Ultra-trace nutritional and toxicological elements in Rome and Florence drinking waters determined by Instrumental Neutron Activation Analysis

In order to ascertain water quality for human consumption, the evaluation of trace and ultra-trace elements in drinking waters of two Italian cities, Rome and Florence, is investigated together with the potabilization processes involved and the relative human exposure to the contaminants. Through a multi-elemental detection with no chemical treatment using Instrumental Neutron Activation Analysis and Proton-Induced X-ray Emission the concentration of 40 elements is determined. Basically, the concentrations of the investigated parameters in drinking waters were within the permissible limits of the World Health Organization drinking water quality guidelines and the Water Pollution Control legislation of Italian authorities. The Rome drinking water shows a chemical water composition quite similar to uncontaminated natural water: potentially toxic elements (e.g., Cr, Hg, Ni, and Sb) are present at very low concentrations whereas the levels of nutritionally essential elements are adequate and low levels of I and Se cannot be considered a cause of deficiency diseases. A multivariate statistical approach was used to identify both the origins and correlations among elements and the six different apportionments contributing to the water supply in Rome. For the drinking waters distributed in Florence, the element levels show a sufficiently good situation, except for Al (range 103–267 μg/L) that is present at reasonable concentrations for almost the entire population due to the hard potabilization procedure involving aluminum salts. The values of Metal Index (MI), that helps to quickly evaluate the overall quality of drinking waters, show a good drinking water quality in Rome (Fe is the only element to be considered critical) whereas in Florence the situation is influenced by Al levels. No relevant differences are found among Rome and Florence water composition and other Italian and world potable waters.This study can be considered a useful reference for studies aimed to highlighting toxicological, nutritional and environmental disease patterns.