Regional variations in water physicochemical properties and residual chlorine concentrations and incidence of cancer in Serbia

Individuals are exposed to local water sources through routine activities in their place of residence. Serbia consists of 26 districts with a population of approximately 6.8 million inhabitants. Individuals in different districts are exposed to varying physicochemical water quality. Irregularities in physicochemical water properties may be linked to malignant diseases. This study aimed to investigate the association between the percentage of water which does not meet the standards for both physicochemical properties and residual chlorine, and standardized incidence of most common malignancies in Serbia. In 2013, 18.9% of 76,758 water samples in Serbia were non-compliant (0% in Kolubara, 97.4% in Middle Banat), and in 2021, 16.5% of 93,144 samples failed standards (0.9% in Macva, 97.8% in North Banat). A significant positive correlation was observed between the percentage of unsatisfactory physicochemical water samples from public water supply systems and water facilities and the standardized incidence of colon and rectal cancer in males and females, any cancer type in both sexes, and ovarian cancer in females. However, no significant correlation was observed for leukemia and pancreatic in males, brain tumors or lung cancer in both sexes. Bladder cancer in males was associated with exposure to residual chlorine which surpass recommended concentrations. Study findings suggest that exposure to water that does not meet adequate physicochemical standards may be associated with an increased risk of various cancer types, while residual chlorine above recommended standards seems associated with increased incidence of bladder cancer. • Poor water quality was associated with increased incidence of any type of cancer • Positive association was found for colon and rectal cancer in both males and females • Females showed positive association with ovarian cancer • High residual chlorine levels were positively associated with bladder cancer in males