COSMOS, Cell Phones, and Cancer

Are Electromagnetic Fields Making Me Ill?

The relationship between cell phones and brain cancer is a controversial topic. Russ Hobbie and I discuss the physics behind the risk of electromagnetic radiation from cell phones in Chapter 9 of Intermediate Physics for Medicine and Biology. I also address this topic in my book Are Electromagnetic Fields Making Me Ill? published in 2022.

A large cohort study, called COSMOS, is now following approximately 100,000 volunteers in United Kingdom and 200,000 in Europe. COSMOS began in 2010, and participants will be followed for 20 years. Each participant will complete an online questionnaire probing their health, lifestyle and cell phone use… COSMOS will avoid recall bias by obtaining cell phone records from mobile phone companies to supplement the questionnaire.

Last year the first results of the COSMOS study were reported in an article titled “Mobile Phone Use and Brain Tumour Risk – COSMOS, A Prospective Cohort Study” published in the journal Environment International (Volume 185, Article Number 108552, 2024). Below is a series of questions and answers about that article. 

 

Q: Let’s jump to the bottom line. What did the article conclude?

A: The last sentence of the abstract says “Our findings suggest that the cumulative amount of mobile phone use is not associated with the risk of developing glioma, meningioma, or acoustic neuroma.” In other words, cell phone radiation didn’t cause brain cancer. 

Q: Is COSMOS an acronym?

A: Yes. It stands for “COhort Study of MObile phone uSe and health”. Okay, the “S” for “uSe” is a bit of a stretch, but it has a nice ring to it. (Get it? phone… ring.)

Q: The “CO” in COSMOS stands for “Cohort”. What’s that? 

A: Two main types of epidemiological research are case-control studies and cohort studies. In a case-control study, researchers look retrospectively at patients diagnosed with some disease, to try and determine the cause. In a cohort study, initially healthy people are followed to see who gets sick with a disease. Cohort studies take longer to perform, require more subjects, and are more expensive, but are less subject to bias. 

Q: Bias? What sort of bias?

A: The main concern is recall bias. In a case-control study, patients who have a disease may be focused on what caused their health issue and search their memory more extensively for causal links, whereas a control group without the disease may not be as careful and complete in their assessment. This can potentially exaggerate the relation between a risk factor and the disease. Recall bias is avoided in a cohort study, because the initial questionnaire and patient history is collected when all the participants are healthy.

 

Q: What makes this study better than previous ones? 

A: The authors state that COSMOS is “the largest prospective cohort study of mobile phone use specifically designed to overcome the well-described shortcomings of both case-control and previous cohort studies, through a more comprehensive prospective collection of exposure information, including both self-report and mobile network operator data, while also addressing longer-term exposure and more recent technologies than previous studies ” 

Q: Who did this research?

A: The first author of the article was Maria Feychting, who is with the Institute of Environmental Medicine at the Karolinska Institutet in Stockholm, Sweden. The last (senior) two authors (who contributed equally to the article) are Giorgio Tettamanti of the Karolinska Institutet and Paul Elliott of the Imperial College London.

Q: How many subjects were studied? 

A: 264,574  

Q: What are glioma, meningioma, and acoustic neuroma? 

A: These are types of brain cancer. A glioma originates in the glial cells of the brain. Gliomas comprise 80% of all malignant brain tumors. Meningiomas form in the meninges, the membranes surrounding the brain, and acoustic neuromas affect the nerve that connects the inner ear to the brain. During the study, 149 gliomas, 89 meningiomas, and 29 acoustic neuromas were diagnosed.

 

Q: Everyone uses a cell phone nowadays. What was the control group?

A: The detailed participant histories and data from phone companies allowed the researchers to estimate the total cumulative hours of cell phone use for each participant. They could then compare users with less use to those with more use. Half the uses had less than 464 cumulative hours of call time, a quarter had between 464 and 1062 hours, and another quarter had more than 1062 hours. 

Q: Cell phones are getting more and more common, with new generations like 5G. Isn’t the exposure much worse now than in the past?

A: Interestingly, the answer is no. New technologies provide less exposure. The authors write “Generally, RF-EMF [radio-frequency electromagnetic field] exposure levels to the head during calls have decreased considerably with each new generation of mobile phone technology, most notably between the 2nd (e.g., GSM introduced in the early 1990s) and 3rd generation (e.g., UMTS introduced in the early 2000s); the contribution to the whole-brain RF-EMF exposure from a mobile phone held to the ear while calling on a GSM phone is orders of magnitude higher than that from a 3G phone.” This trend has continued through 4G and 5G technologies, especially with adaptive power control technology.

 

Q: This COSMOS study sounds expensive. Who paid for it?

A: The list of funding organizations at the end of the article runs for almost a page. Each country (Sweden, Denmark, Finland, the United Kingdom, the Netherlands, and France) has different funding sources. Most appear to be government agencies, although there is some industry funding in some countries. The authors state that “they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ” 

Q: The study has been going on for a little over seven years. Is this long enough to detect slow-growing brain tumors? 

A: This question was raised in a letter to the editor by Michael Kundi. In their response, Feychting et al. point out that although the time between patient registration and the article was seven years, this does not mean the study can only detect cancers initiated in the last seven years. Participants provided information about their exposure history, so researchers could examine the relationship between cell phone use and cancer over a much longer time than seven years. 30% of participants had used a mobile phone for 15 years or longer. The study is ongoing, and is supposed to last 20 years. In about a decade, we should have more definitive data. 

Q: Were there any other letters to the editor about this research?

A: Joel Moskowitz and his colleagues wrote a letter in which they called the COSMOS study “methodologically flawed.” One of their main complaints is that the participant questionnaires and limited cell phone data usage would not be sufficient to access radio-frequency radiation exposure, which depends on the details of the technology used. The authors responded by noting how their exposure estimates are far better than in past studies. They claim “the prospective collection of exposure information in COSMOS is a key strength, together with the use of objective operator data from a sub-sample of participants to improve the exposure estimation based on recall alone. These data were used to calibrate the self-reported mobile phone use, leading to more accurate estimation of the relation between mobile phone use and health outcomes.”

Moskowitz and his coworkers also objected to the lack of an unexposed control group. The authors responded “Today, close to 100 % of the populations in the included countries are mobile phone users. The tiny proportion of non-users is likely to differ from the mobile phone users in many other aspects, and confounding and random variation would be major problems in analyses with non-users as reference group. Comparing low vs. high or long-term vs. short-term exposures is common in epidemiological studies when exposures are prevalent, and internal comparisons within the cohort ensures comparability in the quality of outcome, exposure and confounding information.”

Finally, Moskowitz et al. complained about industry funding, claiming that it would lead to a funding bias. The authors responded “COSMOS was funded through grant applications to publicly funded research councils or organisations, undergoing the same rigorous and competitive evaluation process as other research grant applications. In some countries, industry complemented the funding either through national research programs led by public authorities without any influence from industry, or by using trusted public authorities as a firewall, with agreements that guaranteed the independence of the researchers. It is reasonable that industry contribute to the costs of research into potential health effects of their products, as long as it can be guaranteed that they have no influence on the conduct of the research, and this independence was fully the case in COSMOS.” 

Q: So, what’s your conclusion?

A: When you combine the initial COSMOS results with the Danish cohort study and the Million Women cohort study that I discuss in Are Electromagnetic Fields Making Me Ill?, I conclude that there’s little evidence connecting cell phone use to cancer. It’s just not a problem. 

Q: I love the Q&A, but now I would like to read the paper itself. Unfortunately, I don’t have a subscription to Environmental International. What can I do?

A: You’re in luck. The article, and all the letters to the editor and the author responses, are published open access. Anyone can read them online, using the links I provide above. Enjoy!

Source: http://hobbieroth.blogspot.com/2025/12/cosmos-cell-phones-and-cancer.html