Coldwater creek and cancer risk explained by Harvard experts: Why this small stream in the US linked to cancer

Coldwater Creek, a stream winding through north St. Louis County, Missouri, is getting global attention. Turns out, this peaceful-looking waterway has a dark past. Due to radioactive waste dumped nearby during the World War II Manhattan Project (the one that made atomic bombs), the creek has been quietly soaking up toxic leftovers for decades.

So what went wrong?

Back in the 1940s, uranium waste from bomb-making was poorly stored around Lambert Airport. Over time, it made its way into Coldwater Creek—through runoff, careless dumping, and just plain neglect. That waste included stuff like thorium-230, a radioactive byproduct that sticks around forever. For most of the 20th century, the problem was ignored. Only in the 1990s did the US Army Corps of Engineers start cleaning things up, and it might not be fully done until 2038 (yes, seriously).

What does Harvard say?

A major Harvard study just dropped in JAMA Network Open (July 2025), and it's not good news. Researchers followed over 4,000 folks from the St. Louis Baby Tooth study—kids from the 1950s–70s who lived nearby and donated teeth to test for nuclear fallout. By linking those records to self-reported health issues, the study found that kids who grew up within 1 km of Coldwater Creek were 44% more likely to develop any kind of cancer later in life.

But that’s just the beginning. The odds shot up even more for radiosensitive cancers—think thyroid cancer, leukemia, breast cancer, and bone cancer. For thyroid cancer alone, the risk was 5 times higher in people who lived closest to the creek as kids.


Participants who lived within 1 kilometer of Coldwater Creek during childhood showed a 44% higher odds (OR = 1.44; 95% CI, 0.96–2.14) of developing any form of cancer compared to those living more than 20 kilometers away, though this result bordered on statistical significance. The association was stronger for radiosensitive cancers—those linked scientifically to radiation exposure with an odds ratio of 1.85 (95% CI, 1.21–2.81) for those living closest to the creek versus the furthest. For thyroid cancer, the risk was particularly elevated (OR = 5.00; 95% CI, 1.23–20.32)


Harvard epidemiologists, led by Prof. Marc Weisskopf, emphasized the broader implications of exposure to low-level radioactive waste from nuclear projects, warning that similar risks could emerge as nuclear power and weapons programs expand worldwide

What cancers are we talking about?

• Thyroid cancer
• Leukemia
• Brain tumors
• Bone cancer
• Lung cancer

Even federal agencies like the US Agency for Toxic Substances and Disease Registry are backing this up. They say anyone who lived or played near the creek from the 1960s to the 1990s could face higher cancer risks.

The takeaway?

The closer you lived to Coldwater Creek—and the longer you were there—the higher your chances of developing cancer. It’s a textbook case of radiation exposure risks, and experts are warning this isn’t just Missouri’s problem.