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EHC 238 on ELF - 2007

ISBN: 978-92-4-157238-5

Environmental Health Criteria 238: Extremely Low Frequency Fields. Geneva, World Health Organization; 2007. ISBN 978-92-4-157238-5.

Published under the joint sponsorship of International Labour Organization, the International Commission on Non-Ionizing Radiation Protection, and the World Health Organization - © WHO, Geneva, 2007.


Excerpt : "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."

Table of Contents

PREAMBLE
The WHO Environmental Health Criteria Programme
Electromagnetic Fields
Scope
Procedures
Extremely Low Frequency Environmental Health Criteria
Participants in the WHO Expert Working Groups
Acknowledgements
Abbreviations

1 SUMMARY AND RECOMMENDATIONS FOR FURTHER STUDY
1.1 Summary
1.1.1 Sources, measurements and exposures
1.1.2 Electric and magnetic fields inside the body
1.1.3 Biophysical mechanisms
1.1.4 Neurobehaviour
1.1.5 Neuroendocrine system
1.1.6 Neurodegenerative disorders
1.1.7 Cardiovascular disorders
1.1.8 Immunology and haematology
1.1.9 Reproduction and development
1.1.10 Cancer
1.1.11 Health risk assessment
1.1.12 Protective measures
1.2 Recommendations for research
1.2.1 Sources, measurements and exposures
1.2.2 Dosimetry
1.2.3 Biophysical mechanisms
1.2.4 Neurobehaviour
1.2.5 Neuroendocrine system
1.2.6 Neurodegenerative disorders
1.2.7 Cardiovascular disorders
1.2.8 Immunology and haematology
1.2.9 Reproduction and development
1.2.10 Cancer
1.2.11 Protective measures

2  SOURCES, MEASUREMENTS AND EXPOSURES
2.1 Electric and magnetic fields
2.1.1 The field concept
2.1.2 Quantities and units
2.1.3 Polarization
2.1.4 Time variation, harmonics and transients
2.1.5 Perturbations to fields, shielding
2.2 Sources of alternating fields
2.2.1 Electric fields
2.2.1.1 Naturally occurring fields
2.2.1.2 Artificial fields
2.2.2 Magnetic fields
2.2.2.1 Naturally occurring fields
2.2.2.2 Artificial fields
2.3 Assessment of exposure
2.3.1 General considerations
2.3.2 Assessing residential exposure to magnetic fields: methods not involving measurement
2.3.2.1 Distance
2.3.2.2 Wire code
2.3.2.3 Calculated historical fields
2.3.3 Assessing residential exposure to magnetic fields using measurements
2.3.3.1 Spot measurements in the home
2.3.3.2 Longer-term measurements in homes
2.3.3.3 Personal exposure monitoring
2.3.4 Assessing exposure to magnetic fields from appliances
2.3.5 Assessing exposure at schools
2.3.6 Assessing non-occupational exposure to magnetic fields: discussion
2.3.7 Assessing occupational exposure to magnetic fields
2.3.8 Assessing exposure to electric fields
2.3.9 Exposure assessment: conclusions

3 ELECTRIC AND MAGNETIC FIELDS INSIDE THE BODY
3.1 Introduction
3.2 Models of human and animal bodies
3.3 Electric field dosimetry
3.3.1 Basic interaction mechanisms
3.3.2 Measurements
3.3.3 Computations
3.3.4 Comparison of computations with measurements
3.4 Magnetic field dosimetry
3.4.1 Basic interaction mechanisms
3.4.2 Computations – uniform fields
3.4.3 Computations – non-uniform fields
3.4.4 Computations – inter-laboratory comparison and model effects
3.5 Contact current
3.6 Comparison of various exposures
3.7 Microscopic dosimetry
3.8 Conclusions

4 BIOPHYSICAL MECHANISMS
4.1 Introduction
4.2 The concept of plausibility
4.3 Stochastic effects, thresholds and dose-response relationships
4.4 Induced currents and fields
4.4.1 Currents induced by fields
4.4.2 Comparison with noise
4.4.3 Myelinated nerve fibre stimulation thresholds
4.4.4 Neural networks and signal detection
4.4.5 Transients
4.4.6 Heating effects of induced currents
4.4.7 Summary on induced currents
4.5 Other direct effects of fields
4.5.1 Ionization and breaking of bonds
4.5.2 Forces on charged particles
4.5.3 Forces on magnetic particles
4.5.4 Free radicals
4.5.5 Effects with narrow bandwidths
4.5.5.1 Cyclotron resonance
4.5.5.2 Larmor precession
4.5.5.3 Quantum mechanical resonance phenomena
4.5.6 Stochastic resonance
4.6 Indirect effects of fields
4.6.1 Surface charge and microshocks
4.6.2 Contact currents
4.6.3 Deflection of cosmic rays
4.6.4 Effects on airborne pollutants
4.6.4.1 Production of corona ions
4.6.4.2 Inhalation of pollutant particles
4.6.4.3 Deposition under power lines
4.6.4.4 Implications for health
4.7 Conclusions
5 NEUROBEHAVIOUR
5.1 Electrophysiological considerations
5.2 Volunteer studies
5.2.1 Surface electric charge
5.2.2 Nerve stimulation
5.2.3 Retinal function
5.2.4 Brain electrical activity
5.2.5 Sleep
5.2.6 Cognitive effects
5.2.7 Hypersensitivity
5.2.8 Mood and alertness
5.3 Epidemiological studies
5.3.1 Depression
5.3.2 Suicide
5.4 Animal studies
5.4.1 Perception and field detection
5.4.2 Arousal and aversion
5.4.3 Brain electrical activity
5.4.4 Neurotransmitter function
5.4.5 Cognitive function
5.5 Conclusions

6  NEUROENDOCRINE SYSTEM
6.1 Volunteer studies
6.1.1 The pineal hormone: melatonin
6.1.1.1 Laboratory studies
6.1.1.2 Residential and occupational studies
6.1.2 Pituitary and other hormones
6.2 Animal studies
6.2.1 Melatonin
6.2.1.1 Laboratory rodents
6.2.1.2 Seasonal breeders
6.2.1.3 Non human primates
6.2.2 The pituitary and other hormones
6.2.2.1 Pituitary-adrenal effects
6.2.2.2 Other endocrine studies
6.3 In vitro studies
6.3.1 Effects on melatonin production in vitro
6.3.2 Effects on the action of melatonin in vitro
6.4 Conclusions

7 NEURODEGENERATIVE DISORDERS
7.1 Alzheimer disease
7.1.1 Pathology
7.1.2 Epidemiology
7.2 Amyotrophic lateral sclerosis
7.2.1 Pathology
7.2.2 Epidemiology
7.3 Parkinson disease, Multiple Sclerosis
7.3.1 Pathology
7.3.2 Epidemiology
7.4 Discussion
7.5 Conclusions

8 CARDIOVASCULAR DISORDERS
8.1 Acute effects
8.1.1 Electrocardiogram changes, heart rate, and heart rate variability
8.1.2 Blood pressure
8.2 Long-term effects
8.3 Discussion
8.3.1 Heart rate variability hypothesis
8.3.2 Epidemiologic evidence
8.4 Conclusions

9 IMMUNE SYSTEM AND HAEMATOLOGY
9.1 Immune system
9.1.1 Human studies
9.1.2 Animal studies
9.1.3 Cellular studies
9.2 Haematological system
9.2.1 Human studies
9.2.2 Animal studies
9.2.3 Cellular studies
9.3 Conclusions

10 REPRODUCTION AND DEVELOPMENT
10.1 Epidemiology
10.1.1 Maternal exposure
10.1.1.1 Video display terminals
10.1.1.2 Electrically heated beds
10.1.1.3 Other residential and occupational exposure
10.1.2 Paternal exposure
10.2 Effects on laboratory mammals
10.2.1 Electric fields
10.2.2 Magnetic fields
10.2.2.1 Effects on prenatal development
10.2.2.3 Multi-generation studies
10.2.2.4 Effects on mammalian embryos in vitro
10.2.2.5 Effects of paternal exposure
10.3 Effects on non-mammalian species
10.3.1 Bird embryos
10.3.1.1 Development
10.3.1.2 Interaction with known teratogens
10.3.2 Other non-mammalian species
10.4 Conclusion

11 CANCER
11.1 IARC 2002 evaluation: summary
11.2 Epidemiological studies
11.2.1 Childhood leukaemia
11.2.1.1 Epidemiology
11.2.1.2 Trends and ecologic correlations
11.2.1.3 New data
11.2.1.4 Evaluating epidemiological evidence: possible explanations
11.2.2 Adult cancer
11.2.2.1 Breast cancer
11.2.2.2 Leukaemia and brain cancer
11.2.2.3 Other cancers
11.2.3 Epidemiology: conclusions
11.3 Carcinogenesis in laboratory animals
11.3.1 Rodent bioassays
11.3.1.1 Large scale, life-time studies
11.3.1.2 Leukaemia/lymphoma
11.3.1.3 Brain tumours
11.3.2 EMF exposure combined with carcinogens
11.3.2.1 Liver pre-neoplastic lesions
11.3.2.2 Leukaemia/lymphoma
11.3.2.3 Mammary tumours
11.3.2.4 Skin tumours
11.3.2.5 Brain tumours
11.3.3 Transplanted tumours
11.3.4 Genotoxicity in animals
11.3.5 Non-genotoxic studies
11.3.6 Animal studies: conclusions
11.4 In vitro carcinogenesis studies
11.4.1 Genotoxic effects
11.4.1.1 Genotoxic effects of ELF magnetic fields alone
11.4.1.2 Combined genotoxic effects
11.4.2 Expression of oncogenes and cancer-related genes
11.4.3 Differentiation, proliferation and apoptosis
11.4.4 Gap junction intercellular communications
11.4.5 Free radicals
11.4.6 In vitro conclusions
11.5 Overall conclusions

12 HEALTH RISK ASSESSMENT
12.1 Introduction
12.2 Hazard identification
12.2.1 Biological versus adverse health effects
12.2.2 Acute effects
12.2.3 Chronic effects
12.3 Exposure assessment
12.3.1 Residential exposures
12.3.2 Occupational exposures
12.4 Exposure-response assessment
12.4.1 Threshold levels
12.4.2 Epidemiological methods
12.5 Risk characterization
12.5.1 Acute effects
12.5.2 Chronic effects
12.5.3 Uncertainties in the risk characterization
12.5.3.1 Biophysical mechanisms
12.5.3.2 Exposure metric
12.5.3.3 Epidemiology
12.6 Conclusions

13 PROTECTIVE MEASURES
13.1 Introduction
13.2 General issues in health policy
13.2.1 Dealing with environmental health risks
13.2.2 Factors affecting health policy
13.3 Scientific input
13.3.1 Emission and exposure standards
13.3.2 Risk in perspective
13.4 Precautionary-based policy approaches
13.4.1 Existing precautionary ELF policies
13.4.2 Cost and feasibility
13.5 Discussion and recommendations
13.5.1 Recommendations

APPENDIX: Quantitative risk assessment for childhood leukaemia
A.1 Exposure distribution
A.2 Exposure-response analysis using attributable fraction estimates for EMF and childhood leukaemia