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Mobile and cordless telephones, serum transthyretin and the blood-cerebrospinal fluid barrier: a cross-sectional study

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Söderqvist F, Carlberg M, Hardell L · 2009

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The study reports sex-dependent associations between wireless telephone use patterns and serum transthyretin levels, though the authors characterize this as a hypothesis-generating descriptive study.

Plain English Summary

Summary written for general audiences

This cross-sectional study of 1,000 Swedish subjects examined whether long-term and short-term use of mobile and cordless telephones was associated with changes in serum transthyretin levels, a marker potentially reflecting effects on the blood-cerebrospinal fluid barrier. The study found sex-dependent associations: men showed higher serum transthyretin with longer use of analogue and combined mobile/cordless phones, but lower levels with UMTS phone use, while women showed higher levels with shorter time intervals after recent phone calls.

Why This Matters

Transthyretin is a blood protein that crosses the blood-brain barrier and carries thyroxine and retinol; changes in serum levels could theoretically indicate altered barrier function. The low response rate (31.4%) and multiple statistical comparisons across different phone types and user groups warrant caution in interpreting these findings.

Exposure Information

Specific exposure levels were not quantified in this study.

Cite This Study
Söderqvist F, Carlberg M, Hardell L (2009). Mobile and cordless telephones, serum transthyretin and the blood-cerebrospinal fluid barrier: a cross-sectional study.
Show BibTeX
@article{sderqvist_f_carlberg_m_hardell_l_ce3492,
  author = {Söderqvist F and Carlberg M and Hardell L},
  title = {Mobile and cordless telephones, serum transthyretin and the blood-cerebrospinal fluid barrier: a cross-sectional study},
  year = {2009},
  doi = {10.1016/j.scitotenv.2008.09.051},
  
}
DOI: 10.1016/j.scitotenv.2008.09.051PubMed: 19383125

Quick Questions About This Study

S100B is a protein that increases in blood when the blood-brain barrier is damaged. The blood-brain barrier protects your brain from toxins and harmful substances in your bloodstream, so elevated S100B levels could indicate this protective barrier is compromised.
The study found a weak negative association with cordless phone use, meaning users actually had slightly lower S100B levels. However, this finding wasn't statistically significant and the researchers noted it needs further investigation in larger studies.
Of 1,000 randomly selected Swedish adults contacted, only 314 participated by completing questionnaires and providing blood samples. Low response rates can introduce bias if participants differ systematically from non-participants in their phone use or health status.
Male UMTS (3G network) users showed a statistically significant association with S100B levels based on how recently they started using this technology. However, this finding involved only 31 men and requires confirmation in larger studies.
The study failed to find evidence of blood-brain barrier damage, but the researchers emphasized that larger studies with longer follow-up periods are needed. One biomarker study cannot definitively prove safety or harm for all potential health effects.