Allergological and Toxicological Aspects in a Multiple Chemical Sensitivity Cohort

Background . Multiple chemical sensitivity (MCS) is a chronic condition characterized by an exaggerated response to toxicants. We ascertained the prevalence of allergy to metals and toxicological aspects in MCS patients. Methods . We conducted a retrospective review of medical records of 41 patients with MCS. We performed patch testing ( n = 21) for dental series and did lymphocyte transformation test ( n = 18) for metals. We measured mercury in samples of blood ( n = 19), urine ( n = 19), saliva ( n = 20), and scalp hair ( n = 17) to investigate the association between mercury levels and cases of MCS. Results . The prevalence of metal immune hypersensitivity in a subset of 26 patients was 92.3 percent. Elevations of mercury occurred in 81.2 percent (26 of 32). The mean (±SD) in blood concentrations of mercury was 7.6 ± 13.6  μ g/L; mean in urine was 1.9 ± 2.5  μ g/L; mean in scalp hair was 2.2 ± 2.5  μ g/g; mean in saliva was 38.1 ± 52.1  μ g/L. Subgroup analyses showed that elevation of mercury levels in biological matrices were associated with mercury amalgams in patients with MCS (22 patients), compared with controls (8 patients) (odds ratio 11 : 95 percent confidence interval 1.5 to 81.6; P = 0.023). Conclusions . Our data show an increased prevalence of metal allergy and elevation of mercury levels in bioindicators among patients with MCS.