Nuclear power plant workers report much higher rates of common cancers

Nuclear power plants run tight radiation monitoring programs, yet the question keeps coming up. Do many years of small workplace radiation doses still raise cancer risk?

In a new study, researchers followed 75,350 nuclear power plant workers and linked their individual dose histories to national cancer registries.

They found more cases of melanoma and prostate cancer than expected when compared with incidences in the general population. Melanoma is a serious form of skin cancer that starts in pigment-producing cells.

The researchers also found suggestive dose response patterns within the cohort. The analysis reported fewer lung cancers than expected, and a negative dose trend for that site, which the authors interpret cautiously.

What the cancer risk study did

The work was led by Paul J. Villeneuve of Carleton University. He analyzed incident cancers rather than deaths to capture outcomes with long survival and better timing. The participants were all workers at five Canadian nuclear power plants.

The team drew on personal monitoring records, called dosimetry, a system that tracks how much radiation a worker is exposed to over time. They tallied cumulative effective dose with a five-year lag to reflect disease latency.

The published research paper used a standardized incidence ratio (SIR) to compare observed cancer cases in a group to the number expected in the general population.

The results showed the SIR to be 1.31 for melanoma and 1.27 for prostate cancer. This means that observed cases were higher than expected, after adjusting for age, sex, and calendar period.

For internal dose response, the excess relative risk (ERR) was calculated. This is a measure showing how much cancer risk rises per unit of radiation exposure.

The results showed that the EER per 100 mSv (millisievert) was 0.32 for melanoma, 0.12 for prostate cancer, and −0.18 for lung cancer, with confidence limits that call for prudence.

Low-dose radiation cancer risk

People often think that only big, one time blasts of radiation drive cancer risk. Most workers receive small doses, year-after-year, so total exposure adds up over time.

In Canada, a typical nuclear worker receives about 1 millisievert per year, and that context matters for risk interpretation.

These workers mainly encounter external gamma rays, which are high-energy electromagnetic waves that can penetrate deeply into the body.

In addition, they experience small internal doses from tritium, a radioactive form of hydrogen used in heavy-water reactors.

The study’s design was centered on incidence rather than mortality. This helped separate detection from survival effects in cancers that are often caught early.

Higher prostate cancer and melanoma risk

The SIR for prostate cancer was elevated, and ERR estimates suggested higher risk with dose. This was especially noted among workers who were first exposed at age 55 or older.

That pattern might reflect biology tied to age, the higher baseline risk in later life, or differences in screening rates within the workforce.

Melanoma showed a higher SIR in people of all genders. It had a positive ERR that did not meet conventional thresholds for statistical significance.

The authors note that differences in skin type distribution, which they could not measure, could influence both the population comparison and the internal gradient.

This fits with other cancer risk evidence

Research on large, international cohorts has suggested similar conclusions concerning low-dose risk.

For example, the International Nuclear Workers Study (INWORKS) was a multinational investigation of radiation exposure and cancer in 300,000 workers.

It reported that mortality from solid cancers rose by about 52 percent per gray, a unit that measures absorbed radiation energy, lagged by 10 years.

Analyses of Japan’s atomic bomb survivors, who were exposed to extremely high radiation in 1945, now show a positive dose response for prostate cancer incidence, supporting a link at population scale.

Together, these results strengthen the case that long term, low dose exposures can matter for specific cancer sites.

“We wanted to strengthen the scientific basis for radiation protection by directly studying settings where low-dose exposures occur,” said David B. Richardson of the University of California, Irvine.

That perspective frames why country-specific cohorts like Canada’s are valuable, because practices, worker tasks, and radiation dose distributions differ by system. There is a broader push to sharpen the science behind protection at the low end of dose.

Incidence data and cancer risk

Incidence data – information about newly diagnosed cases rather than deaths – allow investigators to assign more realistic latency windows and to reduce bias from differences in treatment success.

That matters for prostate cancer, which has high survival rates. It is also important for melanoma, which can be caught early with skin checks.

The Canadian team also excluded very high cumulative radiation doses in internal models to focus on low dose ranges that are common today.

Quarters and years of badge readings let them build dose histories tied to job class and time, which helps detect patterns at the margins.

Caveats that should not be ignored

Lifestyle factors, such as smoking and alcohol consumption, were not recorded, and ethnicity was unavailable.

Those gaps limit the ability to adjust for confounding, the effect of outside factors that can make two unrelated things look connected.

For example, there is a strong link between smoking and lung cancer, and a connection between skin type and melanoma risk.

Screening can cut both ways. Workers might get more frequent tests than the general population, which can inflate SIRs for screen detected cancers like prostate cancer.

Internal dose response trends are less prone to that bias, yet they still depend on accurate dose and complete follow up.

Takeaways for workers and policy

The signals for prostate cancer and melanoma support routine, long-term surveillance programs to track disease trends in nuclear workforces.

It also argues for consistent, transparent tracking of dose. Further research is needed that folds in details on job tasks, shift patterns, and non-occupational exposures.

Results align with a cautious approach that keeps doses as low as reasonably achievable while supporting modern operations.

For workers, the main steps – steady monitoring, smart task planning, and shielding where needed – remain the backbone of protection.

Canada’s National Dose Registry is a federal database that tracks radiation exposure for workers across industries and employer changes.

That completeness is rare and gives analysts a clearer view in the low-dose range that matters most today.

The study points to a practical middle ground. Keep building evidence with incidence data, keep tracking low doses carefully, and keep worker health programs tuned to sites that show signals in the data.

The study is published in Occupational and Environmental Medicine.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–