In a landmark study, researchers have found strong evidence that children who grow up near Coldwater Creek, which was contaminated with radioactive waste from the Manhattan Project, face a significantly increased risk of developing cancer later in life. With the help of historical data from the Baby Tooth Survey, the St. Louis Baby ToothLater Life Health Study (SLBT) researchers found that many participants who lived close to the contaminated site during childhood reported higher rates of cancer, especially those exposed early in life.
The uranium used in the first atomic bombs was refined during the 1940s at Mallinckrodt Chemical Works in downtown St. Louis. Radioactive waste was subsequently transferred to the northern part of the city without proper on-site storage. Inadequate containment methods led to toxic leaks into the Coldwater Creek, exposing nearby communities for decades through contaminated soil, water, and air.
Although the U.S. government officially acknowledged the contamination in the late 1980s, concerns about the cancer cluster in the surrounding neighbourhoods had long persisted. Earlier investigations by the Missouri Department of Health and Senior Services (MDHSS) and the Agency for Toxic Substances and Disease Registry (ATSDR) found limited evidence of widespread cancer risk, likely due to restricted exposure data and reliance on post-remediation records.
To address these gaps, SLBT researchers tracked over 4,200 people who had participated in the original Baby Tooth Survey, focusing on those who lived in the St. Louis region as children between the 1940s and 1960s. Exposure levels were estimated by mapping childhood home addresses and measuring their distance from households to Coldwater Creek.
Cancer diagnoses were self-reported and classified into overall cancer, solid tumours, and radiosensitive versus non-radiosensitive cancers. Demographic and socioeconomic characteristics have also been taken into consideration, such as income, race, and education. Statistical models were used to account for potential confounding factors, and sensitivity analyses were carried out to confirm the robustness of the findings.
The results showed that there was a significant association between childhood proximity to Coldwater Creeks and the subsequent development of cancer. Almost 30% of the individuals living within 1 kilometer of the creek reported being diagnosed with cancer, compared to less than 24% among those who lived more than 20 kilometers away. This risk was especially high for solid tumors and radiosensitive cancers like thyroid cancer and leukemia. Among those living within 1 kilometer, total cancer risk increased by 44% and the risk of radiosensitive cancers rose by 85%. There was a 27% increase in total cancer and a 33% rise in solid tumors even in people residing about 1 to 5 kilometers south of the site. There was a dose-response effect where the prevalence of cancer increased with decreasing proximity to the creek during childhood.
This study represents a substantial shift from previous estimates, which might have significantly underestimated the long-term health effects because of short exposure periods and because of uncertain dose reconstructions. Through early-life exposure and historical residency, this examination provides a more accurate picture of the possible health outcomes.
This study’s limitations include dependence on self-reported diagnoses and demographic homogeneity of the sample. Nevertheless, the high quality of the methodology and the uniformity of sensitivity tests increase perceived results credibility.
The SLBT findings show that it is critical to monitor environmental hazards historically and conduct long-term health observation. As more data is gathered, further insights into cancer susceptibility may inform future public health strategies.
Decades later, the examination of the medical records of the residents of St. Louis provides compelling evidence that early-life exposure to radioactive waste contributed to the increased cancer rates in affected communities.
References: Leung M, Tang IW, Lin JJY, et al. Cancer incidence and childhood residence near the Coldwater Creek radioactive waste site. JAMA Netw Open. 2025;8(7):e2521926. doi:10.1001/jamanetworkopen.2025.21926
