Consuming chlorinated drinking water may increase the risk of developing uterine cancer in women by up to 18%, reports infohub.kz.
California researchers published the findings in JAMA Network Open. They analyzed data from more than 53,000 women who had lived at the same address for at least 10 years, used a centralized water supply, and had no history of cancer or hysterectomy.
The researchers matched participants' home addresses with government water quality records from 1990 to 2020. Based on this information, they calculated the average 15-year exposure levels of various substances: nitrates, arsenic, uranium, and disinfection byproducts — trihalomethanes (THMs) and haloacetic acids (HAAs) — which form when chlorine reacts with organic matter. These data were then compared with the California Cancer Registry, adjusting for age, body mass, and smoking history.
During follow-up, 1,038 women were diagnosed with uterine cancer. The analysis showed that exposure to some chemicals used in water disinfection was associated with an increased risk of the disease. Trihalomethanes, especially chloroform, had the strongest link with endometrioid tumors, which account for more than 95% of uterine cancer cases. Women with the highest exposure to THMs had an 18% higher overall risk of developing cancer. Higher exposure to haloacetic acids (HAAs) was associated with nearly a doubling of risk for non-endometrioid tumors. Meanwhile, nitrates, arsenic, and uranium showed no link to uterine cancer.
The researchers stressed that their work identifies a statistical correlation but does not prove a direct cause-and-effect relationship. Despite this, the findings provide water utilities with a reason to consider reducing chemical disinfection byproducts while maintaining reliable protection of water from dangerous infections.