Cell Phone Use and Cancer: A Case Study to Explore the Scientific Method
By Wilma V. Colón Parrilla, Biological Sciences, University of Puerto Rico
Part I—Hang Up!?
―Alisa, please, get off your cell phone already,‖ said her mother.
―But mom! I want to talk with my friends! Plus all my friends use it!‖ Alisa whined in response. Annoyed by her mother’s impatience, she
mumbled: ―Anyway, weekends are for free, you know.‖
―This is not about the money. This is about your health. I’ve heard that there is a link between cell phones and cancer,‖ Alisa’s mother
―You’re right!‖ said Alana, Alisa’s sister, cutting in. ―In my scientific journalism class we are going to discuss some articles about a study
that has been performed on cell phone use and its effect on health. The professor asked us to analyze the titles of those articles,‖ Alana
―And what did the study reveal? Has such a link been proved?‖ asked her mother, interested in hearing more.
―Well, we haven’t read the articles yet, but I have their titles here. You can read them,‖ Alana said as she handed a paper to her mother
with the following list:
1. Long-Term Cell Phone Use Spurs Tumor Growth
2. Study Indicates Mobile Phones Increase Tumor Risk
3. Mobile Phone Use and Acoustic Neuroma
4. Heavy Use of Mobile Phones Increases Cancer Risk, First Evidence of Link Between Mobile Phone Use & Severe Brain Tumors
5. Cell Phone-Tumor Link Found?
―Now I’m even more confused. Do cell phones cause cancer or not? Can I use mine or not?‖ asked Alisa impatiently.
―In my next class we’re going to read the articles, so I will tell you everything then,‖ concluded her sister.
1. What information about the scientific research can be inferred by reading the headlines?
2. Compare headlines 4 and 5. Why is there a difference in the two headlines even when they outline the same scientific research?
3. What questions arise about the methodology and conclusions of the experiment when analyzing the headlines?
Cell Phone Use and Cancer by Wilma V. Colón Parrilla Part II—Journal Groups
You will be organized into groups of three or four and given copies of each of the press articles (see References, below). Each member of
the group has to read one of the articles. Afterwards, you should be able to answer the following questions.
1. What is the purpose of the research outlined in the news articles?
2. Who are the researchers involved in the scientific work and in which institution was the research conducted?
3. What methods did the researchers use?
4. Explain the difference between an observational study like this and a controlled experiment.
5. State the results of the study.
6. What conclusions were drawn from the study?
7. Compare the scientific information described in articles 4 and 5: ―Study Links Mobile Phones, Benign Tumors,‖ and ―Cell Phone-
Tumor Link Found?‖ Which of the two headlines better describes the results of the scientific research? Why?
8. How much credibility do you give to the results of the study? Why?
9. Give suggestions on how to improve the study.
10. How do scientists report the results of their experiments? Why is it important to disseminate this information?
Long-Term Cell Phone Use Spurs Tumor Growth. (headline #1). eHealthy News You Can Use, Mercola.com, issue 581. October 27, 2004.
http://www.mercola.com/2004/oct/27/cell_phone_tumor.htm Last accessed: 10/24/06.
Long-Term Cell Phone Use Spurs Tumor Growth
If you have used your mobile phone for more than 10 years, you might have
increased your risk of developing acoustic neuroma, a benign tumor on the
Interestingly enough, studies found that the risk was confined to the side
of the head that was used most often while talking on the phone. As a
matter of fact, the risk of acoustic neuroma was nearly four times greater
on the side of the head that the phone was most frequently held compared
to the other side, which appeared normal.
A study revealed that the number of years of phone usage seemed to play a
factor in the development of the tumor, as those using their phone 10
years or more were shown to nearly double their risk of acoustic neuroma.
On the other hand, those who used their phone for less than 10 years
didn't show any signs of increases risk.
Participants of the study included 150 people with acoustic neuroma and
600 healthy people.
Since the only types of phones used during the study were analog mobile
phones, researchers questioned whether or not the same results would apply
to long-term use of the digital phones, which have since replaced the
bulkier and less advanced analog phones.
In response to the study results, the mobile phone industry claimed there
wasn't any scientific evidence to supporting findings showing that using
mobile phones causes negative health effects.
USA Today October 14, 2004
Study Indicates Mobile Phones Increase Tumor Risk. (headline #2). USA Today, October 14, 2004.
http://www.usatoday.com/ Last accessed: 10/24/06.
Study indicates mobile phones increase tumor risk
STOCKHOLM (Reuters) — Ten or more years of mobile phone use increases the risk of developing acoustic
neuroma, a benign tumor on the auditory nerve, according to a study released on Wednesday by Sweden's
The risk was confined to the side of the head where the phone was usually held and there were no indications
of increased risk for those who have used their mobile for less than 10 years, the Karolinska Institute said in a
The institute, one of Europe's largest medical universities and a clinical and biomedical research center,
awards the Nobel Prize in physiology or medicine.
"At the time when the study was conducted only analogue mobile phones had been in use for more than 10
years and therefore we cannot determine if there results are confined to use of analogue phones or if the
results would be similar also after long-term use of digital (GSM) phones," it said.
The mobile phone market is now dominated by GSM phones, which replaced the bulkier and less advanced
analogue phones in many markets the mid- and late-1990s.
The mobile phone industry has said there is no scientific evidence of negative health effects from use of
The Karolinska Institute said 150 people with acoustic neuroma and 600 healthy people participated in the
"The risk of acoustic neuroma was almost doubled for persons who started to use their mobile at least 10
years prior to diagnosis," the institute said.
"When the side of the head on which the phone was usually held was taken into consideration, we found that
the risk of acoustic neuroma was almost four times higher on the same side as the phone was held and
virtually normal on the other side."
Finland's Nokia is the world's biggest mobile phone maker.
Other large producers include Motorola of the United States, South Korea's Samsung Electronics, Germany's
Siemens and Swedish-Japanese joint venture Sony Ericsson.
Global mobile phone sales have been booming as thousands of new users sign up every day and existing
subscribers replace their old handsets with new ones, capable of taking pictures or playing music.
Mobile Phone Use and Acoustic Neuroma. (headline #3). Press release by the Swedish Research Council. October 13, 2004.
http://www.eurekalert.org/index.php Last accessed: 10/24/06.
Mobile phone use and acoustic neuroma
A study from the Institute of Environmental Medicine (IMM) at Karolinska
Institute, Sweden, found that 10 or more years of mobile phone use increase the
risk of acoustic neuroma and that the risk increase was confined to the side of
the head where the phone was usually held. No indications of an increased risk
for less than 10 years of mobile phone use were found.
At the time when the study was conducted only analogue (NMT) mobile phones had
been in use for more than 10 years, and therefore we cannot determine if the
results are confined to use of analogue phones, or if the results would be
similar also after long term use of digital (GSM) phones.
In close collaboration with the clinics where these patients are treated all new
patients with acoustic neuroma were identified during a three-year period in
certain parts of Sweden. Persons without the disease were randomly selected from
the population registry (controls). A nurse contacted all patients and controls
and asked them if they wanted to participate in the study. All who agreed
participated in a personal interview where detailed questions were asked about
their mobile phone use and other issues of importance for the study.
A total of about 150 acoustic neuroma patients and 600 healthy controls
participated in the study. The risk of acoustic neuroma was almost doubled for
persons who started to use their mobile phone at least 10 years prior to
diagnosis. When the side of the head on which the phone was usually held was
taken into consideration, we found that the risk of acoustic neuroma was almost
four times higher on the same side as the phone was held, and virtually normal on
the other side.
Acoustic neuroma is a benign tumor on the auditory nerve that usually grows
slowly over a period of years before it is diagnosed. It occurs in less than one
adult per 100,000 per year.
This is the first report from the Swedish part of the so-called INTERPHONE study,
an international collaboration coordinated by WHO's cancer research institute,
IARC (International Agency for Research on Cancer). The Swedish results need to
be confirmed in additional studies before firm conclusions can be drawn. Other
centers within the INTERPHONE study where a sufficient number of long term mobile
phone users can be included – primarily the Nordic – will contribute valuable
data. This Swedish study, and eventually other INTERPHONE reports, will be
reviewed by the scientific community and a coherent evaluation will gradually
emerge. It can also be expected that these results will stimulate experimental
research, which will also contribute information of importance for the
interpretation of the findings.
The study was funded by the European Union Fifth Framework Program, "Quality of
Life and Management of living Resources" (contract QLK4-CT-1999-01563), the
Swedish Research Council, and the International Union against Cancer (UICC). The
UICC received funds for this purpose from the Mobile Manufacturers' Forum and GSM
Association. Provision of funds to the INTERPHONE study investigators via the
UICC was governed by agreements that guaranteed INTERPHONE's complete scientific
independence. These agreements are publicly available at http://www.iarc.fr/
Heavy Use of Mobile Phones Increases Cancer Risk, Study Finds, First Evidence of Link Between Mobile Phone Use and Severe Brain
Tumors - By Larry West, About.com (headline #4). http://environment.about.com/od/healthenvironment/a/cancerphones.htm
Cell Phone-Tumor Link Found? (headline #5). CBS News October 14, 2004.
http://www.cbsnews.com/ Last accessed: 10/24/06.
Cell Phone-Tumor Link Found?
Swedish Study Finds Some Cell Phone Users At Risk For Benign Tumor
STOCKHOLM, Sweden, Oct. 14, 2004
(AP) A Swedish study suggests that people who use a cell phone for at least 10 years
might increase their risk of developing a rare benign tumor along a nerve on the side of
the head where they hold the phone.
In an interview Thursday with The Associated Press, one of the researchers behind the
preliminary study, Anders Ahlbom, said the results were surprising and more research is
Several previous studies have investigated whether the use of cell phones is linked to an
increased risk of brain tumors. Although experiments have shown radiation from mobile
phones can affect brain cells in a lab, more relevant studies on people have found no
evidence that the phones pose a health risk. However, experts have said that because
children's brains are developing, it may not be a good idea for youngsters to use the
phones for long periods.
The three-year study by Ahlbom and Maria Feychting, professors at the Karolinska
Instituted in Stockholm, focused on 750 Swedes who had used cell phones for at least 10
years. It was published in the International Journal of Epidemiology.
In the study, researchers questioned 150 patients already diagnosed with acoustic
neuroma, a benign tumor on the auditory nerve that takes several years to grow before
being diagnosed, and 600 who did not have it, about their cell phone use.
All 750 subjects had been using cell phones for at least 10 years, nearly all early
analog models that emit more electromagnetic radiation than the digital models now on the
market. Digital phones emit radiation in pulses; the older analog varieties emit
continuous waves. Since cell phones exploded in popularity in the late 1990s, most of
those sold used digital technology.
"At the time the study was conducted, only analog mobile phones had been in use for more
than 10 years and therefore we cannot determine if the results are confined to use of
analog phones or if the results would be similar after long-term use of digital phones,"
the report said.
The risk of developing a tumor was almost double for those who started to use phones
before their diagnosis. In addition, the tumor risk was almost four times higher on the
side of the head where the phone was held, Ahlbom and Feychting said.
Retrospective questionnaires are not considered the most accurate method of determining a
link between behavior and disease. Many links that emerge from such studies turn out not
to be true under more rigorous study.
Acoustic neuroma tumors, which can affect hearing, occur in less than one adult per
100,000 people annually. The tumor pushes on the surface of the brain, but doesn't grow
into the brain itself, according to the Atlanta-based Acoustic Neuroma Association.
The study was funded by the European Union and is part of the wider Interphone study
coordinated by the International Agency for Research on Cancer.
Previous studies, including one by Finnish scientists in 2002, found that electromagnetic
radiation emitted by phones can affect brain tissue, but others have said that's not the
The wireless industry has always maintained there is no link between mobile phones and
The Wireless Association in Washington, D.C., a trade group representing American cell
phone manufacturers, urged more research. "The wireless industry agrees that more
research is needed in this area to provide definitive answers to any questions that might
still exist," it said in a statement Wednesday.
Ahlbom conceded more research was needed, adding the study was not an excuse to avoid
using cell phones. "You could say also, of course, if that someone is concerned about
these results the easy way to avoid any risk is to use a hands-free set," he said.
Case Teaching Notes for “Cell Phone Use and Cancer: A Case Study to Explore the Scientific Method”
By Wilma V. Colón Parrilla, Biological Sciences, University of Puerto Rico
Introduction / Background
This case study provides an effective way to analyze scientific information on topics that interest the students. It helps the students develop
skills in critical thinking and, because it is based on a current issue, it makes science relevant to them. It also provides students an
opportunity to critically analyze press articles.
The case requires little preparation or prior knowledge of the issue on the part of the students. In fact, it was designed as an exercise for
exploring the student’s knowledge of the scientific method. As stated in the constructivist-learning model, when facing a new topic, the
first step is to determine what the student knows beforehand and then start constructing over that initial knowledge, adding and organizing
new material (von Glasserfeld, 1987).
In introductory biology courses for non-majors, one of our goals is to give students practice in analyzing scientific research. However,
students are reluctant to read scientific papers due to their technical complexity, which makes them difficult to understand. This way of
introducing students to the task of analyzing a piece of research was found effective because the student first identifies the essential
elements of a scientific investigation in a news article before reading the journal article on the same investigation, which is usually written at
a higher level of difficulty. When the student then starts reading the original article, he or she has already done a previous analysis of the
subject and is looking for answers to questions that arose earlier when analyzing the news articles.
The selection of the scientific article was based on the interest that the topic could arouse in the students. Professors that use case studies
in their classes know that the students feel more motivated if the concepts they are learning are interesting and useful or relate to their lives.
Young people spend a great deal of time on their cell phones and it is in their interest to know if this poses a risk to their health. This
presents an opportunity for students who are non-science majors to appreciate the process of science and how it affects their lives. The
American Council on Science and Health has a website where they list the ―Top Ten Unfounded Scares of 2004‖ (Kava et al., 2004). This
website can prove very useful when searching for and selecting topics of general interest.
The case was designed for groups of 30 students in an introductory course in biological sciences for non-majors. However, it can be used
for larger groups, in courses for biology majors, or in other courses that study the scientific method. It can also be used in a scientific
journalism course. For all audiences, the emphasis should be to encourage discussion and understanding of scientific processes. For science
journalism students, special emphasis should be placed on their responsibility to educate people about the field of science. A better
understanding of how science works will allow them in turn to better inform and educate people. Acquisition of scientific information
allows people to make choices concerning issues that will affect their lives. For many individuals, science news articles will be their only
contact with scientific information for the rest of their lives.
In working through this case, students will:
* Identify the basic elements of a scientific research study.
* Evaluate a scientific study and offer suggestions for improvement.
* Analyze the appropriateness of the headlines of news articles in relation to their content.
* Compare the accuracy of information offered to the public in a news article with the information presented in a scientific paper.
* Appreciate the nature of science and how science affects their lives.
The case study is divided into three parts. Part I consists of analyzing the headlines of five news articles that outline a scientific research
study published in the journal Epidemiology in 2004 (Lönn et al., 2004; this article is not included here with the case—instructors are
expected to retrieve a copy from their campus library or through interlibrary loan). This activity should take about 15–20 minutes. It is
desirable for the instructor to run a general discussion with the entire class about the case, identifying the problem stated and the
differences among the news story headlines. At this point in the case, students will be highly motivated to determine if cell phone use is
really hazardous to their health. They will ask a lot of questions about the scientific study, trying to determine if such a link exists, and will
be eager to read the actual news articles.
Part II of the case involves reading the news articles (for copies, see the password-protected Resources file associated with this case—
eligible instructors may apply for a password account), discussing previously prepared questions on the articles in small groups, and then
having the entire classroom discuss them as a group. Organize the class in groups of three or four students. Hand out a copy of each article
to every group. Each member of the small group has to read one of the articles. It should take the students about 10 minutes to read their
articles. Afterwards, the students will work in small groups to answer the questions listed in Part II. This should take about 30–45 minutes.
The entire classroom discussion should take about 80 minutes. Throughout this exercise the instructor should emphasize the components
of scientific research. The student should be able to identify the problem, describe the methodology employed, state the results and
conclusions, and critically evaluate a scientific study and offer suggestions for improvement.
Mobile Phone Technology
Today, cell phones are an essential element in the life of our students. With cell phones, students not only communicate frequently among
themselves but also play games, send text messages, get information and music from the Internet, send or receive e-mails, set reminders,
take photos and videos, make task lists, and use the calculator. It is expected that 2 billion people will use cell phones by this year.
There are three main types of mobile or cellular phone services in the United States: analog, digital, and PCS. Analog cellular systems are
considered a first generation cell phone technology and were introduced in the 1980s. They were primarily used for voice transfer. They
used an analog transmission protocol called frequency-division multiple access (FDMA), which operates in the 824–894 MHz frequency.
FDMA uses separate frequencies for each call, reducing the interference between them. Nevertheless this limits the number of users.
In the early 1990s, a second generation of cellular systems was introduced, using digital techniques. Digital systems are more versatile: they
carry information as e-mails, news, or other forms of data and also allows connection to the Web. The different types of digital systems
include time-division multiple access (TDMA), hybrid TDMA/FDMA, and code-division multiple-access (CDMA), which operate in the
same frequency band as the analog systems. TDMA increases the efficiency of the network because it allows different users in the same
frequency without interference among them.
Personal Communication Services (PCS) is a newer wireless digital system that uses both TDMA and CDMA technologies. It operates in
the 1800–2000 MHz frequency range. PCS exhibits considerable improvement in sound quality and in calls capacity.
The progression of cell phone technology from analog to digital systems has led to a reduction of the cell phone transmitter powers. [For
further information see IEEE Committee on Man and Radiation (Safety Issues Associated with Base Stations Used for Personal Wireless
Communications, 2000) and Mobile phone (2006).]
Cell Phone Electromagnetic Emissions
The increasing use of appliances and equipment such as microwave ovens, cell phones, and base stations that receive and transmit signals
has led to an increase in humans being exposed to radiofrequency (RF) energy. The extensive use of these appliances/apparatus has been
accompanied by public concerns about their possible adverse effects on human health, including cancer. RF energy (or radio waves) is one
form of electromagnetic energy that makes up the electromagnetic spectrum. It has several common uses such as radio and TV
broadcasting, wireless phones, pagers, cordless phones, police and fire department radios, microwave ovens, and medical treatments.
Unlike the X-rays and gamma rays that can ionize molecules in biological tissues, causing damage to the DNA, RF is a non-ionizing
radiation. Thus, the RF energy is not great enough to cause the ionization of molecules or damage to biological tissues. Exposure to RF
could affect health by thermal (heating) effects. Although large amounts of RF energy can heat tissue, causing damage and increasing body
temperatures, the amount of RF radiation from cell phones is too low to produce damage (Cell Phone Facts, 2003). Still, many people have
concerns about the possible health effects of low levels of RF energy from their cell phones, particularly by long-term exposures.
Standards for Human Exposure to RF Energy
Several national and international organizations have developed standards to protect health for human exposure to radio frequency (RF)
energy. In the United States, the Federal Communications Commission (FCC) has established guidelines derived from the
recommendations of the National Council on Radiation Protection and Measurements (NCRP) and the Institute of Electrical and
Electronics Engineers (IEEE). These recommendations were developed by scientists and engineers after the examination of scientific
literature to identify potential hazards of RF exposure. The limits for safe exposure to RF energy adopted by the FCC are given as the
Specific Absorption Rate (SAR). SAR is a measure of the amount of RF energy absorbed by the body. According to the FDA and the FCC
(Cell Phone Facts, 2003), both NCRP and IEEE have identified a SAR value of 4 watts per kilogram (4 W/kg) as ―a threshold level of
exposure at which harmful biological effects may occur.‖ The FCC limit for human exposure from cell phones is 1.6 W/kg of tissue. Cell
phones used in the United States are required to operate within this limit of safe exposure and manufacturers are required to report the
SAR measure of their cell phone products to the FCC (Radio Frequency Safety, FCC, 2006).
Studies of RF Exposures and Human Cancer
Public concern about RF radiation and human cancer began in 1993 when, in a lawsuit in Florida, a man claimed that his wife had died of
brain cancer caused by cell phone RF emissions. A particular public concern is that long-term use of cell phones may be linked to brain or
to other types of cancer. Several review articles have been published to address whether the available studies show that exposure to RF
energy from cell phones causes tumors in humans. Among the most recent reviews are Moulder et al. (2005), Ahlbom et al. (2004), and
Elwood et al. (2003). According to the epidemiological, animal, and in vitro studies outlined in those reviews, no convincing evidence links
cell phone usage with cancer. The epidemiological studies, however, have certain flaws or limitations in their design and/or conduct such
that their results are not unequivocal. Major limitations of those studies include: (1) no data are available on the consequences of childhood
exposure; (2) inadequate exposure assessment: the results are based on the subjects’ recall of hours of use, on billing records, or on the
duration of subscription to cell phone services; (3) short lag periods for health effects to occur; and (4) the published data concentrate on a
small number of outcomes (e.g., brain tumor and leukemia).
In view of the increasing use of cellular phones, the public concerns about the health effects of RF radiation in the growing population of
cell phone users, and the limitations of the epidemiological studies, the International Agency for Research on Cancer (IARC, an agency of
the World Health Organization) coordinated in 1998–99 an international study in 14 countries. The INTERPHONE project includes a
series of epidemiological studies to determine whether cell phone use increases the risk of certain types of cancers in the head and neck
(brain tumors: gliomas and meningiomas), tumors of the parotid gland (a salivary gland tumor) and acoustic neurinomas. Results from
some of these studies have been published (Christensen et al. 2004; Lönn et al. 2004; Christensen et al. 2005; Lönn et al. 2005; Hepworth et
al. 2006; Lönn et al. 2006; and Schüz et al. 2006). The overall results are consistent with most published studies, which do not support the
hypothesis that cell phone use is related to an increased risk of certain tumors like glioma, meningioma, paratid gland, or acoustic neuroma.
Nevertheless, the Lönn et al. (2004) data suggests an increased risk of acoustic neuroma associated with long-term use of analog cell
phones (≥10 years). It seems at present that additional studies with a sufficient number of cases and long-term users are needed to firmly
assess the potential risk of long-term use of cell phones.
Cancer is a disorder characterized by an uncontrolled division of cells and by the ability of those cells to invade other tissues of the
organism. It is caused by damage to the DNA, resulting in mutations to genes that control cell cycle: the proto-oncogenes, tumor
suppressor genes, and mutator genes (Russell 2002). These mutations can be caused by carcinogens (chemical agents and radiation) or by
certain types of viruses. The development of the majority of cancers depends on the accumulation of mutations in a number of genes over
long periods of time—probably several decades—during a person’s life. The cause of a cancer must be determined in order to establish the
latency period, which is described as the time between exposure and diagnosis. The uncontrolled division of cells can lead to either a
benign or a malignant tumor. Unlike benign tumors, malignant tumors tend to spread to other tissues, and therefore are considered life
threatening. The INTERPHONE project focused on cancers that occur in the head and neck, areas of relatively high exposure to RF
energy during cell phone usage. Among the brain cancers are the meningiomas and gliomas. Meningiomas are a type of tumor that
develops from the meninges, the membrane covering the brain. Although 90% of meningiomas are benign, they can be life threatening
when the tumor grows and constricts the brain. Most adult brain tumors are glial cell cancers or gliomas. They develop from glial cells,
which play a supportive role with neurons. Gliomas can be benign or malignant. Acoustic neurinoma is another type of benign tumor that
develops from an overproduction of the Schwann cells that support the acoustic nerve. If the tumor becomes large, it can constrict the
facial nerve or the brain. Finally, the majority of the salivary gland tumors originate in the parotid glands and most of them are not
cancerous. (For further information, see the National Cancer Institute website at http://www.cancer.gov/.)