Study finds increased risks of tumors from long-term use of cellular phones
English Language Press Release, Feb 20, 2021
By Professor Seung-Kwon Myung, MD, PhD, Dean of National Cancer Center Graduate School of Cancer Science and Policy, South Korea (Corresponding author)
- Meta-analysis led by Prof. Seung-Kwon Myung of National Cancer Center in Korea in collaboration with research teams from Seoul National University and UC Berkeley
- A new research finding showed if you use a cellular phone longer, then the risks of benign and malignant tumors would increase.
- The National Cancer Center in Korea announced this finding from the meta-analysis of case-control studies published from 1999 to 2015, which was conducted by Professor Seung-Kwon Myung (Dean of the National Cancer Center Graduate School of Cancer Science and Policy; MD, PhD, Board-certified Family Physician) in collaboration with research groups from the Department of Preventive Medicine, Seoul National University (Professor Yun-Chul Hong and Dr. Yoon-Jung Choi) and the Center for Family and Community Health, School of Public Health, University of California, Berkeley (Director, Dr. Joel M. Moskowitz).
- The research team led by Prof. Seung-Kwon Myung performed a meta-analysis of a total of 46 case-control studies searched from the two databases, PubMed and EMBASE. In the meta-analysis of all studies, compared with never or rarely having used a cellular phone, regular use was not associated with tumor risk in the random-effects meta-analysis. However, in the subgroup meta-analysis by research group, there was a statistically significant positive association (harmful effect) in the Hardell et al. studies (odds ratio* = 1.15, 95% confidence interval = 1.00 to 1.33), a statistically significant negative association (beneficial effect) in the INTERPHONE-related studies (multi-national case-control studies coordinated by the International Agency for Research on Cancer; odds ratio = 0.81, 95% confidence interval = 0.75 to 0.89), and no statistically significant association in other research groups’ studies. Further, cellular phone use with cumulative call time more than 1,000 hours statistically significantly increased the risk of tumors (odds ratio = 1.60, 95% confidence interval = 1.12 to 2.30). This comprehensive meta-analysis of case-control studies found evidence that linked cellular phone use to increased tumor risk.
- In 2009, Prof. Seung-Kwon Myung, the lead author of the new study already reported that the use of cellular phones could increase the risk of tumors in the meta-analysis of 23 case-control studies published in Journal of Clinical Oncology, which is one of the top scientific journal in the oncology field. Since then, the World Health Organization/International Agency for Research on Cancer (IARC) has classified radiofrequency electromagnetic fields (EMFs) as "possibly carcinogenic to humans" (Group 2B) based on the evidence from literature. This recent research updated the findings from the meta-analysis of subsequently published observational studies for another 10 years.
- “This study supports the research findings from several laboratory studies and animal studies that exposure to radiofrequency electromagnetic fields (EMFs) emitted from cellular phones (ranging from 800 to 2,000 MHz, which fall in the microwave spectrum) promote the development of cancer,” said Prof. Myung.
- “When we combined all 46 studies, there was no association between the use of cellular phone use and the risk of tumors. Interestingly, however, when we performed the subgroup analysis by type of study group, different findings were obtained. All of the published studies for the past 20 years can be classified into three groups: Hardell et al’s studies from Sweden, the INTERPHONE studies (multi-national case-control studies coordinated by WHO/IARC), and other studies. In the subgroup meta-analysis by type of study group, Hardell et al’s studies showed a harmful effect of cellular phone use on tumor risk, the INTERPHONE studies appeared to have a beneficial effect, and other studies found no significant association,” stated Prof. Myung regarding the different findings by study group.
- “We identified that the reasons for the discrepancies in findings among the study groups were related to the quality of the study (high vs. low), difference in response rates of study participants to a research questionnaire (smaller vs. larger, by about 15%), and funding sources (cellular phone industry funding vs. not funded). The Hardell studies were not funded by the cellular phone industry, mostly had high quality, mostly reported high response rates (>70%) with smaller differences in response rates between the case group and the control group. On the contrary, all of the INTERPHONE studies were partly funded by the cellular phone industry (precisely, supported by funding from the International Union against Cancer, which received funds from the Mobile Manufacturers’ Forum and Global System for Mobile Communications Association) except for the INTERPHONE-Japan studies; most studies had low quality and larger differences in response rates between the case group and the control group. Thus, Hardell et al’s findings that cellular phone use increases tumor risk are more plausible than those from the INTERPHONE studies,” explained Prof. Myung.
- “This meta-analysis included only case-control studies, which might have some important biases such as selection bias and recall bias leading to a distortion of facts. Thus, we need to confirm our findings through further prospective cohort studies giving us a higher level of evidence. Nevertheless, based on the ‘precautionary principle’, until the harms of cellular phone use are confirmed in the future, I recommend to use a cellular phone less, avoid its use in elevators and cars where electromagnetic waves are emitted a lot, and use wired earphones or earbuds or keep your cellphone at least 2-3 centimeters or 1 inch away from your head,” emphasized Prof. Myung.
- This research was published in the journal, International Journal of Environment Research and Public Health in November, 2020.
- Article link: http://bit.ly/cellphonetumor
*Odd ratio and 95% confidence interval: An odds ratio is a statistic that quantifies the strength of the association between two events, A and B. In this study, A is ‘use of cellular phones’, and B is ‘risk of tumors’. If the odds ratio is greater than 1, the use of cellular phones increases the risk of tumors. If the odds ratio is less than 1, the use of cellular phones decreases the risk of tumors. If a 95% confidence interval includes ‘1’, it means that there is no statistically significant difference, whereas if it doesn’t include ‘1’, it means that there is a statistically significant difference. For example, because 95% confidence intervals from both Hardell et al and the INTERPHONE studies don’t include ‘1’ (1.00 from Hardell et al’s confidence interval is actually 1.00x, which is greater than 1), there is a statistically significant difference, which means that their odds ratios indicate statistically significantly increased or decreased risks of tumors, respectively.
Song Soo-yeon, Youth Doctor Newsletter, February 15, 2021 (Google translation from Korean)
Research shows that using a mobile phone for a long time increases the risk of developing cancer such as brain tumors.
Prof. Seung-Kwon Myung (President of Graduate School) of National Cancer Center, Professor of Preventive Medicine, Seoul Medical University, and Joel Moskowitz, Director of Center for Family and Community Health, UC Berkeley School of Public Health. It was revealed on the 15th that the meta-analysis of 46 case-control studies published in international journals from 1999 to 2015 revealed the result.
As a result of a meta-analysis of 46 research papers through literature search in the major medical databases, PUBMed and EMBASE, the researchers found the relationship between people who use mobile phones and those who do not did not make a big difference.
However, the results of detailed meta-analysis by major research groups and qualitative levels were different. Sweden's Hardell team, who published the most research on the subject, announced that the use of mobile phones increases the risk of developing tumors.
Professor Myung, who led the study, emphasized, "This study supports the results of some laboratory and animal studies that show that high-frequency electromagnetic fields (frequency 800-2000 MHz) exposed when using mobile phones can accelerate cancer development."
He said, “As a result of analyzing the reasons for the differences in the results of each research team, it was possible to confirm that the quality of the research, the response rate of the research subjects, and the availability of research funding from the mobile phone company were important factors.” The quality of the study is high, there is little difference in response rate between the patient group and the control group, while research funding is not provided from a mobile phone company, a multinational interphone study organized by the International Cancer Research Organization (IARC) under the World Health Organization The team's research was of low quality, there was a lot of difference in response rate, and the research funding was provided by mobile phone companies.”
He said, “The results of the Hardell research team's research that the use of mobile phones increases the risk of tumors can be interpreted as more convincing,” he said. “Moreover, regardless of the research team, the case of using a mobile phone for more than 1,000 hours* the tumor risk was statistically significantly higher (interval ratio 1.60, 95% confidence interval 1.12-2.30)”.
He continued, “Even before the dangers of cell phones are clearly identified, we recommend that you refrain from using cell phones for a long period of time based on the precautionary principle. It is necessary to reduce the use, and when using a mobile phone, keep it 2~3 centimeters away from the face and use earphones with wires as much as possible.”
The research results were published in the November 2020 issue of the International Journal of Environmental Research and Public Health, an international academic journal of SCIE.
A review of research on cell phone use and tumor risk found that cell phone use with cumulative call time more than 1000 hours significantly increased the risk of tumors.
(Berkeley, CA, November 2, 2020) Today, the International
Journal of Environmental Research and Public Health published a
systematic review and meta-analysis of the case-control research on cell phone use and tumor risk.
This study updates our original meta-analysis
(i.e., quantitative research review)
published in the Journal of Clinical Oncology in 2009. The new review examined twice as many studies as our original paper.
"In sum, the updated comprehensive meta-analysis of case-control studies found significant evidence linking cellular phone use to increased tumor risk, especially among cell phone users with cumulative cell phone use of 1000 or more hours in their lifetime (which corresponds to about 17 min per day over 10 years), and especially among studies that employed high quality methods."
The abstract and excerpts from this open access paper appear below:
Yoon-Jung Choi+, Joel M. Moskowitz+, Seung-Kwon Myung*,
Yi-Ryoung Lee, Yun-Chul Hong*. Cellular Phone Use and Risk of Tumors: Systematic
Review and Meta-Analysis. International Journal of Environmental Research and
Public Health. 2020, 17(21), 8079;
We investigated whether cellular phone use was associated with increased risk of tumors using a meta-analysis of case-control studies. PubMed and EMBASE were searched from inception to July 2018. The primary outcome was the risk of tumors by cellular phone use, which was measured by pooling each odds ratio (OR) and its 95% confidence interval (CI). In a meta-analysis of 46 case-control studies, compared with never or rarely having used a cellular phone, regular use was not associated with tumor risk in the random-effects meta-analysis. However, in the subgroup meta-analysis by research group, there was a statistically significant positive association (harmful effect) in the Hardell et al. studies (OR, 1.15—95% CI, 1.00 to 1.33— n = 10), a statistically significant negative association (beneficial effect) in the INTERPHONE-related studies (case-control studies from 13 countries coordinated by the International Agency for Research on Cancer (IARC); (OR, 0.81—95% CI, 0.75 to 0.89—n = 9), and no statistically significant association in other research groups’ studies. Further, cellular phone use with cumulative call time more than 1000 hours statistically significantly increased the risk of tumors. This comprehensive meta-analysis of case-control studies found evidence that linked cellular phone use to increased tumor risk.
+Contributed equally to this study as the first author. *Correspondence.
3.5. Exposure–Response Relationship Between Use of Cellular Phones and Risk of Tumors
Table 3 shows an exposure-response relationship between cellular phone use and tumor risk. In the subgroup meta-analysis by time since first use or latency, overall the risk of tumors by cellular phone use non-significantly increased from an OR of 0.97 to 1.29 as latency increased from less than 5 years to 10 or more years. This finding was observed in each subgroup meta-analysis by research group. Especially, statistically significant increased tumor risk was observed for latency of 10 or more years in the Hardell studies (OR, 1.62; 1.03 to 2.57; n = 5; I2 = 39.9%). Similarly, the use of cellular phones non-significantly increased the risk of tumors as the cumulative or lifetime use in years and the cumulative number of calls increased in all studies and in each study group. Remarkably, in the subgroup meta-analysis of all studies by cumulative call time, cellular phone use greater than 1000 hours statistically significantly increased the risk of tumors (OR, 1.60; 1.12 to 2.30; n = 8; I2 = 74.5%). Interestingly, the use of cellular phones overall and in the Hardell studies (OR, 3.65; 1.69 to 7.85; n = 2, especially in the Hardell studies) non significantly increased the risk of tumors with cumulative call time of 300–1000 h and more than 1000 h, while it decreased the risk of tumors in most subgroup meta-analyses of the INTERPHONE studies.
In sum, the updated comprehensive meta-analysis of case-control studies found significant evidence linking cellular phone use to increased tumor risk, especially among cell phone users with cumulative cell phone use of 1000 or more hours in their lifetime (which corresponds to about 17 min per day over 10 years), and especially among studies that employed high quality methods. Further quality prospective studies providing higher level of evidence than case-control studies are warranted to confirm our findings.
This open access paper and supplemental material can be downloaded at http://bit.ly/cellphonetumor.
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