Correlation between trihalomethane concentrations and various cancers in Massachusetts counties

Understanding the impact of water pollution on human health can guide new policies and technologies to improve human safety. Trihalomethanes (THMs) have become a prevalent pollutant in drinking water as the practice of chlorine disinfection has become common. As THMs are lipophilic (fat-soluble), they can accumulate in fatty tissues, including organs such as the liver and kidneys, raising concerns about long-term health effects. We examined the correlation between THM concentrations in drinking water and the rates of two cancer types: intrahepatic cholangiocarcinoma (ICC) and kidney and renal pelvis cancer. We hypothesized that a strong positive correlation would exist between total trihalomethane (TTHM) concentrations and the incidence and mortality rates for both cancers. To investigate this, we utilized data on annual mean TTHM concentrations in community water sources by Massachusetts county from the Centers for Disease Control (CDC) and age-adjusted cancer incidence and mortality rates from the Massachusetts Cancer Registry (MCR) for the years 2016-2020. Using this data, we found evidence of a positive correlation between TTHM concentrations and ICC incidence and mortality rates, as well as kidney and renal pelvis cancer incidence and mortality rates. Our results, combined with the results from other animal and human studies, raise concern that exposure to THMs, even at low levels, could contribute to an increase in incidence rates of intrahepatic bile and kidney and renal pelvis cancers.