Does Proximity to Nuclear Power Plants Increase Cancer Risk?
New research finds correlation between disease and living close to a facility
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.
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.
–Yazan Alwadi
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.
[Alwadi’s] work fills a critical gap in the literature by providing large-scale, systematic evidence on a question that has remained unresolved for decades.
–Professor Petros Koutrakis
From Refugee Camp to Research
Alwadi grew up in a camp in Jordan, where his grandparents settled as Palestinian refugees. “I remember standing in very long lines with my grandmother to receive a bag of flour each week,” says Alwadi. “I understood that if I wanted to change my situation, I would have to do it through hard work and persistence.”
Alwadi attended school in the camp run by the United Nations Relief and Works Agency before moving to public schools for 11th and 12th grade. He dreamed of becoming an engineer. “I remember waking up to the sound of rain hitting the metal roof of my grandparents’ house, built from wood, asbestos, and iron cladding, and thinking that I wanted to build them a proper home one day,” he says.
To study engineering, he would have to score high on the Tawjihi, the national high school exam. He studied hard and ultimately achieved the highest score in his area, enabling him to pursue a bachelor’s degree in civil and structural engineering from the Jordan University of Science and Technology. Alwadi credits his grandmother as a major motivating force. “She constantly encouraged me and made me believe that I could become whatever I set my mind to,” he says. “She was central in shaping my work ethic and ambition.”
After graduating, Alwadi spent the next 10 years as an engineer at the oil and gas company, Petrofac. He rapidly climbed through the ranks and, by the end of his time with the company, managed a $4.2 billion construction project. “At some point, I had a team of 1,200 people. Changing ideas into action is the thing I used to do,” says Alwadi. Despite his success, he realized something was missing. “I wanted to leave, to do something that has an impact,” says Alwadi, “I don't want to just live for myself.” He decided to go back to school and study environmental engineering, building on his experience in the energy sector. “This seemed like the path where I can have the highest positive impact,” Alwadi says.
While presenting at a conference in Jordan, Alwadi met Harvard T.H. Chan professors John Evans and Marc Weisskopf. “After my presentation, I was introduced to them, and we had in-depth discussions about my ideas and their work. I remember really enjoying those conversations,” says Alwadi. Later, Evans taught a three-day course on risk assessment, and Alwadi attended and engaged actively, asking questions and sharing his ideas. Evans invited Alwadi to take the full course online. “After completing the final exam, he told me that I had achieved the highest score that year, including among PhD students at Harvard Chan. That experience helped open the door for my transition into public health,” says Alwadi.
With only one month left before the deadline, Alwadi applied to the PhD Program in Population Health Sciences at Harvard Griffin GSAS. “I saw all the amazing work [Evans and Weisskopf] were doing when they presented in Jordan, so it was a no-brainer for me,” he says. “I wanted to go beyond applying existing knowledge to developing new methods and contributing original work.”
When Alwadi was accepted into the program, he intended to study climate change and public health, drawing on his background in the energy sector. Then, Koutrakis invited him to a viewing and discussion of The San Onofre Syndrome, a documentary about the mismanagement of radioactive waste and its impact on the health and safety of local communities in Southern California. “He completely changed my view of what I wanted to do for my PhD,” Alwadi says. “He said, ‘We need to help these people. Let’s figure out if they are affected or not.’”
I wanted to leave [industry], to do something that has an impact. I don't want to just live for myself.
–Yazan Alwadi
Alwadi joined the Koutrakis lab. Today, he calls the relationship with his mentor “the best thing about my PhD” and “a match made in heaven.” “I had Zoom calls with him for six to seven hours where we just brainstormed and coded and looked at data,” he says. “We still do.”
The efficiency and diligence Alwadi carried with him from his engineering career enabled him to complete his dissertation in only 22 months. “Moving from an idea to a paper is very natural for me because of the experience,” he notes.
Digging Deeper
Since graduation, Alwadi has continued his work in the Koutrakis lab as a postdoctoral fellow. Today, he tracks the relationship between nuclear facility proximity and cancer within individuals, rather than populations. He says this cohort analysis will provide stronger evidence for the nature of the association by reducing bias and clarifying the temporality of nuclear facility exposure to cancer development.
Ultimately, Alwadi hopes to lead a lab of his own in environmental epidemiology and public health. He’s got a plethora of questions he wants to tackle, so to him, it’s just a matter of time and resources to get the work done. “We see a signal, we keep digging,” he says.
