Predicted intake of trace elements and minerals via household drinking water by 6-year-old children from Krakow, Poland. Part 5: Zinc

Zinc (Zn) exposure in pre-school children via household drinking water collected by a double sampling method (morning, evening) was evaluated in a sample of the Polish population. Zn concentration was measured by flame atomic absorption spectrometry. Rural and suburban Krakow sites were non-distinguishable in respect of Zn concentrations. However, significantly lower Zn was found in urban as compared with non-urban sites [geometric mean (95% confidence interval) 0.14 (0.01-1.95) mg l-1 versus 0.52 (0.03-10.2) mg l-1, p 0.001.] Zn levels in water standing overnight in pipelines were higher in all sites by 0.36 mg l-1 on average, but observed really contaminations were higher. The Zn limit based on the taste and colour of drinking water (3 mg l-1) was exceeded in 1% and 10% of households from urban and non-urban sites, respectively. The Zn intake predictions for evening water samples for 6-year-old children averaged between 2% and 9% of the recommended dietary allowance (RDA, 10 mg day-1) for urban and non-urban sites, respectively. Mean Zn intake prediction for the exceedance fraction was 64% of RDA. In conclusion, overnight contamination of drinking water from in-house pipelines was significant and common to all sites investigated. Secondly, drinking water can be considered a significant contributor to dietary Zn intake by children in non-urban sites and may shift the population borderline of deficiency.