Can cell phones cause cancer or other health problems? Does this concern still exist?

What are the two main reasons that worried (or still worry) cell phone users?

First, cell phones emit radiation (in the form of radiofrequency radiation, or radio waves), and second, cell phone use is now widespread. Thus, considering the high number of people who use cell phones, a small increase in the risk of developing cancer would be worrying.

An encouraging explanation for cell phone users would be that the radiation emitted by cell phones would fall into a non-ionizing range (considered to be low frequency and low energy). That energy would be too low to damage DNA.

Ionizing radiation, which includes X-rays, radon, and cosmic rays, is unlike high-frequency and high-energy, and the energy of ionizing radiation can damage DNA. DNA damage can cause changes in genes that can increase the risk of cancer.

Another discussion is heating the area of ​​the body in contact with the cell phone: the ear and the head. Could this facilitate the absorption of radiation? It seems that this would not be enough.

And was the incidence of brain and central nervous system cancer increased during cell phone use? Some studies have shown that the incidence rates for gliomas, pediatric brain tumors, acoustic neuromas, and meningioma have remained stable. These studies have been carried out in recent decades in the United States, Nordic countries, and Australia.

There are, however, some criticisms of the design of these studies, as they did not compare the risk of developing cancer in two distinct populations: those who use cell phones and those who do not use cell phones. These studies simulated different scenarios to determine cancer incidence trends and some findings may have been skewed.

In addition, studies using cancer incidence data have tested different scenarios (simulations) to determine whether incidence trends align with various levels of risk, as reported in studies of cell phone use and brain tumors between 1979 and 2008. These simulations showed that many risk changes reported in case-control studies were not consistent with the incidence data, implying that assumptions and errors in these studies may have skewed the findings.

How was radiation exposure measured in these epidemiological studies?

These studies used information from a variety of sources, including questionnaires and data from cellular service providers, to estimate exposure to radiofrequency radiation in groups of people. Some questions were often part of these questionnaires, such as:

• How often do study participants use cell phones (the number of calls per week or month)
• Age and year when study participants first used the cell phone, and age and year of last use (this allows investigators to calculate the duration of use and the time since initiation of use)
• The average number of cell phone calls per day, week, or month (frequency)
• The average duration of a typical cell phone call
• Total lifetime hours of use, calculated from the duration of typical call times, frequency of use, and duration of use

What has research shown about the link between cell phone use and cancer risk?

These epidemiological studies (also called observational studies) are non-interventional research studies. Researchers look at groups of individuals (populations) and gather information about them, but seek not to change anything about the groups.

These studies can look at associations between cell phone use and cancer risk (people who have tumors and people who don’t have tumors) or they can follow a large group of people who don’t have cancer at the start of the study, over some time, and to compare the occurrence of cancer in those who used a cell phone and compared with those who did not use a cell phone. As the research source often involves a list of subscribers, some failures may occur, as the subscriber is not necessarily the user of the telephone.

Three large epidemiological studies (Interphone, the Danish Study, and the Million Women Study) did not show a possible association between cell phone use and cancer. Two reviews of these studies, in 2015 and 2019, confirmed the absence of this association. Importantly, these studies involved participants in Europe, Israel, Canada, Australia, New Zealand, and Japan who had used cell phones for ten or more years.

Other epidemiological studies, carried out in the US (sponsored by the NCI), and in France (the CERENAT study), have not shown a relationship between cell phone use and the risk of glioma, meningioma, or acoustic neuroma in adults. However, in the study carried out from 2004 to 2006, in several areas of France, unlike regular cell phone users, those who used their cell phones very frequently had significantly increased risks of gliomas and meningiomas compared to non-users.

Furthermore, the pooled analysis of two case-control studies conducted in Sweden showed statistically significant trends toward an increased risk of brain cancer for people who started using cell phones before age 20, as per the total amount of use of their cell phones. and years of use. But the conclusions of another Swedish study were different; this third other study did not find an increased risk of brain cancer among cell phone users for many years.

Two studies (CEFALO and MOBI-Kids) conducted with groups of children diagnosed with brain cancer found no relationship between cell phone use (or cordless phones) and the risk of brain cancer.

A population-based case-control study conducted in Connecticut found no association between cell phone use and thyroid cancer risk.

Many other studies have sought to find other possible effects of cell phone use on the human body. In 2011, two studies evaluated brain glucose metabolism in people after cell phone use. The studies involved a small group of participants and the results were not consistent: one of them showed increased glucose metabolism in the region of the brain close to the telephone contact site compared to tissues on the opposite side of the brain and another study found differently a reduction in glucose metabolism on the side of the brain where the phone was used. Many factors can contribute to these inconsistencies: the difficulty in adequately estimating the amount of telephone use, the assessment of the effects of temperature, and the design of the studies (the information is not blind to the investigators).

On the other hand, another study found no evidence of a blood flow effect on the brain of people exposed to radiofrequency radiation from cell phones.

And the experiments on laboratory animals, what did they show? In these early studies, there was no evidence of an increased risk of cancer or cancer-causing effects from radiofrequency radiation.

Exposure to radiofrequency radiation associated with the use of cell phones was studied in 1999 in animal models through the National Toxicology Program (NTP) guided by the FDA (Food and Drug Administration). These studies involved rats and mice that were exposed to intermittent radiofrequency radiation exposures for 18 hours a day for periods of 5 or 7 days a week. The primary outcomes observed were a small number of Schwann cell cancer and non-cancerous hyperplastic changes in the heart of male rats, but not found in female rats or mice.

The findings of this FDA-led study lead to the further discussion because heart cancers are extremely rare in humans. Heart Schwann cells in rodents are similar to the type of cells in humans that give rise to acoustic neuromas (also known as vestibular schwannomas), which some studies have suggested are increased in people with higher cell phone use.

In another study conducted by researchers at the Italian Ramazzini Institute, with a design similar to that of the NTP, an increase in cardiac schwannomas in male rats and non-malignant growth of Schwann cells in the heart in male and female rats was also observed.

These studies were critically evaluated by ICNIRP (an independent non-profit organization that provides scientific advice and guidance on the effects of non-ionizing radiation on health and the environment) which concluded that both studies followed good laboratory practices, but also identified their main shortcomings in conducting studies and statistical analyses. ICNIRP concluded that these limitations preclude better conclusions about the ability of radiofrequency exposures to cause cancer.

The results found in different studies on cell phone use and cancer risk have been inconsistent. Why?

Some studies have shown some evidence of a statistical association between cell phone use and brain tumor risks in humans, but most studies have found no association. The information from the study participants, through the implemented questionnaires, is often inaccurate. They do not remember details of their illnesses, time, and frequency of cell phone use. The short follow-up time in some studies and the statistical power and inadequate methods to detect very small risks or risks that affect small subgroups of people are other shortcomings for definitive conclusions. On the other hand, people with diseases are more likely to participate in studies than healthy people.

Another important aspect is that older studies evaluated exposure to radiofrequency radiation from analog cell phones. Today, cell phones with digital technology operate at a different frequency and a lower power level than analog phones. And everything indicates that we will certainly have more advances in cell phone technology.

Are there other possible health effects of cell phone use?

The most consistent health risk associated with cell phone use is distracted driving and vehicle accidents.

Several other potential health effects have been reported from cell phone use. The neurological effects are particularly worrisome in young people. But studies of memory, learning, and cognitive function have generally yielded inconsistent results.

But, back to cancer risk from cell phone use.

In 2011, a group of experts appointed by the International Agency for Research on Cancer (IARC), linked to the World Health Organization, reviewed all available evidence on cell phone use. These experts based on the various studies evaluated concluded that cell phone use is “possibly carcinogenic to humans”. This working group recognizes that investigating the risk of brain cancer associated with cell phone use presents complex research challenges.

But, the American Cancer Society also commented on the matter with the following message: “It is not clear at this time that RF waves (radio frequency) from cell phones cause harmful effects on people’s health, but the studies that are being done must provide a clearer picture of possible health effects in the future.”

Current scientific evidence, according to the National Institute of Environmental Health Sciences (NIEHS), does not establish a conclusive link between cell phone use and any adverse health problems. The NIEHS indicates that more research is needed.

The FDA comments that the biological changes associated with radiofrequency radiation reported by some studies have not been replicated and that most epidemiological studies in humans have failed to show a relationship between exposure to radiofrequency radiation from cell phones and health problems. And after reviews of studies by the NTP, the FDA more recently (in 2018) stated that “Based on this current information, we believe that current safety limits for cell phones are acceptable to protect public health.” The US Centers for Disease Control and Prevention (CDC) states that no scientific evidence definitively answers whether cell phone use causes cancer.

The Federal Communications Commission (FCC) concludes that currently, no scientific evidence establishes a definitive link between the use of wireless devices and cancer or other diseases.

In 2015, the European Commission’s Scientific Committee on Emerging and Newly Identified Health Risks concluded that, in general, epidemiological studies on exposure to radiofrequency electromagnetic radiation from cell phones do not show an increased risk of brain tumors or other cancers in the region of the head and neck. The committee also stated that epidemiological studies do not indicate an increased risk for other malignancies, including childhood cancer.

Perhaps, some studies that are in progress can provide more definitive answers. The prospective COSMOS study (Cohort Study on Cell Phone Use and Health) on cell phone use and its possible long-term health effects, launched in Europe in March 2010, will be able to provide answers to these questions conclusively. Participants in this study aged 18 and over will be followed for 20 to 30 years. About 300 000 mobile phone users are already registered.

And in children? Was radiofrequency radiation emitted by cell phone use associated with cancer risk in this age group?

Many researchers consider that the potential health effects of cell phone use should be investigated separately in children. They indicate that the child’s nervous system is still developing and thus more vulnerable to factors that can cause cancer. And they add that the child’s head is smaller than that of the adult and, therefore, has proportionally greater exposure to the radiation emitted by cell phones. Children still have the potential to accumulate more years of cell phone exposure than adults.

However, it is worth remembering that so far, data from studies of children with cancer do not suggest that children have an increased risk of developing cancer from cell phone use. The first published analysis came from a large case-control study called CEFALO, carried out in Europe. The study included 352 children aged between 7 and 19 years who were diagnosed with brain tumors between 2004 and 2008. They were matched for age, sex, and geographic region with 646 youths randomly selected from population registries. The researchers did not find an association between cell phone use and brain tumor risk by the amount of use or the location of the tumor.

There is also the MOBI-Kids study.

The MOBI-Kids study, involving 14 countries, included 899 young people aged 10 to 24 who were diagnosed with brain tumors between 2010 and 2015. They were matched for sex, age, and region with 1,910 young people who underwent surgery for appendicitis. The researchers found no evidence of an association between wireless phone use and brain tumors in young people.

What can we do (we who are cell phone users) to reduce our exposure to radiofrequency radiation?

So, while we don’t have a definitive answer to this question, we could follow along with some advice from the FDA:

• Using wired or wireless headphones reduces the amount of RF radiation exposure to the head because the phone is not held against the head. Using a hands-free device, such as wired headphones, imposes a greater distance between the phone and the user’s head. Exposures decrease dramatically when cell phones are used hands-free.
• Reserve cell phone use for shorter conversations or times when the landline is unavailable.

This subject was “reheated” with a new British study, published on March 29, 2022. This study showed no relationship between brain tumors and cell phone use, even in individuals who used the device every day and/or for a long time. more than 10 years.

Study author Kirstin Pirie, Master of Science, Cancer Epidemiology Unit at Oxford Population Health, UK, stated that “These results support the accumulating evidence that showed that cell phone use under usual conditions does not increase the risk of brain tumor”.

However, an important limitation of the study was that it only recruited middle-aged or older women, and these people generally use their cell phones less than younger women or men. The authors noted that, in this study’s cohort, cell phone usage was low, with only 18% of users talking on the phone for 30 minutes or more weekly.

There were some positive comments from Prof. Malcolm Sperrin, Oxford University Hospitals (non-study participant): This study is “a welcome addition to the body of knowledge on the risk of cell phones, specifically about the occurrence of certain types of tumors. It is a well-designed prospective study. which does not identify any causal relationship”. “There is always a need for further research, especially as phones, wireless internet, etc., are becoming ubiquitous, but this study should allay many fears that exist today.”

However, the study and its conclusions were heavily criticized by Dr. Devra Davis, President of the Environmental Health Trust and Fellow of the American College of Epidemiology: “Studies that rely on outdated data are dangerous because they don’t consider how people use cell phones today for hours throughout the day.” “Incorrect ages, incorrect questions, incorrect exposure information.”

The Environmental Health Trust adds that “numerous” human and animal studies have found associations between cell phone radiation and cancer, and continues to recommend that the public, especially children, reduce exposures to cell phone radiation.

Dr. Joachim Schüz, Ph.D., Head of the Environment and Radiation Section at IARC, was invited to comment on the British study and noted that “mobile technologies are being updated all the time, so the latest generations of devices emit a substantially lower output.”

But, he added, “even so, given the lack of evidence for abusive users, advising cell phone users to reduce unnecessary exposure remains a good preventive approach.”

In summary: Fears about the risk of cancer, particularly of brain tumors related to cell phone use, have been circulating for decades, and to date, some 30 epidemiological studies have been carried out on this subject.

For now, it may be prudent to follow the advice of the FDA and Dr. Schüz.

References:

• National Cancer Institute — Cell phones and Cancer risk — March 10, 2022
• J Natl Cancer — March 29, 2022
• Nelson R — Medscape — March 30, 2022

Note: Thanks to Freepik for permission to use the images.