Flawed “Validation” Studies Do Not Negate The Established Evidence…

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Flawed “Validation” Studies Do Not Negate The Established Evidence That Cell Phone Radiation Causes Cancer In Rats.

ICBE-EMF – 12aug2026.

A new paper published by experts of the International Commission on the Biological Effects of Electromagnetic Fields (ICBE-EMF) in Environmental Health finds that the Japanese and Korean animal studies do not prove cell phone safety, as they were underpowered and used too few exposure doses to legitimately challenge the U.S. National Toxicology Program’s landmark findings of increased cancer from long-term cell phone radiation exposure. Long-overdue policy changes to reduce public exposure are urgently needed.

BERKELEY, CA: A new peer reviewed paper published in the journal Environmental Health states that two industry-linked “validation” studies from Japan and Korea published in 2026, designed to verify the U.S. National Toxicology Program’s (NTP) finding that cell phone radiofrequency (RF) radiation causes cancer in rats, were so underpowered and narrowly designed such that they could never have confirmed or refuted the original results, regardless of the outcome. The authors state that these “validation” studies should not comfort the public when it comes to the safety of cell phones and other wireless devices.

The paper “Conflicting views in experimental carcinogenesis: A commentary on design and methodological deficiencies in the follow-up validation studies on radiofrequency radiation,” authored by Ronald L. Melnick (formerly of the National Institute of Environmental Health Sciences), Joel M. Moskowitz (University of California, Berkeley), and Paul Héroux (McGill University) on behalf of the International Commission on the Biological Effects of Electromagnetic Fields (ICBE-EMF), examines the design and interpretation of the Japan and Korea studies against long-standing scientific and regulatory standards for animal carcinogenicity testing.

Background

In 2011, the World Health Organization’s International Agency for Research on Cancer (IARC) classified RF radiation as “possibly carcinogenic to humans,” based largely on results from human epidemiological studies. In 2018, the National Toxicology Program, which is part of the U.S. Department of Health and Human Services, issued the final report of their $30 million animal studies concluding there is “clear evidence” that male rats exposed to cell phone (RF) radiation for two years developed malignant heart schwannomas, a rare tumor, along with “some evidence” of brain gliomas and adrenal tumors. The NTP study was designed to provide greater sensitivity than international guidelines for rigorous cancer-testing.

A study conducted by the Ramazzini Institute in 2018 reported increased tumors similar to those observed in the NTP. These new animal cancer findings, along with additional human studies, prompted the WHO/IARC advisory group to repeatedly recommend a new evaluation of the scientific evidence on the carcinogenicity of wireless radiation. Many scientists with expertise in environmental carcinogenicity then – published – their – conclusion that the current evidence is now consistent with IARC criteria for the classification of wireless RF radiation as a “probable human carcinogen” (IARC Group 2A), – or – even “carcinogenic to humans” (Group 1).

However, after the NTP study was released, new animal studies were launched in Japan and Korea, under an “International Validation Project,” aiming to test whether the NTP’s findings were reproducible. Their results, separately – published in 2026, concluded that long-term RF radiation exposure did not produce reproducible carcinogenic or genotoxic effects.

However, according to the new paper, the Japanese and Korean animal studies did not replicate the NTP study and had several deficiencies, including:

  • Severely Reduced Statistical Power: The follow-up studies used only 70 animals per group, compared to 90 per group in the NTP study. Power calculations indicate that detecting a significant response for rare tumors at the lower exposure level used in those studies would require many more animals per group.
  • Omission of High-Dose Groups: The follow-up studies tested only a single exposure level (4 W/kg) and dropped the NTP’s highest exposure level (6 W/kg), where significant carcinogenic effects were most statistically pronounced.
  • Violation of FDA and the Organization for Economic Co-operation and Development Guidelines: Testing guidelines by these groups require at least three different doses plus a control group to conduct a critical dose-response trend analysis. Single-dose studies eliminate the ability to detect dose-dependent trends.
  • Overlooked Signals of Harm: Despite being underpowered, the Korean study actually observed a 3% incidence rate of heart schwannomas in exposed rats (versus 0% in controls), matching the tumor rate observed at 3 W/kg in the NTP study, yet the researchers surprisingly dismissed the finding.
  • Prominent Role of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and Industry-Friendly Advisors: The project’s principal investigator was an ICNIRP member, and the advisory committee overseeing the research was heavily composed of current and former ICNIRP members, several of whom have served as industry consultants. The Japan/Korea studies were aimed at protecting ICNIRP’s current cell phone radiation safety limits rather than at documenting radiation risks.

The authors of the new analysis conclude that the Japan and Korea studies’ conclusion of “no reproducible carcinogenic potential” of cell phone radiation is simply not supported by the studies’ design and, in the case of the Korean study, is undercut by its own data. Therefore, the Japan and Korea studies do not alter the National Toxicology Program’s finding of “clear evidence” of cancer.

In a paper published earlier this year, Melnick and Moskowitz concluded that, based on the NTP cancer findings, current FCC and ICNIRP exposure limits would need to be at least 200 times lower to protect against cancer risk from 8 hours of daily exposure. The International Commission on the Biological Effects of Electromagnetic Fields is calling on governments to implement policies that reduce public exposure and inform cell phone users on how to minimize their risk.

Ronald L. Melnick, PhD, lead author and retired toxicologist at the National Institute of Environmental Health Sciences, who led the design of the original NTP radiofrequency radiation studies:

“The Japan and Korea studies cannot be used as proof of safety. To properly verify a study that found clear evidence of rare tumors like heart schwannomas, follow-up research must be designed with equal or greater sensitivity. By dropping the highest exposure level, testing only a single dose, and using fewer animals, these follow-up underpowered studies failed to meet basic FDA and OECD testing guidelines and were systematically biased toward finding no significant effect. These studies appear to be engineered to come back negative, no matter what the true biology is.

In short, the Japan and Korea studies cannot be used to invalidate the National Toxicology Program’s peer-reviewed findings of carcinogenicity or to justify the FCC’s and ICNIRP’s thermal-based exposure limits.”

Joel M. Moskowitz, PhD, School of Public Health, University of California, Berkeley, whose research focuses on the public health implications of wireless radiation exposure:

“Millions of people carry cell phones against their bodies for hours a day, and children are being exposed over far longer lifetimes than any generation before them. Public health decisions about safety limits should be built on the most rigorous animal evidence available, not on studies constructed in a way that was unlikely to detect harm even if it exists. We cannot allow flawed experimental designs to shield outdated safety guidelines from necessary, health-protective revisions. The scientific evidence on cancer and other biological effects is sufficient to warrant policies to reduce exposure.”

Dr. Paul Héroux, Department of Epidemiology, Biostatistics and Occupational Health, McGill University:

“These studies did not reproduce the original methodology, exposure assessment, or study conditions. From a biostatistical perspective, testing only 70 animals at a single dose level leaves a study severely underpowered to detect rare carcinogenic events. Without multiple dose groups and adequate sample sizes, finding ‘no statistically significant effect’ is an artifact of poor study design rather than evidence of safety. Importantly, when the NTP and Korean and Japanese studies are considered together, the overall evidence confirms cancer risk.”

Implications for Public Policy and Public Health

The authors state that governments have a responsibility to protect public health by ensuring that exposure limits for cell phone and cell tower radiation are based on the strongest available scientific evidence, not on studies that lack the scientific rigor necessary to detect known hazards. They conclude that the Japanese and Korean follow-up studies cannot be relied upon to dismiss the U.S. National Toxicology Program’s findings or to delay protective action. Before negative validation studies can be interpreted as evidence against the NTP’s findings, they must match or exceed the original study’s design, including the same animal model, exposure regimen, adequate group sizes, multiple exposure levels, and sufficient statistical power. Accordingly, they state that the WHO’s International Agency for Research on Cancer (IARC) and regulatory agencies should base hazard evaluations and public health policies on the strongest available evidence.

ICBE-EMF maintains that current U.S. and ICNIRP exposure limits for cell phones, Wi-Fi, smart meters, and cell towers are not adequately protective because a substantial body of research reports cancer and other biological effects, including DNA damage, oxidative stress, neurological effects, and reproductive harm. The Commission calls on governments to halt the rollout of new wireless technologies until independent safety assessments are completed and to adopt policies that reduce RF radiation exposure risks.

Scientific reference:

Melnick, R.L., Moskowitz, J.M., Héroux, P. et al. Conflicting views in experimental carcinogenesis: a commentary on design and methodological deficiencies in the follow-up validation studies on radiofrequency radiation. Environ Health 25, 66 (2026). https://doi.org/10.1186/s12940-026-01324-5 .

Conflicting views in experimental carcinogenesis: a commentary on design and methodological deficiencies in the follow-up validation studies on radiofrequency radiation. Environ Health

Read the Press Release at ICBE-EMF

More ICBE-EMF Resources

ICBE-EMF has written several scientific letters to policymakers, issued position statements, convened press conferences, and filed numerous scientific comments in government proceedings internationally.

Sources – ICBE-EMF – NewsEmail / Press release – Flawed “Validation” Studies Do Not Negate the Established Evidence That Cell Phone Radiation Causes Cancer in Rats, Scientists Conclude