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Electromagnetic fields, radon, and cancer
In addition, it would be a pity if the opportunity were not taken to reinforce the message that those who were HIV negative should continue to take steps to maintain this status: HIV is an avoidable disease in industrialised
countries. J E Banatvala Guy’s and 1
St Thomas’s NHS Trust, London, UK
NHS Executive. Strategic Review of Pathology Services. London: HM Stationery Office, 1995.
Physicians can’t heal themselves It might be thought that a health service would provide a work environment conducive to health-or at least that when its staff fall ill they would receive high-quality treatment. The UK National Health Service is reputed to be the largest employer in Europe yet British doctors are worried about the support available when they become ill. In an extensive study of the self-reported health of hospital doctors and general practitioners McKevitt and colleagues’ found that doctors, when ill, were less likely than a comparable professional group to take sick leave or to consult their own GP. 30% of GPs and 22% of hospital doctors reported dissatisfaction with their job, and GPs in particular reported high levels of stress. The second part of the study-exploring the views of doctors who were or had been ill and who had volunteered to talk about their experiences-revealed the cultural and organisational barriers that prevent doctors from seeking help when under stress or in the early stages of illness. How should the NHS respond to this highly unsatisfactory situation? Although the substantial contribution of alcohol abuse to medical ill-health may reduce in years to come, as a cohort of older, heavy-drinking doctors retire,the general health experience of some British doctors may be worse than that of their peers in other countries.’ The key issue for health service managers is public safety and this concern, along with the constant drive for greater efficiency, can conflict with the spirit of openness and support that would encourage doctors to seek help when they first need it. There are confidential services which a doctor can turn to but there is no coordinated system which can provide access to all the types of help that may be required. This is especially true for GPs, who work as independent contractors within small organisations, and rarely if ever have access to an occupational health service. A Nuffield Provincial Hospitals Trust working-party4 recommends a network of independent regional bodies in the UK to urge improvements in the working conditions of doctors, to review the services available for sick doctors, and to identify a senior doctor in the region who would act as the first point of contact for doctors seeking help. The working party recommends that this service be funded by the NHS, a proposal that is likely to attract the opposition of other health professions, notably nurses whose sickness record is far worse than that of doctors. The problem with doctors is that they do not take sick leave, not that they take too much of it; also they are also less likely to make use of normal services, such as registration with a GP. !,5 The outcome when doctors enter an organised treatment programme is reported to be better than that for the general population.6
If NHS money is to be invested in this area it would be better spent on strengthening existing occupational health services, which cover all employees.’ These services have had their task made much more difficult by the fragmentation of the NHS into many separate and self governing employers. Issues of differential levels of provision, poor knowledge of the services amongst doctors, and concerns about confidentiality will all have to be addressed. And the remit of NHS occupational health services, will have to be extended to cover primary care staff, including GPs. Should patients have the right to know that their doctors have health problems that affect their performance?H At all times patients should be given information on substantial risks of treatment, and it can be argued that such risks included an illness in a doctor that affects his or her skill. The danger of leaving matters to independent, medically dominated bodies is that patients’ rights are sidelined. Gabriel
Scally
NHS Executive South & West, Bristol, UK 1 2 3
4
5 6
7
8
McKevitt C, Morgan M, Simpson J, Holland W. Doctors’ health and needs for services. London: Nuffield Provincial Hospital Trust, 1996. Harrison D. Trends in alcoholism among male doctors in Scotland. Addiction 1994; 89: 1613-17. Whitley TW, Allison EJ, Gallery ME, et al. Work-related stress and depression among practicing emergency physicians: an international study. Ann Emerg Med 1994; 23: 1068-71. Nuffield Provincial Hospitals Trust. Taking care of doctors’ health: report of a working party. London: Nuffield Provincial Hospital Trust, 1996. Pullen D, Cam DE, Doughty MV, Lonie CE, Lyle DM. Medical care of doctors. Med J Aust 1995; 162: 481-84. Femino J, Nirenburg TD. Treatment outcome studies on physician impairment: a review of the literature. Rhode Island Med 1994; 77: 345-50. NHS Executive. Occupational health services for NHS staff. Leeds: NHSE, 1994. Bok S. Impaired physicians: what should patients know? Camb Quart Healthcare Ethics 1993; 2: 341-52.
Electromagnetic fields, radon, and
cancer
suggesting a possible mechanism by which electric fields might increase cancer incidence for individuals living near powerlines has initiated considerable discussion. On the basis of their studies of the behaviour of aerosols in an electric field, Henshaw and colleagues’ suggest that the presence of an electromagnetic field (EMF) might increase the radiation dose received by individuals from environmental radon in homes near high-power transmission lines (figure), thereby increasing the risk for childhood leukaemia. Childhood leukaemia is the most often cited possible adverse health effect from exposure to power frequency EMF. To assess the merit of this suggestion one needs to consider several factors. Does the presence of an electric field increase the airborne concentration of radon progeny; does it enhance biological uptake of airborne radon progeny; does it affect the attached and unattached fractions of radon progeny; does the presence of an electric or magnetic field influence the absorption of radon progeny in the body; and, if the exposure is increased, within what tissue would one expect the dose to be delivered and would any increased dose affect the incidence of childhood leukaemia?
A report
1059
are more
Figure: Power
over
people
Science Photo Library
Henshaw and his colleagues suggest several ways in which electric fields might increase the concentration of radon progeny. First, the aerosols containing radon progeny might migrate along field lines and concentrate in the vicinity of a power source. This conclusion follows Henshaw’s experiments showing that aerosols tend to migrate along field gradients. Such migration would seem to increase the radon concentrations near the powerline where the fields are strongest. Their hypothesis is amenable to measurement but it seems to suggest a reduction, not an increase, in exposure in houses near powerlines, other than those directly under a powerline. Henshaw et al also suggest that the electric fields generated by the static charge accumulated on individuals (fields as high as 50 kV/m in the vicinity of the face have been detected from static charge in a typical office) might attract aerosols and increase the radon and radon progeny concentration close to the body, thus leading to enhanced biological uptake. Since they have also shown that high electric fields enhance the deposition efficiency of aerosols, this high field associated with the body would seem to cause deposition of aerosols on the face but not necessarily to increase inhalation of radon and radon progeny. The small perturbation imposed by external fields such as a nearby powerline seems negligible besides the static field generated by other factors. Another mechanism suggested by Henshaw and his colleagues is the influence of electric fields, particularly AC fields, on the release and redistribution of progeny on aerosols, thus changing the ratio of attached to unattached fractions. The effect of such a mechanism is difficult to estimate and considerable research would be required to determine how it affects the amount and location of energy deposited by the decay of radon progeny. Certainly an increase in the unattached fraction could tend to increase the dose delivered to local lung tissue. It is not evident, however, to what extent external powerlines might alter the aerosol distributions in the mixed EMF environment of residential homes, and one would not expect the powerline fields to otherwise have an influence on internal deposition. Any environmental electric fields would be strongly attenuated by tissue in the body, as the researchers recognise. Also powerline electric fields are readily shielded by most building materials. Magnetic fields are not so easily shielded, which is why these fields
1060
usually involved
in discussions of associations of
childhood cancer and EMF. If electric fields do increase the concentrations and biological uptake of radon progeny, what tissue might be expected to be at risk? Deposition on the face or other areas of skin might be expected, but skin cancer has not generally been associated with exposure to radon. Even with high concentrations of radon progeny (eg, in mines) there has been only a non-statistically significant suggestion of an increase in skin cancer.2 In most exposed regions of the body alpha particles from radon decay would not reach basal cells. Nor has there been a significant increase in leukaemia or any cancer other than lung cancer in miners. Furthermore, only for very large body burdens, such as those found in patients treated with radium, has a significant increase in leukaemia from ingested alpha emitters been observed.2.3 Lung cancer has not been detected in excess in people living near powerlines. I am inclined to discount the electric fields/radon proposal as the explanation for any connection there may be between childhood cancer and EMF exposure.
Larry H Toburen Department of Physics, East Carolina University, Greenville, NC, USA; and Board
on
Radiation Effects Research, National Research Council, DC
Washington, 1
2
3
Henshaw DL, Ross AN, Fews AP, Preece AW. Enhanced deposition of radon daughter nuclei in the vicinity of power frequency electromagnetic fields. Int J Radiat Biol 1996; 69: 25-38. National Research Council Committee on the Biological Effects of Ionizing Radiation. Health risks of radon and other internally deposited alpha-emitters (BEIR IV). Washington, DC: National Academy Press, 1988. National Research Council Committee on the Biological Effects of Ionizing Radiation. Health effects of exposure to radon: time for reassessment?. Washington, DC: National Academy Press, 1994.
Medicine and the media See page 1087 Who could forget the Ebola virus epidemic in Kikwit, Zaire, in early 1995? The related news coverage, in which newspapers, news agencies, and television current affairs programmes depicted a doomsday scenario of a killer virus out of control, satisfied the public’s voracious appetite for things ghoulish. The events in Zaire provided all the ingredients for a newsworthy story. A year on saw another outbreak of Ebola, this time in Gabon, West Africa, but news coverage was meagre in comparison. Why the difference? Our new eight-part series on medicine and the media might help to give some insight into such apparent vagaries in newsreporting. We will explore newsworthiness; the sources of news and the issue of scientific fraud; the influence and power of the media; how television doctor shows
shape patients’ expectations; the questions surrounding embargoes, the Ingelfinger rule, and journal peer review; and the enduring tensions between scientists and journalists. We are indebted to Dorothy Nelkin, University Professor at New York University; her enthusiastic guidance throughout the planning and commissioning of the series has been outstanding. We begin on page 1087 with Jon Turney’s article on the public understanding of science.
Pia Pini The Lancet, London, UK
countries. J E Banatvala Guy’s and 1
St Thomas’s NHS Trust, London, UK
NHS Executive. Strategic Review of Pathology Services. London: HM Stationery Office, 1995.
Physicians can’t heal themselves It might be thought that a health service would provide a work environment conducive to health-or at least that when its staff fall ill they would receive high-quality treatment. The UK National Health Service is reputed to be the largest employer in Europe yet British doctors are worried about the support available when they become ill. In an extensive study of the self-reported health of hospital doctors and general practitioners McKevitt and colleagues’ found that doctors, when ill, were less likely than a comparable professional group to take sick leave or to consult their own GP. 30% of GPs and 22% of hospital doctors reported dissatisfaction with their job, and GPs in particular reported high levels of stress. The second part of the study-exploring the views of doctors who were or had been ill and who had volunteered to talk about their experiences-revealed the cultural and organisational barriers that prevent doctors from seeking help when under stress or in the early stages of illness. How should the NHS respond to this highly unsatisfactory situation? Although the substantial contribution of alcohol abuse to medical ill-health may reduce in years to come, as a cohort of older, heavy-drinking doctors retire,the general health experience of some British doctors may be worse than that of their peers in other countries.’ The key issue for health service managers is public safety and this concern, along with the constant drive for greater efficiency, can conflict with the spirit of openness and support that would encourage doctors to seek help when they first need it. There are confidential services which a doctor can turn to but there is no coordinated system which can provide access to all the types of help that may be required. This is especially true for GPs, who work as independent contractors within small organisations, and rarely if ever have access to an occupational health service. A Nuffield Provincial Hospitals Trust working-party4 recommends a network of independent regional bodies in the UK to urge improvements in the working conditions of doctors, to review the services available for sick doctors, and to identify a senior doctor in the region who would act as the first point of contact for doctors seeking help. The working party recommends that this service be funded by the NHS, a proposal that is likely to attract the opposition of other health professions, notably nurses whose sickness record is far worse than that of doctors. The problem with doctors is that they do not take sick leave, not that they take too much of it; also they are also less likely to make use of normal services, such as registration with a GP. !,5 The outcome when doctors enter an organised treatment programme is reported to be better than that for the general population.6
If NHS money is to be invested in this area it would be better spent on strengthening existing occupational health services, which cover all employees.’ These services have had their task made much more difficult by the fragmentation of the NHS into many separate and self governing employers. Issues of differential levels of provision, poor knowledge of the services amongst doctors, and concerns about confidentiality will all have to be addressed. And the remit of NHS occupational health services, will have to be extended to cover primary care staff, including GPs. Should patients have the right to know that their doctors have health problems that affect their performance?H At all times patients should be given information on substantial risks of treatment, and it can be argued that such risks included an illness in a doctor that affects his or her skill. The danger of leaving matters to independent, medically dominated bodies is that patients’ rights are sidelined. Gabriel
Scally
NHS Executive South & West, Bristol, UK 1 2 3
4
5 6
7
8
McKevitt C, Morgan M, Simpson J, Holland W. Doctors’ health and needs for services. London: Nuffield Provincial Hospital Trust, 1996. Harrison D. Trends in alcoholism among male doctors in Scotland. Addiction 1994; 89: 1613-17. Whitley TW, Allison EJ, Gallery ME, et al. Work-related stress and depression among practicing emergency physicians: an international study. Ann Emerg Med 1994; 23: 1068-71. Nuffield Provincial Hospitals Trust. Taking care of doctors’ health: report of a working party. London: Nuffield Provincial Hospital Trust, 1996. Pullen D, Cam DE, Doughty MV, Lonie CE, Lyle DM. Medical care of doctors. Med J Aust 1995; 162: 481-84. Femino J, Nirenburg TD. Treatment outcome studies on physician impairment: a review of the literature. Rhode Island Med 1994; 77: 345-50. NHS Executive. Occupational health services for NHS staff. Leeds: NHSE, 1994. Bok S. Impaired physicians: what should patients know? Camb Quart Healthcare Ethics 1993; 2: 341-52.
Electromagnetic fields, radon, and
cancer
suggesting a possible mechanism by which electric fields might increase cancer incidence for individuals living near powerlines has initiated considerable discussion. On the basis of their studies of the behaviour of aerosols in an electric field, Henshaw and colleagues’ suggest that the presence of an electromagnetic field (EMF) might increase the radiation dose received by individuals from environmental radon in homes near high-power transmission lines (figure), thereby increasing the risk for childhood leukaemia. Childhood leukaemia is the most often cited possible adverse health effect from exposure to power frequency EMF. To assess the merit of this suggestion one needs to consider several factors. Does the presence of an electric field increase the airborne concentration of radon progeny; does it enhance biological uptake of airborne radon progeny; does it affect the attached and unattached fractions of radon progeny; does the presence of an electric or magnetic field influence the absorption of radon progeny in the body; and, if the exposure is increased, within what tissue would one expect the dose to be delivered and would any increased dose affect the incidence of childhood leukaemia?
A report
1059
are more
Figure: Power
over
people
Science Photo Library
Henshaw and his colleagues suggest several ways in which electric fields might increase the concentration of radon progeny. First, the aerosols containing radon progeny might migrate along field lines and concentrate in the vicinity of a power source. This conclusion follows Henshaw’s experiments showing that aerosols tend to migrate along field gradients. Such migration would seem to increase the radon concentrations near the powerline where the fields are strongest. Their hypothesis is amenable to measurement but it seems to suggest a reduction, not an increase, in exposure in houses near powerlines, other than those directly under a powerline. Henshaw et al also suggest that the electric fields generated by the static charge accumulated on individuals (fields as high as 50 kV/m in the vicinity of the face have been detected from static charge in a typical office) might attract aerosols and increase the radon and radon progeny concentration close to the body, thus leading to enhanced biological uptake. Since they have also shown that high electric fields enhance the deposition efficiency of aerosols, this high field associated with the body would seem to cause deposition of aerosols on the face but not necessarily to increase inhalation of radon and radon progeny. The small perturbation imposed by external fields such as a nearby powerline seems negligible besides the static field generated by other factors. Another mechanism suggested by Henshaw and his colleagues is the influence of electric fields, particularly AC fields, on the release and redistribution of progeny on aerosols, thus changing the ratio of attached to unattached fractions. The effect of such a mechanism is difficult to estimate and considerable research would be required to determine how it affects the amount and location of energy deposited by the decay of radon progeny. Certainly an increase in the unattached fraction could tend to increase the dose delivered to local lung tissue. It is not evident, however, to what extent external powerlines might alter the aerosol distributions in the mixed EMF environment of residential homes, and one would not expect the powerline fields to otherwise have an influence on internal deposition. Any environmental electric fields would be strongly attenuated by tissue in the body, as the researchers recognise. Also powerline electric fields are readily shielded by most building materials. Magnetic fields are not so easily shielded, which is why these fields
1060
usually involved
in discussions of associations of
childhood cancer and EMF. If electric fields do increase the concentrations and biological uptake of radon progeny, what tissue might be expected to be at risk? Deposition on the face or other areas of skin might be expected, but skin cancer has not generally been associated with exposure to radon. Even with high concentrations of radon progeny (eg, in mines) there has been only a non-statistically significant suggestion of an increase in skin cancer.2 In most exposed regions of the body alpha particles from radon decay would not reach basal cells. Nor has there been a significant increase in leukaemia or any cancer other than lung cancer in miners. Furthermore, only for very large body burdens, such as those found in patients treated with radium, has a significant increase in leukaemia from ingested alpha emitters been observed.2.3 Lung cancer has not been detected in excess in people living near powerlines. I am inclined to discount the electric fields/radon proposal as the explanation for any connection there may be between childhood cancer and EMF exposure.
Larry H Toburen Department of Physics, East Carolina University, Greenville, NC, USA; and Board
on
Radiation Effects Research, National Research Council, DC
Washington, 1
2
3
Henshaw DL, Ross AN, Fews AP, Preece AW. Enhanced deposition of radon daughter nuclei in the vicinity of power frequency electromagnetic fields. Int J Radiat Biol 1996; 69: 25-38. National Research Council Committee on the Biological Effects of Ionizing Radiation. Health risks of radon and other internally deposited alpha-emitters (BEIR IV). Washington, DC: National Academy Press, 1988. National Research Council Committee on the Biological Effects of Ionizing Radiation. Health effects of exposure to radon: time for reassessment?. Washington, DC: National Academy Press, 1994.
Medicine and the media See page 1087 Who could forget the Ebola virus epidemic in Kikwit, Zaire, in early 1995? The related news coverage, in which newspapers, news agencies, and television current affairs programmes depicted a doomsday scenario of a killer virus out of control, satisfied the public’s voracious appetite for things ghoulish. The events in Zaire provided all the ingredients for a newsworthy story. A year on saw another outbreak of Ebola, this time in Gabon, West Africa, but news coverage was meagre in comparison. Why the difference? Our new eight-part series on medicine and the media might help to give some insight into such apparent vagaries in newsreporting. We will explore newsworthiness; the sources of news and the issue of scientific fraud; the influence and power of the media; how television doctor shows
shape patients’ expectations; the questions surrounding embargoes, the Ingelfinger rule, and journal peer review; and the enduring tensions between scientists and journalists. We are indebted to Dorothy Nelkin, University Professor at New York University; her enthusiastic guidance throughout the planning and commissioning of the series has been outstanding. We begin on page 1087 with Jon Turney’s article on the public understanding of science.
Pia Pini The Lancet, London, UK