NTP Summary: https://www.niehs.nih.gov/health/materials/cell_phone_radiofrequency_radiation_studies_508.pdf
Smith-Roe SL, Wyde ME, Stout MD, Winters JW, Hobbs CA, Shepard KG, Green AS, Kissling GE, Shockley KR, Tice RR, Bucher JR, Witt KL. Evaluation of the genotoxicity of cell phone radiofrequency radiation in male and female rats and mice following subchronic exposure. Environ Mol Mutagen. 2019 Oct 21. doi: 10.1002/em.22343.
Lin JC. The Significance of Primary Tumors in the NTP Study of Chronic Rat Exposure to Cell Phone Radiation [Health Matters]. IEEE Microwave Magazine. 20(11):18-21. Nov 2019. DOI:10.1109/MMM.2019.2935361.
“In all fairness, the primary cancer or overall cancer rates detected in any organ or tissue inside the animal body do not appear to have been purposefully overlooked or unnoticed. Indeed, the results for total primary cancer or tumor occurrences in NTP animal studies can be found in the appendices of its final reports . However, although the data may not have been purposefully disregarded or ignored, the NTP excluded them from its publicized report summaries. An independent analysis of the data showed that rats exposed to GSM and CDMA RF radiation had significantly higher overall or total primary tumor rates than did the concurrent control rats .
 J. Moskowitz, “National toxicology program publishes final cell phone radiation study reports,” Electromagn. Radiation Safety, Nov. 2018. [Online]. Available: https://www.saferemr.com/2018/
November 1, 2018 (Updated: Nov 16, 2018)
In 1999, the U.S. Food and Drug Administration (FDA) asked the NTP to conduct cell phone radiation studies on animals.The FCC's exposure guidelines for cell phone radiation adopted in 1996 and still in effect today were designed to protect humans from thermal (or heating) effects. However, scientists at that time were concerned that low level exposures could increase cancer risk through nonthermal mechanisms. This was the basis for the FDA's request to the NTP in 1999:
"The existing exposure guidelines are based on protection from acute injury from thermal effects of RFR exposure, and may not be protective against any non-thermal effects of chronic exposures. Animal exposure research reported in the literature suggests that low level exposures may increase the risk of cancer by mechanisms yet to be elucidated, but the data is conflicting and most of this research was not conducted with actual cellular phone radiation."Nineteen years later on November 1, 2018, the NTP published the final reports on the effects of two-years of exposure to 2G (GSM and CDMA) cell phone radiation on rats and mice. Since these studies utilized radiation levels that would not induce significant heating (greater than one degree Centigrade), any observed effects would be due to nonthermal mechanisms (e.g., oxidative stress).
The NTP final reports found "clear evidence" of increased cancer risk in male rats from low level (i.e., nonthermal) exposures (c.f., heart schwannoma). Furthermore, many hundreds of peer-reviewed studies have found evidence of biologic and health effects from low level exposures to cell phone radiation. Hence, the FCC's exposure guidelines must be re-assessed as they are likely inadequate to protect human health.
Information about the NTP study and the peer review process is available at:
National Toxicology Program (NTP) Finds Cell Phone Radiation Causes Cancer
We should learn from our colleagues who study tobacco research. Early toxicology research on the effects of tobacco found low incidences of many types of tumors among animals exposed to tobacco smoke. Scientists dismissed this evidence because they assumed an agent could not cause cancer in different types of tissue. History later proved them wrong.
The highest cancer rates (i.e., malignant tumors) were found in male rats exposed to 3 watts per kilogram of either GSM (42%) or CDMA (46%) cell phone radiation and the lowest rate was found in the sham control group (27%). Here too, the exposed groups had significantly higher overall cancer rates than the sham controls.
Ramazzini Institute Cell Phone Radiation Study Replicates NTP Study
5G Wireless Technology: Millimeter Wave Health Effects
National Toxicology Program. NTP technical report on the toxicology and carcinogenesis studies in Hsd:Sprague Dawley SD rats exposed to whole-body radio frequency radiation at a frequency (900 MHz) and modulations (GSM and CDMA) used by cell phones. NTP TR 595. Research Triangle Park, NC. November, 2018. https://www.niehs.nih.gov/ntp-temp/tr595_508.pdf
For future studies, NTP is building smaller RFR exposure chambers that will make it easier to evaluate newer telecommunications technologies in weeks or months, rather than years. These studies will focus on developing measurable physical indicators, or biomarkers, of potential effects from RFR. These may include changes in metrics like DNA damage in exposed tissues, which can be detected much sooner than cancer.
According to NTP Report (NTP TR 595, p. 25):
"The FDA does not currently regulate the use of wireless communications devices or the devices themselves. The FDA also does not require safety evaluations for radiation-emitting wireless communication devices. It does maintain the authority to take regulatory action if it is demonstrated that exposure to the emitted cell phone RFR from these devices is hazardous to the user."Dr. Bucher, an NTP senior scientist and former associate director, stated in the NTP's press release (Nov 1, 2018), "We believe that the link between radio frequency radiation and tumors in male rats is real, and the external experts agreed.”
Nonetheless, the FDA dismissed the NTP results in its press release. FDA Center Director, Dr. Shuren, stated “these findings should not be applied to human cell phone usage ... we believe the existing safety limits for cell phones remain acceptable for protecting the public health.”
This is rather odd since the FDA requested that the NTP conduct these animals studies in 1999 because the agency was concerned that the FCC's cell phone "safety limits" did not protect human safety since the limits were based on a thermal model. Now that we have hundreds of animal studies demonstrating non-thermal biologic effects and several major epidemiologic studies demonstrating increased cancer risk in heavy cell phone users, FDA should be more concerned than ever that the FCC exposure guidelines are inadequate.
"We know that cell phones are an important, everyday tool to most Americans. We use them now for much more than just talking—from booking travel on an app to using mobile wallets to pay for groceries. Our ubitquitious use of cell phones inevitably means that we must continue to review and ensure their safety.
The Food and Drug Administration is charged with ensuring cell phones— and any radiation-emitting electronic product—are safe for the public to use. Our scientific expertise and input, along with other health agencies, are used by the Federal Communications Commission (FCC) to set the standards for exposure limits of radiation from cell phones, called radiofrequency energy.
We have relied on decades of research and hundreds of studies to have the most complete evaluation of radiofrequency energy exposure. This information has informed the FDA’s assessment of this important public health issue, and given us the confidence that the current safety limits for cell phone radiofrequency energy exposure remain acceptable for protecting the public health.
When new studies or information becomes available, the FDA conducts thorough evaluations of the data to continually inform our thinking. We reviewed the recently finalized research conducted by our colleagues at the National Toxicology Program (NTP), part of the National Institute of Environmental Health Sciences within the National Institutes of Health, on radiofrequency energy exposure. After reviewing the study, we disagree, however, with the conclusions of their final report regarding “clear evidence” of carcinogenic activity in rodents exposed to radiofrequency energy.
In the NTP study, researchers looked at the effects of exposing rodents to extremely high levels of radiofrequency throughout the entire body. This is commonly done in these types of hazard identification studies and means that the study tested levels of radiofrequency energy exposures considerably above the current whole body safety limits for cell phones. Doing this was intended to help contribute to what we already understand about the effects of radiofrequency energy on animal tissue. In fact, we only begin to observe effects to animal tissue at exposures that are 50 times higher than the current whole body safety limits set by the FCC for radiofrequency energy exposure.
Our colleagues at NTP echoed this point in a statement earlier this year about their draft final report, including the important note that “these findings should not be directly extrapolated to human cell phone usage.”
We agree that these findings should not be applied to human cell phone usage.
NTP hosted a three-day peer review of this study in March, as part of their normal process for issuing scientific reports. The FDA was not a participant in that process, but was invited to observe the panel discussions, which included an assessment of the study methods and data by a panel of 15 peer reviewers to determine the basis of evidence for the final report. Based on their assessment, the panel voted to upgrade the conclusions from some evidence to clear evidence for malignant heart schwannomas in male rats, and from equivocal (ambigious) to some evidence for malignant gliomas of the brain and benign tumors of the adrenal gland in male rats. It’s important to note that the vote does not mean new data or findings were reported in the final assessment.
In addition, as we’ve noted previously, there were unusual findings in the study, such as: the rats exposed to whole body radiofrequency energy lived longer than rats that were not exposed to any radiation (control group); only male rats exposed to the highest radiofrequency energy dosage developed a statistically significant number of heart schwannomas, which are very rare in humans, when compared to the control group in this experiment. There was also no true dose response, or a lack of a clear relationship between the doses of radiation administered to the animals and their subsequent tumor rate.
Researchers will need to consider all of the findings when exploring future human epidemiological studies.
As scientists, we welcome new studies. Animal studies like this one contribute to our discussions on this topic, but we must remember the study was not designed to test the safety of cell phone use in humans, so we cannot draw conclusions about the risks of cell phone use from it. We also must thoroughly evaluate and take into consideration the totality of the data, and do so within the context of the complete body of evidence rather than drawing conclusions from the results of a single study.
As part of our commitment to protecting the public health, the FDA has reviewed, and will continue to review, many sources of scientific and medical evidence related to the possibility of adverse health effects from radiofrequency energy exposure in both humans and animals and will continue to do so as new scientific data are published.
Based on our ongoing evaluation of this issue, the totality of the available scientific evidence continues to not support adverse health effects in humans caused by exposures at or under the current radiofrequency energy exposure limits. We believe the existing safety limits for cell phones remain acceptable for protecting the public health.
The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, products that give off electronic radiation, and for regulating tobacco products."