NTP Cell Phone Radiation Study: Final Reports
woensdag, 13 november 2019 - Categorie: Onderzoeken
23 okt. 2019
NTP Study: DNA damage found in rats and mice from 14-19 weeks of exposure to cellphone radiation
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.
The National Toxicology Program tested two common radiofrequency radiation (RFR) modulations emitted by cellular telephones in a 2-year rodent cancer bioassay that included interim assessments of additional animals for genotoxicity endpoints.
Male and female Hsd:Sprague Dawley SD rats and B6C3F1/N mice were exposed from gestation day 5 or postnatal day 35, respectively, to code division multiple access (CDMA) or global system for mobile (GSM) modulations over 18 hours per day, at 10 minute intervals, in reverberation chambers at specific absorption rates (SAR) of 1.5, 3, or 6 W/kg (Watts/kilogram) (rats, 900 MHz) or 2.5, 5, or 10 W/kg (mice, 1900 MHz). After 19 (rats) or 14 (mice) weeks of exposure, animals were examined for evidence of RFR-associated genotoxicity using two different measures. Using the alkaline (pH > 13) comet assay, DNA damage was assessed in cells from three brain regions, liver cells, and peripheral blood leukocytes; using the micronucleus assay, chromosomal damage was assessed in immature and mature peripheral blood erythrocytes.
Results of the comet assay showed significant increases in DNA damage in the frontal cortex of male mice (both modulations), leukocytes of female mice (CDMA only), and hippocampus of male rats (CDMA only). Increases in DNA damage judged to be equivocal were observed in several other tissues of rats and mice. No significant increases in micronucleated red blood cells were observed in rats or mice. In conclusion, these results suggest that exposure to RFR is associated with an increase in DNA damage.
The NTP bioassay was designed to evaluate non-thermal effects of cell phone RFR exposure, which meant that body temperature could not change more than 1 degree Centigrade under our exposure conditions .... Therefore, we consider it unlikely that thermal effects were a confounding factor for our genetic toxicity tests, although more work in general is needed to clarify the thermal effects of RFR on different tissues, and the degree to which increases in body or tissue temperature affect genomic integrity.
... our results and the results of other experiments suggest that non-thermal exposure of cells or whole organisms to RFR may result in measurable genotoxic effects, despite varied and weak responses across studies overall (Brusick et al., 1998; Ruediger, 2009; Verschaeve et al., 2010). Induction of oxygen radicals or interference with DNA repair processes have been proposed as possible mechanisms by which RFR could cause DNA damage (Ruediger 2009; Yakymenko et al. 2015).
... NTP Technical Reports on the results of the 2-year cancer bioassay for exposure to RFR for rats (TR 595) and mice (TR 596) were finalized, peer reviewed, and made publicly available in 2018. The NTP concluded that results demonstrated clear evidence of carcinogenic activity of cell phone RFR (both modulations) based on incidences of malignant schwannomas of the heart in male rats. Malignant gliomas in the brain were also observed in male rats exposed to cell phone RFR and were considered to be related to exposure. Female rats exhibited malignant schwannomas of the heart and malignant gliomas, but incidences of these tumors were considered equivocal. The observation that cell phone RFR affects heart and brain tissue in Sprague Dawley rats after long-term exposure was replicated in a similar study (that used only the GSM modulation) by the Ramazzini Institute (Falcioni et al., 2018). The gliomas and schwannomas observed in rats are similar to the tumor types reported in some epidemiology studies to be associated with cell phone use. The NTP bioassay findings in mice, in which different organs were affected compared to rats, were considered equivocal....
The highest exposure of 6 W/kg in rats and 10 W/kg in mice, for a total of 9 hours 10 minutes a day (achieved by cycling for 10 min on, 10 min off over 18 hours 20 minutes), produced higher exposures than experienced by humans under normal cellular phone use conditions. Thus, whether the findings in the NTP animal studies (e.g. malignant gliomas in the brain and malignant schwannomas in the hearts of male rats; increased levels of DNA damage in hippocampal cells of male rats and the frontal cortex of male mice) indicate a potential for adverse health outcomes in humans remains a question. Because one of the most important questions prompted by our results concerns the mechanism(s) by which RFR might induce biological effects, follow-up studies by the NTP to investigate mechanisms of genetic damage associated with RFR exposure are underway.
The Significance of Primary Tumors in the NTP Study of Chronic Rat Exposure to Cell Phone Radiation
The following paper by Dr. James C. Lin, Professor of Electrical Engineering, Professor of Bioengineering, and Professor of Physiology and Biophysics at the University of Illinois at Chicago, was published in the November issue of the IEEE Microwave Magazine. Dr. Lin was one of the 14 scientists selected by the National Institute of Environmental Health Sciences to perform the expert review of the $30 million cell phone radiation study conducted by the National Toxicology Program. Dr. Lin has received numerous professional awards and honors over the past four decades.
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.
Most media accounts of the U.S. National Toxicology Program's (NTP's) final report have understandably focused on the statistically significant finding of ''clear evidence'' that both GSM and code-division multiple access (CDMA)-modulated 900-MHz wireless RF radiation led to the development of malignant schwannoma, a rare form of tumor, in the hearts of male rats. In addition to this, unusual patterns of cardiomyopathy, i.e., damage to heart tissue, were observed in both RF-exposed male and female Sprague-Dawley rats compared with concurrent control animals, although the findings for female rats were deemed as providing only uncertain or ''equivocal'' evidence for schwannomas and malignant gliomas, compared to concurrent controls.
''A Closer Look at the NTP Findings
“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 1. 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 4.
In particular, the highest overall cancer (or malignant tumors) rates were found in male rats exposed to whole-body SARs of 3 W/kg from 900-MHz cell phone RF radiation (42 and 46% for GSM and CDMA, respectively), and the lowest rate was found in the concurrent control group (27%). Thus, the RF-exposed groups had significantly higher overall or total primary cancer rates than did the concurrent control rats. Moreover, the highest overall tumor rates (either a benign or malignant tumor in any organ or tissue) were observed in male rats exposed to SARs of 3-W/kg (87 and 84% for GSM and CDMA, respectively) cell phone RF radiation. As stated previously, the lowest rate was seen in the concurrent control group (63%). The RF-exposed groups had significantly higher overall tumor rates than did the concurrent control rats. Male rats in the lowest RF-exposed groups (whole-body SARs of 1.5 W/kg) had significantly higher rates of benign primary tumors (76 and 73% for GSM and CDMA, respectively) than did concurrent or sham control groups (54%).”
4 J. Moskowitz, “National toxicology program publishes final cell phone radiation study reports,” Electromagn. Radiation Safety, Nov. 2018. Online. Available: www.saferemr.com/2018/11/NTP-final-reports31.html
The International Agency for Research on Cancer (IARC) assessed the then available scientific literature and concluded that the epidemiological studies on humans that
had reported increased risks for malignant gliomas and acoustic neuromas among heavy or long-term users of cell phones were sufficiently strong to support a classification of 2B, i.e., possibly carcinogenic to humans 9. With its classification of RF radiation as a 2B carcinogen, the IARC suggested that it also believed the available scientific evidence was incomplete and limited, especially with regard to results from animal experiments.
“The time is right for the IARC to upgrade its previous epidemiology-based classification of RF exposure to higher levels in terms of the carcinogenicity of RF radiation for humans. Recently, two relatively well-conducted RF and microwave exposure studies employing the Sprague–Dawley strain of rats—without, however, using any cancer-promoting agents (or cocarcinogens)—showed consistent results in significantly increased total primary cancer or overall tumor rates in animals exposed to RF radiation.”
It is important to note that the recent NTP and Ramazzini animal RF exposure studies presented similar findings in heart schwannomas and brain gliomas. The increased schwannomas and abnormal heart tissue development/damage to heart tissue are significant findings in RF-exposed animal research studies. In addition to this, the incidence of benign pheochromocytomas of the adrenal medulla was found to be higher in the exposed group than in the sham controls for the 2,450-MHz circular waveguide experiment 6. Interestingly, in the recent NTP study, there was “some evidence” of carcinogenicity in the adrenal gland. The number of pheochromocytomas was significantly higher (p <0.05) in male rats at 1.5 and 3 W/kg, compared with the concurrent controls. Moreover, the increase in malignant tumor-like hyperplasia in the adrenal gland of female rats was significantly higher at 6 W/kg, relative to the concurrent controls (p <0.05).''
... It is important to note that the recent NTP and Ramazzini animal RF exposure studies presented similar findings in heart schwannomas and brain gliomas. The increased schwannomas and abnormal heart tissue development/damage to heart tissue are significant findings in RF-exposed animal research studies....
A particular perspective to keep in mind is that, with the induction of cancer by a carcinogen, an agent is typically considered carcinogenic if it induces a significant response in a specific tissue.”
November 1, 2018 (Updated: Nov 16, 2018)
The official summaries of the final reports of the National Toxicology Program (NTP) cell phone radiation studies, the NTP press release, and a new NTP fact sheet can be found below along with the FDA press release that addresses these studies.
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.
Following are my comments about the studies based primarily on the NTP's press release and media teleconference conducted on October 31.
The NTP final reports indicate that the NTP staff has accepted the peer review committee’s recommendations about the carcinogenicity of cell phone radiation. A summary of these recommendations can be found at: bit.ly/NTP180330.
Information about the NTP study and the peer review process is available at:
National Toxicology Program (NTP) Finds Cell Phone Radiation Causes Cancer
National Toxicology Program: Peer & public review of cell phone radiation study reports
Besides ''clear evidence'' (the highest category) of cancer in male rats from long term exposure to cell phone radiation, the NTP found degeneration in the hearts of male and female rats, decreased birth weights in rats exposed prenatally, and DNA damage in mice and rats as compared to sham controls.
Nonetheless, the NTP seems to be downplaying the significance of the results for public health of their $30 million cell phone radiation studies.
In my opinion, the results of the NTP cell phone radiation studies in conjunction with the results of the recent Ramazzini Institute study provide conclusive evidence that long term exposure to cell phone radiation causes DNA damage and cancer.
To follow up on the comments I submitted to the NTP in March, during the telebriefing yesterday, I asked whether the NTP conducted a statistical analysis of the overall tumor rates (across all organs) for each group. Dr. Bucher responded that there is a ''philosophical difference'' about whether to examine overall tumor risk in toxicology studies because the overall tumor rate is generally ''driven by common tumors.'' Thus, such an analysis is usually overly conservative (i.e., biased toward the null).
However, there is a precedent for conducting such an analysis in the NTP cellphone studies since the entire body of the animals was exposed to cellphone radiation. A 5-year, $5 million Air Force study found low incidences of many types of tumors in male rats exposed to microwave radiation (Chou et al, 1992). In that study, the exposed rats were three times more likely to get cancer than the control rats. The study employed much lower intensity microwave radiation than the NTP studies.
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.
Dr. Wyde's response to my question was that the overall tumor rates appear in Appendices A through D of the NTP final reports. Unfortunately, these results remain buried in the appendices when in my opinion they should be featured as key results of the study.
The data in the following tables were extracted from Tables A2 and C2 in the NTP final report on the 2-year rat study (pp. 149-150 and 203-204). The tumor rates across all organs for the male rats are tabled by exposure condition for GSM and CDMA cell phone radiation for benign tumors, malignant tumors, and for either type of tumors.
For the further remaining large part of the report see the link on top
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