Ecological study in an area supplied with Drinking Water from Cyanotoxin Contaminated Reservoirs

Objectives Sardinia populations experienced continuous shortage of water resources for thousands of years. To solve this problem, during 1950-1980, the main rivers were dammed creating 45 reservoirs which rapidly became eutrophic or hypertrophic, with toxic cyanobacterial blooms and a generally poor water quality. In order to investigate relations between some cancers occurrence and drinking water consumption from eutrophic reservoirs an ecological study was performed in two Sardinia provinces between 2002-2011 comparing cancer incidence between an exposed area and a reference area. Indications on the actions to be pursued in the future to protect human health from cyanobacterial blooms exposure are suggested. Methods The provinces of Sassari and Olbia Tempio are the study area and the Ragusa Province (Sicily) the reference area since its water sources are just groundwaters and springs. Cancer incidence rates were calculated for the study area and compared to those of the reference area. Results and conclusions Among Sardinian men, for the entire study period risk excesses for cancer of esophagus (SRR=3.50), colon-rectum (SRR=1.04), liver (SRR=1.21) and pancreas (SRR=1.24) are observed. Between 2002 and 2011, women showed risk excesses for cancer of esophagus (SRR=3.44) and pancreas during the first (SRR=1.44) and third (SRR=1.67) sub-periods and risk defects for stomach (SRR=0.79) and colon-rectum (SRR=0.92) cancer during the whole study period. Exposure from cyanobacterial blooms can be considered a risk factor for the onset of cancers of the digestive organs. Further studies on individual exposure, effective daily intake and chlorination by-product presence are therefore needed, as well as prevention and water body remediation measures.