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| Derivation of Exposure Limits for RF/MW in China | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Comments by Roger Coghill, Coghill Research Laboratories, July 2003
I have not to date seen anywhere in the UK debative literature any consideration of the Chinese permitted exposure limits (PELs) or exposure limit values (ELVs) for EMFs, certainly neither by the Stewart Committee nor the NRPB, so I present here a brief review of their standards, and how they were derived. It should be recognised at the outset that China has a population of 1.3 billion people, is self sufficient in food, and seventh in world GNP ranking. Its high technology and increasingly diversified industrial base allows the country a 2.5 million standing army - over twice the size of US and Europe armed forces combined - , equipped with the most sophisticated ordnance, spending $7.5 billion annually on defence (albeit a fraction of the US spend), and capable of massive nuclear response. It is a significant arms exporter. This technical expertise and need to protect its workers and also its troops in battle scenarios will not have arisen without consideration for the effects of non-ionising exposure bioeffects, as well as the aggressive military use of EMFs in Electromagnetic Pulse (EMP) or crowd control. Its approach to environmental protection and population control is much more responsible and cautious than in the West. Accordingly any debate about RF/MW standards must take into account the Chinese expertise and conclusions about EMF exposure. It is totally wrong of the NRPB Con completely to ignore this evidence, and in the absence of corrective effort the lacuna needs addressing by a Question in the House, in my view. There are two regulatory bodies, the Chinese Public Health Ministry (CPHM) and the Chinese Environmental Protection Agency (CEPA). These used different exposure criteria. The former based its ELVs on thermal and non thermal considerations, while the CEPA based its standards on SAR. To cut to the chase, CPHM adopted a 20-fold safety factor reduction over the experimental threshold limit values (TLVs), and decided that 50microWatts/cm2 was the ELV for all microwaves, whereas for CEPA the limit for long medium and short waves is 5-25 Volts/metre and 10 microWatts/cm2 in areas where there is a requirement for absence of health hazard. The CEPA SAR limits are 0.1W/kg for occupational exposure (8 hr day, any 6 mins continuously), and 0.02W/kg for general public exposure. (All standards for general public exposure in China are one fifth of the occupational levels). The derivation of these standards goes back to the 1970s. The first ELVs for microwaves were issued in 1979 by the Chinese Ministry of 4th Machine Industry (CM4MI) as "temporary sanitary rules for workplace"., but these were extended and amended in 1989 by CMPH. CM4MI had carried out during 1975-77 a large cross sectional epidemiological study with a working group including Zhejiang Medical University, Beijing Jiuxian Qiao Hospital and another 15 epidemic preventive stations in factories and institutions. In this large study four groups were formed, 0, <50,<200, and > 200 microWatts/cm2. The results showed a higher prevalence of neurosis, bradycardia, ST-T level, delayed P and QRS intervals (all greater than 1 second) changes in electrocardiography (ECG) abnormal ECG, disorders of the nervous system, decreased white blood counts (WBC) - less than 5000/mm3, and blood platelets - less than 105/mm3. Vacuoles were noted in the lens of the two groups exposed to the higher radiation levels (a feature also reported in several western studies. e.g. by Milton Zaret ). Even the group exposed to less than 50 microWatts/cm2 also reported symptoms of increased neurosis compared with controls. Acute and subacute experiments were also performed on animals, establishing a TLV of 1mW/cm2. Allowing for a 20-fold safety factor the ELV was therefore set at 300 microWatts/cm2, that is 38microWatts/cm2 for an 8 hour working day. A similar epidemiologic study was carried out by CMPH. The amended ELV for microwaves was however set at 50 microwatts/cm2 for an 8 hour working day. Thus the ELVs were firmly based on at least two large scale human population health effects studies. By contrast the Western values were derived from a few small acute studies on rodents and small primates. It is obvious to any reasonable person the Chinese conclusions are far more realistically based. ELVs for ultra short waves (30-300MHz) were established by the Beijing Medical University, the Institute of Beijing Electronics Occupational Health (formerly Jiuxian Qiao Hospital) and the Epidemic Station in Pingliang Gansu province, using an approach similar to the microwave ELV. Higher prevalence of neurosis, trichiomadesis (premature loss of scalp hair), blurred vision, and some obvious changes in EEG recordings occurred among the exposed group. Animal experiments found that the thermal TLV in chronic exposures was 1.5mW/cm2, together with decreased body weight, elevation of rectal temperature by 0.5 degrees centigrade, and even (in one of the five test rabbits) atrophy of the testis. The exposure limits were set at 0.05mW/cm2 for continuous waves, and 0.025 mW/cm2 for pulsed waves. In 1986-1987 a further largescale epidemiological study was performed on 1170 students and children exposed to environmental EMFs (published in China in 1987, and reported in English as a brief communication (Chiang and Yao, 1989) in J Bioelectricity). We provided a copy of this information to the Stewart Committee as part of our submission but they ignored it, and it is not cited in the references of their May 2000 report, a disgraceful abdication of responsibility in our view, especially since one of its members, Colin Blakemore, actually worked in China and arguably should have been aware of these studies. Whether this constitutes criminal neglect is not for me to judge. In that study the results indicated that neutrophil phagocytosis was enhanced in subjects exposed to EMF very low intensities (4-11V/m) and reduced significantly in subjects exposed to relatively high intensities. In the latter group visual reaction time was prolonged and scores on a short term memory test were lower. The nub of all this is that the Chinese advise that "the maximum level of power density should not exceed 5 mW/cm2 at any duration of exposure" and "measures for personal protection should be taken when the exposure level exceeds 1mW/cm2". The average cellphone emits upto 20mW/cm2 at user distances. Get out of that, Lawrie Challis! Chen, chen. The tables below summarise the Chinese position. Table 1: Permitted ELVs for microwaves in the work environment in China
Table 2: Permitted ELVs for ultra short waves in work environment in China
Table 3: General public exposure limits (PELs) to RF/MW radiation in China Table 3. Arterial diseases
* there are no adverse health effects ** there is potential for adverse health effects Table 4: Standards for RF/MW exposure at work in China
SAR <0.1 W/kg for 8 hrs day, any 6 minutes continuously, for whole body Table 5: Standards for RF/MW exposure in general public environments
SAR <0.02W/kg for 24 hrs, any 6 minutes continuously, for whole body. The reason given for setting 50 microWatts/cm2 as a standard by CMPH is that abnormal ECG patterns occurred in subjects exposed to microwave radiation at 50-200 microWatts/cm2 in field conditions. A lower SAR (<0.4 W/kg) was adopted by CEPA taking into consideration non-thermal effects. The question is, if this great nation, (who in 1421 circumnavigated the globe seventy years before Columbus found a small part of the New World) has decided to recognise non thermal effects, why should not the less well-informed Western civilisation also recognise them? Or must we, like Columbus, wait another seventy years before enlightenment? |
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