Qazi Rashid Ahmad ( Department of Pharmacology, Ayub Medical College, Abbottabad. )
M.A.J. Kamran ( Department of Pharmacology, Ayub Medical College, Abbottabad. )
Taj Mohammad ( Department of Chemistry, Government Postgraduate College, Abbottabad. )
One hundred water samples collected from different water supply sources in Hazara Division were analysed for their mineral constituents. The concentrations of almost all the mineral constituents did not exceed the desirable limits. Fluorides and iodides were either absent in some samples or were in very low concentrations indicating a possible correlation with the mottling of teeth in children and a high incidence of endemic goitre in the hilly areas of Hazara Division (JPMA 38 :100, 1988).
Practically all the natural waters contain dissolved minerals. Some inorganic substances occur - relatively frequently in drinking water in significant concentrations. When water comes in contact with the soil, rocks or deposits of certain minerals, some of the mineral matter dissolves in it. Sometimes water takes up these minerals from wastes and sewage. In the routine examination of thinking water (which has already been carried out by the authors)1 some of these constituents are overlooked, but their importance cannot be denied because of the growing population of the world and the interference of man in his surroundings by imparting domestic and industrial wastes to water supply sources. Therefore, search should be made for rare matallic and other chemical factors which may impair acceptability of water2. Hence it becomes necessary to analyse water for such substances which are either considered harmful for human health or have some nutritional importance and act as mineral supplement of the diet. In addition to common mineral constituents of water, the present survey was extended to the estimation of silica, as well as lithium which have gained importance in recent years as the expected essential nutrients.
MATERIAL AND METHODS
Water samples were collected in chemically clean bottles by the recommended method of W.H.O3. Chemical analysis of the water samples was started soon after the sample was received in the laboratory. Calcium and magnesium were determined by complexometric titration with E.D.T.A. using eriochrome black-T and murexide as indicators. Sodium, potassium, and lithium were determined by flame photometer. Fluoride was determined photometrically by alizarine red-S, iodide by ceric ammonium sulphate method, while silica and phosphate were estimated by ammonium molibdate photometric method. The methods were adopted from the “Standard methods for the examination of water and waste water”4.
The analytical data has been recorded in tables I - IV.
The results of chemical analysis are summarized below.
1. SPRINGS: Fifty samples of spring water were analysed. The mean values for calcium, magnesium, sodium and potassium were found to be 48.9 ppm, 10.3 ppm, 63.6 ppm and 2.14 ppm respectively. Lithium was absent in 26 samples and the mean value for the remaining 24 samples was 0.47 ppm. Fluorides and iodides were absent in 17 and 13 samples respectively. In rest of the samples the average values for fluoride and iodide were 0.27 ppm and 0.00 14 ppm respectively. Phosphate and silica averaged to 1.7 ppm and 1.75 ppm respectively.
2. WELLS: Twenty seven samples were analysed from the wells of various depths. The average concentrations of calcium, magnesium, sodium and potassium were found to be 72 ppm, 24.3 ppm, 87.9 ppm and 2.86 ppm respectively. Fifteen samples were free from lithium, 11 samples from fluoride and 5 samples from iodide. Among the remaining samples, the average lithium content was found to be 0.4 ppm, fluoride 0.34 ppm and iodide 0.002 ppm. The mean value for phosphate and silica appeared to be 1.83 ppm and 1.73 ppm respectively.
3. TAPS: Fifteen water samples were analysed from taps. The mean concentrations of calcium, magnesium, sodium and potassium were detected to be 58 ppm, 12.4 ppm, 64 ppm and 1.75 ppm respectively. Lithium was found nil in 8 samples, fluoride in 6 samples and iodide in one sample. In rest of the samples the mean figure for lithium was 0.23 ppm, for fluoride 0.26 ppm and for iodide 0.0012 ppm. The average values for phosphate and silica were found to be 1.48 ppm and 1.9 ppm respectively.
4. STREAMS (NALAS): Eleven samples were analysed which included one sample from river and one from lake. The average figures for calcium, magnesium, sodium and potassium were found to be 38.4 ppm, 9.6 ppm, 32.4 ppm and 1.77 ppm respectively. Lithium was found absent in 7 sathples, fluoride in 4 samples and iodide in 2 samples. Among the remaining samples the mean values for lithium, fluoride and iodide were worked out to be 034 ppm, 0.24ppm and 0.0011 ppm respectively. The average for phosphate was 2 ppm and that for silica was 1.9 ppm.
Mineral constituents of drinking water have not only on its potability and also influence the human health. The individual minerals which have been surveyed in Hazara water supplies are discussed below.
CALCIUM: Some investigators believe that calcium in water can be used by the body as a supplement to the calcium. in the diet. There is also evidence of adverse physiological effects from an insufficiency of calcium in water. Urovsk disease, a severe type of rickets, occurs in regions where the concentration of calcium in drinking water is low5. An inverse correlation between the calcium content of waters and cardiovascular diseases has been reported; i.e., high calcium is associated with a low incidence of heart attacks6. The maximum permissible level for calcium is 200 ppm3. In our, study, only one sample from well (Hadobandi) containing 219 ppm calcium, exceeded that limit. The rest of the samples were within the normal range.
MAGNESIUM: At high concentrations, magnesium may cause undesirable taste and gastrointestinal irritation, particularly in new users. The upper limit for magnesium is 30 ppm where water contains more than 250 ppm sulphate. But if sulphate is less than 250 ppm, then magnesium is tolerable upto 150 ppm3. In our survey only one sample (Hadobandi) containing 178 ppm, magnesium exceeded the upper limit rendering the water unfit for drinking.
SODIUM: It has been reported that neonates fed on fresh cow’s milk (which contains 580 ppm sodium as compared to human breast milk containing 150 ppm sodium) are at considerable risk of hypernatraemia when they become dehydrated. The low concentrating power of immature kidneys prevents excretion of sufficient sodium to maintain equilibrium. It has been suggested that hypernatraemia might be an important contributory factor in post-neonatal mortality and in sudden infant death syndrome7. In drinking water, excess of sodium may be harmful to persons suffering from cardiac, renal and circulatory diseases and as much as 200 ppm sodium from drinking water may be injurious5. In Hazara water supplies, only 5 samples from various sources were found to contain above 200 ppm sodium indicating a possible risk factor. The remaining water samples were satisfactory in this respect.
POTASSIUM: Potassium is an essential constituent of intracellular fluid and it is also important in sodium—potassium balance. But excessive quantity of potassium in water acts as cathartic. In our survey, all of the’ samples contained less than 12 ppm potassium representing a satisfactory condition.
LITHIUM: The concentration of lithium in drinking water appears to be inversely related to the prevalence of coronary heart disease8. It has been recommended that lithium in water for drinking and cooking purposes should not exceed 5 ppm5. Hazara water supplies were found to be poor in lithium contents. Fifty six samples contained no lithium while the rest contained less than 2.3 ppm lithium indicative of a desirable concentration.
FLUORIDE: Effect of fluoride on tooth enamel is reflected in the prevalence of dental caries but in excess this element is extremely harmful. In certain areas, notably in India, high concentrations are accompanied by several skeletal abnormalities. In the Indian Punjab natural waters are known with upto 14 ppm of fluoride. Children in parts of Uttar Pradesh usually exhibit the dental mottling and discolouration commonly associated with excess fluorine intake.9 It has been reported that 0.8 to 1.5 ppm of fluoride ion in drinking water aids in reduction of dental decay, especially among children5. It is therefore suggested either low concentrations of fluoride than permissible levels in excess, both are associated with dental abnormalities. In Hazara water supplies 38 samples were having no fluorides. Dental caries are commonly seen in some parts of Hazara Division among children which may be attributed partly to the absence of fluoride in drinking water. The remaining samples contained ‘less than 1.3 ppm fluoride representing normal concentration.
IODIDE: The most important element for human health that is frequently absent from soil is iodine deficiency which may lead to endemic goitre or endemic cretinism. The most notorious goiterous centres of the world are in high mountains: the Pyrenees, Alps, Himalayas and Andes where the terrain has been subjected to flooding or glaciation and leaching of iodine10. In the present survey, 21 samples were found free from iodine. Among the rest of 79 samples the maximum iodide was found to be 0.0085 ppm which is stifi lower than the reported safe limit of 0.0086 ppm11. The endemic goiter, among the dwellers of the hilly areas of Hazara, is very common, which is clearly indicative of low iodine content in water used for drinking and cooking.
PHOSPHATE: Phosphate may occur in surface or ground waters as a result of leaching from minerals, from agricultural drainage or as one of the stabilized products of the decomposition of organic matter. Excessive phosphate is undesirable in water used for preparing food, as it has a buffering action on the acids of the stomach5. Only 7 samples from Hazara waters were found to have no phosphate. The maximum phosphate was detected to be 5.8 ppm. Hence there is no danger from phosphate concentration to the consumers.
SILICA: Until recently, silicon was thought to be an environmental contaminant of human tissue. But some recent studies suggested that silicon plays an essential role in the growth of animals, i.e., rats and chicks12. Silicon is found in human body in the forms of hyaluronic acid, chondroitin sulphate and keratin sulphate. There is a trend towards decreasing concentrations with age in the human dermis and aorta. With development of atherosclerosis, the concentration of silicon in the arterial wall decreases12,13. It has been reported that people consuming hard water with high silica contents were having lower rate of heart disease as compared to those consuming water with low silica content10,14. In our survey, all of the water samples contained silica. The maximum concentration was found to be 4.2 ppm. So all water samples may be considered satisfactory in this respect.
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2. Essex-carter, J.A. A manual of public health and community medicine. Bristol, Wright 1979, p.475.
3. World Health Organization International standards for thinking water 3rd ed Geneva, WHO, 1971 P. 18-39.
4. Amerlean Publlc Health Association Inc. Standard methods for the examination of water and wastewater 11th ed. New York Apha, 1960. P. 106—230.
5. McKee, J.E. and Harold, W.W. Water quality criteria California, State water Resources Control Board, 1971,p. 151.
6. Morris, J.N. , Crawford, M.D. and Heady, J.A. Hardness of local water-supplies and mortality from cardiovascular disease in the County Borough of England and Wales. Lancet, 1961; 1:860.
7. Robertson, J.S. Aspects of environmental monitoring, in recent advances in community medicine. tunea oy Smith, A. Lonuon, Cnurcum Living stone, 1982, p. 118.
8. Davidson, 5.8. Passmore, R., Brock, J.F. and Truswell, A.S. Human nutrition and dietetics 6th ed. Edinburgh, Churchill Livingstone, 1975,p. 139.
9. Teotia, M., Teotia, S. P.S. and Kunwar, K.B. Endemic skeletal flucrosis. Arch. Dis. Child., 1971 ;46:686.
10. Kelly, E.C. and Snedden, W.W.Prevalence and geographical distribution of endemic goiter. W.H.O. Monograph Ser., 1960;44:27.
11. Akhtax, T., Salarzai and Zahoorullah. Quality of drinking water in N.W.F.P. Pakistan J. Med. Res., 1986;25:82.
12. Carlisle, E.M. In vlvo requirement for silicon in articular cartilage and connective tissue formation in the chick. J. Nutr., 1976; 106:478.
13. Schwarz, K. Recent dietary trace element research exemplified by tin, fluorine and silicon. Fed.Proc., 1974;33:1748.
14. Thresh, J.C. et al. The examination of water and water supplies London, Churchill, 1958, p. 33.