Background: There are studies suggesting effects on sleep from pulse-modulated radiofrequency fields used in mobile and cordless phones. So far, reports of adverse effects in observational studies are of limited value for risk assessment while effects from experimental studies seem to be more consistent but unclear as to their importance for health. The aim of this study was to investigate whether use of wireless phones is associated with lower concentrations of β-trace protein (lipocalin-type prostaglandin D synthase), a key enzyme in the synthesis of prostaglandin D(2), an endogenous sleep-promoting neurohormone.
Methods: Three hundred and fourteen people, aged 18-65 years and living in the municipality of Örebro, Sweden, were recruited randomly using the population registry. Total and age-specific linear regression analyses adjusted for known covariates were used to calculate associations between levels of β-trace protein and short- and long-term use of wireless phones.
Results: Overall, no statistically significant association between use of wireless phones and the serum concentration of β-trace protein was found, neither with respect to short-term nor long-term use. Age-specific analyses, however, yielded negative associations for long-term use (cumulative hours of use) and β-trace protein in the youngest age group (18-30 years).
Conclusion: This study provided no overall evidence of an association between wireless phone use and serum concentrations of β-trace protein. While the findings in the 18-30 year age group indicating lower concentrations with more cumulative hours of use should be further investigated, no causal inferences can be made from the results of the present study.