Health symptoms and potential effects on the blood-brain and blood-cerebrospinal fluid barriers associated with use of wireless telephones

Abstract: Recent years have seen a rapid increase in the use of wireless telephones, yet little systematic data exist on the actual use of such devices in the general population. Mobile and cordless telephones emit radiofrequency fields (RF) raising concern about possible adverse health effects. As children and teenagers might be more vulnerable and have longer expected lifetime exposures to RF from these devices than adults, who started to use them later in life, they are a group of special concern. The aims of papers I and II in this thesis were to increase our knowledge of use of wireless telephones in the age group of 7-19 years, to study what factors could explain such use; and furthermore, whether the use among the 15-19 year group was associated with self-reported health symptoms and well-being. For collection of data a posted questionnaire was used. Among the 7-14 group (n=1423) nearly all had access to a mobile telephone, a cordless telephone or both, although the percentage of regular users was rather low, totally. Use of wireless telephones increased with age and was more common among girls than boys, especially among the 15-19 year group (n=1269). Relatively few regular users of mobile telephones reported to use a handsfree. Besides age and gender the probability of using either a mobile or cordless telephone was associated mainly with watching TV extensively and below average household income. Regular users more often had health symptoms and reported poorer perceived health than did non-regular users. However, the latter should be interpreted with caution since bias and chance findings due to multiple testing might have influenced the results. Methodologically more sophisticated studies are needed to confirm these results and also investigate directions of possible associations. The aim of papers III-V was to investigate the potential effects of wireless telephone emissions on the integrity of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) using biomarkers. In paper III – an observational study on adults (n=314) – use of mobile and cordless telephones combined was not associated with serum levels of S100B as a marker of BBB disruption. Analyzing the different telephone types separately yielded a weak association of decreasing concentrations with minutes since last use of cordless telephone on the day of leaving blood and a statistically significant association of higher concentrations the more years since first use of a 3G-telephone. However, the latter is probably a result of chance or confounding. Paper IV comprised the same data set as in paper III using serum transthyretin (TTR) as a marker of BCSFB dysfunction. The main finding was that the number of years since first use of mobile and cordless telephones combined was statistically significantly associated with higher serum levels of TTR regardless of how much each telephone type had been used. However, extra-cerebral sources of TTR might have confounded the results, if associated with exposure. Paper V was an experimental study investigating a possible short-term effect of an 890-megahertz mobile phone-like exposure on the BBB and the BCSFB of 41 volunteers. Repeated blood sampling before and after the provocation showed no statistically significant increase in the serum levels of S100B, while for TTR a small but statistically significant increase was seen in the final blood sample 60 minutes after the end of the provocation as compared to the prior sample taken immediately after provocation. The possible clinical significance of this finding is unknown. Larger randomized studies that employ use of additional more brain-specific markers and multiple exposure conditions are needed.