Mobile phone use and possible cancer risk: Current perspectives in India

Abstract

Mobile communication is now essentially ruling our daily lives through better connectivity and intelligent smartphone services. There has been a tremendous growth in Indian communication industry along with growing concerns regarding health effects of mobile radiation exposure. Concerns posed are especially regarding carcinogenesis and other health-related effects of mobile radiation exposure. In the effort to establish or refute any such concerns, many studies have been undertaken in the past three decades, mostly case-control designs or cross-sectional surveys. However, most of them considerably failed to establish causal association primarily owing to potential biases and errors in their conduct and analysis. Past cohort studies have provided contradictory results leading to continued uncertainty regarding tumorigenic potential of mobile radiation exposure. In India, there remains a huge knowledge gap pertaining to this particular topic and only few studies are presently underway such as the Indian Council of Medical Research (ICMR) cell phone study in the National capital region (NCR). International Agency for Research on Cancer (IARC) has classified radiofrequency electromagnetic fields associated with wireless phone use as possibly carcinogenic to humans (Group 2B), causing major concerns worldwide among mobile companies and subscribers equivocally. The World Health Organization (WHO) is presently carrying formal risk assessment of all studied health outcomes from radio frequency field's exposures and is likely to publish it by the year 2016.

INTRODUCTION

Mobile phones are an integral part of modern telecommunication systems and are widely used worldwide. In many countries, over half the population use mobile phones and the market is growing rapidly with estimated 7 billion subscriptions globally in 2014.[1] There has been unprecedented growth in the communication industry in India in the recent years. The cost of mobile phone technology has fallen, leading to increased number of subscribers in the country (725 million). There is a growing public concern regarding possible adverse health effect due to mobile radiation exposures, which, keeping in view huge number of mobile subscribers seems justified.[2] Therefore, it is very important today to carefully investigate, understand, and monitor any potential public health impact of increasing mobile phone usage in India.

Mobile phones communicate by transmitting radio frequency waves through a network of fixed antennas known as base stations. Such radiations are produced by mobile phones and other household devices such as Wi-Fi, television (TV), and radio transmitters etc. Radiofrequency waves are electromagnetic fields, and unlike ionizing radiation such as X-rays or gamma rays, can neither break chemical bonds nor are powerful enough to damage our deoxyribonucleic acid (DNA). However, they are likely to be absorbed by tissues closest to device exposure site and produce mild local thermal effect. Among studies conducted to assess exposures to mobile phone radiations, a study near schools and hospitals in Chandigarh, Punjab found the highest density of 11.48 mW/mm, which is 1,148% of the biological limit. The study concluded that exposure levels in the city were much above the biological safety limit above which the biological system of humans and animals starts getting affected.[3]

The amount of radiofrequency energy exposure additionally depends on mobile set technology, the extent and type of use, phone's antenna, and cell phone tower's distance from the user. Physicists have analyzed every other conceivable interaction between mobile radiation and biological processes, for e.g., physical deformations of proteins, activation of signaling pathways, and docking with receptors on cell membranes. In every case, the calculated strength of mobile radiation has been negligible to affect any pathological transformation.[4]

A large number of studies have been performed over the last two decades to assess potential health risks of mobile phones. Some of them have suggested that people can have a higher risk of brain cancer specifically on the side of the head, pertaining to mobile use. But these studies have not reported an overall increased risk of cancer, or a lower risk of tumors on the other side of the head. A recent study showed higher levels of glucose metabolism in the brain tissues exposed to mobile radiation on a prolonged use for 50 min or more. Although, researches mentioned that results were preliminary and possible health outcomes from this increase in glucose metabolism remain still unknown.[5] So far, no good biological mechanism has been established to link mobile radiation and risk of head cancer. Therefore, the present literature review attempts to understand various perspectives and progress in understanding a possible carcinogenic risk linked to mobile phone use.

SHORT-TERM EFFECTS

A number of studies have investigated the effects of radiofrequency fields on brain electrical activity, cognitive function, sleep, heart rate, and blood pressure etc. In a study conducted on male students of National Institute of Technology (NIT), Kerala, India. Headache, dizziness, numbness in the thigh, and heaviness in the chest were reported among frequent mobile phone users. The study reported an increase in heart rate variability when the mobile phone is kept close to the chest and a decrease when kept close to the head. However, these observations were not found significant in comparison to conditions without mobile phone.[6] To date researches have not suggested any consistent evidence of adverse health effects from exposure to radiofrequency fields except the tissue heating effect. Further, researches have not been able to provide support for a cause and effect relationship between exposure to electromagnetic fields and any self-reported symptoms such as electromagnetic hypersensitivity among mobile users.[7]

LONG-TERM EFFECTS

Epidemiological researches examining potential long-term risks from radiofrequency exposure have mostly looked for an association between brain tumors and mobile phone use. However, as many cancers remain undetectable until many years after the interactions that led to the tumor, and because mobile phones were not widely used until the early 1990s, epidemiological studies were restricted only to those cancers that become evident within shorter time periods. Results of animal studies have consistently shown no increase in the cancer risk due to long-term exposure to radiofrequency fields.[5] Few studies have tried to look for other possible long-term health effects of exposure to mobile radiation. In a study conducted in Amritsar, Punjab, India, a correlation between mobile phone use (exposure to radio frequency radiations) and DNA and chromosomal damage in lymphocytes of mobile phones users was observed. Such damages can have long-term consequences in terms of increased risk of neoplasia or other age-related changes.[8] Indian experimental animal studies conducted on rats have additionally shown that mobile phone radiations may affect brain function and cause several neurological disorders and chronic exposure to nonionizing microwave (MW) radiation may lead to infertility via free radical/oxidative species-mediated pathway.[9,10]

In a study conducted on inhabitants living near mobile phone towers, higher risk for developing neuropsychiatric problems and some changes in neurobehavioral functions were observed, therefore, advocating due caution in such regard.[11] A systematic review on the health effects of exposure to radiofrequency electromagnetic fields from mobile phone towers, however, did not indicate an association between any health outcome and radiofrequency electromagnetic field exposure at levels typically encountered in people's everyday environment.[12,13]

CANCER IN HUMANS

Extensive evidence reviews have been conducted to understand possible carcinogenic risks posed by mobile radiation in the past decade. In a meta-analysis of studies on intracranial tumors and mobile phone use published by the end of 2012, high heterogeneity was detected across estimates of glioma and acoustic neuronal risk in long-term users due to methodological differences embedded in the variable study groups. Overall, the results detracted from the hypothesis that mobile phone use affects the occurrence of intracranial tumors.[14] In an extended follow-up of Danish nationwide cohort, no evidence for an association between tumor risk and cellular telephone use among either short-term or long-term users was found.[15]

Similarly, the largest retrospective case-control study INTERPHONE, conducted by a consortium of researchers from 14 countries and coordinated by the International Agency for Research on Cancer (IARC), showed no statistically significant increase in brain or central nervous system cancers related to higher amounts of mobile phone use.[16] However, the workgroup did not ignore the limited evidence in humans for the carcinogenicity of radiofrequency radiation as positive associations. The study group observed association between exposure to radiofrequency radiation from wireless phones and glioma and acoustic neuroma, but it was statistically not insignificant.[17] The Hardell-group conducted two case control studies on brain tumors during 1997-2003 with cases being reported from the Swedish Cancer Registries. Consistent pattern of the increased risk of glioma and acoustic neuroma associated was seen with use of mobile phones and cordless phones. Supportive evidence came from anatomical localization of the tumor to the most exposed area of the brain, cumulative exposure, and latency time that all add to the biological relevance of an increased risk. Based largely on data suggesting increased risk for glioma, a malignant type of brain cancer, the IARC in May 2011 classified radiofrequency electromagnetic fields as possibly carcinogenic to humans.[18] Possibly carcinogenic (Group 2B) means that there is some evidence for a risk but it's not that convincing and only “limited evidence” regarding cancer causation among people, and even the evidence from animal studies is “less than sufficient”. This group usually ends up being a bit of a catch-all category, and 2B items remain plagued by controversy regarding their carcinogenicity. Despite classification, speculations remain large as the INTERPHONE study quoted by IARC could be laced with recall bias and authors themselves had acknowledged this potential source of error. There exist diverse opinions with deep skepticism regarding possibility of carcinogenesis by radiofrequency electromagnetic fields based on biophysical principles or epidemiologic findings that remain less convincing. Following the IARC decision, the World Health Organization (WHO) issued a reassuring new “Fact Sheet on mobile phones and public health” that mentioned no adverse health effects being established and related to mobile phone usage.[5] Though, possibility of carcinogenesis continues to receive worldwide media attention and it remains of great interest to the public, reflecting the increasing use of mobile phones in our lives.

RECOMMENDATIONS BY EXPERT AGENCIES

WHO states that “A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use. WHO will conduct a formal risk assessment of all studied health outcomes from radiofrequency field's exposure by 2016”.[19]

Indian Council of Medical Research (ICMR) states that “In a number of studies it has been reported that exposure to radiation from mobile phones causes adverse health effects. But there is no conclusive data available so far on this issue, however, the growing body of scientific evidences indicates some bio-effects and possible adverse health effects of Radio Frequency Radiation (RFR) which merit further investigations.”[20]

The American Cancer Society (ACS) states that “The IARC classification means that there could be some risk associated with cancer, but the evidence is not strong enough to be considered causal and needs to be investigated further. Individuals who are concerned about radiofrequency exposure can limit their exposure, including using an ear piece and limiting mobile phone use, particularly among children”.[21]

The U.S. Centers for Disease Control and Prevention (CDC) states that “There is no scientific evidence that provides a definite answer if cell phone causes cancer. Some organizations recommend caution in cell phone use. More research is needed before we know if using cell phones causes health effects.”[22]

WAY FORWARD

Despite astounding growth of mobile phone industry and consistently increasing usage among Indian population, there is a paucity of literature regarding health effects of mobile radiation exposure. Studies conducted in the past have considerably failed to furnish any conclusive evidence in such regard. The ICMR is conducting a multidisciplinary cohort study in Delhi and the National Capital Region (NCR) to find out adverse effects of Radio Frequency Radiation (RFR), if any, emitted from cell phones on the adult Indian population. The study involves clinical and laboratory investigations to examine whether the use of cell phone is associated with reproductive dysfunctions, male infertility, neurological disorders (cognitive behavior, sleep related disorders, depression etc.), cardiovascular disorders, otorhinolaryngology (ENT) disorders, and if it promotes cancer, in Human Volunteers.[20]

There are some international mobiles and cancer risk studies that are currently underway to gathers brain-tumor data with mobile radiation exposure. MOBI-KIDS is an international case-control study assessing potential links between communications devices, environmental risk factors and brain tumors in young people. Over five years, 2,000 individuals between the ages of 10 and 24 years with brain tumors, and 2,000 without tumors will be participating in this important global study. It involves research groups in 13 countries, including Canada, Australia, Israel, Taiwan, and the Netherlands etc., and the study is funded by European Community's Seventh Framework Programme.[23]

Another study is COSMOS which is a large cohort study launched in Europe in March 2010, it is investigating possible health effects from long term use of mobile phones and other wireless technologies. Approximately 250,000 cell phone users over the age of 18 are part of this 20-30 year study. This study will specifically assess changes in symptoms such as headaches and sleep disorders as well as risks for cancer, tumors, neurological, and cerebrovascular diseases. Additionally, WHO is to conduct a formal risk assessment of all studied health outcomes from radio frequency field's exposure by 2016.[24]

LIMITATIONS OF EXISTING LITERATURE

Consideration of alternate explanations regarding the use of mobile phones and the increased risk of brain cancer has shown inconclusive trends. The incidence of cancer cases should be surging because the use of mobile phones has risen dramatically over the last few decades, but only limited research suggests such trends. Brain cancers can take many years to develop, so it is possible that trends would only start rising after some more time. Case-control studies can be largely affected by recall bias, as people have heard about mobiles and brain cancer in the media, because brain cancer can distort memory, or simply because people misremember things that happened a long time ago. There is no clear ways of assessing someone's actual exposure to mobile phone radiation. Instead, studies use questionnaires to work out the exposures, which can lead to erroneous assessment and false results. There are conflicts of interest as mobile phone industry has provided funding for some major research projects namely-Interphone study[16] and the Danish study[15] etc., In both cases, funds have been administered through independent, third-party organizations. Mobile technology has changed considerably over the last decades and it is not clear if studies based on the use of old models will apply to modern ones.

RECOMMENDATIONS ON MOBILE USE

IARC's 2B (possible risk) classification remains a cornerstone advisory in formulation of recommendations by government or major public health agencies. In the present situation, we cannot be completely sure about the long-term effects of mobile radiation exposure. In addition, there have not been enough studies to look at how the use mobile phones could affect the health of children. In the current scenario, preventive approach remains the best option to mobile phones users, who could be recommended to minimize their exposure by keeping their calls short. People should ensure that their mobile device has low specific absorption rate (SAR) of radio frequency and children, adolescent, and pregnant women taking special precautions. Mobile phones should be kept away from the body (head) by using text messaging, or using a “hands free” devices lowering exposure to radiofrequency fields and, hence, better protection.[25]

CONCLUSION

Overall evaluations show that the current evidence for a causal association between cancer and exposure to mobile radiation is weak and unconvincing. Some of the studies establishing association had significant limitations and weaknesses and, therefore, remain unreliable. Studies have highlighted that using these phones for about 10 years is unlikely to cause cancer. But as mobile phones are still a new technology and there is little evidence about effects of longer-term use, therefore, prevention seems the best approach.

Existing epidemiological research is limited and the possibility of epigenetic and other long-term health effects has not yet been thoroughly evaluated, warranting additional research a more thorough assessment of the possibility of a causal connection between cancer and mobile phone radiations. People are highly concerned regarding possible health effects of mobile phones, especially because they are widely used and carried for longer durations by the users. Additionally, there is an ever-increasing need for clear roles, adoption, and compliance of health-based standards by various governments on this topic. Public information program and dialogue with stakeholders remain the key strategies to allay relevant fears and concerns. There is an urgent need of promoting further research and better technological interventions in field of mobile technology for ensuring health and safety of subscribers worldwide.

Financial support and sponsorship

Nil.

Conflict of interest

There are no conflict of interest.