Radiofrequency (RF) electrocutions are uncommon. A case of electrocution at 196 MHz is presented partly because there are no previous reports with frequencies as high as this, and partly to assist in safety standard setting. A 53-year-old technician received two brief exposures to both hands of 2A current at 196 MHz. He did not experience shock or burn. Progressively over the next days and months he developed joint pains in the hands, wrists and elbows, altered temperature and touch sensation and parasthesiae. Extensive investigation found no frank neurological abnormality, but there were changes in temperature perception in the palms and a difference in temperature between hands. His symptoms were partly alleviated with ultra-sound therapy, phenoxybenzamine and glyceryl trinitrate patches locally applied, but after several months he continues to have some symptoms. The biophysics and clinical aspects are discussed. It is postulated that there was mainly surface flow of current and the micro-vasculature was effected. Differences to 50 Hz electrocution are noted. Electrocution at 196 MHz, even in the absence of burns may cause long-term morbidity to which physicians should be alerted. Safety standards should consider protection from electrocution at these frequencies. (+info)
Interspecific variability in sensitivity to UV radiation and subsequent recovery in selected isolates of marine bacteria.
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The interspecific variability in the sensitivity of marine bacterial isolates to UV-B (295- to 320-nm) radiation and their ability to recover from previous UV-B stress were examined. Isolates originating from different microenvironments of the northern Adriatic Sea were transferred to aged seawater and exposed to artificial UV-B radiation for 4 h and subsequently to different radiation regimens excluding UV-B to determine the recovery from UV-B stress. Bacterial activity was assessed by thymidine and leucine incorporation measurements prior to and immediately after the exposure to UV-B and after the subsequent exposure to the different radiation regimens. Large interspecific differences among the 11 bacterial isolates were found in the sensitivity to UV-B, ranging from 21 to 92% inhibition of leucine incorporation compared to the bacterial activity measured in dark controls and from 14 to 84% for thymidine incorporation. Interspecific differences in the recovery from the UV stress were also large. An inverse relation was detectable between the ability to recover under dark conditions and the recovery under photosynthetic active radiation (400 to 700 nm). The observed large interspecific differences in the sensitivity to UV-B radiation and even more so in the subsequent recovery from UV-B stress are not related to the prevailing radiation conditions of the microhabitats from which the bacterial isolates originate. Based on our investigations on the 11 marine isolates, we conclude that there are large interspecific differences in the sensitivity to UV-B radiation and even larger differences in the mechanisms of recovery from previous UV stress. This might lead to UV-mediated shifts in the bacterioplankton community composition in marine surface waters. (+info)
Human brain activity during exposure to radiofrequency fields emitted by cellular phones.
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OBJECTIVES: The aim of this study was to explore the possible influence of radiofrequency (RF) radiation exposure on human brain function. METHODS: The electroencephalographic (EEG) activity of 19 volunteers was quantitatively analyzed. Ten of the subjects were men (28-48 years of age) and 9 were women (32-57 years of age). The sources of exposure were 5 different cellular phones (analogue and digital models) operating at a frequency of 900 MHz or 1800 MHz. The EEG activity was recorded in an awake, closed-eyes situation. Six 30-minute experiments, including 1 sham exposure, were made for each subject. The duration of a real exposure phase was 20 minutes. RESULTS: Exposure to one of the phones caused a statistically significant change in the absolute power at the delta band of the EEG recording. However, no difference was seen in the relative power of the same band, and no changes occurred during exposure to other phones at any frequency bands. CONCLUSIONS: The findings of this study suggest that exposure to radiofrequency fields emitted by cellular phones has no abnormal effects on human EEG activity. The observed difference in 1 parameter was probably caused by statistical chance. (+info)
The data sources which may help strengthen the epidemiological evidence for the hormonal hypothesis of sex determination in man.
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The hypothesis that parental hormone levels around the time of conception partially control offspring sex ratios-though here taken to be true in substance-will need a great deal of work to specify with any accuracy. We do not know with any certainty which hormones are involved, nor how they are implicated. Answers to these two questions are only likely to emerge after prolonged experimental work. And it is fair to say that that work has not yet started. I assume that experimental workers will not embark on such a project until it is perfectly clear that there is a watertight case that mammalian parental hormone levels somehow influence offspring sex ratios. The present note indicates where further (human) evidence for that case will be found. In regard to human beings, much of the required information is held by clinics and registries not primarily concerned with reproductive biology. This point is illustrated here in regard to toxicology, teratology, radiation medicine, neurology, psychiatry, oncology, dermatology, rheumatology, occupational medicine and sports medicine as well as obstetrics and gynaecology. Tests (based on the hypothesis) are offered for intrauterine endocrine causes of malformations, and for pre- and post-natal endocrine causes of disease. (+info)
Low-energy extracorporeal shock-wave treatment (ESWT) for tendinitis of the supraspinatus. A prospective, randomised study.
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We have performed a controlled, randomised study to analyse the effects of low-energy shock-wave therapy (ESWT) on function and pain in tendinitis of the supraspinatus without calcification. There were 20 patients in the treatment group and 20 in the control group. The former group received 6,000 impulses (energy flux density, 0.11 mJ/mm2) in three sessions after local anaesthesia. The control group had 6000 impulses of sham ESWT after local anaesthesia. The patients were examined at six and 12 weeks after treatment by an independent observer who evaluated the Constant score and level of pain. We found an increase in function and a reduction of pain in both groups (p < or = 0.001). Statistical analysis showed no difference between the groups for the Constant score and for pain. We therefore do not recommend ESWT for the treatment of tendinitis of supraspinatus. (+info)
Extremely low frequency electromagnetic fields (EMF) and brain cancer in adults and children: review and comment.
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Epidemiologic and experimental research on the potential carcinogenic effects of extremely low frequency electromagnetic fields (EMF) has now been conducted for over two decades. Cancer epidemiology studies in relation to EMF have focused primarily on brain cancer and leukemia, both from residential sources of exposure in children and adults and from occupational exposure in adult men. Because genotoxic effects of EMF have not been shown, most recent laboratory research has attempted to show biological effects that could be related to cancer promotion. In this report, we briefly review residential and occupational EMF studies on brain cancer. We also provide a general review of experimental studies as they relate both to the biological plausibility of an EMF-brain cancer relation and to the insufficiency of such research to help guide exposure assessment in epidemiologic studies. We conclude from our review that no recent research, either epidemiologic or experimental, has emerged to provide reasonable support for a causal role of EMF on brain cancer. (+info)
Safety assessment of near infrared light emitting diodes for diffuse optical measurements.
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BACKGROUND: Near infrared (NIR) light has been used widely to monitor important hemodynamic parameters in tissue non-invasively. Pulse oximetry, near infrared spectroscopy, and diffuse optical tomography are examples of such NIR light-based applications. These and other similar applications employ either lasers or light emitting diodes (LED) as the source of the NIR light. Although the hazards of laser sources have been addressed in regulations, the risk of LED sources in such applications is still unknown. METHODS: Temperature increase of the human skin caused by near infrared LED has been measured by means of in-vivo and in-vitro experiments. Effects of the conducted and radiated heat in the temperature increase have been analyzed separately. RESULTS: Elevations in skin temperature up to 10 degrees C have been observed. The effect of radiated heat due to NIR absorption is low--less than 0.5 degrees C--since emitted light power is comparable to the NIR part of sunlight. The conducted heat due to semiconductor junction of the LED can cause temperature increases up to 9 degrees C. It has been shown that adjusting operational parameters by amplitude modulating or time multiplexing the LED decreases the temperature increase of the skin significantly. CONCLUSION: In this study, we demonstrate that the major risk source of the LED in direct contact with skin is the conducted heat of the LED semiconductor junction, which may cause serious skin burns. Adjusting operational parameters by amplitude modulating or time multiplexing the LED can keep the LED within safe temperature ranges. (+info)
Magnetic field effects on pineal indoleamine metabolism and possible biological consequences.
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In recent years, there has been a great deal of publicity concerning the possible health effects of electric and/or magnetic field exposure. One of the most frequently reported observations after the exposure of animals to either electric or magnetic fields relates to alterations in the metabolism of serotonin (5HT) to melatonin within the pineal gland. This review summarizes these results particularly in animals exposed to intermittently inverted, non-time varying magnetic fields, i.e., pulsed static magnetic fields. When exposure occurs at night, the conversation of 5HT to melatonin is typically depressed, not unlike that after light exposure at night. The mechanisms by which pulsed magnetic fields alter the ability of the pineal to convert 5HT to the chief pineal hormone melatonin remains unknown but may involve effects on any or all of the following: the retinas, the suprachiasmatic nuclei, the peripheral sympathetic nervous system, and the pinealocytes. Results to date suggest that induced electrical currents (eddy currents) produced by the pulsed magnetic fields are particularly detrimental to pineal indoleamine metabolism and may be an important causative factor in the metabolic changes measured. The physiological consequences of perturbations in the melatonin rhythm induced by magnetic field exposure remain unknown. (+info)