Mineral element contents in drinking water - aspects on quality and potential links to human health

Detta är en avhandling från Inst. of Chemical Engineering, LTH

Sammanfattning: Mineral elements in drinking water have been in focus for more than a decade, especially as the habit of drinking bottled water has increased, not the least among young people. Minerals in drinking water have become more important since minerals in food, especially in vegetables, have decreased substantially the last decades. This thesis includes four different studies. In the first study 20 municipal raw and treated waters in southern Sweden were investigated. In the second study the concentrations of about 44 metals and ions in 33 different brands of bottled waters on the Swedish market were determined. In the third study 46 acid well waters from acid regions dominated by primary rocks of gneiss and granite were compared with 43 well waters in a district in southern Sweden situated on limestone sediments. Hair samples were obtained from all participants, who also answered a questionnaire about their self-experienced health status. In the last study the concentrations of about 30 trace elements and ions were determined in blood, urine, hair and drinking water in 38 women with defined fibromyalgia and 41 referent women, matched for age and location. The studies of well waters and municipal waters showed that water with primary rock bedrock origin had significantly lower concentrations of elements like Ca, HCO3, Mo, Se and SO4 than water from lime stone bedrock. The highest concentrations of a number of ions, e.g. Ca, HCO3, Cr, Sr, Mg and Ti were at pH 7-8 in well waters. At lower pH-values the ions probably had been leached, and at higher pH they probably were precipitated as sulphates, carbonates and hydroxides. Cu showed a concentration peak around pH 6. Fewer women drinking acid well water reported themselves as healthy compared to women drinking alkaline well water. The method for elimination of Fe and Mn from raw municipal water was efficient in all treatment plants investigated, at some plants giving concentrations in the treated water below the detection limits. Softening filters produced water with Ca-concentrations comparable to the softest waters. Adjustment of pH by the use of chemicals like lye, soda or limestone, modified the consumer water composition significantly, besides raising the pH, where limestone increased Ca and many other elements. The concentrations of potentially toxic metals such as Al, Pb and U were low. In the study of bottled waters ten of the 33 brands showed Ca concentrations below 10 mg L-1 and Mg levels below 3 mg L-1, i.e. they were very mineral poor waters. These brands were collected from areas with thin soils on primary rock bedrock. Nine of the brands were collected from limestone regions. They had high Ca-levels, with a maximum of 289 mg L-1 and Mg exceeding 90 mg L-1 in two brands. Two soft and carbonated waters were supplemented with Na2CO3 and NaCl, resulting in high concentrations of Na: 644 and 648 mg L-1 and Cl: 204 and 219 mg L-1. Storage of carbonated drinking water in Al cans seemed to increase the Al-concentration. Despite choosing referents from the same parish, the fibromyalgia women had lower concentrations of many elements and ions in drinking water compared to the referents in the fibromyalgia study. No obvious changed mineral pattern was observed in blood, water, urine or hair of women with fibromyalgia compared to referents. The daily contribution of mineral elements from different drinking waters varied substantially, depending on e.g. the bedrock situation, acidification, water treatment methods. Suitable levels of minerals elements in drinking water are suggested.

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