Physiologic and Symptomatic Responses to Low-Level Substances in Individuals with and without Chemical Sensitivities: A Randomized Controlled Blinded Pilot Booth Study

Abstract

We conducted a pilot study using a randomized, single-blind, placebo-controlled exposure among 10 individuals with and 7 without reported chemical sensitivities in a dedicated testing chamber. Objectives of the study were to explore the length of the adaptation period to obtain stable readings, evaluate responses to different substances, and measure the level and type of symptomatic and physiologic reactions to low-level exposures. Reported and observed symptoms, electrodermal response, heart rate, skin temperature, surface electromyogram, respiratory rate, contrast sensitivity, and the Brown-Peterson cognitive test were used and compared between cases and controls and between test substances (glue, body wash solution, dryer sheet) and control substances (unscented shampoo and clean air). Subjects with chemical sensitivities (cases) took longer to adapt to baseline protocols than did controls. After adaptation, despite small study numbers, cases displayed statistically significant responses (all measures, p < 0.02) in tonic electrodermal response to test substances compared with controls and compared with the control substance. Symptoms were also higher in cases than in controls for the body wash solution (p = 0.05) and dryer sheets (p = 0.02). Test–retest showed good agreement for both symptoms and tonic electrodermal responses (McNemar’s test, p = 0.32 and p = 0.33, respectively). Outside of skin conductance, other measures had no consistent patterns between test and control substances and between cases and controls. This study shows the importance of using an adaptation period in testing individuals with reported chemical sensitivities and, despite small numbers, raises questions about underlying mechanisms and level of reactivity to low-level chemical exposures in sensitive individuals.

Multiple chemical sensitivities: A systematic review of provocation studies

“…20 Studies were categorized by the quality of blinding used: double-or single-blind studies that also included an odorous masking agent to prevent identification of the stimuli (Table I), [21][22][23][24][25][26] double-blind studies without masking (Table II), 11,12,[15][16][17][18][19][27][28][29][30][31][32] single-blind studies without masking (Table III), 13,14,[33][34][35][36][37][38][39][40][41][42][43][44] and open-label studies or studies with unclear blinding (see Table E1 in the Online Repository at www.jacionline.org). 10,[45][46][47] Studies using olfactory masking agents or nose clips Three studies testing 70 chemically sensitive participants incorporated blinding and an olfactory mask and failed to show any significant effects on subjects with MCS after provocation with chemicals.…”

“…[24][25][26] None of these studies used olfactory masking agents. Participants in these studies showed some response to active provocations, and the authors suggested that participants might have perceived provocations through the eyes.…”

The feasibility of aromatherapy massage to reduce symptoms of Idiopathic Environmental Intolerance: A pilot study

“…Perfume is one of the primary trigger substances for provoking IEI symptoms; therefore, it was unclear whether IEI patients could tolerate an aromatherapy intervention. In addition, IEI patients report a variety of symptoms [6][7][8][9][10][11] , thus for the pilot study, we chose a non-blinded crossover trial in which aromatherapy was given to all of the participants on a randomised crossover basis, despite the limitation of the absence of blinding.…”

“…7 Patients with IEI report a variety of symptoms, including fatigue, anxiety, headaches, insomnia, lack of concentration, or depression without physical signs or abnormalities on biomedical tests. [6][7][8][9][10][11] Although the prevalence of IEI varies due to the different definitions of the condition, the estimated number of people suffering from IEI cannot be ignored.…”

Is multiple chemical sensitivity a learned response? A critical evaluation of provocation studies

“…The third study, by Joffres et al [16], tested 10 patients who fulfilled the 1999 Consensus Criteria for MCS and seven individuals without chemical sensitivities. None of the patients had a major comorbid disease or history of major depression.…”