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Health Effects of Mobile Phones: Recent Scientific and Policy Developments

Kenneth R. Foster

Department of Bioengineering
University of Pennsylvania
Philadelphia PA 19104 USA

John E. Moulder

Department of Radiation Biology
Medical College of Wisconsin
Milwaukee,WI 53226 USA


Presented at COST259 workshop

"The Mobile Terminal and Human Body Interaction"

Bergen, Norway 27 April 2000


This talk will review recent scientific evidence related to possible links between brain cancer and use of mobile phones, and recent regulatory developments related to human exposure to radiofrequency (RF) energy.


The issue of possible health effects of mobile telephones and mobile telephone base stations is very much alive in the public’s mind. Motivated by health concerns, a new wave of research has been undertaken in the United States and elsewhere, searching for possible links between cell phone radiation and health problems, including cancer. Also motivated by citizens’ health concerns, several European countries have instituted new policies for siting of mobile base stations, based on the precautionary principle.

Both subjects of this talk – health effects of RF energy and regulation of RF exposure, are broad and contentious. For nonspecialists, good sources of further information on the scientific issues are found in references 1-3, and from a different perspective in Ref. 4.

Cell Phones and Brain Cancer: Emerging Evidence

In the public’s mind, the most distressing issue is the possible link between mobile telephones with brain cancer. The issue arose with the a lawsuit filed in a US court in mid-1992 by David Reynard, alleging that the use of a cell phone caused his wife's fatal brain cancer.

The difficulty in interpreting such reports is that brain cancer occurs naturally in the human population (with an incidence of about 6 per 100,000 people per year). Thus, many users of mobile phones would develop the disease even if there were no connection between the phones and the disease. Reynard’s lawsuit, and several other American lawsuits with similar claims, were dismissed by the courts for lack of valid scientific evidence. Nevertheless, they raised questions for which no satisfactory answers existed at the time they were filed.

In response to public fears that these suits and their attendant publicity have raised, a wave of research was begun, both within and outside of the US, and funded both by industry and government. A recent review of the issue (presented at a WHO sponsored conference in Erice, Sicily in November 1999) identified more than 200 ongoing and recently completed studies related to possible health hazards of RF energy, including a dozen epidemiology studies, more than 60 cancer-related animal studies, and 75 cellular studies. Additional studies involve noncancer endpoints, including behavioral effects, and safety issues such as interference of cell phones with medical devices and driving performance.

Epidemiology Studies. Several major large scale epidemiology studies were undertaken shortly after the Reynard lawsuit created the issue, and their results have recently been reported.

In 1996, in the first follow-up study to the brain cancer allegations, Rothman et al. reported a study that reviewed health records of more than 250,000 mobile phone users. The investigators found no difference in mortality between the users of hand-held portable phones (where the antenna is placed close to the head) and mobile cellular phones (where the antenna is mounted on the vehicle). In a later followup study, published in November 1999, the same group examined the causes of death among nearly 300,000 mobile phone users in several US cities. The study found no increase in death rates, for any cause of death, that correlated with use of mobile telephones (minutes of daily use of length of service) – except for motor vehicle collisions.

Most recently, in a study published in March 2000, Morgan et al. reported a study of nearly 200,000 Motorola employees representing 2.7 million person-years of possible exposure between 1976 and 1996. The investigators concluded that their findings "do not support an association between occupational RF exposure and brain cancers or lymphoma/leukemia."

Other epidemiology studies on cell phone users have been mostly, or entirely, negative. In a study that received extensive press coverage even before it was published in 1999 Hardell and colleagues assessed mobile phone use in 209 Swedish brain tumor patients in comparison to 425 healthy controls. The study was negative in virtually all respects. There was no increased incidence of brain tumors in the mobile phone users, either in analog or digital phone users, and no tendency towards increased brain tumor incidence with increased duration of use (either years of use or hours of use per year). One aspect of the study received wide coverage in the news -- users of mobile phones who had developed certain types of brain tumors were more likely to get them on the side of their heads where they said they had used the phones. But this correlation was not statistically significant (and may have been a statistical artifact). Recall bias – a greater tendency of subjects with brain tumors to report using their telephones on the side of their heads with the tumor – may have been a factor also.

These studies, while reassuring, have important limitations. They have limited statistical power, i.e. because of their finite size they are unable to detect small increases in risk. More importantly, brain cancer takes years to decades to develop, and these studies can easily overlook a risk that might only become apparent after decades of use of cell phones.

Animal Studies

To supplement epidemiology studies, health agencies look to specialized animal studies when investigating possible carcinogens. Several animal studies have been reported, whose designs are appropriate for identifying brain cancinogenesis or brain tumor promoting effects of RF energy – and they too are unsupportive of such links. (Table).

In a Motorola-funded study designed specifically to look for brain cancer, Adey and colleagues reported in a 1999 paper that pulse-modulated 837 MHz RF energy (such as emitted by some digital cell phones) does not cause or promote brain cancer in rats. At a meeting in 1997 (but not so far in a published paper) Adey reported a lack of initiation or promotion from continuous wave RF (such as emitted by analog cell phones); and in a 1999 meeting report, Zook reported confirmation of all four observations. Other studies in the Table were not focused on brain cancer, but they evaluated the animals for this disease and would have observed a pronounced increase in this disease had one occurred.

In short, both epidemiology and animal studies undertaken in the aftermath of the Reynard lawsuit are strongly unsupportive of links between use of mobile phones and brain cancer. This does not prove that mobile phones are "safe" (since the studies could have overlooked a small risk or one that only becomes apparent after many years of use of the telephones). Nevertheless, the epidemiology studies were large and seemingly well designed and well conducted, and the animal studies were appropriately designed to identify possible carcinogenic or tumor promotion effects of RF fields. Many other studies are presently underway and will be reported in due time.

Resolution of the Scientific Issues

A variety of government and private expert groups are presently evaluating the evidence, and will issue their reports in due course. An expert committee in the United Kingdom is scheduled to release a report in May 2000, and a formal cancer risk assessment will be conducted by the International Agency for Research on Cancer (IARC) for RF fields in 2003.

An indication of the probable nature of their findings is provided by a statement issued in February 2000 by the [US] Food and Drug Administration: "there is currently insufficient scientific basis for concluding either that wireless communication technologies are safe or that they pose a [health] risk to millions of users."

This statement – "no proof of danger, no proof of safety" -- reflects the complexity of risk assessment, particularly regarding complex issues such as cancer. The animal and epidemiology studies conducted so far certainly do not provide adequate basis to conclude that a hazard exists from RF energy from mobile phones or base stations under real-world exposure condition.

It also reflects the reluctance of health agencies to certify any technology as "safe". "Safety", if considered to be the absence of risk, cannot be proven scientifically in any event. Instead, health agencies focus instead on weighing evidence for hazards. The amount of evidence they require, and how it is weighed, depends on complex legal and regulatory constraints, not on the ability to attain scientific certainty. For example, IARC would almost certainly want more data, including the results of multiple animal and epidemiology studies, before evaluating evidence relating to mobile telephones and cancer. Even with such data, IARC virtually never pronounces an agent to be a "noncarcinogen", and therefore is unlikely to do so with RF energy.

Another factor in the issue is the complexity of the microwave bioeffects literature, which is murky and inconsistent in many places. Scientists have been looking for health and safety problems with RF energy since World War II, and thousands of studies are in the primary scientific literature. Clearly identified hazards are associated with excessive tissue heating, and international exposure guidelines offer adequate protection against them. The few reported injuries from RF energy involve exposure levels far above regulatory limits, and typically are related to accidents involving high-powered sources.

However, the scientific literature also contains reports of biological effects of RF energy at exposure levels below current exposure guidelines. Many of these effects have unclear or no relation to health. Often the "effects" are small (close to the noise level in the studies), were reported only in preliminary studies, do not vary in any predictable way with exposure level, or cannot be independently confirmed by other scientists. The literature of the former Soviet Union in particular has many reports of effects of RF energy, sometimes at very low exposure levels, which are frequently lacking important information needed to judge their reliability, or are only available to Western scientists in the form of brief abstracts. Interpreting these diverse reports has been controversial among scientists and in the public arena for many years.

Moreover, the scientific literature also contains many allegations of human health problems associated RF exposure. Notable among these are many reports from the former Soviet Union of "microwave sickness" in workers in factories making RF equipment. This sickness, which was characterized by nonspecific symptoms such as headache and neurasthenia, is not recognized by Western medicine. (Its treatment often consisted of prescribed rest at a spa, which may have contributed to its prevalence.) Indeed, the studies reporting the disease are too briefly reported to be independently evaluated, or have serious methodological problems. Nevertheless, these (and other Russian and Eastern European) studies raise the issue of health effects of RF energy, and create public fears even as they fail to persuade most Western scientists of the existence of a problem.

In short, scientific questions about health effects of RF energy at low exposure levels have been longstanding and difficult to resolve. Unless major new scientific developments occur, the present situation is likely to continue, with health agencies unwilling to either certify low-level (below international guidelines) exposure to RF energy as safe or pronounce it dangerous. Given the many (several thousand) bioeffects studies involving RF energy, the probability of astonishing new revelations seems remote. There are, however, many open questions that need to be addressed by further research.

There is also the need for careful evaluation of the scientific data, as well as harmonization of international exposure standards, which show wide variations around the world. The World Health Organization (WHO) is taking a leading role in these important tasks.

Social Dimensions

"Safety" has strong social (including ethical, legal, and economic) and scientific components, and cannot be understood properly by considering scientific studies alone. People’s responses to risk depend very much on factors such as the nature of the adverse outcome, and whether the risk is voluntary or not.

Thus, there are very real differences between handsets and base stations both in the level of RF exposure and in the question of imposed vs. voluntary risk. The levels of RF exposure from wireless base stations are far lower than those from handsets, yet the former have triggered widespread public outcries while the latter have not. To a large extent, this is because of the involuntary nature of the exposure to people living near base stations, and the lack of perceived value of the base stations to individuals. People can choose to use wireless handsets or not – and very often do, since they find them to be very useful.

The issue of imposed risk is extremely important because it brings into play the risk communication literature especially Bischoff, Covello, Sandman, Chess, Lee, Kemp, Weideman etc. Good risk communication becomes an imperative with base station siting.

The Precautionary Principle and Mobile Telephone Base Stations

A recent, and very important change, has occurred in European regulations concerning RF exposure. In response to public concerns about possible health effects of mobile base stations, several European countries (Slovenia, Italy, and most recently Switzerland) have instituted strict limits for RF exposure from transmitters, based on the precautionary principle. The exposure limits are far below international exposure guidelines such as those of ICNIRP; the Swiss limit is below that of the former Soviet Union and its former Eastern European allies while the Italian and Slovene limits are similar to it. Also, as a precautionary response, various countries are considering proposals to regulate the siting of mobile telephone base stations near schools, hospitals, or other "sensitive" locations.

This precautionary approach has widespread popular support. However, from the point of view of risk management (and perhaps also from a legal perspective) the precautionary approach is problematic. The precautionary principle is elusive in meaning, and lawyers and policymakers disagree about just what it entails. Different statements of it in various treaties and nontreaty declarations can be used to support a wide range of positions, with the "hardest" position being to require that cellular providers offer "proof of harmlessness" of RF energy before building out systems. A recent EU communication (February 2000) on the precautionary principle outlines a more moderate approach, which requires a careful risk assessment, including a cost benefit analysis, before instituting precautionary policies. (A World Health Organization background paper on the precautionary principle as related to electromagnetic field guidelines is on the World Wide Web at

One difficulty in applying cautionary policies in a consistent way to mobile communications is the fact that modern society has many sources of RF energy, many operating at far higher levels than mobile base stations, widely scattered throughout the landscape. Indeed, some proposals aimed at cellular base stations may have far greater impact on police/fire/emergency communications systems and broadcast facilities than on the base stations. A lack of consistency in regulating different sources of RF energy might make these precautionary approaches vulnerable to legal challenge.

Implications for Industry

Meanwhile, industry has to realize that it is facing a difficult problem in risk perception and risk communication, whatever the actual risks or nonrisks may be with wireless communications.

This has two important implications for industry. First, these are human problems, from which industry cannot count on science to bail them out. In our opinion, one contributing factor in the public outcry about wireless base stations has been insensitive practices of industry in siting them. A base station located within sight of a school, or whose antennas appear to be aimed directly at buildings where people live, is bound to raise a public outcry. Such fears have led directly to demands for precautionary approaches in siting these facilities. Wireless providers should use whatever flexibility they have in siting base stations to avoid such situations.

Second, industry has to realize that the conclusions that people draw about risk depend very strongly on the way that information is presented to them. Subtle differences in a message or in the manner of its delivery can make a large difference in its credibility. In our opinion, industry has made the public issue more intense by insensitive or poorly considered efforts at risk communication. Engineers, whatever their technical expertise may be, are not necessarily adept at risk communication. Companies should not use radiofrequency engineers to communicate about risks (or nonrisks) of RF energy with the public – not, at least, without careful instruction in risk communication.

By the same token, government and expert panels need to improve the precision of many of their statements about the issue. It is neither helpful nor correct to say that "we do not know enough to conclude that RF energy is safe". (One can never prove the negative with any amount of evidence.) Rather, scientists need to give the public a sensible assessment of safety and risk. Other difficult issues such as genetically modified foods and "mad cow disease" pose similar challenges in risk communication and management, and it would be very good to get the risk communication right in the mobile phone issue and then use it as a model for risk communication in other issues.

Finally, the difficulties in providing a clear-cut scientific resolution to the health issue, together with the widespread and deeply held public health concerns, points to the need for creative solutions to address public fears of RF energy. This will require joint efforts by all stakeholders, including industry, government, and the public.

The Authors

Kenneth R. Foster is Professor of Bioengineering at the University of Pennsylvania, immediate past president of IEEE Society on Social Implications of Technology, and immediate past chair of IEEE EMBS Committee on Man and Radiation.

John E. Moulder is Professor of Radiation Biology at Medical College of Wisconsin, Milwaukee. He is a specialist in cancer biology and author of a highly respected Internet site on health and safety issues related to electromagnetic fields.


1. COMAR technical information statements: Safety Issues Associated with Base Stations Used for Personal Wireless Communications and Human Exposure to Radio Frequency and Microwave Radiation from Portable and Mobile Telephones and Other Wireless Communication Devices <>

2. JE Moulder: Cell Phone Base Antennas and Human Health FAQs <>

3. Moulder et al: Cell Phones and Cancer: What Is the Evidence for a Connection? Radiation Research 151(5):513-531, May 1999.

4. WHO Fact Sheets are at the WHO EMF website at


Disclaimer This paper presents the views of the authors, and not those of their employers or sponsors of their research.



Table: Recent animal studies relevant to brain cancer risks.

Authors Exposure Carcinogenesis Promotion
Chou et al. (1992) 2450 MHz (FM)

0.15-0.4 W/kg, 100 wks

No brain tumors in 100 RF-exposed rats Not assessed
Toler et al. (1997) 435 MHz (FM)

0.32 W/kg, 84 wks

No difference in brain tumor incidence between 200 RF-exposed and 200 sham-exposed mice Not assessed
Frei et al. (1998) 2450 MHz (pulsed)

0.3 W/kg, 72 wks

No brain tumors in 100 RF-exposed mice Not assessed
Frei et al. (1998) 2450 MHz (pulsed)

1.0 W/kg, 72 wks

No brain tumors in 100 RF-exposed mice Not assessed
Adey et al. (1999) 837 MHz (FM)

0.3-1.6 W/kg, 88 wks

Insignificant decrease in brain tumor incidence in 60 RF-exposed rats compared to 60 sham-exposed rats No promotion of chemically-induced brain tumors in 56 rats
Adey et al. (1997) 837 MHz (pulsed)

0.1-2.3 W/kg, 88 wks

No difference in brain tumor incidence between 90 RF-exposed rats and 90 sham-exposed rats No promotion of chemically- induced brain tumors in 90 rats
Zook et al. (1999) 860 MHz (FM)

1 W/kg, 88 wks

No difference in brain tumor incidence between 60 RF-exposed and 60 sham-exposed rats No promotion of chemically- induced brain tumors in 120 rats
Zook et al. (1999) 860 MHz (pulsed)

1 W/kg, 88 wks

No difference in brain tumor incidence between 60 RF-exposed and 60 sham-exposed rats No promotion of chemically- induced brain tumors in 120 rats