Multiple Chemical Sensitivity: Catching up to what kind of science?

Abstract

The recent review of Molot et al. (2023) appropriately emphasizes Multiple Chemical Sensitivity (MCS) as a growing health issue and the necessity of dedicated healthcare and medical education. The authors explain MCS mainly as the result of the sensitization of transient receptor potential (TRP) receptors, notably TRPV1 and TRPA1, and oppose this explanation to psychological processes as a causal explanation. We argue that: 1. critical evidence from double-blind exposure studies showing patients’ inability to discriminate between actual and sham exposure questions this claim; 2. the interpretation of the role of TRP-receptors fails to appreciate the importance of chemicals as stressors for MCS patients and may confound cause and effect; 3. the evidence supporting a causal role of psychological processes is largely neglected; 4. the opposition between biological and psychological causes is not helpful in trying to understand MCS. Most importantly, treatment suggestions based only on the hypothetical role of TRP-receptors may aggravate the burden of MCS on both patients and society.