Drinking Water Byproducts Linked to Uterine Cancer

A large cohort study published in JAMA Network Open found that long-term exposure to disinfection byproducts in drinking water, specifically trihalomethanes (THMs) and haloacetic acids (HAAs), is associated with an increased risk of uterine cancer. The study followed over 53,000 women from the California Teachers Association for nearly 20 years. Higher THM levels were linked to an 18% higher risk of uterine cancer overall and a 23% higher risk of endometrioid tumors, with chloroform showing the strongest association. Higher HAA levels were associated with an 86% higher risk of nonendometrioid tumors. No associations were found with nitrate, arsenic, or uranium. The findings were consistent with the Iowa Women s Health Study. The study's authors, led by Rena R. Jones of the United States — National Cancer Institute, noted that the associations are biologically plausible due to endocrine-disrupting properties of these chemicals. An accompanying commentary by Shady Abohashem of Massachusetts General Hospital and Harvard Medical School called for re-examining regulatory limits, as risks were observed even at levels meeting current safety standards.