Prevalence data
There is no official prevalence data for diagnosed cases, but self-reported chemical sensitivity is quite common. A 2019 study by Anne Steinemann found 16.3% of people in the UK reported chemical sensitivity, with 27.8% sensitive to fragranced products. Another survey across four countries found 19.9% reported chemical sensitivity, though only 7.4% had a formal MCS diagnosis.
Early Immune System Research in Multiple Chemical Sensitivity (MCS)
Taskforce update, November 2025
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A historical overview of early immune research in MCS (not as current clinical guidance).
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Emphasise that these findings were exploratory, decades old, and not widely adopted in mainstream medicine.
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Acknowledge that no recent research was found to confirm or refute these older findings.