The measurement of radioactivity in Italian drinking waters

Abstract

Drinking waters generally contain variable amounts of radioactivity. Many radionuclides, like 40K and those belonging to the natural decay series of 238U, 235U and 232Th, are transferred to the water from the aquifer rocks by erosion and dissolution mechanisms. In recent years, a great interest arose towards the natural radioactivity in drinking water. The European Council Directive 98/83/EC, subsequently enforced in Italian law, pushed public authorities to organize tap water surveys. Parameter values for radioactivity levels in water are given, according to World Health Organization recommendations. Maximum concentration values for radon are separately proposed in a European Commission Recommendation. For this reason, during the latest years, the Regional Environment Protection Agency (ARPA) has been performing an extensive monitoring of tap waters in the Lombardia district of Italy. Natural radioactivity content was measured to check the compliance with recent European and Italian rules. Analyses were performed by an ultra-low level scintillation counter equipped with an alpha–beta discrimination device. Specifically arranged procedures, requiring quick and easy pre-treatments, allowed to measure gross alpha and beta activity, 222Rn, 226Ra, and uranium isotopes concentrations in a relatively short time. Subsequently, more complex procedures, involving radiochemical separation of radionuclides, are currently being studied for 210Pb, 210Po and 228Ra. Method performances were carefully tested by both internal validation procedures and international intercomparison exercises. These procedures have been employed for a wide range screening in the Lombardia district in Italy. Obtained results showed that in most cases gross alpha activity was lower than the parameter value given by the cited regulations. When these values were exceeded, a more detailed survey was planned: at present three of them, in the western and south-western part of Lombardia and in the city of Milan have been carried out.