Case–control study of multiple chemical sensitivity, comparing haematology, biochemistry, vitamins and serum volatile organic compound measures

Abstract

Background Multiple chemical sensitivity (MCS), although poorly understood, is associated with considerable morbidity. AimTo investigate potential biological mechanisms underlying MCS in a case-control study. MethodsTwo hundred and twenty-three MCS cases and 194 controls (urban females, aged 30-64 years) fulfilled reproducible eligibility criteria with discriminant validity. Routine laboratory results and serum levels of volatile organic compounds (VOCs) were compared. Dose-response relationships, a criterion for causality, were examined linking exposures to likelihood of case status. ResultsRoutine laboratory investigations revealed clinically unimportant case-control differences in means. Confounder-adjusted odds ratios (OR) showed MCS was negatively associated with lymphocyte count and total plasma homocysteine, positively associated with mean cell haemoglobin concentration, alanine aminotransferase and serum vitamin B6, and not associated with thyroid stimulating hormone, folate or serum vitamin B12. More cases than controls had detectable serum chloroform (P = 0.001) with the OR for detectability 2.78 (95% confidence interval = 1.73-4.48, P < 0.001). Chloroform levels were higher in cases. However, cases had significantly lower means of detectable serum levels of ethylbenzene, m&p-xylene, 3-methylpentane and hexane, and means of all serum levels of 1,3,5-and 1,2,3-trimethylbenzene, 2-and 3-methylpentane, and m&p-xylene. ConclusionsOur findings are inconsistent with proposals that MCS is associated with vitamin deficiency or thyroid dysfunction, but the association of lower lymphocyte counts with an increased likelihood of MCS is consistent with theories of immune dysfunction in MCS. Whether avoidance of exposures or different metabolic pathways in cases explain the observed lower VOC levels or the higher chloroform levels should be investigated.

Double-blind non-controlled chemical challenge with environmental toxicological assessment in a Multiple Chemical Sensitivity case

“…Many investigators looked for laboratory testing to confirm the diagnosis, or at least a relation between symptoms and chemical exposure [5][6][7]. Provocation test and odor perception differences were also proposed to discriminate MCS patients from controls [8][9][10].…”

Sickness‐related dysfunction in persons with self‐reported multiple chemical sensitivity at four levels of severity

“…People are often ‘unremarkable’ on routine examinations. However, Baines et al. (2004) found these biological markers in a sample of 223 persons with MCS vs. controls: lower lymphocyte count and homocysteine levels; elevated haemoglobin concentration (MCHC), alanine‐aminotransferase (ALT), vitamins B12 and B6; and detectable levels of chloroform and benzene.…”

A physiologically based toxicokinetic model of inhalation exposure to xylenes in Caucasian men

“…Samples of exhaled breath and blood concentrations of deuterium-labeled xylene isomers were obtained for each of 27 Caucasian men who underwent repeated controlled inhalation exposure to xylene isomers. The isomers were isotopically labeled to distinguish administered dose from background exposures (Baines et al, 2004). Individual measurements of age, height, body weight, and adipose tissue fraction were recorded, and the latter two used in the model which was intended to closely predict the kinetics of the xylene isomers in adult men, and was tested using experimental data.…”