safety aspects of rf radiation presentation by les barclay [email protected]
TRANSCRIPT
Independent Expert Group on Mobile Phones
• Chairman: Sir William Stewart
• Minister of Public Health asked NRPB to establish the group
• 12 Members
• With observers from DTI and DoH
• Secretariat from NRPB
Terms of Reference
• To consider concerns about the possible health effects from the use of mobile phones, base stations and transmitters
• To conduct rigorous assessment of existing research
• Make recommendations on further work to improve the basis for sound advice
Thermal Effects
• International Commission on Non-Ionizing Radiation Protection (ICNIRP)
• Identified behavioural changes i.e. a rise in whole body temperature in excess of 1°C at a Specific Energy Absorption Rate (SAR) of 1- 4w/kg
• No firm evidence that health would be impaired at lower levels of exposure.
Thermal Effects (cont.)
• The ICNIRP SAR levels are the basis for occupational exposure
• Guidelines for the general public recommend levels 5 times lower
ICNIRP basic restrictions on exposure on the frequency range 10MHz to 10GHz
TissueRegion
SAR LimitW/kg
AverageParameters
Occupational GeneralPublic
Mass(g)
Time(mins)
WholeBody
0.4 0.08 - 6
Head andTrunk
10 2 10 6
Limbs 20 4 10 6
ICNIRP Reference Levels for Public Exposure
Frequency Electric FieldStrength V/m
Magnetic FieldStrength A/m
Power DensityW/m2
1MHz –10MHz
87/f 1/2 0.73/f -
10MHz –400MHz
28 0.073 2
400MHz –2GHz
1.375f 1/2 0.0037f 1/2 F/200
2GHz –300GHz
61 0.16 10
Non -Thermal Effects
Considerable concern from the public, now faced with very many highly visible radio masts -
but with little visualisation or understanding
of radiowave propagation
Physical considerations
• Energy quanta of RF far below level needed to break chemical bonds in DNA
• Oscillation induced in ions too small to cause effects
Physical considerations (cont.)
• Resonant absorption by biological tissue doubtful
• Cell polarisation negligible
• Current flows across cell membranes negligible
Experimental studies
• Nervous system - changes in the brain or behavioural effects
• Cancer related studies - carcinogenic process
Effects of RF radiation on People
• Effects on the heart and blood pressure
• Brain Function– Studies of the cognitive performance – Electroencephalogram
Epidemiological Studies
• People using mobile phones– Mortality and cancer incidence– Other health effects
• Exposure to RF radiation through work and hobbies– Cancer– Health outcomes other than cancer
• Residence near transmitters
IEGMP Conclusions
• There is good evidence that exposure to mobile phones signals at intensities within existing ICNIRP guidelines has direct, short term effects on the electrical activity of the human brain and on cognitive function. These could have their origin in a variety of biological phenomena, for which there is some evidence from experiments on isolated cells and animals.
IEGMP Conclusions (cont.)
• There is an urgent need to establish whether these direct effects on the brain have consequences for health, because, if so, and if a threshold can be defined, exposure guidelines will have to be reconsidered. It is also important to determine whether these effects are caused by local elevation of temperature or by a ‘non thermal’ mechanism.
IEGMP Conclusions (cont.)
• The evidence currently available does not suggest that RF exposure causes cancer. This conclusion is compatible with the balance of biological evidence, which suggests that microwave fields below guideline levels do not cause mutation, or initiate or promote tumour formation. However…..
IEGMP Conclusions (cont.)
• mobile phones have not been in use long enough to allow comprehensive epidemiological assessment of their impact on health, and we cannot, at this stage, exclude the possibility of some association between mobile phone technology and cancer. In view of widespread concern about this issue, continued research is essential.
IEGMP Conclusions (cont.)
• Experimental studies on cells and animals do not suggest that mobile phone radiation below guideline levels has damaging effects on the heart, on blood, on the immune system or on reproduction and development. Moreover, even prolonged exposure does not appear to affect longevity.
Pulsed Modulation
• Continuing suggestions that amplitude modulation, or pulsed emissions have greater effects.
• Modulation frequencies up to 100 or 200Hz have been identified
• Implications for TDMA technologies
Selected IEGMP Recommendations
• Main Conclusions– Balance of evidence suggests exposure below
guidelines does not cause adverse health affects– However, evidence to suggest there may be
biological effects at exposures below guidelines– Therefore, not possible to say that exposure is
totally without potential health effects– Precautionary approach recommended
Selected IEGMP Recommendations (cont.)
• Advice to Government - Standards– That ICNIRP guidelines for public exposure be
adopted in the UK rather than NRPB guidelines– Not convinced of the need to incorporate the
ICNIRP guidelines in statutes– Register of occupationally exposed workers be
established and health effects monitored
Selected IEGMP Recommendations (cont.)
• Advice to Government - Exclusion Zones– Establishment of clearly defined exclusion
zones around base stations or cells, forming part of planning protocols
– The design of the logo should be taken forward by the BSI and implemented within 12 months
– Warning signs should be incorporated into microcell and picocell transmitters, indicating that they should not be opened when in use
Selected IEGMP Recommendations (cont.)
• Advice to Industry– International standard for the assessment of
SAR from mobile phones be adopted in the UK once demonstrated to be scientifically sound
– Information on the SAR for phones readily accessible to consumers at point of sale, on leaflets in stores, as menu option on phones, as a label on the phone and on a national website
Selected IEGMP Recommendations (cont.)
• In relation to Children
– If there are currently unrecognisable effects from the use of mobile phones, children may be more vulnerable because of their developing nervous system, the greater absorption of energy in the tissues of the head and a longer lifetime of exposure. Therefore...
Selected IEGMP Recommendations (cont.)
• The widespread use of mobile phones by children for non-essential calls should be discouraged
• The mobile phone industry should refrain from promoting the use of mobile phones by children
Implications for Wireless Home Area Networks
• Be precautionary and keep emissions to the minimum
• ICNIRP levels should be the guide
• Avoid TDMA
• Mark transmitters
• Give clear guidance for proper use