February 2005

Three studies examine aspects of RFR exposure

Three recent studies, published in the journal "Radiation Protection Dosimetry", have examined various aspects of exposure to radiofrequency radiation (RFR).

The first, by Cooper and associates from the National Radiological Protection Board in the UK, describes the use of a personal monitor by individuals who are occupationally exposed to RFR. The authors developed a data logger that could be attached to the monitor by a fibre-optic cable. The workers could wear the monitor and logger in their daily tasks. The authors say that the instruments could be useful in epidemiological studies, but point out that logging personal monitors, with sensors and logger combined in a single compact unit, have recently become commercially available.

Adda and colleagues from Torino in Italy, validated a ray-tracing model for electromagnetic field calculation, to predict irradiation from base stations in urban environments. They found that the ray-tracing model calculates electric fields with good accuracy.

The third paper, also from Italy, used special phones that had been modified to allow the continuous logging of power emitted during calls. In this way Ardoino and colleagues were able to determine the average power emitted by the phones in different conditions of use. They could also measure the distribution of power levels over prolonged periods of normal use of phones.

Cooper TG, Allen SG, Blackwell RP, Litchfield I, et al. Assessment of occupational exposure to radiofrequency fields and radiation. Radiat Prot Dosim 2004;111:191-203.

Adda S, Anglesio L, d'Amore G, Mantovan M, et al. Ray-tracing techniques to assess the electromagnetic field radiated by base stations: application and experimental validation in an urban environment. Radiat Prot Dosim 2004;111:339-342.

Ardoino L, Barbieri E, Vecchia P. Determinants of exposure to electromagnetic fields from mobile phones. Radiat Prot Dosim 2004;111:403-406.

RF exposure does not alter melatonin output in rats

Several laboratory studies have shown no effect of radiofrequency radiation on melatonin excretion by animals. A new study from Japan adds to the list. Rats subjected to 4 hours of RFR at 1439 MHz (SAR to the brain of 7.5 W/kg, about four times as much as that from cell phones) did not alter their secretion of melatonin. Melatonin has excited interest because some authorities believe that it plays a role in cancer prevention. The authors of the study emphasize the need for studies of longer exposure.

For more, see "Research- Toxicological Experiments - Others - Hormones".

Reference: Hata K, Yamaguchi Y, Tsurita G, Watanabe S, et al. Short term exposure to 1439 MHz pulsed TDMA field does not alter melatonin synthesis in rats. Bioelectromagnetics 2005;26:49-53.

No effect of long-term EMF exposure on development of rat brain tumours

There have been 3 studies of the effect of exposure to electromagnetic fields (EMF) on rats that have been exposed also to N-ethylnitrosurea (ENU), which promotes the development of brain tumours. Another study has now been published, and, like the others, showed no increase in the incidence of brain tumours in rats exposed to EMF, compared with those sham-exposed. The rats were exposed to EMF at 1.439 GHz frequency for about 2 years, at SAR of 0.67 W/kg in one group and 2.0 W/kg in another.

For more, see "Research - Toxicological experiments - cancer studies - tumour growth and development".

Reference: Shirai T, Kawabe M, Ichihara T, Fujiwara O, et al. Chronic exposure to 1.439 GHz electromagnetic field used for cellular phones does not promote N-ethylnitrosourea induced central nervous system tumors in F344 rats. Bioelectromagnetics 2005;26:59-68.

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