December 2011 EMF Science Update
The following is a quick summary of another twenty papers that have come out over the last few months related to effects of electromagnetic radiation. Some of the papers are notable papers that have been published very recently, others are papers that were published a few months ago that have not yet made it to one of the Science Updates.
1. P Kaufman DW et al, (November 2009) Risk factors for leukemia in Thailand, Ann Hematol. 2009 Nov;88(11):1079-88. Epub 2009 Mar 18 [View Comments and Links] [View on Pubmed]
A case-control study of adult-onset leukemia was conducted in Bangkok, Thailand to explore the contribution of cellular telephone use and other factors to the etiology of the disease; 180 cases (87 acute myeloblastic leukemia, 40 acute lymphoblastic leukemia, 44 chronic myelogenous leukemia, eight chronic lymphocytic leukemia, one unclassified acute leukemia) were compared with 756 age- and sex-matched hospital controls. Data were obtained by interview; odds ratios (ORs) were estimated by unconditional logistic regression. There was no clear association with cellular telephone phone use, but durations were relatively short (median 24-26 months), and there was a suggestion that risk may be increased for those with certain usage practices (ORs, 1.8-3.0 with lower confidence intervals >1.0) and those who used GSM service (OR, 2.1; 95% confidence interval, 1.1-4.0). Myeloid leukemia (acute and chronic combined) was associated with benzene (OR, 3.9; 95% confidence interval, 1.3-11), a nonspecific group of other solvents (2.3; 1.1-4.9), occupational pesticides that were mostly unspecified (3.8; 2.1-7.1), and working with or near powerlines (4.3; 1.3-15). No associations were found for diagnostic X-rays, cigarette smoking, or other occupational exposures.
2. - Cam ST et al, (June 2011) Occupational exposure to magnetic fields from transformer stations and electric enclosures in Turkey, Electromagn Biol Med. 2011 Jun;30(2):74-9 [View Comments and Links] [View on Pubmed]
We aimed to provide a systematic evaluation of magnetic field (MF) exposure of staff working in the offices located above or close to transformer stations (TS) and electric enclosures (EE). Occupational short-term "spot" measurements with Narda EFA-300 and isotropic magnetic field probe were carried out in two National Banks and one Industrial Company having more than 500 employees. Extremely low-frequency (ELF) MFs up to several tens of µT were measured in the mentioned working environments. 25% of the measured MFs were found less than 0.3 µT, the background exposure level that staff receive at home, 75% were above 0.3 µT with the highest value of 6.8 µT. The mean and median personal exposures were calculated to be 1.19 µT and 0.56 µT, respectively. Most of the staff (83%) is under risk based on epidemiological studies that reported a statistically significant association between risk of leukemia and averaged magnetic fields of 0.2 µT or over. Results showed that risk evaluation should be considered to minimize the possibility of the workers being harmed due to exposure to work-related electromagnetic sources.
3. P Ravera S et al, (June 2011) Extremely low-frequency electromagnetic fields affect lipid-linked Carbonic anhydrase, Electromagn Biol Med. 2011 Jun;30(2):67-73 [View Comments and Links] [View on Pubmed]
In the last years, the effect of extremely low-frequency electromagnetic fields (ELF-EMF) on the activity of different enzymes were investigated. Only the membrane-anchored enzymes did decrease their activity, up to 50%. In this work, the effect of ELF-EMF on bovine lung membrane carbonic anhydrase (CA) were studied. Carbonic anhydrases are a family of 14 zinc-containing isozymes catalyzing the reversible reaction: CO(2)+H(2)O = HCO(3)(- )+H(+). CA differ in catalytic activity and subcellular localization. CA IV, IX, XII, XIV, and XV are membrane bound. In particular, CA IV, which is expressed in the lung, is glycosyl phosphatidyl inositol-linked to the membrane, therefore it was a candidate to inhibition by ELF-EMF. Exposure to the membranes to a field of 75 Hz frequency and different amplitudes caused CA activity to a reproducible decrease in enzymatic activity by 17% with a threshold of about 0.74 mT. The decrease in enzymatic activity was independent of the time of permanence in the field and was completely reversible. When the source of enzyme was solubilized with Triton, the field lost its effect on CA enzymatic activity, suggesting a crucial role of the membrane, as well as of the particular linkage of the enzyme to it, in determining the conditions for CA inactivation. Results are discussed in terms of the possible physiologic effects of CA inhibition in target organs.
4. - van Rhoon GC et al, (2011) Health Council of The Netherlands: no need to change from SAR to time-temperature relation in electromagnetic fields exposure limits, Int J Hyperthermia. 2011;27(4):399-404 [View Comments and Links] [View on Pubmed]
The Health Council of the Netherlands (HCN) and other organisations hold the basic assumption that induced electric current and the generation and absorption of heat in biological material caused by radiofrequency electromagnetic fields are the only causal effects with possible adverse consequences for human health that have been scientifically established to date. Hence, the exposure guidelines for the 10 MHz-10 GHz frequency range are based on avoiding adverse effects of increased temperatures that may occur of the entire human body at a specific absorption rate (SAR) level above 4 W/kg. During the workshop on Thermal Aspects of Radio Frequency Exposure on 11-12 January 2010 in Gaithersburg, Maryland, USA, the question was raised whether there would be a practical advantage in shifting from expressing the exposure limits in SAR to expressing them in terms of a maximum allowable temperature increase. This would mean defining adverse time-temperature thresholds. In this paper, the HCN discusses the need for this, considering six points: consistency, applicability, quantification, causality, comprehensibility and acceptability. The HCN concludes that it seems unlikely that a change of dosimetric quantity will help us forward in the discussion on the scientific controversies regarding the existence or non-existence of non-thermal effects in humans following long duration, low intensity exposure to electromagnetic fields. Therefore, the HCN favours maintaining the current approach of basic restrictions and reference levels being expressed as SAR and in V/m or µT, respectively.
5. - Ziskin MC, Morrissey J, (2011) Thermal thresholds for teratogenicity, reproduction, and development, Int J Hyperthermia. 2011;27(4):374-87 [View Comments and Links] [View on Pubmed]
The human embryo and foetus may be especially vulnerable to chemical and physical insults during defined stages of development. In particular, the scheduled processes of cell proliferation, cell migration, cell differentiation, and apoptosis that occur at different times for different organ structures can be susceptible to elevated temperatures. With limited ability to regulate temperature on its own, the developing embryo and foetus is entirely dependent upon the mother's thermoregulatory capacity. As a general rule, maternal core body temperature increases of ~2°C above normal for extended periods of time, 2-2.5°C above normal for 0.5-1 h, or =4°C above normal for 15 min have resulted in developmental abnormalities in animal models. Significant differences in thermoregulation and thermoneutral ambient temperatures make direct extrapolation of animal data to humans challenging, and the above temperatures may or may not be reasonable threshold predictions for adverse developmental effects in humans. Corresponding specific absorption rate (SAR) values that would be necessary to cause such temperature elevations in a healthy adult female would be in the range of =15 W/kg (whole body average or WBA), with ~4 W/kg required to increase core temperature 1°C. However, smaller levels of thermal stress in the mother that are asymptomatic might theoretically result in increased shunting of blood volume to the periphery as a heat dissipation mechanism. This could conceivably result in altered placental and umbilical blood perfusion and reduce heat exchange with the foetus. It is difficult to predict the magnitude and threshold for such an effect, as many factors are involved in the thermoregulatory response. However, a very conservative estimate of 1.5 W/kg WBA (1/10th the threshold to protect against measurable temperature increases) would seem sufficient to protect against any significant reduction in blood flow to the embryo or foetus in the pregnant mother. This is more than three times above the current WBA limit for occupational exposure (0.4 W/kg) as outlined in both IEEE C95.1-2005 and ICNIRP-1998 international safety standards for radiofrequency (RF) exposures. With regard to local RF exposure directly to the embryo or foetus, significant absorption by the mother as well as heat dissipation due to conductive and convective exchange would offer significant protection. However, a theoretical 1-W/kg exposure averaged over the entire 28-day embryo, or averaged over a 1-g volume in the foetus, should not elevate temperature more than 0.2°C. Because of safety standards, exposures to the foetus this great would not be attainable with the usual RF sources. Foetal exposures to ultrasound are limited by the US Food and Drug Administration (FDA) to a maximum spatial peak temporal average intensity of 720 mW/cm(2). Routine ultrasound scanning typically occurs at lower values and temperature elevations are negligible. However, some higher power Doppler ultrasound devices under some conditions are capable of raising foetal temperature several degrees and their use in examinations of the foetus should be minimised.
6. N Roosli M, Hug K, (May 2011) Wireless communication fields and non-specific symptoms of ill health: a literature review, Wien Med Wochenschr. 2011 May;161(9-10):240-50 [View Comments and Links] [View on Pubmed]
This is an update of a previous systematic review on the association between radiofrequency electromagnetic field (RF-EMF) exposure and health-related quality of life that included studies published before August 2007. Since then, nine randomized trials addressed short-term exposures from close-to-body RF-EMF sources such as mobile phones, and two observational studies investigated the effects of mobile phone use on health-related quality of life. Six randomized trials addressed short-term far-field exposure arising, for instance, from mobile phone base stations, and eight studies evaluated the effects of environmental far-field RF-EMF exposure. In most of the randomized trials, no exposure-response association was observed. The sporadically reported associations did not show a consistent pattern regarding the type of symptoms or the direction of the effects (increase/decrease). Similarly, most of the recent observational studies did not show associations between RF-EMF exposure and non-specific symptoms. However, the exposure gradients were small and possible exposure misclassification is a limitation of these studies. Longitudinal studies as well as studies in children and adolescents are scarce. In summary, recent research did not indicate health-related quality of life to be affected by RF-EMF exposure in our everyday environment. Furthermore, none of the studies showed that individuals with self-reported electromagnetic hypersensitivity (EHS) were more susceptible to RF-EMF than the rest of the population. Nevertheless, the rapid technological development and anticipated increase in exposure levels warrant the conduct of further longitudinal studies. Due to the widespread use of wireless communication technologies potential adverse health effects would have major public health consequences.
7. - Bornkessel C, (May 2011) Assessment of exposure to mobile telecommunication electromagnetic fields, Wien Med Wochenschr. 2011 May;161(9-10):233-9 [View Comments and Links] [View on Pubmed]
Typical general public exposures around mobile radio service base stations consume only tiny fractions of exposure levels. Maximal immissions at maximal transmit power of base stations amount to several percent of power density reference levels; typical immission levels are about one tenth of a percent or even less. The distance to base stations is no reliable exposure classifier. More important are the orientation relative to the main lobe of the station and sight conditions from measurement point to the base station. Mobile phones cause higher exposures to the user than base stations. At maximal transmit power up to 80 percent of the basic restrictions are consumed. Therefore, actions to minimize exposure to mobile phones, e.g. by using a headset, have a larger potential than shielding against emissions from base stations. Both base stations and mobile phones apply power control mechanisms, capable to significantly reducing the transmit power and the associated exposure depending on the communication traffic. Present research investigates, whether children are more exposed to mobile telecommunication systems than adults.
8. N Wallace D et al, (January 2012) Cognitive and physiological responses in humans exposed to a TETRA base station signal in relation to perceived electromagnetic hypersensitivity, Bioelectromagnetics. 2012 Jan;33(1):23-39. doi: 10.1002/bem.20681. Epub 2011 Jun 6 [View Comments and Links] [View on Pubmed]
Terrestrial Trunked Radio (TETRA) technology ("Airwave") has led to public concern because of its potential interference with electrical activity in the brain. The present study is the first to examine whether acute exposure to a TETRA base station signal has an impact on cognitive functioning and physiological responses. Participants were exposed to a 420 MHz TETRA signal at a power flux density of 10 mW/m(2) as well as sham (no signal) under double-blind conditions. Fifty-one people who reported a perceived sensitivity to electromagnetic fields as well as 132 controls participated in a double-blind provocation study. Forty-eight sensitive and 132 control participants completed all three sessions. Measures of short-term memory, working memory, and attention were administered while physiological responses (blood volume pulse, heart rate, skin conductance) were monitored. After applying exclusion criteria based on task performance for each aforementioned cognitive measure, data were analyzed for 36, 43, and 48 sensitive participants for these respective tasks and, likewise, 107,125, and 129 controls. We observed no differences in cognitive performance between sham and TETRA exposure in either group; physiological response also did not differ between the exposure conditions. These findings are similar to previous double-blind studies with other mobile phone signals (900-2100 MHz), which could not establish any clear evidence that mobile phone signals affect health or cognitive function.
9. P Cardis E et al, (September 2011) Risk of brain tumours in relation to estimated RF dose from mobile phones: results from five Interphone countries, Occup Environ Med. 2011 Sep;68(9):631-40. Epub 2011 Jun 9 [View Comments and Links] [View on Pubmed]
The objective of this study was to examine the associations of brain tumours with radio frequency (RF) fields from mobile phones. Patients with brain tumour from the Australian, Canadian, French, Israeli and New Zealand components of the Interphone Study, whose tumours were localised by neuroradiologists, were analysed. Controls were matched on age, sex and region and allocated the 'tumour location' of their matched case. Analyses included 553 glioma and 676 meningioma cases and 1762 and 1911 controls, respectively. RF dose was estimated as total cumulative specific energy (TCSE; J/kg) absorbed at the tumour's estimated centre taking into account multiple RF exposure determinants. ORs with ever having been a regular mobile phone user were 0.93 (95% CI 0.73 to 1.18) for glioma and 0.80 (95% CI 0.66 to 0.96) for meningioma. ORs for glioma were below 1 in the first four quintiles of TCSE but above 1 in the highest quintile, 1.35 (95% CI 0.96 to 1.90). The OR increased with increasing TCSE 7+ years before diagnosis (p-trend 0.01; OR 1.91, 95% CI 1.05 to 3.47 in the highest quintile). A complementary analysis in which 44 glioma and 135 meningioma cases in the most exposed area of the brain were compared with gliomas and meningiomas located elsewhere in the brain showed increased ORs for tumours in the most exposed part of the brain in those with 10+ years of mobile phone use (OR 2.80, 95% CI 1.13 to 6.94 for glioma). Patterns for meningioma were similar, but ORs were lower, many below 1.0. There were suggestions of an increased risk of glioma in long-term mobile phone users with high RF exposure and of similar, but apparently much smaller, increases in meningioma risk. The uncertainty of these results requires that they be replicated before a causal interpretation can be made.
10. - Cardis E et al, (September 2011) Estimation of RF energy absorbed in the brain from mobile phones in the Interphone Study, Occup Environ Med. 2011 Sep;68(9):686-93. Epub 2011 Jun 9 [View Comments and Links] [View on Pubmed]
The objective of this study was to develop an estimate of a radio frequency (RF) dose as the amount of mobile phone RF energy absorbed at the location of a brain tumour, for use in the Interphone Epidemiological Study. We systematically evaluated and quantified all the main parameters thought to influence the amount of specific RF energy absorbed in the brain from mobile telephone use. For this, we identified the likely important determinants of RF specific energy absorption rate during protocol and questionnaire design, we collected information from study subjects, network operators and laboratories involved in specific energy absorption rate measurements and we studied potential modifiers of phone output through the use of software-modified phones. Data collected were analysed to assess the relative importance of the different factors, leading to the development of an algorithm to evaluate the total cumulative specific RF energy (in joules per kilogram), or dose, absorbed at a particular location in the brain. This algorithm was applied to Interphone Study subjects in five countries. The main determinants of total cumulative specific RF energy from mobile phones were communication system and frequency band, location in the brain and amount and duration of mobile phone use. Though there was substantial agreement between categorisation of subjects by cumulative specific RF energy and cumulative call time, misclassification was non-negligible, particularly at higher frequency bands. Factors such as adaptive power control (except in Code Division Multiple Access networks), discontinuous transmission and conditions of phone use were found to have a relatively minor influence on total cumulative specific RF energy. While amount and duration of use are important determinants of RF dose in the brain, their impact can be substantially modified by communication system, frequency band and location in the brain. It is important to take these into account in analyses of risk of brain tumours from RF exposure from mobile phones.
11. P Dominici L et al, (December 2011) Genotoxic hazard evaluation in welders occupationally exposed to extremely low-frequency magnetic fields (ELF-MF), Int J Hyg Environ Health. 2011 Dec;215(1):68-75. Epub 2011 Aug 20 [View Comments and Links] [View on Pubmed]
Electric arc welding is known to involve considerable exposure to extremely low-frequency magnetic fields (ELF-MF). A cytogenetic monitoring study was carried out in a group of welders to investigate the genotoxic risk of occupational exposure to ELF-MF. This study assessed individual occupational exposure to ELF-MF using a personal magnetic-field dosimeter, and the cytogenetic effects were examined by comparing micronuclei (MN) and sister chromatid exchange (SCE) frequencies in the lymphocytes of the exposed workers with those of non-exposed control subjects (blood donors) matched for age and smoking habit. Cytogenetic analyses were carried out on 21 workers enrolled from two different welding companies in Central Italy and compared to 21 controls. Some differences between the groups were observed on analysis of SCE and MN, whereas replication indices in the exposed were found not to differ from the controls. In particular, the exposed group showed a significantly higher frequency of MN (group mean ± SEM: 6.10 ± 0.39) compared to the control group (4.45 ± 0.30). Moreover, the increase in MN is associated with a proportional increase in ELF-MF exposure levels with a dose-response relationship. A significant decrease in SCE frequency was observed in exposed subjects (3.73 ± 0.21) compared to controls (4.89 ± 0.12). The hypothesis of a correlation between genotoxic assays and ELF-MF exposure value was partially supported, especially as regards MN assay. Since these results are derived from a small-scale pilot study, a larger scale study should be undertaken.
12. N Cardis E et al, (October 2011) Acoustic neuroma risk in relation to mobile telephone use: results of the INTERPHONE international case-control study, Cancer Epidemiol. 2011 Oct;35(5):453-64. Epub 2011 Aug 23 [View Comments and Links] [View on Pubmed]
A case-control study of 1105 patients with newly diagnosed acoustic neuroma (vestibular schwannoma) and 2145 controls was conducted in 13 countries using a common protocol. Past mobile phone use was assessed by personal interview. In the primary analysis, exposure time was censored at one year before the reference date (date of diagnosis for cases and date of diagnosis of the matched case for controls); analyses censoring exposure at five years before the reference date were also done to allow for a possible longer latent period. The odds ratio (OR) of acoustic neuroma with ever having been a regular mobile phone user was 0.85 (95% confidence interval 0.69-1.04). The OR for =10 years after first regular mobile phone use was 0.76 (0.52-1.11). There was no trend of increasing ORs with increasing cumulative call time or cumulative number of calls, with the lowest OR (0.48 (0.30-0.78)) observed in the 9th decile of cumulative call time. In the 10th decile (=1640 h) of cumulative call time, the OR was 1.32 (0.88-1.97); there were, however, implausible values of reported use in those with =1640 h of accumulated mobile phone use. With censoring at 5 years before the reference date the OR for =10 years after first regular mobile phone use was 0.83 (0.58-1.19) and for =1640 h of cumulative call time it was 2.79 (1.51-5.16), but again with no trend in the lower nine deciles and with the lowest OR in the 9th decile. In general, ORs were not greater in subjects who reported usual phone use on the same side of the head as their tumour than in those who reported it on the opposite side, but it was greater in those in the 10th decile of cumulative hours of use. There was no increase in risk of acoustic neuroma with ever regular use of a mobile phone or for users who began regular use 10 years or more before the reference date. Elevated odds ratios observed at the highest level of cumulative call time could be due to chance, reporting bias or a causal effect. As acoustic neuroma is usually a slowly growing tumour, the interval between introduction of mobile phones and occurrence of the tumour might have been too short to observe an effect, if there is one.
13. P Legros A et al, (September 2011) Neurophysiological and behavioral effects of a 60 Hz, 1,800 uT magnetic field in humans, Eur J Appl Physiol. 2011 Sep 6. [Epub ahead of print] [View Comments and Links] [View on Pubmed]
The effects of time-varying magnetic fields (MF) on humans have been actively investigated for the past three decades. One important unanswered question is the potential for MF exposure to have acute effects on human biology. Different strategies have been used to tackle this question using various physiological, neurophysiological and behavioral indicators. For example, researchers investigating electroencephalography (EEG) have reported that extremely low frequency (ELF, <300 Hz) MF can increase resting occipital alpha rhythm (8-12 Hz). Interestingly, other studies have demonstrated that human motricity can be modulated by ELF MF: a reduction of anteroposterior standing balance or a decrease of physiological tremor intensity have been reported as consequences of exposure. However, the main limitation in this domain lies in the lack of results replication, possibly originating from the large variety of experimental approaches employed. Therefore, the present study aimed to investigate the effects of a 60 Hz, 1,800 µT MF exposure on neurophysiological (EEG) and neuromotor (standing balance, voluntary motor function, and physiological tremor) aspects in humans using a single experimental procedure. Though results from this study suggest a reduction of human standing balance with MF exposure, as well as an increase of physiological tremor amplitude within the frequency range associated with central nervous system contribution, no exposure effect appeared on other investigated parameters (e.g., EEG or voluntary motor control). These results suggest that 1 h of 60 Hz, 1,800 µT MF exposure may modulate human involuntary motor control without being detected in the cortical electrical activity.
14. N Lee HJ et al, (September 2011) Combined effects of 60 Hz electromagnetic field exposure with various stress factors on cellular transformation in NIH3T3 cells, Bioelectromagnetics. 2011 Sep 6. doi: 10.1002/bem.20700. [Epub ahead of print] [View Comments and Links] [View on Pubmed]
Epidemiological studies have suggested that extremely low-frequency magnetic fields (ELF-MF) are associated with an increased incidence of cancer. Studies using in vitro systems have reported mixed results for the effects of ELF-MF alone, and the World Health Organization (WHO) Research Agenda published in 2007 suggested that high priority research should include an evaluation of the co-carcinogenic effects of ELF-MF exposure using in vitro models. Here, the carcinogenic potential of ELF-MF exposure alone and in combination with various stress factors was investigated in NIH3T3 mouse fibroblasts using an in vitro cellular transformation assay. NIH3T3 cells were exposed to a 60 Hz ELF-MF (1 mT) alone or in combination with ionizing radiation (IR), hydrogen peroxide (H(2) O(2) ), or c-Myc overexpression, and the resulting number of anchorage-independent colonies was counted. A 4 h exposure of NIH3T3 cells to ELF-MF alone produced no cell transformation. Moreover, ELF exposure did not influence the transformation activity of IR, H(2) O(2) , or activated c-Myc in our in vitro assay system, suggesting that 1 mT ELF-MF did not affect any additive or synergistic transformation activities in combination with stress factors such as IR, H(2) O(2) , or activated c-Myc in NIH3T3 cells.
15. P Kumar S et al, (2011) The therapeutic effect of a pulsed electromagnetic field on the reproductive patterns of male Wistar rats exposed to a 2.45-GHz microwave field, Clinics (Sao Paulo). 2011;66(7):1237-45 [View Comments and Links] [View on Pubmed]
Environmental exposure to man-made electromagnetic fields has been steadily increasing with the growing demand for electronic items that are operational at various frequencies. Testicular function is particularly susceptible to radiation emitted by electromagnetic fields. This study aimed to examine the therapeutic effects of a pulsed electromagnetic field (100 Hz) on the reproductive systems of male Wistar rats (70 days old). The experiments were divided into five groups: microwave sham, microwave exposure (2.45 GHz), pulsed electromagnetic field sham, pulsed electromagnetic field (100 Hz) exposure, and microwave/pulsed electromagnetic field exposure. The animals were exposed for 2 hours/day for 60 days. After exposure, the animals were sacrificed, their sperm was used for creatine and caspase assays, and their serum was used for melatonin and testosterone assays. The results showed significant increases in caspase and creatine kinase and significant decreases in testosterone and melatonin in the exposed groups. This finding emphasizes that reactive oxygen species (a potential inducer of cancer) are the primary cause of DNA damage. However, pulsed electromagnetic field exposure relieves the effect of microwave exposure by inducing Faraday currents. Electromagnetic fields are recognized as hazards that affect testicular function by generating reactive oxygen species and reduce the bioavailability of androgen to maturing spermatozoa. Thus, microwave exposure adversely affects male fertility, whereas pulsed electromagnetic field therapy is a non-invasive, simple technique that can be used as a scavenger agent to combat oxidative stress.
16. - Lagroye I et al, (December 2011) ELF magnetic fields: Animal studies, mechanisms of action, Prog Biophys Mol Biol. 2011 Dec;107(3):369-73. Epub 2011 Sep 8 [View Comments and Links] [View on Pubmed]
Animal studies can contribute to addressing the issue of possible greater health risk for children exposed to 50-60 Hz extremely low frequency (ELF) magnetic fields (MFs), mostly in terms of teratological effects and cancer. Teratology has been extensively studied in animals exposed to ELF MFs but experiments have not established adverse developmental effects. Childhood leukaemia has been the only cancer consistently reported in epidemiological studies as associated with exposure to ELF MFs. This association has been the basis for the classification as "possibly carcinogenic to humans" by the International Agency for Research on Cancer in 2002. Animal experiments have provided only limited support for these epidemiological findings. However, none but one study used an animal model for acute lymphoblastic leukaemia (ALL), the main form of childhood leukaemia, and exposures to ELF MFs were not carried out over the whole pregnancy period, when the first hit of ALL is assumed to occur. Moreover, there are no generally accepted biophysical mechanisms that could explain carcinogenic effects of low-level MFs. The radical pair mechanism and related cryptochromes (CRY) molecules have recently been identified in birds and other non-mammalian species, as a sensor of the geomagnetic field, involved in navigation. The hypothesis has to be tested in mammalian models. CRY, which is part of the molecular circadian clock machinery, is a ubiquitous protein likely to be involved in cancer cell growth and DNA repair. In summary, we now have some clues to test for a better characterization of the interaction between ALL and ELF MFs exposure.
17. N Aydin D et al, (August 2011) Mobile phone use and brain tumors in children and adolescents: a multicenter case-control study, J Natl Cancer Inst. 2011 Aug 17;103(16):1264-76. Epub 2011 Jul 27 [View Comments and Links] [View on Pubmed]
It has been hypothesized that children and adolescents might be more vulnerable to possible health effects from mobile phone exposure than adults. We investigated whether mobile phone use is associated with brain tumor risk among children and adolescents. CEFALO is a multicenter case-control study conducted in Denmark, Sweden, Norway, and Switzerland that includes all children and adolescents aged 7-19 years who were diagnosed with a brain tumor between 2004 and 2008. We conducted interviews, in person, with 352 case patients (participation rate: 83%) and 646 control subjects (participation rate: 71%) and their parents. Control subjects were randomly selected from population registries and matched by age, sex, and geographical region. We asked about mobile phone use and included mobile phone operator records when available. Odds ratios (ORs) for brain tumor risk and 95% confidence intervals (CIs) were calculated using conditional logistic regression models. Regular users of mobile phones were not statistically significantly more likely to have been diagnosed with brain tumors compared with nonusers (OR = 1.36; 95% CI = 0.92 to 2.02). Children who started to use mobile phones at least 5 years ago were not at increased risk compared with those who had never regularly used mobile phones (OR = 1.26, 95% CI = 0.70 to 2.28). In a subset of study participants for whom operator recorded data were available, brain tumor risk was related to the time elapsed since the mobile phone subscription was started but not to amount of use. No increased risk of brain tumors was observed for brain areas receiving the highest amount of exposure. The absence of an exposure-response relationship either in terms of the amount of mobile phone use or by localization of the brain tumor argues against a causal association.
18. N Reid A et al, (October 2011) Risk of childhood acute lymphoblastic leukaemia following parental occupational exposure to extremely low frequency electromagnetic fields, Br J Cancer. 2011 Oct 25;105(9):1409-13. doi: 10.1038/bjc.2011.365. Epub 2011 Sep 13 [View Comments and Links] [View on Pubmed]
Earlier studies have reported moderate increases in the risk of acute lymphoblastic leukaemia (ALL) among children whose mothers have been occupationally exposed to extremely low frequency (ELF) electromagnetic fields. Other studies examining parental occupational exposure to ELF and ALL have reported mixed results. In an Australian case-control study of ALL in children aged < 15 years, parents were asked about tasks they undertook in each job. Exposure variables were created for any occupational exposure before the birth of the child, in jobs 2 years before birth, in jobs 1 year before birth and up to 1 year after birth. In all, 379 case and 854 control mothers and 328 case and 748 control fathers completed an occupational history. Exposure to ELF in all time periods was similar in case and control mothers. There was no difference in exposure between case and control fathers. There was no association between maternal (odds ratio (OR)=0.96; 95% CI=0.74-1.25) or paternal (OR=0.78; 95% CI=0.56-1.09) exposure to ELF any time before the birth and risk of childhood ALL. We did not find an increased risk of ALL in offspring of parents with occupational exposure to ELF.
19. - Polzl C, (December 2011) EMF recommendations specific for children?, Prog Biophys Mol Biol. 2011 Dec;107(3):467-72. Epub 2011 Sep 28 [View Comments and Links] [View on Pubmed]
When discussing health risks for children due to electromagnetic fields it is crucial to translate scientific knowledge both into adequate protection and precautionary measures for the general public and, more particularly into specific recommendations for children. It is often aimed at influencing health-related attitudes and behaviour by means of information about health affecting behaviour, health risk factors, and health promoting possibilities. Children have to be treated differently from adults in addressing their ability and willingness to modify behaviour and their competence to comprehend cognitively the sense of behavioural recommendations. Research has shown that adults can be motivated to adjust their own behaviour in order to protect their children or to be role models for their children. Hence one way to modify children's behaviour is to address the parents and care persons. Generally education in the family, the social environment and in peer groups, nursery school and at school plays an important role in forming and influencing individual behaviour. The age of the target group has also to be taken into consideration. An important question is how to deal with scientific uncertainties when expressing EMF recommendations for children. Accentuating scientific uncertainties may under certain circumstances raise risk awareness. This can be an intended effect. But the expression of scientific uncertainties can also lead to unintended consequences in parent's behaviour or even senseless dealing with the respective EMF source. The paper points out relevant aspects of risk communication regarding EMF and children and suggests how recommendations for children might be designed.
20. N Colak C et al, (October 2011) Effects of electromagnetic radiation from 3G mobile phone on heart rate, blood pressure and ECG parameters in rats, Toxicol Ind Health. 2011 Oct 13. [Epub ahead of print] [View Comments and Links] [View on Pubmed]
Effects of electromagnetic energy radiated from mobile phones (MPs) on heart is one of the research interests. The current study was designed to investigate the effects of electromagnetic radiation (EMR) from third-generation (3G) MP on the heart rate (HR), blood pressure (BP) and ECG parameters and also to investigate whether exogenous melatonin can exert any protective effect on these parameters. In this study 36 rats were randomized and evenly categorized into 4 groups: group 1 (3G-EMR exposed); group 2 (3G-EMR exposed + melatonin); group 3 (control) and group 4 (control + melatonin). The rats in groups 1 and 2 were exposed to 3G-specific MP's EMR for 20 days (40 min/day; 20 min active (speech position) and 20 min passive (listening position)). Group 2 was also administered with melatonin for 20 days (5 mg/kg daily during the experimental period). ECG signals were recorded from cannulated carotid artery both before and after the experiment, and BP and HR were calculated on 1st, 3rd and 5th min of recordings. ECG signals were processed and statistically evaluated. In our experience, the obtained results did not show significant differences in the BP, HR and ECG parameters among the groups both before and after the experiment. Melatonin, also, did not exhibit any additional effects, neither beneficial nor hazardous, on the heart hemodynamics of rats. Therefore, the strategy (noncontact) of using a 3G MP could be the reason for ineffectiveness; and use of 3G MP, in this perspective, seems to be safer compared to the ones used in close contact with the head. However, further study is needed for standardization of such an assumption.
http://www.powerwatch.org.uk/news/20111213-science-update.asp
No comments:
Post a Comment