals in milk and in-products derived from it is important because it provides data on the contribution of nutrients from milk that are important for humans. Furthermore, it helps in identifying quality markers, including health parameters for the protection and evaluation of dairy products.  Cow milk could be an indicator of the status of the environment and an animal's internal biochemistry. The composition of milk undergoes continuous changes depending on the breeds, feeds, and cattle management. There is no literature pertaining to the minerals in cow milk samples of Kudankulam, South India, where a nuclear power station is under construction. Further, various minerals in cow milk are analogs of natural and anthropogenic radionuclides and a study on stable elements would help to assess the behavior of their radioactive counterparts. This study would provide baseline data, which could be specific to the Kudankulam area because of its unique climatic conditions. In this paper, levels of potassium (K), magnesium (Mg), calcium (Ca), copper (Cu), zinc (Zn) and manganese (Mn) in cow milk samples from this region are given.
| Materials and Methods|| |
The study area is situated around the Kudankulam Nuclear Power Project site (8° 10′7.78′′N, 77°42′44.96′′E) in Tirunelveli and Kanniyakumari districts of Tamil Nadu, India [Figure 1]. The annual rainfall in this area is generally lesser than 1000 mm, and ranged from 597 mm to 802 mm during the years 2004-2008. Because of the low-annual rainfall, rain-fed cultivation is seen in pockets. Cattle are reared in this region mainly for milk, and includes, hybrids and a few native breeds. The soils of the semi-arid zone are moderately to severely alkaline because of the presence of lime. 
Cow milk samples were collected fresh from household dairy farms in clean polyethylene containers. A single sample was collected at a time during mornings. Twenty-five samples from 10 sampling locations were collected during the study period [Table 1].
Sample processing and analysis
About 100 ml of the fresh milk samples was acid-digested (HNO 3 , HCl and H 2 O 2 ) until a white residue was obtained, for quantitative and qualitative determination of minerals present. The digested residue was then dissolved in 0.5 N HCl, filtered to remove insoluble material and the volume made-up to 30 ml with 0.5 N HCl. Deionized water was used for diluting acids. All glassware were washed using deionized water and acid throughout the analysis. , The minerals present in the samples were determined by using a Z5000 series Hitachi atomic absorption spectrophotometer. Standards were used to check the correctness of the measurements. A few samples were measured twice to check the repeatability of the measurements. About 25% of the samples in a set were replicated. The performance of the method was evaluated by analysing the reference material, IAEA fish tissue homogenate (IAEA-407). The relative differences of the measured values from the reference values are as follows: K (0.4%), Mg (8.5%), Ca (1.85), Zn (3.45%), Cu (0.9%), and Mn (6.8%); note that except for Mg and Zn, the values of all the minerals were within the 95% confidence interval given for IAEA-407 [Table 2]. Minimum Detectable Limit MDL values were K-0.1, Mg-0.05, Ca-0.05, Zn-0.05, Cu-0.05, and Mn-0.1 (μg/g). The mineral levels are reported as g/L for K, Mg and Ca, and mg/L for Zn, Cu, and Mn, respectively.
|Table 2: Observed values in the reference material, IAEA fish tissue (Reference Sheet, IAEA 407, 2003)|
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| Results and Discussion|| |
Macro- and micro-mineral levels
Milk samples (n = 25) in the study area were analyzed for macro-minerals (K, Mg and Ca) and micro-minerals (Zn, Cu and Mn) [Table 3]. The concentration levels of major and trace minerals were in the order Ca > K > Mg and Zn > Cu > Mn, respectively. The concentration of K, Ca, Mg, Zn, Cu, and Mn in milk ranged from 0.77 ± 0.26 g/L to 2.01 ± 1.51 g/L, 1.15 ± 0.22 g/L to 2.02 ± 1.33 g/L, 0.069 ± 0.013 g/L to 0.11 ± 0.07 g/L, 2.55 ± 0.8 mg/L to 4.83 mg/L, 0.026 ± 0.005 mg/L to 0.090 ± 0.030 mg/L and 0.031 ± 0.002 mg/L to 0.059 ± 0.013 mg/L, respectively. Among the six minerals analyzed, positive correlations were noted between K and Mg, Ca, Zn; Mg and Ca; and Ca and Zn [P < 0.05, n = 25; [Table 3] and [Table 4]].
|Table 3: Mineral content in cow milk from different sampling locations (mean± SD)|
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Elevated calcium levels
The concentration of Ca was comparatively higher than that of K and Ca values reported in the literature [Table 5]. Differences in feeds have been found to be responsible for the anomalies in the concentrations of elements in milk.  The hardness of the water in the study area is very high and the CaCO 3 mean concentration was found to be 242.82 mg/L in water samples collected from bore wells. About 30% of the samples were above the desirable limit of 300 mg/L (E. M. Ross, Personal Observation). The high-Ca content in cow milk reported in the present study may be due to the nature of the water taken by cows. It has been experimentally proven that Ca level in milk of cows and camels could be increased by the supplementation of Ca in cattle feed. ,
It has been proven that milk contains more carotene, and vitamins A, D, and E in summer (or during the period of grazing) than in winter.  Norman (1979)  has shown that in temperate regions the increased amount of sunlight during the summer months leads to an increase in the production of vitamin D, leading to higher Ca levels in milk. This is also true of tropical environments like Kudankulam, where elevated calcium levels were found in milk samples all through the year. Higher Ca levels than K in cow milk have been observed worldwide and vice-versa [Table 5]. However, there is one additional reason for the higher Ca levels present in the milk samples of this study: The higher intake of Ca through water.
Impact of elevated Ca levels in cow milk on radionuclides
It is also evident from the literature that elevated Ca levels would have an immense impact on the levels certain chemically similar of natural and anthropogenic radionuclides such as 226 Ra and 90 Sr in cow milk. The influence of stable Ca on the secretion of radioactive strontium in milk has been widely studied during the last two decades; however, studies on secretion of radium in milk are scarce. The higher milk Ca levels in the present samples may therefore be relevant, in terms of radionuclide behavior in cows. In several aspects, the alkaline-earth elements calcium, strontium, barium, and radium form a consistent series; the behavior of each is related to that of its predecessor in the series in a consistent way.  In the present study, this aspect is being specifically discussed in terms of the radionuclides strontium and radium. 90 Sr, being a fall out radionuclide, has its own importance around any nuclear installation. On the other hand, 228 Ra and 226 Ra with its abundance in soil due to the rich thorium beds is a significant radionuclide, in the present study area.
Intake of excessive dietary calcium is generally not associated with any specific toxicity. However, excessive calcium could interfere with trace mineral absorption.  This indicates that excessive calcium can have a similar interfering effect on toxic elements. Crout et al., (1998)  pointed out that high-Ca intake has the potential to reduce radio-strontium contamination of goat milk. This result is similar to that of Howard et al., (1995)  who performed a review of the available data for dairy cows. Studies have shown that there is a relationship between calcium intake and the transfer coefficient (Fm) of radio strontium from feed to milk.  An increase in the daily Ca intake can lead up to a 7-fold decrease in 90 Sr Fm values. Enrichment of a dairy animal diet with Ca is most effective when the feed is Ca-deficient.  When fed orally to cows, Sr, Ba, Ra, and Ca were secreted in the order Sr/Ca > Ba/Ca > Ra/Ca. 
From the above-mentioned studies it can be inferred that elevated calcium levels can influence strontium and radium levels in milk. As far as, the Kudankulam region is concerned, radioactive strontium has not yet been detected in the pre-operational environment. There are two probable scenarios: (i) There can be a positive (inhibitory/interfering) effect of elevated Ca levels on radio strontium levels in milk, because the Ca levels in milk continue to be higher and will remain so in the coming decades; (ii) there can be almost no effect of the elevated Ca level on radio strontium level in milk, which may be due to a future alteration of the present calcium levels in the feed. The second scenario is possible only under the condition where the complete feed pattern of the dairy animals is altered. Radium, on the other hand, would be influenced by Ca in the same way it is being influenced now. At present, the milk-consuming population of this region may intake less or almost no stable strontium through Ca-enriched milk; the same condition can be expected of radioactive strontium as well. The same may be the case with radium and the milk-consuming population may intake less or almost no Ra through Ca-enriched milk.
| Conclusions|| |
The Ca level in cow milk samples collected from the Kudankulam region was found to be higher than Indian average. The nature of feed (high water Ca levels) and tropical semi-arid conditions might be the reasons behind the high-Ca levels observed in milk samples.
Further studies are necessary to find out the exact reason behind these high-Ca levels. Note that, a higher Ca level would have some implications in terms of human nutritional and health; the other mineral concentrations were comparable with the values reported in literature. It may well be that the elevated levels of Ca in milk would affect the human and animal biokinetics of fall out strontium and naturally occurring radium.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]