Health Risk Analysis from Multi-Exposure to Trihalomethanes in Public Indoor Swimming Pools. A Case Study.

Disinfection mitigates the risk of waterborne disease proliferation, but produces some by-products (SPDs), resulting from chlorine’s reaction with natural organic matter and may lead to the presence of potentially carcinogenic substances, such as trihalomethanes (THMs). The primary objectives of this research were to evaluate the health risks associated with multi-exposure to THMs in several swimming pools located in the municipality of Porto (Portugal), assessing both carcinogenic and non-carcinogenic risks across different exposure and analysis scenarios. Risk assessment uses a calculation model (CRacel), based on the USEPA’s model, with several modifications in input parameters. This model calculates Cancer Risk (CR) and Hazard Index (HI) values for multi-pathway exposure among different user groups. Considering a non-severe exposure scenario, results indicated that CR values in all swimming pools exceeded the risk threshold of 10⁻⁶. However, under a severe exposure scenario, CR was up to 250 times higher than the acceptable limit.