Health Time

Exposure to a continuous TETRA-like signal may lead to fatigue and trouble concentrating.

PMID:

Occup Environ Med. 2011 May ;68(5):339-44. Epub 2010 Sep 23. PMID: 20864469

Abstract Title:

Can exposure to a terrestrial trunked radio (TETRA)-like signal cause symptoms? A randomised double-blind provocation study.

Abstract:

OBJECTIVES: Concerns have been raised about possible health effects from radiofrequency fields pulsing at around 16 Hz. A radio system used by UK police (TETRA) employs signals which pulse at 17.6 Hz. We tested whether exposure to a continuous wave signal at 385.25 MHz or a TETRA-like signal resulted in symptoms among users reporting sensitivity to TETRA compared to users not reporting sensitivity to TETRA.METHODS: 60 sensitive and 60 non-sensitive users were exposed to three 50 min conditions: a signal with a 16 Hz component, a continuous wave condition and a sham condition. The mean radiated power for the 16 Hz and continuous wave conditions was 250 mW. The order of conditions was randomised and testing was conducted double-blind. Participants reported the severity of eight symptoms during and after each exposure, their mood state at the end of each exposure, and whether they could tell which sessions involved active signals. The study was registered in advance with the ISRCTN register.RESULTS: Exposure to the continuous wave signal increased ratings of headache in all participants, fatigue in non-sensitive participants and difficulty concentrating in sensitive participants. Paradoxically, it reduced sensations of itching in sensitive participants. These effects were not observed in the condition with 16 Hz pulsing, except for those relating to concentration. Adjusting for multiple comparisons removed most significant effects, but not those relating to itch.CONCLUSIONS: The results suggested that exposure to TETRA signals is not responsible for symptoms reported by some users, although exposure to a continuous wave signal may affect symptoms. Clinical trial number ISRCTN 73321766.

Of the 59 studies examined in this review, industry funded studies were less likely to report a statistically significant association between mobile phone use and negative health effects.

PMID:

Environ Health Perspect. 2007 Jan ;115(1):1-4. PMID: 17366811

Abstract Title:

Source of funding and results of studies of health effects of mobile phone use: systematic review of experimental studies.

Abstract:

OBJECTIVES: There is concern regarding the possible health effects of cellular telephone use. We examined whether the source of funding of studies of the effects of low-level radiofrequency radiation is associated with the results of studies. We conducted a systematic review of studies of controlled exposure to radiofrequency radiation with health-related outcomes (electroencephalogram, cognitive or cardiovascular function, hormone levels, symptoms, and subjective well-being).DATA SOURCES: We searched EMBASE, Medline, and a specialist database in February 2005 and scrutinized reference lists from relevant publications.DATA EXTRACTION: Data on the source of funding, study design, methodologic quality, and other study characteristics were extracted. The primary outcome was the reporting of at least one statistically significant association between the exposure and a health-related outcome. Data were analyzed using logistic regression models.DATA SYNTHESIS: Of 59 studies, 12 (20%) were funded exclusively by the telecommunications industry, 11 (19%) were funded by public agencies or charities, 14 (24%) had mixed funding (including industry), and in 22 (37%) the source of funding was not reported. Studies funded exclusively by industry reported the largest number of outcomes, but were least likely to report a statistically significant result: The odds ratio was 0.11 (95% confidence interval, 0.02-0.78), compared with studies funded by public agencies or charities. This finding was not materially altered in analyses adjusted for the number of outcomes reported, study quality, and other factors.CONCLUSIONS: The interpretation of results from studies of health effects of radiofrequency radiation should take sponsorship into account.

This study indicates that occupational exposure MRI emissions may be related to health complaints of nurses. There is also a possible dose-response relationship between the prevalence of health complaints and the strength of the MRI.

PMID:

Eur J Radiol. 2011 Nov ;80(2):510-3. Epub 2010 Oct 14. PMID: 20950976

Abstract Title:

Health complaints among nurses working near MRI scanners–a descriptive pilot study.

Abstract:

A questionnaire-based descriptive pilot study was conducted among all nurses routinely working with MRI in the Northern part of Sweden to provide an indication of the self-reported prevalence of health complaints related to working with MRI systems. Fifty-nine nurses (88% response rate), with on average 8 (±6) years experience with MRI scanning procedures, returned the questionnaire. In total, 9 nurses (15%) reported regularly experiencing at least one of the health complaints (1-5% for specific health complaints) attributed to arise or be aggravated by their presence in the MRI scanning room. Stratification of the results indicated that reporting of adverse symptoms was not related to the level of occupational workload/stress. However, reporting of health complaints was related to the strength of the magnet(s) the nurses worked with, with 57% of symptoms reported by those nurses working with the strongest systems (both 1.5 and 3T scanners in this population). Although this descriptive study did not include a control population and was based on self-reporting of health complaints, these data indicate that the prevalence of reported health complaints is not related to perceived work load or occupational stress, but does confirm data from other occupational sectors and indicates that the prevalence of adverse health complaints increases with the strength of the MRI system for nurses as well.

Extremely low frequency magnetic fields in cell culture incubators may contribute to the variability in results from in vitro studies and should be taken into consideration.

PMID:

Cell Biol Int. 2009 Jul ;33(7):755-7. Epub 2009 Apr 23. PMID: 19393752

Abstract Title:

Background ELF magnetic fields in incubators: a factor of importance in cell culture work.

Abstract:

Extremely low frequency (ELF) magnetic fields in cell culture incubators have been measured. Values of the order of tens of muT were found which is in sharp contrast to the values found in our normal environment (0.05-0.1microT). There are numerous examples of biological effects found after exposure to MF at these levels, such as changes in gene expression, blocked cell differentiation, inhibition of the effect of tamoxifen, effects on chick embryo development, etc. We therefore recommend that people working with cell culture incubators check for the background magnetic field and take this into account in performing their experiments, since this could be an unrecognised factor of importance contributing to the variability in the results from work with cell cultures.

Some scientists view data on the health effects of electromagnetic fields as strongly suggestive and argue that if the association is true, the ubiquity of exposure may be resulting in a marked underestimation of the actual risk.

PMID:

Mt Sinai J Med. 1995 Oct ;62(5):356-9. PMID: 7500965

Abstract Title:

Health risk implications of magnetic field exposures.

Abstract:

Magnetic field exposures pose serious questions to the public. The science is not sufficiently clear or consistent to result in a consensus. Some scientists view the data as strongly suggestive and argue that if the association is true, the ubiquity of exposure may be resulting in a marked underestimation of the actual risk. Others argue that the inconsistencies in the data and the specific limitations of the studies suggest that there is no association and no reason for concern. The state of the science is such that a definitive resolution is unlikely in the next few years. In light of this uncertainty, I believe that the most prudent course of action is the prevention or limitation of exposure where feasible at limited cost and inconvenience. Be it at home or at work, prevention of exposure is simply good public health practice.

This review analyzes potential bias in studies assessing risk of childhood leukemia associated with electromagnetic fields. The authors find that most data suggest that, if a bias exists, it is a bias towards the lack of association.

PMID:

Bioelectromagnetics. 2001 ;Suppl 5:S32-47. PMID: 11170116

Abstract Title:

The potential impact of bias in studies of residential exposure to magnetic fields and childhood leukemia.

Abstract:

Bias can have a major impact on the results of epidemiologic studies. In investigations of the possible association between residential exposure to magnetic fields and the occurrence of childhood leukemia, many have raised questions about selection bias, including participation bias and information bias. In this review, the data on these possible sources of bias are summarized and their likely impact is evaluated. Most data suggest that if a bias exists, it is a bias towards the lack of association between exposure to magnetic fields and childhood leukemia. In addition, given the wide variety of study populations and measurement protocols, it is unlikely that a single design flaw has resulted in consistent effects across all studies and can be the sole explanation for the reported associations.

This meta-analysis predicts that, If an association between electromagnetic fields and childhood leukemia exists, as many as 175-240 cases of childhood leukemia in the US may be due to magnetic field exposure.

PMID:

Bioelectromagnetics. 2001 ;Suppl 5:S86-104. PMID: 11170120

Abstract Title:

Residential EMF exposure and childhood leukemia: meta-analysis and population attributable risk.

Abstract:

The controversy over the possible association between magnetic field exposure and childhood leukemia has led several researchers to summarize the literature using meta-analysis. This paper reviews these previous meta-analyses and extends them by adding results from four studies published since the most recent analysis. The analyses include odds ratio calculations based on both dichotomous and continuous exposure models, heterogeneity analysis including subgroup summaries and meta-regression,"leave one out"influence analyses, and publication bias assessments. In addition, there is a review of some of the considerations of the exposure assessments used in the studies and their implications for cross-study comparisons. Finally, the results of the analyses using dichotomous and continuous exposure model are combined with national exposure data to estimate the population attributable risk of childhood leukemia among children in the US. If an association exists, as many as 175-240 cases of childhood leukemia in the US may be due to magnetic field exposure.

This review indicates that a causal relationship between electromagnetic fields and childhood leukemia cannot be dismissed due to a trend of a dose-response relationship is past exposure assessment studies.

PMID:

Am J Prev Med. 1995 Jul-Aug;11(4):263-70. PMID: 7495604

Abstract Title:

Do power frequency magnetic fields cause leukemia in children?

Abstract:

The possibility of a causal relationship between exposure to electromagnetic fields and childhood leukemia has been studied for more than 10 years. This review evaluates the epidemiologic findings relevant to a possible causal association between exposure to power frequency magnetic fields during childhood and leukemia. The nine published studies on this topic were analyzed, with a focus on the selection of subjects, assessment of exposure, and control of confounding. Consistency of a positive association and dose-response relationship are evident for assessment of past exposure: among the five recent studies, relative risk estimates vary from 1.5 to 2.7 for past exposure assessment, and a significant dose-response relation was found in three studies. These observations cannot be explained by misclassification of exposure or consistent selection bias, and a confounder effect could hardly explain such results. Even if there is no currently understood biological plausibility for such an association, its possible causal nature cannot be dismissed. The impact on public health of such a possible causal association is difficult to assess precisely but could be significant. Therefore, it might be prudent to consider interim preventive measures while we await results of further research.

This review concludes that hypersensitivity to environmental electric and magnetic fields is an unclear health problem whose nature has yet to be determined.

PMID:

Environ Health Perspect. 2002 Aug ;110 Suppl 4:613-8. PMID: 12194895

Abstract Title:

Hypersensitivity of human subjects to environmental electric and magnetic field exposure: a review of the literature.

Abstract:

Hypersensitivity to exposure to electric and magnetic fields (EMFs) has been reported for nearly 20 years; however, the literature on the subject is still very limited. Nearly all the literature published concerns a dermatological syndrome that consists of mainly subjective symptoms (itching, burning, dryness) and a few objective symptoms (redness, dryness) appearing after individuals begin working with video display units and decreasing during absence from work. Case-control studies as well as some good but limited double-blind trials have not found any clear relationship between this syndrome and exposure to EMFs. A"general syndrome"with more general symptoms has been rarely described but seems to have a worse prognosis. The symptoms often associated with skin disorders are mainly of neurasthenic type and can cover a lot of nonspecific symptoms present in other atypical syndromes such as multiple chemical sensitivity or chronic fatigue. Most of these symptoms are allegedly triggered by exposure to different sources of EMFs, but there have been no valid etiological studies published on this more general syndrome. It appears that the so-called hypersensitivity to environmental electric and magnetic fields is an unclear health problem whose nature has yet to be determined.

The population of individuals with the ability to differentiate personal exposure to electromagnetic fields is larger than reported by non-ionizing radiation governing bodies.

PMID:

Bioelectromagnetics. 2003 Sep ;24(6):387-94. PMID: 12929157

Abstract Title:

Electrosensibility and electromagnetic hypersensitivity.

Abstract:

Electromagnetic sensibility, the ability to perceive electric and electromagnetic exposure, and electromagnetic hypersensitivity (EHS), developing health symptoms due to exposure to environmental electromagnetic fields, need to be distinguished. Increased electrosensibility is a necessary, however, not a sufficient condition for electromagnetic hypersensitivity. At an extended sample of the general population of 708 adults, including 349 men and 359 women aged between 17 and 60 years, electrosensibility was investigated and characterized by perception threshold and its standard deviation. By analyzing the probability distributions of the perception threshold of electric 50 Hz currents, evidence could be found for the existence of a subgroup of people with significantly increased electrosensibility (hypersensibility) who as a group could be differentiated from the general population. The presented data show that the variation of the electrosensibility among the general population is significantly larger than has yet been estimated by nonionizing radiation protection bodies, but much smaller than claimed by hypersensitivity self-aid groups. These quantitative results should contribute to a less emotional discussion of this problem. The investigation method presented, is capable of exclusion diagnostics for persons suffering from the hypersensitivity syndrome.