Tài liệu Environmental Health Criteria 238 EXTREMELY LOW FREQUENCY FIELDS

EXTREMELY LOW FREQUENCY FIELDS

Paperback: 545 pages
Publisher: WHO; Environmental health criteria 238 edition (18 Mar 2008)
Language: English


Environmental Health Criteria
CONTENTS
PREAMBLE .xi
The WHO Environmental Health Criteria Programme .xi
Electromagnetic Fields xi
Scope .xii
Procedures xiii
Extremely Low Frequency Environmental Health Criteria .xiv
Participants in the WHO Expert Working Groups .xv
Acknowledgements .xx
Abbreviations .xxi
1 SUMMARY AND RECOMMENDATIONS FOR FURTHER
STUDY .1
1.1 Summary .1
1.1.1 Sources, measurements and exposures 1
1.1.2 Electric and magnetic fields inside the body .2
1.1.3 Biophysical mechanisms .3
1.1.4 Neurobehaviour .5
1.1.5 Neuroendocrine system .6
1.1.6 Neurodegenerative disorders .7
1.1.7 Cardiovascular disorders .8
1.1.8 Immunology and haematology 8
1.1.9 Reproduction and development .8
1.1.10 Cancer 9
1.1.11 Health risk assessment .11
1.1.12 Protective measures .12
1.2 Recommendations for research .14
1.2.1 Sources, measurements and exposures 14
1.2.2 Dosimetry 15
1.2.3 Biophysical mechanisms .15
1.2.4 Neurobehaviour .16
1.2.5 Neuroendocrine system .17
1.2.6 Neurodegenerative disorders .17
1.2.7 Cardiovascular disorders .17
1.2.8 Immunology and haematology 17
1.2.9 Reproduction and development .17
1.2.10 Cancer 17
1.2.11 Protective measures .18
2 SOURCES, MEASUREMENTS AND EXPOSURES .21
2.1 Electric and magnetic fields 21
2.1.1 The field concept .21
2.1.2 Quantities and units .22
2.1.3 Polarization 22
2.1.4 Time variation, harmonics and transients 23
2.1.5 Perturbations to fields, shielding .24
2.2 Sources of alternating fields . 25
2.2.1 Electric fields 25
2.2.1.1 Naturally occurring fields 25
2.2.1.2 Artificial fields 26
2.2.2 Magnetic fields 28
2.2.2.1 Naturally occurring fields 28
2.2.2.2 Artificial fields 30
2.3 Assessment of exposure 54
2.3.1 General considerations 54
2.3.2 Assessing residential exposure to magnetic fields:
methods not involving measurement 56
2.3.2.1 Distance . 56
2.3.2.2 Wire code 56
2.3.2.3 Calculated historical fields 58
2.3.3 Assessing residential exposure to magnetic
fields using measurements 59
2.3.3.1 Spot measurements in the home 59
2.3.3.2 Longer-term measurements in homes . 60
2.3.3.3 Personal exposure monitoring . 63
2.3.4 Assessing exposure to magnetic fields from appliances . 65
2.3.5 Assessing exposure at schools 66
2.3.6 Assessing non-occupational exposure to magnetic fields:
discussion 67
2.3.7 Assessing occupational exposure to magnetic fields 68
2.3.8 Assessing exposure to electric fields . 71
2.3.9 Exposure assessment: conclusions 72
3 ELECTRIC AND MAGNETIC FIELDS INSIDE THE BODY 73
3.1 Introduction . 73
3.2 Models of human and animal bodies 74
3.3 Electric field dosimetry . 76
3.3.1 Basic interaction mechanisms . 76
3.3.2 Measurements . 77
3.3.3 Computations 77
3.3.4 Comparison of computations with measurements 83
3.4 Magnetic field dosimetry 85
3.4.1 Basic interaction mechanisms . 85
3.4.2 Computations – uniform field . 85
3.4.3 Computations – non-uniform fields 89
3.4.4 Computations –
inter-laboratory comparison and model effects . 90
3.5 Contact current 91
3.6 Comparison of various exposures . 92
3.7 Microscopic dosimetry . 93
3.8 Conclusions . 95
4 BIOPHYSICAL MECHANISMS . 97
4.1 Introduction . 97
4.2 The concept of plausibility . 97
4.3 Stochastic effects, thresholds and dose-response relationships 98
4.4 Induced currents and fields .100
4.4.1 Currents induced by fields .100
4.4.2 Comparison with noise 100
4.4.3 Myelinated nerve fibre stimulation thresholds 101
4.4.4 Neural networks and signal detection .102
4.4.5 Transients 103
4.4.6 Heating effects of induced currents .103
4.4.7 Summary on induced currents .103
4.5 Other direct effects of fields 104
4.5.1 Ionization and breaking of bonds 104
4.5.2 Forces on charged particles .105
4.5.3 Forces on magnetic particles .105
4.5.4 Free radicals .107
4.5.5 Effects with narrow bandwidths 109
4.5.5.1 Cyclotron resonance 109
4.5.5.2 Larmor precession .109
4.5.5.3 Quantum mechanical resonance phenomena .109
4.5.6 Stochastic resonance 110
4.6 Indirect effects of fields 110
4.6.1 Surface charge and microshocks .110
4.6.2 Contact currents .110
4.6.3 Deflection of cosmic rays 111
4.6.4 Effects on airborne pollutants 112
4.6.4.1 Production of corona ions 112
4.6.4.2 Inhalation of pollutant particles .113
4.6.4.3 Deposition under power lines 114
4.6.4.4 Implications for health .115
4.7 Conclusions .115
5 NEUROBEHAVIOUR .118
5.1 Electrophysiological considerations .118
5.2 Volunteer studies .121
5.2.1 Surface electric charge 121
5.2.2 Nerve stimulation 123
5.2.3 Retinal function .124
5.2.4 Brain electrical activity .125
5.2.5 Sleep 131
5.2.6 Cognitive effects 132
5.2.7 Hypersensitivity .136
5.2.8 Mood and alertness 137
5.3 Epidemiological studies 143
5.3.1 Depression .143
5.3.2 Suicide .143
5.4 Animal studies .145
5.4.1 Perception and field detection .145
5.4.2 Arousal and aversion .147
5.4.3 Brain electrical activity .151
5.4.4 Neurotransmitter function . 152
5.4.5 Cognitive function . 153
5.5 Conclusions . 160
6 NEUROENDOCRINE SYSTEM 162
6.1 Volunteer studies 162
6.1.1 The pineal hormone: melatonin 162
6.1.1.1 Laboratory studies . 162
6.1.1.2 Residential and occupational studies . 163
6.1.2 Pituitary and other hormones 165
6.2 Animal studies 171
6.2.1 Melatonin 171
6.2.1.1 Laboratory rodents 171
6.2.1.2 Seasonal breeders 172
6.2.1.3 Non human primates . 177
6.2.2 The pituitary and other hormones . 178
6.2.2.1 Pituitary-adrenal effects . 178
6.2.2.2 Other endocrine studies . 179
6.3 In vitro studies 179
6.3.1 Effects on melatonin production in vitro 181
6.3.2 Effects on the action of melatonin in vitro 182
6.4 Conclusions . 185
7 NEURODEGENERATIVE DISORDERS . 187
7.1 Alzheimer disease . 188
7.1.1 Pathology 188
7.1.2 Epidemiology 189
7.2 Amyotrophic lateral sclerosis . 196
7.2.1 Pathology 196
7.2.2 Epidemiology 196
7.3 Parkinson disease, Multiple Sclerosis . 202
7.3.1 Pathology 202
7.3.2 Epidemiology 203
7.4 Discussion . 203
7.5 Conclusions . 206
8 CARDIOVASCULAR DISORDERS 207
8.1 Acute effects . 207
8.1.1 Electrocardiogram changes, heart rate,
and heart rate variability 207
8.1.2 Blood pressure . 210
8.2 Long-term effects 211
8.3 Discussion . 218
8.3.1 Heart rate variability hypothesis . 218
8.3.2 Epidemiologic evidence 219
8.4 Conclusions . 220
9 IMMUNE SYSTEM AND HAEMATOLOGY 221
9.1 Immune system . 221
9.1.1 Human studies . 222
9.1.2 Animal studies .224
9.1.3 Cellular studies 226
9.2 Haematological system .233
9.2.1 Human studies .233
9.2.2 Animal studies .233
9.2.3 Cellular studies 236
9.3 Conclusions .237
10 REPRODUCTION AND DEVELOPMENT .239
10.1 Epidemiology 239
10.1.1 Maternal exposure .239
10.1.1.1 Video display terminals .239
10.1.1.2 Electrically heated beds .239
10.1.1.3 Other residential and occupational exposure .242
10.1.2 Paternal exposure 246
10.2 Effects on laboratory mammals .247
10.2.1 Electric fields .247
10.2.2 Magnetic fields 247
10.2.2.1 Effects on prenatal development .247
10.2.2.3 Multi-generation studies 250
10.2.2.4 Effects on mammalian embryos in vitro 250
10.2.2.5 Effects of paternal exposure 251
10.3 Effects on non-mammalian species .252
10.3.1 Bird embryos .252
10.3.1.1 Development 252
10.3.1.2 Interaction with known teratogens .253
10.3.2 Other non-mammalian species 253
10.4 Conclusion 254
11 CANCER .255
11.1 IARC 2002 evaluation: summary .256
11.2 Epidemiological studies 263
11.2.1 Childhood leukaemia .263
11.2.1.1 Epidemiology .263
11.2.1.2 Trends and ecologic correlations .266
11.2.1.3 New data 268
11.2.1.4 Evaluating epidemiological evidence:
possible explanations .270
11.2.2 Adult cancer 276
11.2.2.1 Breast cancer 277
11.2.2.2 Leukaemia and brain cancer 291
11.2.2.3 Other cancers .305
11.2.3 Epidemiology: conclusions .307
11.3 Carcinogenesis in laboratory animals .308
11.3.1 Rodent bioassays .308
11.3.1.1 Large scale, life-time studies .308
11.3.1.2 Leukaemia/lymphoma .309
11.3.1.3 Brain tumours 310
11.3.2 EMF exposure combined with carcinogens 312
11.3.2.1 Liver pre-neoplastic lesions . 312
11.3.2.2 Leukaemia/lymphoma . 312
11.3.2.3 Mammary tumours 313
11.3.2.4 Skin tumours 314
11.3.2.5 Brain tumours 315
11.3.3 Transplanted tumours 316
11.3.4 Genotoxicity in animals 316
11.3.5 Non-genotoxic studies . 321
11.3.6 Animal studies: conclusions 321
11.4 In vitro carcinogenesis studies 322
11.4.1 Genotoxic effects 323
11.4.1.1 Genotoxic effects of ELF magnetic fields alone . 323
11.4.1.2 Combined genotoxic effects 324
11.4.2 Expression of oncogenes and cancer-related genes 327
11.4.3 Differentiation, proliferation and apoptosis 335
11.4.4 Gap junction intercellular communications 339
11.4.5 Free radicals 346
11.4.6 In vitro conclusions . 347
11.5 Overall conclusions . 347
12 HEALTH RISK ASSESSMENT . 349
12.1 Introduction . 349
12.2 Hazard identification . 350
12.2.1 Biological versus adverse health effects . 350
12.2.2 Acute effects 350
12.2.3 Chronic effects 350
12.3 Exposure assessment . 351
12.3.1 Residential exposures 351
12.3.2 Occupational exposures 351
12.4 Exposure-response assessment . 352
12.4.1 Threshold levels 352
12.4.2 Epidemiological methods 352
12.5 Risk characterization . 353
12.5.1 Acute effects 353
12.5.2 Chronic effects 353
12.5.3 Uncertainties in the risk characterization 354
12.5.3.1 Biophysical mechanisms . 354
12.5.3.2 Exposure metric . 355
12.5.3.3 Epidemiology 355
12.6 Conclusions . 355
13 PROTECTIVE MEASURES 357
13.1 Introduction . 357
13.2 General issues in health policy . 357
13.2.1 Dealing with environmental health risks . 357
13.2.2 Factors affecting health policy 359
13.3 Scientific input 361
13.3.1 Emission and exposure standards 361
13.3.2 Risk in perspective 362
ix
13.4 Precautionary-based policy approaches 362
13.4.1 Existing precautionary ELF policies .362
13.4.2 Cost and feasibility 366
13.5 Discussion and recommendations .367
13.5.1 Recommendations .372
APPENDIX: Quantitative risk assessment for childhood leukaemia .374
A.1 Exposure distribution 374
A.2 Exposure-response analysis using attributable
fraction estimates for EMF and childhood leukaemia 375
A.3 Risk characterization .377
14 REFERENCES .385
15 GLOSSARY 431
16 RESUME ET RECOMMANDATIONS RELATIVES AUX
ETUDES A MENER .446
16.1 Résumé 446
16.1.1 Sources, mesurage et expositions 446
16.1.2 Champs électriques et magnétiques dans l’organisme 447
16.1.3 Mécanismes biophysiques .449
16.1.4 Neurocomportement 450
16.1.5 Système neuroendocrinien 452
16.1.6 Troubles neurodégénératifs .453
16.1.7 Troubles cardio-vasculaires .454
16.1.8 Immunologie et hématologie .454
16.1.9 Reproduction et développement 455
16.1.10 Cancer 455
16.1.11 Evaluation du risque pour la santé .457
16.1.12 Mesures de protection 459
16.2 Recommandations en matière de recherche 461
16.2.1 Sources, mesurage et expositions 461
16.2.2 Dosimétrie .462
16.2.3 Mécanismes biophysiques .463
16.2.4 Neuro-comportement .463
16.2.5 Système neuroendocrinien 464
16.2.6 Troubles neurodégénératifs .464
16.2.7 Troubles cardio-vasculaires .465
16.2.8 Immunologie et hématologie .465
16.2.9 Reproduction et développement 465
16.2.10 Cancer 465
16.2.11 Mesures de protection 466
17 РЕЗЮМE И РЕКОМЕНДАЦИИ ДЛџ ДАЛЬНЕЙШИХ
ИССЛЕДОВАНИЙ .470
17.1 Резюме .470
17.1.1 Источники, измерения и воздействия на организм
человека .470
17.1.2 Электрические и магнитные поля в организме .472
17.1.3 Биофизические механизмы 473
17.1.4 Нейроповедение 475
17.1.5 Нейроэндокринная система 477
17.1.6 Нейродегенеративные расстройства . 479
17.1.7 Сердечно-сосудистые расстройства . 479
17.1.8 Иммунология и гематология 479
17.1.9 Воспроизводство и развитие 480
17.1.10 Онкологические заболевания 481
17.1.11 Оценка риска для здоровья . 483
17.1.12 Мероприятия по защите 485
17.2 Рекомендации для научных исследований 487
17.2.1 Источники, измерения и воздействие на организм . 488
17.2.2 Дозиметрия . 489
17.2.3 Биофизические механизмы 489
17.2.4 Нейроповедение 490
17.2.5 Нейроэндокринная система 491
17.2.6 Нейродегенеративные расстройства . 491
17.2.7 Сердечно-сосудистые нарушения . 491
17.2.1 Иммунология и гематология . 491
17.2.9 Репродуктивные аспекты и развитие . 492
17.2.10 Онкологические заболевания . 492
17.2.11 Мероприятия по защите 493
18 RESUMEN Y RECOMENDACIONES PARA ESTUDIOS
POSTERIORES 497
18.1 Resumen . 497
18.1.1 Fuentes, mediciones y exposiciones . 497
18.1.2 Campos eléctricos y magnéticos dentro del cuerpo 498
18.1.3 Mecanismos biofísicos 500
18.1.4 Neurocomportamiento . 501
18.1.5 Sistema neuroendocrino 503
18.1.6 Trastomnos neurodegenerativos . 504
18.1.7 Trastornos cardiovasculares 505
18.1.8 Inmunología y hematología . 505
18.1.9 Reproducción y desarrollo . 506
18.1.10 Cáncer . 506
18.1.11 Evaluación de los riesgos de salud . 508
18.1.12 Medidas de protección 510
18.2 Recomendaciones para la investigación 512
18.2.1 Fuentes, mediciones y exposiciones 512
18.2.2 Dosimetría 513
18.2.3 Mecanismos biofísicos . 514
18.2.4 Neurocomportamiento 514
18.2.5 Sistema neuroendocrino . 515
18.2.6 Trastornos neurodegenerativos 515
18.2.7 Trastornos cardiovasculares . 515
18.2.8 Inmunología y hematología . 516
18.2.9 Reproducción y desarrollo . 516
18.2.10 Cáncer . 516
18.2.11 Medidas de protección 517






ACKNOWLEDGEMENTS
This monograph represents the most thorough health risk assessment currently
available on extremely low frequency electric and magnetic fields.
WHO acknowledges and thanks all contributors to this important publication.
In particular, thanks go to the experts that drafted the initial version of the
various chapters, including Prof. Paul Elliot, Prof. Maria Stuchly, and Prof.
Bernard Veyret, the members of the Working Groups and the members of the
Task Group.
Special thanks go to Dr Eric van Rongen, from the Health Council of the
Netherlands, and Dr Rick Saunders, from the Health Protection Agency,
United Kingdom, for their continuing work throughout the development of
this monograph, and to Prof. Leeka Kheifets, who continued her involvement
in the development of the document long after she left WHO.
WHO also acknowledges the generous support of the Health Council of the
Netherlands for providing the scientific and language editing, and for performing
the final layout of the document.
Dr. Emilie van Deventer
Acting Coordinator, Radiation and Environmental Health
World Health Organization
1 June 2007

1 SUMMARY AND RECOMMENDATIONS FOR FURTHER
STUDY
This Environmental Health Criteria (EHC) monograph addresses
the possible health effects of exposure to extremely low frequency (ELF)
electric and magnetic fields. It reviews the physical characteristics of ELF
fields as well as the sources of exposure and measurement. However, its
main objectives are to review the scientific literature on the biological effects
of exposure to ELF fields in order to assess any health risks from exposure to
these fields and to use this health risk assessment to make recommendations
to national authorities on health protection programs.
The frequencies under consideration range from above 0 Hz to 100
kHz. By far the majority of studies have been conducted on power-frequency
(50 or 60 Hz) magnetic fields, with a few studies using power-frequency
electric fields. In addition, there have been a number of studies concerning
very low frequency (VLF, 3–30 kHz) fields, switched gradient magnetic
fields used in magnetic resonance imaging, and the weaker VLF fields emitted
by visual display units and televisions.
This chapter summarizes the main conclusions and recommendations
from each section as well as the overall conclusions of the health risk
assessment process. The terms used in this monograph to describe the
strength of evidence for a given health outcome are as follows. Evidence is
termed “limited” when it is restricted to a single study or when there are
unresolved questions concerning the design, conduct or interpretation of a
number of studies. “Inadequate” evidence is used when the studies cannot be
interpreted as showing either the presence or absence of an effect because of
major qualitative or quantitative limitations, or when no data are available.
Key gaps in knowledge were also identified and the research
needed to fill these gaps has been summarized in the section entitled “Recommendations
for research”.