Auteurs

Hardell L, Söderqvist F, Carlberg M, Zetterberg H, Mild KH. (2010). Exposure to wireless phone emissions and serum beta-trace protein. Int J Mol Med. 26(2):301-6.

Introduction
The lipocalin type of prostaglandin D synthase (L-PGDS) or b-trace protein is the key enzyme in the synthesis of prostaglandin D2, a sleep-promoting neurohormone. Therefore, b-trace protein plays an important role in sleep regulation. It is synthesized in the central nervous system and secreted into the cerebrospinal fluid. b-trace protein is present in serum at much lower concentrations. The prevalence of sleep disturbances has increased in the Swedish population in the recent years, which may be explained by lifestyle and work-related factors. Results of several studies suggest that electromagnetic radiation from mobile phones may affect sleep.

Objective
In this connection, it was of interest to analyze b-trace protein in an experimental study with exposure to a GSM signal.

Methods
In the first part of the study, the temporal brain region of 40 volunteers (18-30 years of age) was exposed to a 890 MHz GSM signal at a specific absorption rate of 1.0 W/kg for 30 minutes. Blood was drawn for analysis of b-trace protein 10-15 minutes after arrival to the hospital, after 30 minutes rest, just before the mobile phone exposure, immediately after the exposure, and 60 minutes after the exposure. Serum was frozen for later analyses. Twenty-two volunteers (18-30-year old) were recruited separately, and their blood was drawn to analyze the stability of the protein in relation to time between the sampling and the freezing. Blood was drawn at the same time intervals as in the first group, but the subjects were not exposed to electromagnetic radiation, and two samples instead of one were taken on the first two occasions. One sample was handled in the same way as in the exposed subjects. The other was centrifuged and frozen immediately after the blood was drawn. All the 62 study participants answered the same questionnaire on mobile and cordless phone use and also on health and lifestyle factors.

Results
There was no significant effect of time between the sampling and the freezing on the level of b-trace protein. No significant difference in b-trace protein concentrations was observed between men and women. Its concentrations in the younger people were slightly higher. There was a significant decreasing trend in the level of b-trace protein with increasing number of years of mobile and cordless phone use. A similar (but not statistically significant) decreasing trend was observed for cumulative use in hours.

Interpretation
These results suggest that emissions from wireless phones affect the synthesis of b-trace protein. Findings from the experimental part of the study may be considered as providing support for the questionnaire study results. There was no significant change in the level of b-trace protein after the exposure to the GSM signal. In contrast, b-trace protein level increased significantly over time in the 22 subjects who were not exposed to the GSM signal, which may be related to “a relaxed situation”. However, the awareness of exposure may bias these results.

Conclusion

The results suggest that that electromagnetic radiation from mobile phones down-regulate the synthesis of b-trace protein, and this mechanism may play a role in sleep disturbances. However, caution is required in interpretation of the study findings because the use of wireless phones was self-reported and because, in the experimental study, the subjects were aware of the exposure.

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