Expert Reaction to Rodney Crofts Criticism of the National Toxicology Program Findings
Dr. Rodney Croft, Director of the Australian Centre for Electromagnetic Bioeffects Research at the University of Wollongong has stated a “number of criticisms” to the findings of the National Toxicology Program study. His criticisms included his statements “that the rats treated with RF lived longer than the controls…the controls did not have ‘any’ tumours… and the lack of clear dose-response relationships. He concluded that “the NTP report does not provide reason to move from the current scientific consensus that mobile phone-like exposure does not impact health.” Read Rodney Croft’s Reaction to the NTP here.
January 3, 2018: Dr. Ron Melnick has provided a response to the comments made by Rodney Croft.
Dr. Rodney Croft states, “rats treated with RF lived longer than the controls”
Dr. Ronald Melnick responds:
“Actually, there was no statistical difference in survival between control male rats and the exposure group with the highest rate of gliomas and heart schwannomas (CDMA-exposed male rats, SAR= 6.0 W/kg). Also, no glial cell hyperplasias (potential precancerous lesions) or heart schwannomas were observed in any control rat, even though glial cell hyperplasia was detected in RF-exposed rats as early at week 58 of the 2-year study and heart schwannomas were detected as early as week 70 in exposed rats. Thus, survival was sufficient to detect tumors or pre-cancerous lesions in the brain and heart of control rats.
Dr. Rodney Croft states “controls did not have ‘any’ tumors”
Dr. Ronald Melnick responds:
“Control rats did have tumors (63% of males and 92% of control female rats); however, the tumor responses associated with exposure to RF (gliomas and schwannomas of the heart) were not detected in controls. Gliomas and schwannomas of the heart are uncommon tumors that occur rarely in control Sprague-Dawley rats. It is not unusual to observe a zero incidence of uncommon tumors in groups of 50-90 control rats. The most important control group in an experimental study is the concurrent control group.
Dr. Rodney Croft states “lack of dose-response relationships”
Dr. Ronald Melnick responds:
“Actually, significant positive trends were found for gliomas in male rats exposed to CDMA-modulated RF radiation and for heart Schwannomas in male rats exposed to GSM or CDMA-modulated RF.”
Dr. Rodney Croft states “one significant result would appear consistent with chance”
Dr. Ronald Melnick responds:
“There was much more than one significant result. In addition to the significant trends, the incidence of heart Schwannomas was increased significantly in male rats exposed to either GSM and CDMA-modulated RF radiation. In addition, the incidences of gliomas plus glial cell hyperplasias and Schwannomas plus Schwann cell hyperplasias (hyperplasias are proliferative preneoplastic lesions) were increased significantly with both GSM and CDMA-modulated RF radiation.”
Dr. Rodney Croft states “results do not appear consistent with cancer rates within the human population, nor with the majority of other experimental research”
Dr. Ronald Melnick responds:
“In 2011, IARC classified radio frequency radiation as a “possible human carcinogen” based largely on increased risks of gliomas and acoustic neuromas (which are Schwann cell tumors on the acoustic nerve) among long term human users of cell phones. The concordance between rats and humans in cell type affected by RF radiation strengthens the animal-to-human association. Thus, the animal data show much consistency with available human data.”
Dr. Rodney Croft states “the very high exposure levels, which are many times higher than humans are exposed to”
Dr. Ronald Melnick responds:
“This statement misrepresents risk to the brain from the whole-body exposures used in the NTP study. While the exposure limit to RF radiation in the US is 0.08 W/kg averaged over the whole body, the localized exposure limit is 1.6 W/kg averaged over any one gram of tissue. Body tissues located nearest to the cell phone antenna receive much higher exposures than tissues located distant from the antenna. Thus, when an individual uses a cell phone and holds it next to his or her head, exposure to the brain will be much higher than exposures averaged over the whole body. When considering organ-specific risk (e.g., risk to the brain) from cell phone RF, the important measure of exposure is the SAR value of 1.6 W/kg averaged over any gram of tissue. In the NTP study in which animals were exposed to whole-body RF at SARs of 1.5, 3, and 6.0 W/kg, exposures in the brain were within 10% of the whole-body exposure levels. Therefore, in the NTP study, exposure intensities in the brain of rats were similar to or only slightly higher than localized human exposures from cell phones held next to the head.”
I hope these comments are helpful and clarify misunderstandings about the NTP study that have been promoted by individuals with limited knowledge about the interpretation of such studies.
Best regards,
Ronald Melnick PhD
Dr. Ronald L. Melnick is Senior Advisor To the Environmental Health Trust and has served as a toxicologist for 28+ years at the National Institute of Environmental Health Sciences (NIEHS) and the National Toxicology Program (NTP), before retiring in 2009. At NTP/NIEHS, Dr. Melnick was involved in the design, monitoring and interpretation of toxicology and carcinogenesis studies of numerous environmental and occupational agents including 1,3-butadiene, chloroprene, isoprene, water disinfection byproducts, etc. He led the design of the NTP carcinogenicity studies of cell phone radiofrequency radiation in rodents. In addition, his research has focused on the use of mechanistic data in assessing human health risks of environmental chemicals. He was manager of the NIEHS Experimental Toxicology Unit, Carcinogenesis and Toxicology Evaluation Branch, and group leader of the NIEHS Toxicokinetics and Biochemical Modeling Group, in the Laboratory of Computational Biology and Risk Analysis. He has served on numerous scientific review boards and advisory panels, including those of the International Agency for Research on Cancer (IARC) and the U.S. Environmental Protection Agency. He is a fellow (emeritus) of the Collegium Ramazzini. Dr. Melnick is the recipient of the American Public Health Association’s 2007 David P. Rall Award for science based advocacy in public health.
EHT has collected several expert responses to critical statements concerning the NTP findings.
Please see these relevant resources for more information.
NTP: Cell Phone RF Breaks DNA, Consistent with Higher Tumor Counts, 20 Years After Landmark Lai-Singh Study, Microwave News
Dr. Joel Moskowitz 0fUC Berkeley, Storyline vs. Rest-of-the-story: Brain cancer incidence, cellphone use & trends data
Myth Fact on the National Toxicology Program Study of Radio Frequency Radiation
Click on the Myth and Misleading criticisms of the NTP study to get the Facts.
Myth 1: The rats radiation exposure was far too high to be relevant to human health.
Myth 2: Rat research does not relate to human health risk.
Myth 3: The National Toxicology Program study is just a small “single rat study.”
Myth 4: The study was underpowered and statistically unable to detect a true effect.
Myth 5: Cancer rates were only increased in the male rats, not the females.
Myth 6: The control group should have developed cancer at the usual rate.
Myth 7: The NTP study shows our cell phones which emit a “safe” level of radiation.
Myth 8: The control group did not live long enough to develop tumors.
Myth 9: Other effects from exposure like decreased birthweight are trivial and irrelevant.
Myth 10: The results are weak and confounding.
Myth 11: It makes no sense that CDMA exposed rats had a different response than GSM exposed rats.
Myth 13: Previous animal research has not shown a cancer link.
Myth 14: There is no human evidence linking brain and heart tumors to cell phones.
Myth 16: The lack of an epidemic of brain cancer demonstrates that cell phones pose no risk.
Myth 18: NIH’s own reviewers could not accept the study conclusions.
Myth 19: The New York Times review of the NTP study proves the study is bad.
Myth 20: The NTP study has been fully discredited by scientists due to major flaws.
Myth 21: This study needs to be replicated before we believe it.
Myth 23: The NTP study was not peer reviewed and was rejected by medical journals.
