January 14, 1998
The Honorable Edward J. Markey
Ranking Minority Member
Subcommittee on Telecommunications,
Trade, and Consumer Protection
Committee on Commerce
House of Representatives
Washington, D.C. 20515-2107
Dear Mr. Markey:
This is in response to your letter of November 21, 1997, regarding the status of the
Food and Drug Administration's (FDA or the Agency) oversight and investigation of wireless
communication health effects. The Agency is committed to protecting the public health from
hazards associated with radiation-emitting products. As you will note from the answers
provided below, there is no new information indicating that use of cellular phones is a
human health risk. It is our hope that ongoing studies and those planned by a number of
other organizations will shed some light on this important health issue.
Our responses to the specific questions you raise in your letter follow.
- Is the FDA monitoring biological health effects other than cancer, for example,
headaches or ocular problems? If so, please describe such research and any available
resulting data.
FDA is aware of reports of headaches among cellular phone users in the U.S. and
overseas. These reports are not unexpected, given the high prevalence of both cellular
phone use and headaches. A study is being conducted by Dr. Kjell Mild in Scandinavia of
the possible relationship between cellular phone use and headaches. A member of the
Radiofreqency Interagency Work Group (not from FDA) is interacting with the project
advisory group for this study. The results of this study are anticipated in 1998.
FDA has not received any reports of ocular effects among wireless phone users. Previous
research that reported ocular changes following radiofrequency radiation (RFR) exposure
were performed using exposures that are not directly relevant to wireless phone RFR
exposures1.
Ongoing work is being conducted under Department of Defense (DOD) sponsorship using high-peak power,
pulsed microwaves2.
- Has the FDA received any information that digital wireless phone technology poses a
greater, or qualitatively different, potential risk to certain users than analog wireless
phone technology? If so, please describe such research and any available resulting data.
There are very few studies in the scientific literature which have directly compared
the effects of analog and digital wireless technology on biological systems. The accuracy
and reproducibility of the few available studies have not been determined at present, and
there is as yet no scientific consensus as to whether either of these technologies pose
any risk to users. There is some suggestion that the digital phone signal might have
greater biological activity than the analog signal, but, again, neither signal has been
demonstrated to pose a definite health risk to the users of cellular phones at the present
time. Studies conducted to date are listed below.
- A recent publication by Pentafiel et al3. explored differences in the biological effects of different types of
wireless telephone modulation. The biological endpoint examined in this study was a
cellular enzyme, ornithine decarboxylase (ODC), which is related to cellular growth and
proliferation, and which is stimulated by the application of chemical agents associated
with cancer promotion, Pentafiel et al. compared the effects of the analog telephone
signal most commonly used in this country (advanced mobile phone system, or AMPS) with the
most commonly used digital signal (digital advanced mobile phone . system, or DAMPS, also
called time division multiple access, or TDMA). These authors reported no increase in
cellular ODC activity following exposure to the analog phone signal but did observe a
small but statistically significant increase in ODC following exposure to the digital
phone signal. The relevance of this effect to human health is not known at present.
- W. Ross Adey has reported results of animal exposures designed to detect a promotion
effect on brain tumors of cellular phone exposures but has not yet published these
findings in the scientific literature. These studies used rats which had been exposed
prenatally to a dose of a chemical carcinogen, ethyl nitroso urea (ENU), which induces
brain tumors in approximately 25% of the rats; subsequent exposure to radiofrequency would
be expected to increase this incidence if it were associated with a tumor promoting
effect. At the 1997 World Congress for Electricity and Magnetism in Biology and Medicine,
Dr. Adey reported that 23 months of exposure to the frequency modulated analog phone
signal did not affect the incidence of brain tumors in rats either with or without the
prenatal treatment with ENU. At the 1996 Bioelectromagnetics Society Annual Meeting, Dr.
Adey reported that 22 months of exposure to the TDMA signal decreased the incidence of
both spontaneous and ENU-induced brain tumors, but the difference was not
statistically significant. While the clear lack of a tumor promoting effect in Dr. Adey's
study has been cited as evidence of the safety of wireless technology, these data remain
to be published and must be interpreted in the context of the Repacholi study discussed
below and which has been fully reported in the scientific literature.
- Repacholi et al. published a study earlier this year (Radiation Research 147, 631-640,
1997) in which mice that have been genetically altered to increase their incidence of
lymphoma were exposed to the Global System for Mobile Communications (GSMC) digital phone
signal for up to 18 months. (There was no group exposed to an analog phone signal for
comparison.) The transgenic mice exposed to the digital phone signal developed more than
twice as many nonlymphoblastic lymphomas as the unexposed control group, a statistically
significant increase. These results suggest a potential effect of the digital phone signal
on the biological process of carcinogenesis in these animals in an as yet undetermined
manner. Although the relationship of this transgenic mouse bioassay to human health risk
is not yet understood, it may prove valuable as a model for interaction of radiofrequency
with biological systems and allow a direct comparison of the effects of the different
types of wireless signals. FDA has recommended, through participation in the WHO
International EMF program, that these results be addressed by further research.
- Has the FDA received any information indicating that current or future base stations
pose a health risk? If so, please describe such research and any available resulting data.
The construction and licensing of cellular telephone and other wireless communications
towers is regulated at the Federal level by the Federal Communications Commission.
- In its May 5, 1997 response, the FDA indicated that CDRH has performed experimental and
computational investigations of energy deposition in the body from cellular phones. Please
describe such research and resulting data. Also in its May 5, 1997 response, the FDA
stated that the Department of Defense conducts research on basic bioeffects of RP
exposure. Please describe such research and resulting data and provide a list of all such
experiments conducted by the Department of Defense.
A Center for Devices and Radiological Health (CDRH) engineer and electronics
technician set up and calibrated implantable electric field probes in a manually operated
system. It was determined that this approach was inadequate and could not produce
dosimetric data with accuracies approaching today's standards of quality. Currently
available cellular phone dosimetry systems cost $100,000-$400,000 and are used by all of
the cellular phone and personal communications systems manufacturers and other dosimetric
measurement labs. CDRH then designed and ordered parts for a computer- controlled e-field
probe measurement system to be built by a local university for $6,000. When the system
arrives, it will be used in a number of applications, including measuring cellular phone
electromagnetic fields for hearing aid and cardiac pacemaker interference.
A senior staff member in the Office of Science and Technology in CDRH is serving as the
Chair of an international technical group composed of experts from government, industry,
and academia that is developing a Recommended Practice for Determining the Spatial Peak
Specific Absorption Rate in the Hand and Head of Hand-Held Personal Wireless Service
Transceiver Users (Standards coordinating Committee 34, Subcommittee 2, of the Institute
of Electrical and Electronics Engineers (IEEE)).
While we are not aware of all the DoD research being conducted in this area, we do have
the following information which describes the DoD research:
- J.C. Toler, W.W, Shelton, M.R. Frei, J,H, Merritt, M,A. Stedham. 1997. Long-term, low-level
exposure of mice prone to mammary tumors to 435-MHZ radiofrequency radiation, Radiation
Research 148(3), p. 227. Mammary tumor-prone mice (C3H/HeJ) were exposed to pulsed 435-MHZ
microwaves for 21 months (22 h/day, 7 days/week). Under the conditions of the study,
microwave exposure did not affect the incidence of mammary tumors, latency to tumor onset,
rate of tumor growth, or animal longevity when compared to sham exposure.
- M,R. Frei, R.E. Berger, S,J, Dusch, V, Guel, J.R, Jauchem, J,H, Merritt, M,A. Stedham.
Chronic exposure of cancer-prone mice to low-level 2450-MHZ radiofrequency radiation,
Bioelectromagnetics, in press. Mammary tumor-prone mice (C3H/HeJ) were exposed to pulsed
2450-MHZ RFR for 18 months (20 hours/day, 7 days/week). Under the conditions of the study,
microwave exposure did not affect the incidence of mammary tumors, latency to tumor onset,
rate of tumor growth, or animal longevity when compared to sham exposure.
- D'Andrea studies cited above (question #1) on ocular effects and contrast sensitivity.
- What provisions have been made to ensure that there are long term monitoring studies of
users of wireless telephones? Are specific studies in place? Who is conducting such
research?
As you know, we have no regulatory authority to require manufacturers of electronic
products to conduct specific long-term studies. The Agency advised Wireless Technologies
Research (WTR) in a letter dated March 13, 1997, (enclosed) that due to the latency of
some of the health effects that have been suggested to be associated with exposure to
non-ionizing radiation, long-term study is essential to test such associations.
We are aware of the following studies monitoring users of cellular telephones.
- As we reported in our earlier communication with you, dated May 5, 1997, Rothman et al.
have published the results of a mortality cohort study of over 250,000 wireless phone
users. No increase in overall mortality was reported, but the follow-up period was
relatively brief. According to the WTR, the mortality experience of this cohort will be
examined for two additional years, 1994 and 1995. The WTR has indicated that legal
obstacles will preclude the continued follow-up of this cohort. We believe that long-term
follow-up of this cohort has scientific merit.
- A case-control study of non-Hodgkin's lymphoma is being conducted by the
National Cancer Institute (NCI). At the suggestion of CDRH, NCI researchers agreed to
examine a possible relationship between wireless phone use and non-Hodgkin's lymphoma in
this study. According to Dr. Martha Linet of NCI, cellular phone use will be assessed
among 600 non-Hodgkin's lymphoma cases and 600 controls, Final results for the study are
expected in the year 2000.
- A case-control study of primary brain cancer and wireless telephone use, by
the American Health Foundation (AHF), is currently underway. This study has received the
majority of its funding from the WTR. The sample size is expected to include 400 cases of
primary brain cancer. The WTR anticipates results to be available in 1998.
- The NCI is performing a case-control study of primary brain cancer and
wireless phone use. The study will encompass gliomas, meningiomas, and acoustic neuromas.
A total of 800 cases and 800 controls are expected to participate. Study completion is
anticipated in 1999.
- A pilot case-control study of acoustic neuromas and cellular telephone use
by the AHF also has been initiated. The funding for this study also was largely obtained
from the WTR. WTR anticipates results to be available in 1998.
- As you may know, WTR's peer review board, coordinated by the Harvard University School
of Public Health Center for Risk Analysis, wrote to WTR on July 15, 1997. In that letter,
the peer review board lauded WTR for its work addressing unanticipated health risks
associated with interference with pacemakers in some patients who use cellular phones.
Does the FDA believe that such creative and decisive action by WTR to address this
discrete issue in a timely fashion can serve as a model when other discrete risks are
identified? Please explain and reference which distinct potential health risks might be
addressed by WTR, or other research entities, in this manner.
Overall, the Agency feels that the clinical study on cellular phone interference
with cardiac pacemakers (D.L. Hayes, P.J. Wang, D.W. Reynolds et al., Interference with
cardiac pacemakers by cellular telephones. New England J. Med. 336: 1473-1479 (1997)) was
well done. In fact, this study is serving as a model for FDA in the study of other medical
devices radio frequency interference issues such as those associated with metal detectors
and electronic article surveillance devices, In contrast, research in biological effects
is longer term and more complex, and this may not be an adequate model for studying
potential long-term effects.
- Also in its July 15, 1997 letter, the WTR's peer review board identified significant
areas for improvement in WTR's activities, including asserting that WTR's "decision
making appears to be less independent of industry and government than it was several years
ago." The board articulated a series of recommendations to WTR including, but not
limited to, revisiting and revising its research agenda, not relying wholly upon industry
to fund certain studies, articulating a plan to support a continued program of health
research, and fully documenting its spending for its first three years. For each of the
peer review board recommendations, please respond as to whether the FDA concurs with the
peer review board's critique and supports its recommendations. In addition, please provide
any additional recommendations that the FDA believes that WTR should implement to further
improve its efforts.
The following is a summary of the WTR Peer Review Board's (PRB) recommendations as
well as FDA's comments on the recommendations. We have no special knowledge of how the PRB
was constituted or of its relationship with WTR. FDA personnel have not participated in or
observed any of their meetings. We can give only general responses, therefore, to some of
their recommendations.
- Recommendation: The PRB recommended that WTR enhance the credibility and
independence of its resource allocation decisions by making greater use of the experience
and expertise of the PRB. The PRB also recommended that WTR consider using the PRB in a
broader scientific advisory capacity.
- FDA Response: The use of an independently constituted peer review process
enhances the credibility and independence of any research effort.
- Recommendation: The PRB recommended that WTR revisit and revise the research
agenda document that was originally created in 1994. The PRB recommended a thorough
evaluation of research priorities including an assessment of scientific and regulatory
needs, recent and forthcoming research conducted worldwide, and research costs and
available funding.
- FDA Response: FDA concurs with this recommendation. Revisiting and revising a
research agenda should be an ongoing process.
- Recommendation: The PRB recommended that WTR fund not only the epidemiologic
studies currently underway but also at least one of the highly rated
case control proposals
that it received in response to its 1995 Request for Proposals. The PRB stated that it
believed that epidemiologic studies are critical research investigations to pursue in
exploring the potential health effects of wireless technology.
- FDA Response: FDA recommends the wireless technology industry fund a long-term
cohort study such as the one being conducted by Dr. Rothman. This may continue past the
term of WTR, Furthermore, FDA continues to recommend that the wireless technology industry
continue to fund epidemiologic research.
- Recommendation: The PRB, recognizing that health-related questions related to the
use of wireless technology will persist when the current WTR program ends, recommended
that WTR clarify its plans for continued research funding and research management after
the active phase of the WTR role in wireless technology research ends.
- FDA Response: FDA believes that research into the safety of wireless technology
and resolution of potential health-related questions is the responsibility of the wireless
technology industry. We believe it would be useful for the industry to clarify its plans
for continued funding and management of research, including what role WTR may have in any
future research activity.
- Recommendation: The PRB recommended that WTR not issue Requests for Proposals for
subchronic and lifetime animal bioassays until there is virtual certainty of the
commitment of funds for completion of the work and until research priorities have been
reexamined and reviewed by the PRB and interested parties in industry and government.
- FDA Response: It is our understanding that WTR does not currently plan to proceed
with the animal bioassays due to the lack of funding. It seems inappropriate, therefore,
to issue Requests for Proposals. As documented in the Agency's March 13, 1997, letter to
WTR, however, we believe there is a need for long-term, low-level animal studies.
- Recommendation: The PRB also recommended that WTR document its spending for the
first three years and make its audited financial statements available to interested
parties.
- FDA Response: The FDA has not taken a position on this issue. Our involvement
with the WTR is limited to providing scientific comment on available research plans and
results, since our role is to evaluate available scientific information on this issue in
order to assure public safety. We have asked WTR on several occasions, however, for a
listing of grants funded, amounts of the grants, principal investigators and institution,
and beginning and ending dates of the grants.
- Recommendation: Finally, the PRB recommended that WTR design and implement its
scientific program in accordance with its revised research agenda, while maintaining its
independence from industry and government.
- FDA Response: FDA believes that government agencies which will ultimately have to
make decisions regarding the relevance of WTR research to public health questions should
continue to advise the WTR with respect to the types of research needed to answer these
questions. We agree that research should not be biased by inappropriate industry
interests. It is important to remember, however, that the evaluation of industry-generated
data, which we have determined to be obtained from properly conducted studies, is the
usual way that FDA fulfills its regulatory responsibility.
- Does the FDA believe that additional government funding is needed to perform scientific
investigations of RF exposure in order to more adequately assess potential risks to the
public? If so, does the Administration plan to request such funding?
The FDA believes additional research in the area of RF exposure is needed. A concerted
effort by all the responsible government agencies would help facilitate obtaining and
understanding the additional information to address this issue. A model for a program that
would more adequately assess the potential risks associated with the use of wireless
technologies is the Energy Policy Act, 1992. Appropriated funds and mandated research and
public information dissemination on the possible health effects of exposure to the
extremely low frequency electric and magnetic fields associated with the generation,
transmission, distribution, and use of electric power. The program was critical to more
adequately assessing the potential risks to the public associated with such exposures.
We hope this information is helpful. If we may be of any further assistance, please let us know.
Sincerely yours,
Diane E. Thompson
Associate commissioner
for Legislative Affairs
Enclosure
1 H.A. Kues, J.C. Monahan, S.A. Danna, D.S. McLeod, G.A.
Lutty, S. Koslov. 1992. Increased sensitivity of the non-human primate eye to microwave
radiation following ophthalmic drug pretreatment. Bioelectromagnetics; 13(5): 379-393, and
H.A. Kues, J.C. Monahan. 1992. Microwave-induced changes to the primate eye,
Johns Hopkins APL Technical Digest 13, pp. 244-255.(Back to Text)
2 J.A. D'Andrea, J.M. Ziriax, S.T. Lu, S. Mathur, et al.
Ocular effects in Second World Congress for Electricity and Magnetism in Biology and
Medicine, Bologna, Italy, 8-13 June, 1997, p. 224, and J.A. D'Andrea, A. Thomas, D.J.
Hatcher, J. Kane, and T.L. DeVietti, Rhesus monkey contrast sensitivity during exposure to
high-peak power 5.6 GHz microwave pulses, Eighteenth Annual Meeting of the
Bioelectromagnetics Society, Victoria, British Columbia, Canada, 9-14 June, 1996, p. 259.
(Back to Text)
3 Role of Modulation on the Effect of Microwaves on
Ornithine Decarboxylase Activity in L929 Cells, Bioelectromagnetics 18, 141-142, 1997.
(Back to Text)
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