F or approximately 150 years, mercury in amalgam has been used as a dental restorative material. Throughout this time the potential toxicity of this metal to patients’” and dental professionals4-9 has been studied and debated. In these reports and many others, problems with mercury contamination and toxicity were uncovered. Although the extent of the problems may be controversial, the overall impact has led to increased emphasis on mercury hygiene in dental schools and in private practice.‘0,1’ Most studies on mercury contamination have concentrated on patients and dentists, with considerably less attention to dental students. This is unfortunate because students, in a sense, serve as a bridge between the two major groups, practicing dentists and their patients. Certainly, problems with mercruy contamination in first-year dental students should be similar to problems in patients. Conversely, problems with mercury contamination or toxicity in fourth-year dental students should reflect problems in practicing dentists. Some attempts have been made to study this unique group. In most of these experiments, however, the number of students screened for different forms of mercury contamination or toxicity has been small, with numbers ranging from 8 to 29 students.‘2-‘6 For this reason, there is little agreement between the results of these pilot studies. In a study by White and Brandt,” however, 298 dental students were screened for allergic responses to mercury. Through the use of epicutaneous patch-test procedures, they showed that the rate of hypersensitivity to mercuric chloride increased as students progressed through the dental curriculum. This observation linking hypersensitivity to mercury to the preparation of alloy restorations suggested that mercury as an allergen was an additional occupational hazard for the dental profession. With increased emphasis on mercury hygiene and the development of improved techniques for preparing amalgam, a second study of this phenomenom was