Intended for healthcare professionals

Letters

Health hazards of mobile phones

BMJ 2000; 321 doi: https://doi.org/10.1136/bmj.321.7269.1155/a (Published 04 November 2000) Cite this as: BMJ 2000;321:1155

Prevalence of headache is increased among users in Singapore

  1. Sin-Eng Chia, associate professor,
  2. Hwee-Pin Chia, assistant professor,
  3. Jit-Seng Tan, medical student (cofcse{at}nus.edu.sg)
  1. Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore, Singapore 117597
  2. Saratov State Medical University, PO Box 1528, Saratov, 410601 Russia

    EDITOR—Hand held cellular telephones, using pulse modulated signals of frequency 870-995 MHz, are being used increasingly. Most reports of health symptoms related to use of these phones are anecdotal. We undertook a cross sectional study of a community in Singapore to study the prevalence of specific central nervous system symptoms among users of hand held cellular phones compared with non-users and to determine any association of risk factors and central nervous system symptoms among users of the phones.1

    From a sampling frame of all flats in a large town we conducted a one stage random cluster sampling of 808 individuals, who were interviewed by trained medical students using a structured questionnaire. Central nervous system symptoms of those who did and did not use hand held cellular telephones were compared and any possible association studied. A two tiered approach was used to try to mask the true purpose of the questionnaire in which headaches and health symptoms were dealt with in the earlier sections before respondents were asked about their use of cellular phones. These steps should help to reduce recall bias among the respondents.

    The prevalence of users of hand held cellular phones in Singapore was 44.8%.1 Headache (according to the International Headache Society's criteria2) was the most prevalent symptom among users compared with non-users, with an adjusted prevalence rate ratio of 1.31 (95% confidence interval 1.00 to 1.70). There was a significant increase in the prevalence of headache with increasing duration of use (min/day) (P=0.038). The prevalence of headache was considerably reduced among those who used hands-free equipment compared with those who never used such equipment (42% v 65%).

    Usage of hand phone and hand-free equipment and prevalence of headache

    View this table:

    Use of hand held cellular phones is not associated with a significant increase in central nervous system symptoms other than headache. We would suggest that more community studies should be conducted before one can make a statement such as “the only established risk is of using one while driving.”3

    References

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    Do laptop computers also pose a risk?

    1. Vasiliy Vlassov, professor (vvvla{at}sgu.ru)
    1. Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore, Singapore 117597
    2. Saratov State Medical University, PO Box 1528, Saratov, 410601 Russia

      EDITOR—In their editorial on the health hazards of mobile phones Maier et al mention that studies in Russia in Soviet times were “inadequately documented”1; they were also not well designed. These studies of so called non-thermal effects of microwaves never prove that these effects are real, and they do not discriminate the physiological effects from the harmful effects. When the eye is reacting to the light it is not a reason to screen out all light; the same argument is true with mobile telephones.

      Research of this “problem” is led by public interest and pressure. A similar object for research and further regulation is laptop computers. They produce heat and microwaves very close to the testes, which are highly sensitive to temperature and radiation damage. The effect of heating is well known to every laptop user. Yet laptops were not studied for the dangers of their waves to the testes (I checked Medline).

      Use by children was not regulated only because laptops are used by a narrower circle of people, who are not overwhelmed by non-existent horrors. I hope that my example will not lead to research into this problem, or to university and industry research programmes into the effects of heating and microwaves on testes.

      References

      1. 1.
      View Abstract

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