Nuclear power stations and cancer

From Harvard Graduate School of Arts and Sciences
By Dr Yazan Alwadi

Nuclear power accounts for 18 to 20 percent of electricity generated in the United States. In some places, the share is much greater—over half the energy generated in Illinois, for instance, the country’s sixth-largest state. As demand rises sharply, particularly from AI data centers, the federal government has increased funding, loans, and tax incentives in an effort to increase nuclear capacity, extend operations of existing reactors, and restart retired ones.

Although public support for nuclear energy has surged in recent years, opposition remains strong. The most common reason? Safety concerns. And they may be valid, according to population health scientist Yazan Alwadi, who received his PhD from the Harvard Kenneth C. Griffin Graduate School of Arts and Sciences in February 2026, months after receiving a master’s degree in biostatistics in November 2025. Now a post-doctoral researcher at the Harvard T.H. Chan School of Public Health, Alwadi’s work uncovers a link between cancer and proximity to nuclear power plants.

Too Close for Comfort?

In the lab of Petros Koutrakis, Akira Yamaguchi Professor of Environmental Health and Human Habitation at the T.H. Chan School, Alwadi investigated whether living close to nuclear facilities impacts a population’s incidence of developing or dying from cancer. The work was motivated by a call from the Department of Public Health in Plymouth County, Massachusetts. Community members were concerned about rising cancer cases, and some wondered whether Plymouth’s Pilgrim Nuclear Power Station, decommissioned in 2019, might have contributed to the uptick.

“We get emails from families, saying that big percentages of people they know get cancer. But of course, these are anecdotal, so it needs hard science and statistical evidence to see if that actually happens or not,” Alwadi says.

As an environmental epidemiologist, Alwadi decided to investigate. “We wanted to know, are we going to find an association between the proximity to plants and cancer or not?” Alwadi says. Regardless of the outcome, he would share his findings.

Alwadi conducted a longitudinal ecological study, comparing Massachusetts zip codes’ proximity to the seven nuclear facilities in the vicinity of the state with that zip codes’ cancer incidence over time (provided by the state’s cancer registry). He used proximity as a proxy for exposure because it encompasses multiple routes of dispersal, like air and water. “We know that distance is a proxy for most [exposure routes]. It's not perfect for any one of them, but a proxy for most,” Alwadi says.

Alwadi discovered a strong association between cancer incidence and proximity to plants for populations over 55 years old living within 5 km of a nuclear power plant. For example, women ages 65-74 living two km away from a nuclear power plant had 2-times higher relative risk of cancer, and men in this age group had 1.75-times higher risk.

To determine whether these results were more broadly generalizable to the United States, Alwadi conducted a similar study comparing nuclear power plant proximity to county-level data on cancer mortality from the US Centers for Disease Control. “We felt that doing [the analysis] nationally would give us enough statistical power to depict effects if they truly exist,” says Alwadi. He discovered that the association he observed in Massachusetts held at the national level, too. “We observe the same association, similar values, same decline of risks with distance across different aggregations, zip codes versus counties . . . for cancers of interest.”

Koutrakis says that his advisee’s research is notable because it is the first series of studies to systematically demonstrate associations between residential proximity to nuclear power plants and cancer outcomes across multiple settings using large, population-based datasets. “This work fills a critical gap in the literature by providing large-scale, systematic evidence on a question that has remained unresolved for decades.”

“[Alwadi’s] results—which suggest that those living close to commercial plants face elevated cancer risks due to emissions from routine operation—are provocative and highly controversial,” says John Evans, retired professor of environmental health at the T.H. Chan School and a co-author on the study. “They are provocative because, since the inception of commercial nuclear power, it has been assumed that routine operations posed essentially no risk and that for public health the relevant issue was the possibility of accidental releases, like those at Chernobyl and Fukushima.”

Importantly, while the study shows a robust association between nuclear plant proximity and cancer, the study’s design cannot determine whether that relationship is causal. “Although these are ecological designs that do not establish causality and are very hard to infer causality from their evidence, the systematic results and the consistency of the findings are exactly what you'd expect to find if a true underlying causal effect existed,” says Alwadi. By systematically demonstrating an association, Alwadi’s discovery provides the impetus for more detailed research to understand the nature of the link between nuclear power plants and cancer.

It might just be an association not causation, and we don't know quite how the incidence of cancer is increased, but it seems very plausible, doesn't it? 

Read about Dr Alwadi's path to Harvard in the second half of the article.