Chemosensory perception, symptoms and autonomic responses during chemical exposure in multiple chemical sensitivity
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Multiple chemical sensitivity (MCS) is a prevalent medically unexplained symptom characterized by symptom reactions to everyday chemical exposure below hygienic thresholds. The aim of this study was to investigate the expressions of hyper-reactivity in MCS during whole-body exposure to low concentrations of the odorant n-butanol.
We exposed 18 participants with MCS and 18 non-ill controls to a low concentration of the odorant n-butanol using an exposure chamber. The first 10 min constituted blank exposure, after which the n-butanol concentration increased and reached a plateau at 11.5 mg/m3.
MCS participants, compared with controls, reported greater perceived odor intensities, more unpleasantness to the exposure and increasing symptoms over time. MCS participants also expressed higher pulse rate and lower pulse rate variability than controls did. No group differences were found for breathing rate or tonic electrodermal activity responses.
We conclude that MCS sufferers differ from healthy controls in terms of autonomic responses, symptoms and chemosensory perception during chemical exposure.
KeywordsMultiple chemical sensitivity Chemical intolerance Environmental intolerance Olfaction Autonomic nervous system
This study was supported by grants from the Swedish Research Council for Health, Working Life and Welfare (2011-0396), the Danish Ministry of the Environment, the Swedish Research Council Formas (2010-1401) and the Swedish Foundation for Humanities and Social Sciences (M14-0375:1).
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards and approved by the Ethics Committee at Umeå University (Dnr 2013-19-31). Informed consent was obtained from all individual participants included in the study. All participants were given written and oral information about the study. All participants were given 500 SEK (~50 EUR) for their participation.
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