Adverse health effects related to mercury exposure from dental amalgam fillings: toxicological or psychological causes?

Background. Possible adverse health effects due to mercury released by amal gam fillings have been discussed in several studies of patients who attribu te various symptoms to the effects of amalgam fillings. No systematic relat ion of specific symptoms to increased mercury levels could be established i n any of these studies. Thus, a psychosomatic aetiology of the complaints s hould be considered and psychological factors contributing to their aetiolo gy should be identified. Methods. A screening questionnaire was used to identify subjects who were c onvinced that their health had already been affected seriously by their ama lgam fillings (N = 40). These amalgam sensitive subjects were compared to a malgam non-sensitive subjects (N = 43). All participants were subjected to dental, general health, toxicological and psychological examinations. Results. The two groups did not differ with respect to the number of amalga m fillings, amalgam surfaces or mercury levels assessed in blood, urine or saliva. However, amalgam sensitive subjects had significantly higher sympto m scores both in a screening instrument for medically unexplained somatic s ymptoms (SOMS) and in the SCL-90-R Somatization scale. Additionally, more s ubjects from this group (50% versus 47%) had severe somatization syndromes. With respect to psychological risk factors, amalgam sensitive subjects had a self-concept of being weak and unable to tolerate stress, more cognition s of environmental threat, and increased habitual anxiety. These psychologi cal factors were significantly correlated with the number and intensity of the reported somatic symptoms. Conclusions. While our results do not support an organic explanation of the reported symptoms, they are well in accord with the notion of a psychologi cal aetiology of the reported symptoms and complaints. The findings suggest that self-diagnosed "amalgam illness" is a label for a general tendency to ward somatization.