Assessment of blood mercury levels in practicing Turkish clinicians, dental students, and dental nurses

Objectives: Potential sources of exposure of the dental health team and their patients to mercury vapor in the dental clinic include accidental spillage of elemental mercury, use of mechanical amalgamators, and dry cutting of old amalgam restorations using high-speed instrumentation. The purpose of this study was to evaluate the extent of mercury exposure in Turkish dental staff by cold-vapor atomic absorption spectrometry. Method and Materials: A total of 211 clinicians, dental students, and dental nurses answered a questionnaire concerning sex, age, occupation, number of amalgam restorations performed per week, number of amalgam restorations removed per week, methods of trituration, number of amalgam restorations present in their own mouths, frequency of fish consumption, smoking, vitamin intake, and bruxism. For each subject, a 5-mL sample of whole blood was drawn and frozen until the time of analysis. Blood mercury levels were measured by means of cold-vapor atomic absorption spectrometry. Blood mercury levels were also analyzed in a control group of 58 non-dental-staff blood donors. Results: Normal blood mercury values are considered to be in the range of 0 to 5 ng Hg/mL. Of the dental staff evaluated, 51.7% had a blood concentration of mercury less than 5 ng Hg/mL, and 33.6% had a blood concentration above 5 ng Hg/mL. The difference between the test and control groups was statistically significant (P .01). Conclusion: Mercury is being absorbed as a result of dental practice but that although there is, in general, a low level of mercury contamination in the dental operatory because of amalgam work, sufficient care is being taken to prevent higher levels of contamination with an increased use of mercury. Keywords: amalgam, blood concentration, mercury, toxication