subset of patients can be found who meet the more rigorous definition proposed by Cullen (1987). If such patients can be identified, it is also important to develop a standardized method for evaluating these patients. Therefore, the purpose of the present paper is to document that this relatively narrow group of patients can be identified and to describe the standardized battery of tests we have chosen to characterize these patients.
Over the past two years approximately 25 patients have presented at our Environmental and Occupational Health Clinical Center with symptoms suggestive of chemical sensitivity. That is, all patients reported becoming symptomatic to low levels of multiple chemicals/substances encountered in their daily lives. Each patient underwent a comprehensive medical examination by an occupational physician. This consisted of a lifetime and current medical history, review of previous medical records, brief psychiatric history, physical examination, and routine hematology, blood chemistry, thyroid and urine studies. Further testing such as spirometry or chest x-ray were done as needed to document organic conditions which might reasonably explain the symptomatology. While previous organic conditions were often present (e.g. asthma) patients were not excluded if these conditions did not explain the current symptoms.
With regard to psychiatric history, patients who reported the following psychiatric diagnoses on their medical questionnaire or during a medical history were not included in the more narrowly defined group of MCS patients:
Evidence of current psychosis, organic brain syndrome, mania, or major depression.
History of treatment, within, 10 years of onset of symptoms attributed to toxic exposure, for psychosis, organic brain syndrome, hypomania, major depression, somatoform disorder, dissociative disorder, phobia, panic disorder, post-traumatic stress disorder, obsessive compulsive disorder, or personality disorder.
Also, individuals were excluded from the rigorously defined subset of chemically sensitive patients if the following were present: 1) in litigation at the time of the evaluation; 2) in treatment with a clinical ecologist. While such patients may have chemical sensitivity, for various reasons these factors may confound the interpretion of the evaluation measures.
For exit-pie, patients involved in litigation or being treated by a clinical ecologist may have altered symptom patterns based on these factors. That is, patients in litigation may have a vested interest in appearing more symptomatic while the treatments or information provided by a clinical ecologist could potentially change a patient's symptom profile.
Based on the above criteria, eleven of the twenty-five patients qualified as presenting symptoms consistent with chemical sensitivity while not having other current or previous conditions or psychosocial factors that could account for their symptoms.
Among those patients who did not qualify, eight did not strictly meet the Cullen (1987) criteria. That is, on careful consideration either they did not have symptoms that wax and wane with exposure or they could not identify a specific point in time or exposure event after which their symptoms began.
Among the remaining six patients, two were involved in litigation, and one had a previous psychiatric history of major depression with electroconvulsive treatment. Three others were not available for further study due to logistic reasons, e.g. moved out of state. Thus, eleven patients met the full criteria proposed by Cullen (1987) and did not have the