Polymorphisms in several genes contribute to interindividual differences in the metabolism of xenobiotics, and may lead to toxicity and disease. The balance between activation and/or detoxification processes may influence an individual's susceptibility to disease. One postulated mechanism underlying multiple chemical sensitivity (MCS) is based on increased metabolism of xenobiotics. The aim of the present study was to determine such polymorphisms in cases with self-reported MCS (sMCS) and controls. sMCS cases (14 men, 45 women, mean age: 48 yr) and controls (14 men, 26 women, mean age: 44 yr) of the same anthroposphere were characterized using the MCS-questionnaire from Huppe and coworkers (2000) and a standardized questionnaire for living conditions and living factors. Allelic frequencies of genomic variations for 5HTT, NAT1, NAT2, PON1, PON2, and SOD2 were determined. The MCS questionnaire from Huppe et al. (2000) differentiated between cases and controls with 87.5% sensitivity and 90% specificity. Compared to controls the sMCS cases had lower exposures, especially to odorous factors, and worse social conditions. No significant differences of the allelic distribution of genetic polymorphisms in the genes for 5HTT, NAT1, NAT2, PON1, PON2, and SOD2 were found between cases and controls. The results are in contrast to the study of McKeown-Eyssen and coworkers (2004) but in accordance with the German MCS multicenter study. Although the MCS questionnaire from Huppe et al. (2000) allowed us to differentiate sMCS cases and controls, it was not strong enough for a discrimination based on sequence variations in genes for enzymes involved in xenobiotic metabolism. Therefore, further research needs to focus on a unique phenomenological characterization of MCS.

Environmental medicine outpatient clinics, counseling centers, and practicing physicians have observed environment-related health disorders in patient groups of mixed age as well as for groups consisting only of adults or children. Practicing physicians suspected correlations between environmental factors and health disorders in 36-45% of cases, environmental medicine outpatient clinics and counseling centers in 4-34% for mixed-age groups, 0-24% for adults, and 9-13% for children. A comparison of these data is difficult due to differences in data acquisition, evaluation methods, and descriptive statistics used. Furthermore, data on children are insufficient. Patient-oriented environmental medicine faces a number of problems regarding determination of exposure, effects, and susceptibility, including a lack of scientifically verified cause-and-effect models as well as incorrect diagnoses, attributions, and conclusions. In view of the scope and intensity of environment-related health disorders, the topic cannot be ignored. A functioning program of environmental medicine counseling and patient care is needed for practicing physicians, universities and/or the public sector to deliver effective primary medical care in this field. As always, the building blocks of environ-mental medicine counseling are medical history, physical examination, differential diagnosis, human biomonitoring, and on-site inspection with environmental monitoring while also taking gender differences into account. Uniform basic documentation procedures and health science analyses will help to optimize patient care in environ-mental medicine. The value of a diagnostic algorithm in the care of patients with environment-related health disorders is beyond dispute. Last but not least, quality assurance and control are a sine qua non of patient-oriented environmental medicine.

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