The purpose of this review was to critically evaluate research on the psychogenic origins of multiple chemical sensitivities (MCS) syndrome. Using as keywords environmental illness, multiple chemical sensitivities, and clinical ecology, two databases--PsychLit and Medline--were searched by computer; reference lists of all articles located were also searched manually. Ten articles meeting three criteria were selected for review. Five sample selection problems, seven measurement problems, and three study design problems were common in all but one of the articles reviewed. Current studies investigating psychogenic hypotheses of MCS syndrome are methodologically problematic and their conclusions questionable. Studies of psychiatric profiles observed in MCS syndrome need to be designed to differentiate between competing psychogenic and biogenic hypotheses.

Self-reported information about health and mental health status and history on (a) three diverse samples of individuals who reported multiple chemical sensitivities syndrome (n = 60) and (b) one sample of the general population (n = 60) was collected by telephone interview. Subjects from the general population were selected randomly from the telephone directory and were matched for age, gender, and socioeconomic status with index subjects. Data on an additional 10 subjects with multiple chemical sensitivities syndrome were also available for comparison on many of the variables of interest. The four diverse groups of patients with multiple chemical sensitivities syndrome had very similar general and specific indices of illness and sensitivity to chemicals. Members of the general population reported mild sensitivity to chemicals, and even those with more sensitivity differed from the multiple chemical sensitivities syndrome groups with respect to number and types of symptoms reported, duration and frequency of response, and associated features. Multiple chemical sensitivities syndrome was associated consistently with only one psychiatric variable, elevated negative affect scores, which were correlated significantly with the presence of illness. Patients with multiple chemical sensitivities syndrome from the diverse samples had very similar characteristic features, despite whether they had or had not received treatment by clinical ecologists.

The aims of this study were to determine whether increased pain sensitivity in patients with irritable bowel is due to physiological differences in perceptual sensitivity or psychological influences on perception, and whether prior sexual abuse accounts for increased pain sensitivity. Seventeen sexually abused and 15 nonabused women with irritable bowel were compared to 13 sexually abused and 14 nonabused women without irritable bowel. Among the nonabused subjects, the volume of rectal distension that produced moderate pain was lower in IBS patients than in controls, replicating earlier studies, but these thresholds were correlated with psychological measures of anxiety and somatization. The ability to discriminate between painful distensions (perceptual sensitivity) was not different between groups. Sexual abuse was not associated with lower pain thresholds. Thus, differences in pain sensitivity appear to be due to psychological influences on perception, but a history of sexual abuse does not contribute significantly to this pain sensitivity.

In this article, investigators report on the presence and nature of chemical sensitivities and other indices of illness in a cohort of workers excavating a new subway tunnel located under a former gasoline station. The workers were exposed to gasoline fumes for up to approximately 2 mo when they inadvertently dug into soil contaminated by gasoline. The cohort was unique in several ways: (a) contact with gasoline was made by the workers at a time when no one had complained of multiple chemical sensitivities syndrome; (b) all were males of low socioeconomic status; (c) the exposure was well documented; (d) the cohort could be considered "naive" because, at the time of the study, the men were not members of support groups and were not being seen by clinical ecologists, and they were not labeled, either by self or others, as having multiple chemical sensitivities syndrome or any related diagnosis; and (e) at the time of interview, all workers we contacted appeared to be either gainfully employed or laid off temporarily and seeking gainful employment. We explored the health status of the workers at two different times: (1) soon after the tunnel was closed as a result of high, measured benzene-exposure levels and (2) 10-13 mo after the tunnel was closed. The workers were chronically overexposed to gasoline fumes, after which approximately one-fourth (26.7%) of our random sample of relatively naive, low-socioeconomic-status male laborers-although neither disabled nor generally litigious-reported the new onset of chemical hypersensitivities and other characteristics that fit conservative criteria for multiple chemical sensitivities syndrome.

When abnormal psychologic/psychiatric symptom data are obtained on personality tests or psychiatric interviews administered to patients who report symptoms of Multiple Chemical Sensitivities Syndrome, investigators typically attribute these to either psychiatric traits or to psychogenic origins of illness. The primary purpose of these studies was the evaluation of the plausibility of nonpsychiatric explanations of psychologic/psychiatric symptom data. In Study 1, patients with Multiple Chemical Sensitivities Syndrome used the Minnesota Multiphasic Personality Inventory 2 (MMPI-2) to describe which items had changed after they developed the condition. In Study 2, three diverse groups of professionals predicted which items on the MMPI-2 might change after a mentally healthy person developed the Syndrome or a condition resembling it. In Study 3, a second sample of Multiple Chemical Sensitivities Syndrome patients completed the MMPI-2 and other questionnaires by mail, which allowed the authors to ascertain whether these patients showed more or different psychopathology than was described by patients and hypothesized by professionals. Data from Study 1 patient informants indicated that developing the syndrome might result in a psychopathological MMPI-2 profile, characterized by abnormal Hypochondriasis and Hysteria scale scores. Professionals in Study 2 showed a consensus about hypothesized MMPI-2 changes following the development of the syndrome. These changes likely elevated the Hypochondriasis, Hysteria, Psychasthenia, Depression, and Schizophrenia scale scores. In Study 3, the patients taking the MMPI-2 showed elevations on the Hypochondriasis, Hysteria, Depression (women only), and Schizophrenia scales. Abnormal scores were associated closely with greater severity of illness and greater adjustment to illness. The strategy of administering psychometric tests to ill populations for the purposes of evaluating psychiatric illness or traits, and/or psychogenic origins of illness was shown to be potentially misleading.