Bell, I R, Szarek, M J, Dicenso, D R et al. · The International journal of neuroscience · 1999 · DOI
Some people experience discomfort or symptoms from exposure to low levels of chemicals and odors. This study measured brain electrical activity (EEG) in people with chemical intolerance before and after exposure to mild chemical odors across two sessions. Researchers found that people with chemical intolerance who had made major lifestyle changes showed different brain patterns than those who hadn't, suggesting the brain may become increasingly sensitive to these exposures over time.
Chemical intolerance is reported by many ME/CFS patients and may involve altered brain sensitization mechanisms. This study provides objective neurophysiological evidence supporting the biological basis of chemical sensitivity rather than purely psychological etiology, which validates the experiences of affected patients and may guide future therapeutic approaches targeting neural sensitization.
This study does not prove that chemical intolerance is primarily caused by neural sensitization, only that it correlates with specific EEG changes. The findings are limited to acute laboratory exposures and may not reflect real-world environmental exposure patterns. Additionally, the small sample and community recruitment strategy limit generalizability to the broader ME/CFS population.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Bell, I R, Szarek, M J, Dicenso, D R, Baldwin, C M, Schwartz, G E, & Bootzin, R R (1999). Patterns of waking EEG spectral power in chemically intolerant individuals during repeated chemical exposures.. The International journal of neuroscience. https://doi.org/10.3109/00207459908994302
BibTeX
@article{mecfsatlas-bell-1999-patterns-waking,
author = {Bell, I R and Szarek, M J and Dicenso, D R and Baldwin, C M and Schwartz, G E and Bootzin, R R},
title = {Patterns of waking EEG spectral power in chemically intolerant individuals during repeated chemical exposures.},
journal = {The International journal of neuroscience},
year = {1999},
doi = {10.3109/00207459908994302},
note = {PubMed: 10681117},
url = {https://www.mecfsatlas.com/evidence/bell-1999-patterns-waking},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/bell-1999-patterns-waking
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