GUIDELINES FOR RISK MANAGEMENT OF CYANOBACTERIA IN ITALIAN WATERS DESTINED TO HUMAN CONSUMPTION

There is growing evidence that the spatial and temporal incidence of harmful algal blooms is increasing in freshwater basins, posing potential risks to human health, ecosystem sustainability and water supply. The management of cyanobacteria and cyanotoxins in source and by treatment water is one of the priority issues in the research activity of many countries. In the framework of a national program supported by the Italian Ministry of Health, a research group has been constituted to develop safety plans and alert levels framework for the control of drinking water in Italy. Consistently with WHO strategies and based on existing knowledge on toxic cyanobacteria in our country, the Italian guidelines were developed to provide updated information on monitoring methodologies, early warning and risk management of cyanotoxins in water for human consumption. This also included sampling requirements, recommended actions in response to threshold breaches and treatment options to provide a graduated response to the onset and progress of a cyanobacterial bloom in source water. Particular attention was paid to data on the spreading of Planktothrix rubescens in 36 Italian lakes and reservoirs, which winter bloom values in some cases exceeded 50109 cell L1 with an associated microcystin-LR (MC-LR) equivalent concentration higher than 34103mgL1. The alert levels were defined by the value of a parameter based on the cell number of the blooming cyanobacterial species and the concentration of its toxin in Italian basins. Each value represents a level of risk to drinking water and results in an associated level of response from increased monitoring to notification to health authorities. In case of microcystin contamination, restriction in the use of drinking water starts when concentration exceeds 1.0 mgL1 of MC-LR equivalents at the consumer tap and it is associated with emergency plans run by local authorities.