Non-ionizing Radiation Protection E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
A comprehensive review of non-ionizing radiation and its public health and environmental risks, for researchers, policy makers, and laymen This book explains the characteristics of all forms of electromagnetic non-ionizing radiation (NIR) and analyzes the relationship between exposure and its biological effects, as well as the known dose-response relationships associated with each. Taking a uniquely holistic approach to the concept of health that builds upon the WHO definition to include not only absence of disease, but the physical, mental and social well-being of individuals and the population, it reviews established and potential risks and protections, along with regulatory issues associated with each. The risks to public health of NIR, whether in the form of UV light, radio waves from wireless devices, or electric and magnetic fields associated with electrical power systems, is currently a cause of great concern among members of the public and lawmakers. But in order to separate established science from speculation and make informed decisions about how to mitigate the risks of NIR and allocate precious resources, policymakers, manufacturers, and individuals need a comprehensive source of up-to-date information based on the current scientific evidence. Written by a team of experts in their fields, this book is that source. Among other things, it: * Summarizes scientific findings on the safety of different forms of NIR and the rationale behind current standards * Describes devices for monitoring NIR along with the established and potential hazards of each form * Explores proper protections against UV light and lasers, RF radiation, ELF fields and other forms of NIR * Discusses how to avoid injuries through occupational training or public awareness programs, and how to perform medical assessments in cases of suspected NIR injuries * Considers how to decide whether or not to spend money on certain mitigation measures, based on cost-benefit analyses Offering expert reviews and analyses of the latest scientific findings and public policy issues concerning the risks to public health and the environment of NIR, Non-ionizing Radiation Protection is an indispensable source of information for manufacturers, government regulators, and regulatory agencies, as well as researchers, concerned laypersons, and students.
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Table of Contents
Cover
Title Page
Copyright
List of Contributors
Foreword
Acknowledgments
Introduction
Chapter 1: Overview: The Electromagnetic Spectrum and Nonionizing Radiation
1.1 What Is Nonionizing Radiation (NIR)?
1.2 Types of NIR
1.3 How Dangerous is NIR?
1.4 Overview Summary of NIR Health Effects Evaluation: Status
Tutorial Problems
References
Part I: Hazard Identification and Assessment: What are the Dangers and How are the Sources Dangerous?
Chapter 2: Hazard Identification: Laboratory Investigation
2.1 Introduction
2.2 The Scientific Method
2.3 Human Volunteer Experiments
2.4 Whole Organism Experiments
2.7 Difference Between “Effects” and “Harmful Effects”: Extrapolation to Human Health Outcomes
2.8 Role of Mathematical Modeling and Mechanism Studies
A.1 Averaging
A.2 Standard Error of the Mean
A.3 When Is a Difference Significant?
A.4 Correlations
A.5 Analysis of Variance
A.6 Statistical Power
A.7 Multiple Comparisons
Tutorial Problems
References
Chapter 3: Hazard Identification: Epidemiological Studies and Their Interpretation
3.1 Introduction
3.2 Causation
3.3 Incidence and Prevalence
3.4 Evidence for Causation
3.5 Types of Epidemiological Study
3.6 Time Dimensions – Prospective, Retrospective, or Cross Sectional
3.7 Some Other Epidemiological Studies
3.8 The Results of Epidemiological Studies: Relative Risk, Confidence Limits, and
P
-Values
3.9 Assessing Causality: Identifying Noncausal Explanations
3.10 Conclusion
Tutorial Problems
References
Part II: Ultraviolet (UV) Light
Chapter 4: UVR and Short-Term Hazards to the Skin and Eyes
4.1 Introduction
4.2 Sources of UVR: Natural and Artificial
4.3 Short-Term Hazards to Skin and Eyes
4.4 UVR Interaction with Biomolecules
4.5 Eye Transmission and Effects
References
Further Reading
Chapter 5: Ultraviolet: Long-Term Risks and Benefits
5.1 Hazards: General
5.2 Benefits: Vitamin D Synthesis
5.3 Reduction in Sun Exposure
5.4 Control of Artificial Tanning
Tutorial Problems
References
Chapter 6: UV Guidelines and Protection Policies
6.1 ICNIRP Guidelines and National Standards
6.2 General Population versus Occupational Exposures
6.3 Occupational Exposures to UVR
6.4 Measured Occupational Exposures to UVR
6.5 Awareness Campaigns
6.6 Protection Measures
References
Further Reading
Chapter 7: UV Measurements
7.1 Radiometry and Spectroradiometry
7.2 Solar UVR
7.3 Solar UVR Broadband Measurements
7.4 Solar UVR Spectral Measurements
7.5 Personal Dosimetry
7.6 Chemical Dosimeters
7.7 Biological Dosimeters
References
Further Reading
Part III: Visible and Infrared (IR) Light
Chapter 8: Laser and Visible Radiation Hazards to the Eye and Skin
8.1 Intense Sources of Optical Radiation
8.2 Basic Principles of a Laser
8.3 Intense Nonlaser Sources of Visible Light
8.4 Biological Effects
8.5 Laser Radiation Safety
Tutorial Problems
References
Chapter 9: Infrared Radiation and Biological Hazards
9.1 Introduction
9.2 Black Body Radiation
9.3 Absorption of Infrared Radiation
9.4 Interaction of Infrared Radiation with the Human Body
9.5 Traditional Sources of Infrared Radiation
9.6 Personal Protective Equipment
9.7 Recent and Emerging Infrared Technologies, Including Lasers, Laser Diodes, LEDs, and Terahertz Devices
9.8 Infrared Exposure Standards and Guidelines
References
Chapter 10: Laser and Optical Radiation Guidelines
10.1 Introduction
10.2 Guidelines and Standards for Lasers
10.3 Laser Standards
10.4 Laser Guidelines
References
Chapter 11: Laser Measurements
11.1 Introduction
11.2 Measurement Parameters for Lasers
11.3 Measurement Methods
11.4 Beam Diameter and Beam Divergence
11.5 Divergence Measurements
Tutorial Problems
References
Further Reading
Part IV: Radiofrequency (RF) and Microwave Radiation
Chapter 12: Thermal Effects of Microwave and Radiofrequency Radiation
12.1 Introduction
12.2 Thermal Effects Relevant to Health and Safety
12.3 Mechanisms for Thermal Effects of RF Energy
12.4 Modeling Thermal Response of Humans to RF Energy Exposure
12.5 Conclusion
References
Chapter 13: RF Guidelines and Standards
13.1 Introduction
13.2 How Do the Standards-Setting Bodies Operate?
13.3 Standard or Guidance Levels
13.4 Basic Restrictions
13.5 Temporal Averaging
13.6 Contact Current Restrictions
13.7 Reference Levels as a Function of Frequency
13.8 Near-Field versus Far-Field
13.9 Dealing with Multiple Frequencies
13.10 Spatial Averaging
13.11 Specific Issues Regarding Risk Management
13.12 Scientific Input
13.13 The Place of Epidemiological and Low-Level Effects Research in Standard Setting
Tutorial Problems
References
Chapter 14: Assessing RF Exposure: Fields, Currents, and SAR
14.1 Introduction
14.2 RF Sources and the Environment
14.3 Planning an Exposure Assessment
14.4 Quantities and Units
14.5 Broadband Field Strength Measurements
14.6 Frequency-Selective Field Strength Measurements
14.7 Induced and Contact Current Measurements
14.8 SAR Measurements
14.9 Computation of Fields, Currents, and SARs
14.10 Calibration of Instruments
14.11 Validation of Computational Tools and Simulations
14.12 Uncertainty in Measurements and Computations
14.13 Compliance with Limits
Tutorial Problems
Glossary
Symbols
References
Chapter 15: Epidemiological Studies of Low-Intensity Radiofrequency Fields and Diseases in Humans
15.1 Introduction
15.2 Mobile Phone Use and Brain Cancer
15.3 Case–Control Studies
15.4 Cohort Studies
15.5 Time Trends in Brain Tumors
15.6 The IARC Report
15.7 Mobile Phone Base Stations
15.8 Radio and Other Transmitters
15.9 Occupational Studies
15.10 Other Diseases
15.11 Conclusions
Tutorial Problems
References
Chapter 16: Possible Low-Level Radiofrequency Effects
16.1 Introduction
16.2 Where Is the Information?
16.3 Thermal and Nonthermal Effects: Formal Definitions
16.4 RF Bioeffects Research: General
16.5 Summary of
In Vitro
Work
16.6 Summary of
In Vivo
Work
16.7
In Vivo
Studies: Other Effects
16.8 Animal Whole of Life Studies
16.9 Human Volunteer Studies
16.10 Other Issues Relating to Mechanism of Interaction of RF with Biological Systems
16.11 Modeling and Dosimetry
16.12 Unanswered Questions
16.13 What More Needs to Be Done?
References
Part V: Extremely Low-Frequency (ELF) Electric and Magnetic Fields
Chapter 17: Electric and Magnetic Fields and Induced Current Hazard
17.1 Introduction
17.2 What Other Hazards Need We Consider?
17.3 The Initiation of an Action Potential
17.4 Endogenous and Exogenous Currents
17.5 Sensation Thresholds
17.6 Effects of Contact Currents
17.7 Inducing a Current in Tissue by an External Magnetic Field
17.8 Effects of External Electric Fields
17.9 Sources of EMFs: Electricity Transmission and Distribution Systems
17.10 Home Appliances and Industrial or Commercial Sources of EMF
17.11 Transportation Systems
17.12 Therapeutic Uses
17.13 Effect on Pacemakers and Other Implantable or Body-worn Electronic Medical Devices
17.14 Electro and Magnetobiology
17.15 Glossary and Further Definitions
Tutorial Problems
References
Chapter 18: Extremely Low-Frequency (ELF) Guidelines
18.1 Introduction
18.2 Standard or Guidance Levels?
18.3 Guidelines/Standards: History
18.4 Basic Restrictions and Reference (or Maximum Permitted Exposure) Levels
18.5 Basic Restrictions
18.6 MPEs/RLs for Electric (
E
) Fields
18.7 MPEs/RLs for Magnetic (
B
) Fields
18.8 Extremities
18.9 Contact Currents
18.10 Time and Space Averaging
18.11 Multiple Frequencies
18.12 The Place of Epidemiological Results in ELF Standard-Setting
18.13 ICNIRP Versus IEEE
Tutorial Problems
References
Chapter 19: Instrumentation and Measurement of ELF Electric and Magnetic Fields
19.1 Introduction
19.2 ELF Instrumentation – General
19.3 Electric Field Instrumentation
19.4 Magnetic Field Instrumentation
19.5 Measurement and Exposure Assessment Considerations
References
Chapter 20: Epidemiological Studies of Low-Intensity ELF Fields and Diseases in Humans
20.1 Leukemia in Children
20.2 Other Cancers
20.3 Occupational Studies
20.4 Neurological Diseases
20.5 Reproductive Outcomes
20.6 Major Reviews
Sources for Updates
Tutorial Problems
References
Chapter 21: Possible Low-Level Extremely Low-Frequency (ELF) Electric and Magnetic Field Effects?
21.1 Exposure to ELF Fields
21.2 Some “Landmark Studies”?
21.3 Mechanism Studies
21.4 Why Is Evidence Regarded as “Inconclusive”?
21.5 Dealing with Scientific Uncertainty in a Prudent Manner
Tutorial Problems
References
Part VI: Static Electric and Magnetic Fields
Chapter 22: Static Electric and Magnetic Field Hazards
22.1 Sources
22.2 Interaction Mechanisms
22.3 Health Effects
22.4 Low-Level Effects
22.5 Interference with Implanted Medical Devices
Tutorial Problems
References
Chapter 23: Static Electric and Magnetic Field Guidelines
23.1 Introduction
23.2 Static Electric Fields
23.3 Static Magnetic Fields
23.4 Magnetic Resonance Imaging Guidelines
23.5 Summary
Tutorial Problems
References
Part VII: Dealing with Hazard Perception
Chapter 24: Perceived Hypersensitivity: Anecdotal Versus Objective Evidence
24.1 Introduction
24.2 Anecdotal Evidence of Sensitivity to Electromagnetic Fields
24.3 Objective Evidence of Sensitivity to Electromagnetic Fields
24.4 Treatment and Intervention Strategies
24.5 Important Considerations for Treatment
References
Chapter 25: Prudent Avoidance
25.1 Introduction
25.2 Public Policy Considerations
25.3 Prudent Avoidance Principles
25.4 Prudent Avoidance – Transmission
25.5 Prudent Avoidance – Distribution
25.6 Miscellaneous
25.7 Conclusions
References
Chapter 26: Radiofrequency Fields and the Precautionary Principle
26.1 Introduction
26.2 What Is the Precautionary Principle?
26.3 Precautionary Approaches to Regulating Human Exposure to Radiofrequency Fields
26.4 Difficulties with Precautionary Approaches to Radiofrequency Field Regulation
Acknowledgment
References
Chapter 27: How to Handle Precaution
27.1 Introduction
27.2 A Precautionary Approach to EMF
27.3 Test Case: Extremely Low Frequency Magnetic Fields
27.4 Conclusion
References
Part VIII: NIR Injury Prevention and Medical Assessment
Chapter 28: Medical Aspects of Overexposures to Nonionizing Radiation
28.1 General Principles of Managing Overexposures
28.2 Considerations of Components of the NIR Spectrum.
References
Chapter 29: Preventive Surveillance Programs
29.1 Introduction
29.2 UV Protection – Influencing Sun Protection Behaviors across the Populations (Sue Heward)
29.3 Preventative Surveillance Programs – Laser Safety (David Urban)
29.4 RF Training Programs (Ray McKenzie)
29.5 Conclusion
Tutorial Problem
References
Part IX: Legal and Community Issues
Chapter 30: Public Consultation and Dissemination of Information. Risk Perception. Public Involvement in Decision-Making Regarding Placement of Broadcast Antennas and Power Transmission Lines
30.1 Introduction
30.2 Why Communicate on NIR?
30.3 Public Perception
30.4 Stakeholder Dialog
30.5 When to Communicate
30.6 What to Communicate
30.7 How to Communicate
30.8 Evaluation Is Essential
30.9 Conclusion
References
Chapter 31: Mitigating Nonionizing Radiation Risks
31.1 Introduction
31.2 Mitigation Strategies – Lasers and Other Optical Sources (David Urban)
31.3 Strategies for Radiofrequency Field Exposure Reduction (Michael Bangay)
31.4 Mitigation Strategies for ELF Electric and Magnetic Fields (Thanh Dovan)
31.5 Conclusion
Tutorial Problem
References
Chapter 32: Some of the Controversies Regarding NIR
32.1 Why Should NIR Attract Such Controversy?
32.2 Extremely Low Frequency
32.3 Radiofrequency
32.4 Laser
32.5 Ultraviolet
32.6 What We Can Learn from These Controversies
References
Chapter 33: Summary and Prospects
33.1 Comparison of Nonionizing Radiation with Ionizing Radiation
33.2 Could the Same Protection Framework Be Applied to Both Ionizing and Nonionizing Radiation?
33.3 Might We Expect a Definitive Answer Soon?
33.4 Comparative Costs and Benefits of Mitigation Measures
33.5 Concept of Acceptable Risk
33.6 Can We Live in a World without NIR Exposure?
References
Appendix A: Answers to Tutorial Problems
Chapter 1
Chapter 2
Chapter 3
Chapter 5
Chapter 8
Chapter 11
Chapter 13
Chapter 14
Chapter 15
Chapter 17
Chapter 18
Chapter 20
Chapter 21
Chapter 22
Chapter 23
Chapter 27
Chapter 29
Chapter 31
Appendix B: List of Suppliers of Survey Equipment
UV/Visible/IR Survey Instruments and Personal Monitors
RF/ELF Survey Instruments and Personal Monitors
RF/ELF Personal Monitors
Appendix C: Websites for Further Information
International
National
Index
End User License Agreement
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Guide
Cover
Table of Contents
Foreword
Begin Reading
List of Illustrations
Chapter 1: Overview: The Electromagnetic Spectrum and Nonionizing Radiation
Figure 1.1 The electromagnetic spectrum, from power frequencies through to γ-rays. Top: wavelength in meters; middle: relative sizes of wavelengths, names, and typical sources; bottom: frequency in waves per second or hertz (Hz) and the relative energy of each type. Source: K. Karipidis, ARPANSA, Australia.
Figure 1.2 A propagating electromagnetic wave, showing electric (
E
) and magnetic (
H
) vectors (arrows), the direction of propagation (
k
), and the wavelength (
λ
). Note that the
E
and
H
vectors are at right angles to each other and also to the direction of propagation. See diagram as supplied for location of all of these symbols (λ, E, k).
Figure 1.3 The relationship between power density and power. The sphere represents an expanding wavefront from the origin. Alternatively, it can represent an imaginary spherical surface across which the radiated power is flowing. Power density is expressed as power per unit area, so if the area considered is
A
in the diagram, proportion of the total power
P
crossing A will be
P
⋅
A
/(4
πr
2
) watts, since 4
πr
2
is the surface area of the entire sphere. Dividing by
A
gives the power density in W/m
2
.
Chapter 4: UVR and Short-Term Hazards to the Skin and Eyes
Figure 4.1 The relative spectral effectiveness of the CIE (--) for erythema compared with the ICNIRP ( —— ) spectral effectiveness for eyes and skin. Both functions show a rapid decrease in effectiveness of several orders of magnitude for UVA wavelengths above 315 nm in comparison with UVB wavelengths.
Figure 4.2 The extraterrestrial solar spectrum (solid line) incident at the top of the atmosphere and the solar spectrum measured at the Earth's surface (line with open circles).
Figure 4.3 A comparison of the extraterrestrial solar spectrum with that measured at the Earth's surface (Melbourne, Australia, January) for the UVR wavelength range 280–400 nm. Also shown are the absorption coefficients of ozone (right axis), which increase sharply at wavelengths below 340 nm and are responsible for reducing the hazardous UVR below 300 nm.
Figure 4.4 The percentage of daily solar UVR within certain time periods. The hours 12 till 2 have 31% of the daily total, while almost 60% of the daily total occurs within 2 hours of solar noon (11 a.m. to 3 p.m.). These percentages will vary for different locations and for different times of the year.
Figure 4.5 Variation of solar UVR with latitude for locations in both the Northern and Southern Hemispheres. Note that the Australian Antarctic Division (AAD) stations in the Antarctic (~60°S) points are higher due to higher solar UVB levels due to regular ozone depletion events, whereas the Macquarie Island AAD Station is unaffected by the ozone hole.
Figure 4.6 The spectral transmission of UVR through the eye.
Chapter 5: Ultraviolet: Long-Term Risks and Benefits
Figure 5.1 Structure of the epidermis. The keratinocytes start in the basal layer (stratum basale) and migrate toward the surface. The melanocytes are shown as colored cells in the basal layer: they produce melanin. Image from www.canstockphoto.com, with reproduction rights agreed.
Figure 5.2 The UV index as used by the U.S. Environmental Protection Agency (U.S. Department of Health and Human Services, 2014).
Chapter 6: UV Guidelines and Protection Policies
Figure 6.1 A comparison of the distributions of UV exposures for school children in Queensland compared to school children in England. The UV exposure distribution for the Queensland schoolchildren has its median centered, so it is approximately twice that of the UK schoolchildren, given that the UV exposure levels in Queensland were approximately twice those of the UK schoolchildren (Diffey and Gies, 1998; Gies et al., 1998). Source: Diffey and Gies (1998) and Gies et al. (1998). Reproduced with permission of Springer.
Figure 6.2 The spectral transmittance of four pre-1990 sunglasses as well as the eye response to visible light (VLSL). Sunglasses numbered 1, 2, and 3 all fail the UV transmittance requirements of AS/NZS Sunglasses and Fashion Spectacles because of their transmittance in the UVR region. Sunglass number 4 is the only pair of sunglasses shown that passes the standard.
Figure 6.3 Sunglasses tested in 2013–2014 with only sunglass number 1 passing the mandatory Sunglass Standard AS/NZS 1067, while sunglass 2 transmits too much visible to qualify as a sunglass and sunglass 4 transmits too little to qualify.
Figure 6.4 The spectral emissions from solaria in Australia, showing the various distributions versus wavelength. The solaria with higher emissions toward the UVB and lower wavelength UVA have the highest resulting UV index, which is shown near each of the respective spectral distribution curves.
Chapter 7: UV Measurements
Figure 7.1 Typical spectroradiometric setup including a light source to be evaluated (a fluorescent lamp in this case).
Figure 7.2 Solar UVR spectral irradiance at the earth's surface for different solar zenith angles and different times of the day.
Figure 7.3 Solar Light 501 UV-Biometers on the roof of the ARPANSA Laboratory for calibration.
Figure 7.4 The dose–response curve of polysulfone film showing the change in absorbance as a function of the erythemal effective dose (EED).
Figure 7.6 A WMC GmbH electronic UV dosimeter that can be worn on the wrist or the lapel.
Figure 7.5 A large batch of personal UV Dosimeters on the roof of the ARPANSA Laboratory undergoing calibration against the calibrated ARPANSA traceable Bentham spectral system.
Figure 7.7 Measurement results for a subject that wore an electronic UV dosimeter while working at the ski fields in Australia in winter. The UV doses vary slightly from day to day depending on the levels of ambient solar UVR. The regular breaks for lunch inside are also clearly evident.
Chapter 8: Laser and Visible Radiation Hazards to the Eye and Skin
Figure 8.1 Optical light region of the electromagnetic spectrum showing the relative sensitivity of the human eye.
Figure 8.2 Diagram showing the difference between noncoherent forms of light and coherent light from a laser.
Figure 8.3 Light from an extended source and a point source being focused by the lens of the eye.
Figure 8.4 Pictorial representation of the atom showing the energy levels (orbitals) in the energetic ground state.
Figure 8.5 An incoming photon with energy
E
2−
E
1 (equal to the difference in energy between the excited and ground state in the atom) interacts with an excited atom. Stimulated emission occurs and two photons result with the same direction and phase, that is, they are coherent.
Figure 8.6 Example of the main components of an optically pumped laser.
Figure 8.7 Energy output difference between a continuous wave laser and a pulsed laser.
Figure 8.8 Spectral irradiance of the solar radiation spectrum at the top of the atmosphere and at sea level.
Figure 8.9 Structure of the eye.
Figure 8.10 Absorption properties of the eye.
Figure 8.11 Light reflections showing the difference between specular reflection from a smooth surface and diffuse reflections from a rough surface.
Chapter 9: Infrared Radiation and Biological Hazards
Figure 9.1 Blackbody radiation intensity as a function of wavelength/frequency for two different blackbody temperatures.
Figure 9.2 Modes of energy absorption by molecules from electromagnetic radiation from UV through to microwave, showing that molecular vibrations predominate in the infrared region.
Source:
Adapted from Pecsok and Shields, 1968 and Schwartz, 1994. Reproduced with permission of Elsevier and Wiley.
Figure 9.3 Absorption of infrared radiation by pure water as reported by numerous authors. Wozniak and Dera, 2007. Reproduced with permission of Springer.
Figure 9.4 Absorption properties of the human skin, as a function of wavelength.
Source:
Adapted from Urbach, 1985, The University of Chicago Press.
Figure 9.5 A cross section through the human eye.
Chapter 11: Laser Measurements
Figure 11.1 Thermopile sensor arrangement for measuring laser power.
Figure 11.2 Setup for measuring divergence with lens and a CCD camera. The lens is placed at the focal length of the lens at the wavelength being measured.
Chapter 12: Thermal Effects of Microwave and Radiofrequency Radiation
Figure 12.1 Energy penetration depth
L
and transmission coefficient
T
tr
for plane wave energy incident on a plane tissue surface with dielectric properties similar to soft tissue. Reprinted from Foster et al. (2016) with permission.
Chapter 13: RF Guidelines and Standards
Figure 13.1 Waveforms of representative radiofrequency electric (
E
) or magnetic (
H
) fields. (a) simple sine wave, showing an average value of 0; (b) the square of the values shown in (a), with an average value of 0.5 and a root mean square value (RMS) of √0.5, or 0.707; (c) an amplitude-modulated wave, with an RMS value of 0.5; and (d) a normally distributed random sequence, with an RMS value of 0.3.
Figure 13.2 Variation of SAR per unit plane wave power density in three orientations in relation to long axis of body:
H
is magnetic field vector parallel,
K
is direction of propagation parallel, and
E
electric field parallel to long axis.
Figure 13.3 The variation in reference levels for occupational exposures (controlled environments) comparing IEEE with ICNIRP. (a) The values are strictly the "equivalent plane-wave" power densities
S
eq
, which refers to any electromagnetic wave that is equal in magnitude to the power density of a plane wave having the same electric (
E
) or magnetic (
H
) field strength. (b,c) The values of
E
and
H
fields, respectively, refer to unperturbed values of RMS fields (unperturbed by the act of measurement).
Chapter 14: Assessing RF Exposure: Fields, Currents, and SAR
Figure 14.1 Response of electrically small dipole (
L
<
λ
/10) and loop (2
πa
<
λ
/10) antennas to an incident electromagnetic field. The voltage
V
o
across the terminals of the dipole is directly proportional to the parallel component of the incident field,
E
p
. For the loop antenna,
V
o
is directly proportional to the
H
field component normal to the plane of the loop,
H
n
.
Figure 14.2 Log-periodic antenna (a) and broadband horn (b).
Figure 14.3 Touch and limb currents in a worker operating an RF welding machine. Touch currents are caused by direct contact with the machine, while stray leakage fields couple to the body causing current to flow to ground.
Figure 14.4 Two-sided confidence range. The best estimate lies at the center of the normal or Gaussian probability distribution probability distribution. The true value is unknown but will lie in the symmetric range between the interval between the lower bound value
μ
− 2
σ
and the upper bound value
μ
+ 2
σ
with 95% confidence.
Figure 14.5 One-sided confidence range. The best estimate lies at the center of the normal or Gaussian probability distribution. The true value is unknown but will be less than the upper bound value
μ
+ 1.64
σ
with 95% confidence.
Figure 14.6 Compliance with a limit. In both the cases, the assessor's expanded uncertainty is within a prescribed allowance. In the first case, the upper bound extends above the limit so that there is close to a 50% chance that the true value exceeds the limit and around a 45% chance that it is between the limit and the upper bound. In the second case, the upper bound is just below the limit and there remains a much lower chance that the true value exceeds the limit.
Chapter 15: Epidemiological Studies of Low-Intensity Radiofrequency Fields and Diseases in Humans
Figure 15.1 Results of the Interphone Study: relative risks (odds ratios) for glioma in deciles of cumulative call time, compared to nonusers (logarithmic scale). Arrows show statistically significant odds ratios.
Chapter 16: Possible Low-Level Radiofrequency Effects
Figure 16.1 Summary of reported SAR values for
in vitro
studies considered in the AGNIR (2012) review. Each row gives values for the types of study shown at right (see text for further explanation), with those showing no effect (NE) and those showing an RF-related effect (Effect) in alternate rows. The vertical line indicates the general public basic restriction.
Figure 16.4 Average (±SD) SAR reported for the types of experiment shown at right. Individual values shown in Figure 16.1–16.3 (except for the SCENIHR data, which is not shown).
Figure 16.2 Summary of reported SAR values for brain and nervous system experiments. For explanation, see Figure 16.1 and text. N.B. the absence of a symbol indicates that no effects have been recorded for that category.
Figure 16.3 Summary of reported SAR values for “other
in vivo
” experiments. For explanation, see Figure 16.1 and text.
Figure 16.5 Ranges of frequency over which enhanced electroencephalographic alpha wave power has been reported in 16 separate studies (identified as codes A–P: see for further details on some of these).
Chapter 17: Electric and Magnetic Fields and Induced Current Hazard
Figure 17.1 Diagram of a typical nerve cell.
Figure 17.2 Strength–duration curve for an excitable cell.
Figure 17.3 A sensory cell such as a retinal rod cell.
Figure 17.4 Induced electric field lines within the body of a person subjected to a 1 mT spatially uniform time-varying magnetic field directed front to back. Units: mV/m.
Figure 17.5 Electric field lines (full) and isopotentials (dotted) for a person subjected to an electric field.
Figure 17.6 Phase cancelation effects: each of the three sine waves is delayed by one-third of a cycle (relative to the previous one). If these three sine waves represent current in the three transmission line conductors, note that at each instant the net current is zero (the first vertical line has values +0.9, 0, −0.9; the second one +0.5, +0.5, −1.0). At positions remote from the transmission line, the magnetic field is determined by the sum of the currents: effectively zero.
Chapter 18: Extremely Low-Frequency (ELF) Guidelines
Figure 18.1 (a) Basic restrictions on internal electric fields (
E
int
) for occupational exposed persons (ICNIRP) or controlled environments (IEEE). (b) Basic restrictions for the general public. Where exposure does not involve the CNS, the PNS restrictions apply throughout (which means a “flat” restriction of 2.1 or 0.9 V/m for IEEE and 0.8 or 0.4 V/m for ICNIRP down to 0.1 and 1 Hz).
Figure 18.2 Reference levels/maximum permitted exposures for occupational groups (OCC)/controlled environment (CE) or general public (GP) for external electric fields, comparing ICNIRP with IEEE.
Figure 18.3 Reference levels/maximum permitted exposures for occupational groups (OCC)/controlled environment (CE) or general public (GP) for external magnetic fields, comparing ICNIRP with IEEE.
Chapter 19: Instrumentation and Measurement of ELF Electric and Magnetic Fields
Figure 19.1 Main types of power frequency electric and magnetic field instrumentation.
Figure 19.2 Measurement of body current in a person standing in an electric field.
Figure 19.3 Diagrammatic representation of the field mill principle for measuring DC electric fields.
Figure 19.4 Example of electric field sources for calibration of electric field meters.
Figure 19.5 Calibration of magnetic field meter using Helmholtz coils.
Chapter 25: Prudent Avoidance
Figure 25.1 Magnetic field profile at 1 m above ground for a typical 500-kV overhead transmission line for various conductor configurations. 1. Single circuit with horizontal flat configuration of phases. 2. Single circuit with triangular configuration of phases. 3. Single circuit with vertical configuration of phases. 4. Double circuit with vertical configuration of phases and with favorable phase sequence (acting to reduce field strength).
Figure 25.2 Magnetic field profile at 1 m above ground for a typical 500-kV double-circuit transmission line with vertical conductor configuration (below), where R W B indicate “red, white, and blue,” the common phase labeling used in the industry.
Figure 25.3 Magnetic field profiles at 1 m above ground for typical overhead and underground lines. 1. Under a 500-kV transmission line with horizontal phase configuration, typically carries 500 A or larger. 2. Under an 11-kV distribution line with horizontal phase configuration, typically carries 200 A or larger. 3. Above an underground three-phase, single-core cable circuit with horizontal phase configuration and 100-mm phase separation, typically carries 200–500 A or larger.
Figure 25.4 Variation of magnetic field with distance under three-phase open type low-voltage busbars, typically carrying 200–1000 A. 1. Balanced current condition. 2. Unbalanced current condition with the net current returning via its neutral busbar. 3. Unbalanced current condition, but the net current returning via an alternative route.
Figure 25.5 Methods of reducing magnetic fields in the home. Note: 1. Insulated twisted service produces 10% of the open wire service fields. 2. Moving the meter box 1 m (as shown above) can reduce fields in the bedroom by 80%.
Chapter 26: Radiofrequency Fields and the Precautionary Principle
Figure 26.1 Number of papers on precautionary principle per year, from a search on Web of Science.
Chapter 28: Medical Aspects of Overexposures to Nonionizing Radiation
Figure 28.1 Flowchart of Medical Management of NIR Overexposure.
Chapter 29: Preventive Surveillance Programs
Figure 29.1 Skin type chart adapted by SunSmart Victoria from Fitzpatrick (1975). Images courtesy of Cancer Research, UK.
Figure 29.2 Examples of classification and safety signage that may be found on a laser product.
Chapter 31: Mitigating Nonionizing Radiation Risks
Figure 31.1 Examples of laser safety signage intended for use in laser work areas.
Figure 31.2 Typical risk assessment chart.
Figure 31.3 Five-step control process for risks. Source: NIOSH – U.S. Department of Health & Human Services.
Figure 31.4 An illustration of the inverse square relationship in power density from a dipole antenna.
Figure 31.5 The directional radiation pattern from the dipole antenna shown in Figure 31.4.
Figure 31.8 Mitigation of environmental signals by shielding: example of dielectric welder. Source: Image courtesy of Nemeth Engineering, Crestwood, KY.
Figure 31.7 Earth strapping to minimize reradiation.
Figure 31.9 Showing a typical scenario of a person touching an unearthed metal fence below a transmission line. See Table 13.1 for typical values for
C
PE
and
C
FE
.
C
LP
and
C
LF
values are usually about 100 times smaller.
List of Tables
Chapter 1: Overview: The Electromagnetic Spectrum and Nonionizing Radiation
Table 1.1 Types of nonionizing radiation.
Chapter 2: Hazard Identification: Laboratory Investigation
Table 2.1 Human (provocation) studies.
Table 2.2 Experiments carried out on experimental animals to determine existence of health effects and level of exposure these occur (if they do occur).
Table 2.3 Check list for inclusion of research report in overall risk assessment process.
Chapter 3: Hazard Identification: Epidemiological Studies and Their Interpretation
Table 3.1 Features of the three major study designs which can assess the relationship between an exposure and an outcome.
Table 3.2 Results of a cohort study.
Table 3.3 Results of a case–control study.
Table 3.4 Results of a cohort study, stratified for men and women.
Chapter 4: UVR and Short-Term Hazards to the Skin and Eyes
Table 4.1 Distribution energy of the extraterrestrial solar spectrum (Thekaekara, 1973) and the solar spectrum measured at the Earth's surface.
Table 4.2 UVR hazards from various types of sources.
Table 4.3 Skin types and their response to solar UVR.
Chapter 10: Laser and Optical Radiation Guidelines
Table 10.1 Differences in laser classification between IEC and ANSI standards.
Chapter 11: Laser Measurements
Table 11.1 Key parameters for characterizing different types of lasers.
Chapter 13: RF Guidelines and Standards
Table 13.1 Recent reviews of research literature (where there are multiple reports the latest one is shown).
Table 13.2 Basic restrictions on specific absorption rate in W/kg for IEEE (IE) and ICNIRP (IC).
Table 13.3 Comparison between basic terminology from the IEEE Standard and the ICNIRP Guidelines: where no formal definition is given, parts of relevant text paraphrased in brackets.
Chapter 15: Epidemiological Studies of Low-Intensity Radiofrequency Fields and Diseases in Humans
Table 15.1 Conclusions of recent major reports on possible health effects of mobile phone base stations.
Chapter 17: Electric and Magnetic Fields and Induced Current Hazard
Table 17.1 Typical values of magnetic fields measured near powerlines and substations.
Table 17.2 Typical values of magnetic fields measured at normal user distance.
Chapter 18: Extremely Low-Frequency (ELF) Guidelines
Table 18.1 Comparison between basic terminology from the ICES standard and the ICNIRP guidelines: where no formal definition is given, parts of the relevant text are paraphrased in brackets.
Table 18.2 Occupational/controlled environment maximum permitted exposures (IEEE) or reference levels (ICNIRP) for
B
-fields at 50 Hz and 3 kHz.
Table 18.3 Power frequency (50 and 60 Hz) limits compared.
Chapter 20: Epidemiological Studies of Low-Intensity ELF Fields and Diseases in Humans
Table 20.1 Pooled analyses of studies of residential magnetic fields and childhood leukemia.
Table 20.2 Case–control study of childhood leukemia and magnetic fields Linet et al. (1997).
Chapter 21: Possible Low-Level Extremely Low-Frequency (ELF) Electric and Magnetic Field Effects?
Table 21.1 Reviews of studies of ELF-EMFs on biological systems, including those at low levels of exposure.
Chapter 22: Static Electric and Magnetic Field Hazards
Table 22.1 Different sources of static magnetic fields and their corresponding magnetic flux densities.
Chapter 23: Static Electric and Magnetic Field Guidelines
Table 23.1 Different static electric field guidelines.
Table 23.2 Different static magnetic field guidelines.
Chapter 24: Perceived Hypersensitivity: Anecdotal Versus Objective Evidence
Table 24.1 Estimated prevalence rates of IEI-EMF.
Chapter 26: Radiofrequency Fields and the Precautionary Principle
Table 26.1 Guidelines for application of the precautionary principle.
a
Chapter 28: Medical Aspects of Overexposures to Nonionizing Radiation
Table 28.1 Considerations of components of the NIR spectrum.
Chapter 31: Mitigating Nonionizing Radiation Risks
Table 31.1 Capacitance values of typical objects.
Table 31.2 Locations of potential discharges.
Table 31.3 Conductor height, electric field, and impacts.
Chapter 33: Summary and Prospects
Table 33.1 Key differences between Ionizing and forms of Nonionizing Radiation.
Table 33.2 Applicability of the 10 safety principles of ionizing radiation to NIR Radiation (ARPANSA 2014).
Non-ionizing Radiation Protection
Summary of Research and Policy Options
Edited by
Andrew W. Wood PhD
Swinburne University of Technology, Melbourne, Australia
Ken Karipidis PhD
Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia
This edition first published 2017 © 2017 John Wiley & Sons, Inc.
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List of Contributors
Michael Bangay
Michael Bangay Consulting
Melbourne
Australia
Rodney J. Croft
University of Wollongong
Illawarra Health & Medical Research Institute
Wollongong
Australia
Anna Dalecki
University of Wollongong
Illawarra Health & Medical Research Institute
Wollongong
Australia
Michael Dolan
Australian Legal Practitioner
Melbourne
Australia
Thanh Dovan
SP AusNet
Melbourne
Australia
Mark Elwood
Epidemiology and Biostatistics
University of Auckland
School of Population Health
Auckland
New Zealand
Paul Flanagan
Aurecon
Neutral Bay
Australia
Kenneth R. Foster
Department of Bioengineering
University of Pennsylvania
Philadelphia
Pennsylvania
USA
Peter Gies
Australian Radiation Protection and Nuclear Safety Agency
Melbourne
Australia
Sue Heward
SunSmart
Cancer Council Victoria
Melbourne
Australia
Bruce Hocking
Specialist in Occupational Medicine
Camberwell
Victoria
Australia
Steve Iskra
Department of Health and Medical Sciences
Faculty of Health, Arts and Design
Swinburne University of Technology
Hawthorn
Victoria
Australia
Telstra Corporation
Melbourne
Australia
John Javorniczky
Australian Radiation Protection and Nuclear Safety Agency
Melbourne
Australia
Ken Karipidis
Australian Radiation Protection and Nuclear Safety Agency
Melbourne
Australia
Sarah P. Loughran
University of Wollongong
Illawarra Health & Medical Research Institute
Wollongong
Australia
Claire Lyngå
Australian Radiation Protection and Nuclear Safety Agency
Melbourne
Australia
Robert L. McIntosh
Department of Health and Medical Sciences
Faculty of Health, Arts and Design
Swinburne University of Technology
Hawthorn
Victoria
Australia
Telstra Corporation
Melbourne
Australia
Ray McKenzie
Faculty of Health, Arts and Design
Swinburne University of Technology
Hawthorn
Victoria
Australia
Garry Melik
Magshield Products (Aust.) International
Melbourne
Australia
Stephen Newbery
Radiation Protection Unit
Department of Health and Human Services
Hobart
Australia
Kevin Nuttall
Energex Limited
Newstead
Queensland
Australia
Colin Roy
Australian Radiation Protection and Nuclear Safety Agency
Melbourne
Australia
Rick Tinker
Australian Radiation Protection and Nuclear Safety Agency
Melbourne
Australia
David Urban
Australian Radiation Protection and Nuclear Safety Agency
Melbourne
Australia
Adam Verrender
University of Wollongong
Illawarra Health & Medical Research Institute
Wollongong
Australia
Andrew Wood
Department of Health and Medical Sciences
Faculty of Health, Arts and Design
Swinburne University of Technology
Hawthorn
Victoria
Australia
Foreword
Nonionizing radiation, or NIR for short, is a type of radiation that is defined by what it does not, that is, it does not cause ionization of molecules. While this definition conveniently separates NIR from ionizing radiation emitted by radioactive substances, during fission and from certain equipment, it is somewhat unsatisfactory to use a negative definition and it is not even always correct (a certain part of the ultraviolet, UV, spectrum may cause ionization). Furthermore, it is not always radiation in a strict sense (e.g., static fields and ultrasound).
Just as we differentiate between different sources and types of ionizing radiation, we may be better off dealing with NIR on the basis of its specific characteristics, which is very different depending on which form of NIR we are considering. For example, radiofrequency radiation, microwaves, laser, and UV have their own very specific characteristics. This leads to different biological actions and responses and ultimately to different types of effects on the health of people and the environment. Understanding the nature of NIR, its biological actions, health effects, and associated risks is vital when deciding on the need for, and nature of, protective measures. Such protective measures also depend on whether the exposure category is the public, workers in their occupational setting, patients undergoing medical examination involving NIR, or the environment.
The real or potential health implications of NIR exposure for both people and environment is a legitimate concern for the community. Exposure to NIR is ubiquitous and exposure to certain forms of NIR has increased with the advent of technologies such as broadcasting and telecommunication. The ability to “opt out” of such exposures is sometimes limited; examples include outdoor work or other outdoor activities leading to UV exposure. The everyday environment in virtually all population centers and workplaces also involves exposure to radiofrequency radiation. At the same time, policymakers and the public in general need to take informed decisions to mitigate risks when they are evident and not invest resources in mitigation of risks that on the basis of current evidence are negligible. Unsubstantiated health concerns could itself cause symptoms of ill health and prevent the beneficial use of technologies involving NIR.
While health effects in both the short and long terms can be clearly attributed to certain forms of NIR exposure in what can be considered “normal” situations (exposure to UV radiation outdoors is one example), there are contrasting views in society as regards the health implications of everyday exposure to, for example, radiofrequency radiation, microwaves, and static fields. Decisions on limitation of exposure and precautionary approaches are often made under uncertainty; one major factor influencing the debate among the public as well as between specialists (whether these are in radiation science, risk communication, or ethics) is how uncertainty, or the “unknown,” should frame decisions on exposure limits and justification of technologies leading to exposure to NIR.
This volume explains and explores, based on scientific norms and methodologies, the characteristics of different forms of NIR, analyzes the relationship between exposure and biological effects and the associated dose–response relationships, and explores health effects and inferred and established health risks. It takes a holistic approach to the concept of “health,” building on the World Health Organization's definition of “health”: which is not only a state of absence of disease but includes also the physical, mental, and social well being of individuals and the population.
It finally addresses awareness, communication, and consultation, all of which are important factors in making it possible for any citizen to form an informed view and for society to take decisions based on the current state of knowledge – including uncertainties. This volume will assist in such judgments. I recommend it to everyone who wants to learn more about the different forms of NIR, the current knowledge on effects of NIR exposure on the health of people and the environment, and the evaluation and mitigation of risks associated with NIR in our everyday environments.
Carl-Magnus LarssonCEO of ARPANSA
Acknowledgments
We are indebted to the following people who read individual chapters and provided comments: Dr Alireza Lajevardipour and Lydiawati Tjong.
Introduction
This is a book about appropriate ways to protect people (and perhaps the environment) against harmful effects of nonionizing radiation (NIR). NIR includes forms such as ultraviolet, visible light, infrared, microwaves, radio waves, and the electric and magnetic fields associated with electric power lines, magnetic resonance imaging (MRI) machines, and other electromagnetic technologies. There are many books about ionizing radiation (IR) protection because the link between X-rays, subatomic particles, and gamma radiation and serious illness such as cancer or in the case of high dose/high-dose rate death within days has been known about for over a century. NIR has always been viewed as a benign form of radiation, with MRI and ultrasound preferred over X-ray, CT, and PET modalities of imaging. Some radiation protection practitioners have labeled NIR as “not interesting radiation” because it seems that there is nothing very much to talk about in terms of dangers to human health. And yet, in many countries, the radiation source that is responsible for the largest numbers of morbidity and mortality is a NIR source, namely the sun. In other areas, the public outcry over the siting of mobile (cell) phone towers, electric transmission lines, and the roll out of Wi-Fi and smart metering services indicates that in the minds of many, NIR is not benign and is a potent and widespread source of illness, particularly cancer. Many have gone as far as labeling these technologies as the new tobacco smoking or asbestos that are established carcinogens. In addition, a section of the community attribute their being unwell to exposure from NIR sources and some have moved away from urban settings and have sought to shield their homes from man-made NIR fields in an attempt to alleviate symptoms.
The public are in general much more aware of NIR in their environment (since much of modern technology is based on electric power and electronics) than IR, which is perceived to be encountered only in specialist hospital departments (or nuclear power plants). The ubiquity of certain types of NIR coupled with the steady stream of media articles about their possible dangers to health have made sections of the community distrustful of “authority” reassurances and perplexed as to why there seem to be such differing views among scientists. This has been amplified by a number of legal challenges to planning approvals and personal injury cases on health grounds, which have tended to pit scientific expert witnesses against each other. Rather than trying to explore through public engagement an appropriate way to deal with scientific uncertainty, government agencies have sometimes bowed to community pressure by introducing unrealistically low exposure limits, which are not science based, believing this to be a precautionary approach. The availability of cheap monitoring instruments has also contributed to media coverage, with activists contacting journalists, having made “do-it-yourself” NIR measurements (often incorrectly). The principle of “not in my backyard” (NIBY) has often been a potent factor in these debates, with possible health effects used as a weapon against the true concerns: negative visual impacts and property devaluation.
Allied to this has been the question of who to go to for unbiased information and advice. The industries involved are best placed to devote resources for producing public information material, but face a significant challenge to appear credible. This having been said, there are now a range of national and international brochures and web-based materials to provide information on the nature of particular forms of NIR, the rationale for standards, summaries of relevant scientific investigations, and possibly also ways to reduce personal exposure. These have been produced by government agencies as well as the industry organizations involved. The fact that they tend to give very similar advice indicates, in general, a willingness of industry to “tell it as it is.”
The source of research funds has also been raised as a possible reason for the disparity of conclusions of scientists, with frequent claims that those who accept research funding from industry are “tainted” and thus unreliable. However, it should be acknowledged that those who believe there to be an unrecognized problem with low-level NIR exposure are also prone to selectivity when quoting earlier scientific studies. The “quality” of individual studies does vary enormously but is very hard to quantify. International agencies have tended to use the “weight of evidence” approach, in which relevant peer-reviewed studies are identified by bibliographic searches and then the outcomes compared for consistency and coherence. Isolated findings that lack replication or confirmation by independent teams of investigators tend not to be given great weight in this approach. However, finding consensus is not always easy and uncertainties remain, particularly where underlying mechanisms have not been identified.
This is not to deny that at sufficiently high intensities of NIR the health effects are immediate and serious: intense beams of ultraviolet and laser light cause tissue burning; radiofrequency (RF) fields at high-power levels can also cause excessive heating and extremely low-frequency (ELF) electric and magnetic fields can induce currents sufficient to cause alteration or cessation of heart or breathing rhythm if high enough. NIR standards are formulated to give a high margin of protection against established effects.
This book attempts to summarize the scientific findings regarding the safety of NIR, the rationale behind prevailing standards, the appropriate instrumentation to monitor this radiation, and the options for handling the associated issues in terms of policy and public information. The first chapter is an overview of the nonionizing portion of the electromagnetic spectrum, to describe the features of the way this energy can be propagated with associated electric and magnetic fields. Some of the NIR spectrum is not strictly radiated and this distinction will be made in this chapter. The remainder of the book is divided into nine sections as follows:
Part I deals with generic issues of how to identify hazard, both by studies in the laboratory (short-term and long-term) and by studying relevant human populations, by the methods of epidemiology. It covers the strengths and weaknesses of the experimental method for determining thresholds above which harmful effects are possible in humans. Those who are already familiar with these methods can skip parts of these chapters.
Part II covers aspects of appropriate protection against ultraviolet (UV) light. The most common source of UV exposure to humans is from the sun, which is an unregulated source. The modification of human behavior is the chief way to limit exposure, which may include obligations in the part of employers or business owners to implement these modifications.
Part III considers the visible part of the spectrum and infrared. Again, the sun is a potent source or radiation in this region, but lasers probably represent the greatest potential hazard, because of their high intensity. As well as coherent sources (lasers) a number of incoherent sources such as high-powered light-emitting diodes (LEDs) require consideration for possible eye or skin damage.
Part IV looks at the RF part of the spectrum (which includes microwaves and terahertz (THz) radiation). Although the portions of the spectrum used in telecommunications, broadcasting, and radar represent the most fully studied, lower RFs, used in welding, smelting, and heat-sealing operations, also need consideration.
Part V covers the ELF portion of the spectrum, which includes the electric and magnetic fields associated with the generation, transmission, distribution, and domestic use of electric power at 50 or 60 Hz. Although the most common, ELF fields are also associated with transportation systems, certain forms of welding and smelting are also involved.
Part VI is about static electric and magnetic fields: the former associated with high-voltage direct current (DC) transmission systems and the latter mainly with MRI machines in hospitals. Static electric fields are also encountered in the atmosphere (especially before and during thunderstorms), and the Earth has a familiar magnetic field.
Part VII moves on to community issues: these are of two types, firstly the nature of perceived hypersensitivity to electric technologies and secondly the types of policy options aimed at making proactive changes or limitations ahead of clear scientific conclusion of hazard at commonly encountered levels of exposure, the so-called cautionary approach (or Precautionary Principle). A chapter deals with examples of how to decide on whether or not to spend money on certain mitigation measures, based on cost-benefit analyses.
Part VIII covers the question of how to avoid injury (by occupational training or public awareness programs) and in the event of suspected NIR injury, how a medical assessment could be carried out.
Part IX
