Mercury in dental practice. I. The working environment of dental personnel and their exposure to mercury vapor.

Eighty-two dental clinics in the county of Västerbotten, Sweden, were examined. The dentists answered questionnaires concerning working routines, consumption of mercury and the amount of amalgam therapy. Measurings of mercury vapor were performed in 109 operatories and in 35 sterilizing rooms in Public Dental Care (Ftv) and in 59 operatories and 48 sterilizing rooms in Private Dental Care (Ptv). In order to trace the sources of mercury exposure measurings were made at predetermined places. Peak values exceeding 150 micrograms/m3 were found in the operatories in Ftv in 2 places of measuring and in Ptv at 5 places and also at 2 places in the sterilizing rooms. The average amount of mercury vapor in the breathing zone (Hg-index) never exceeded 25 micrograms/m3. The exposure was higher in the operatories than in the sterilizing rooms and was higher in Ptv than in Ftv. Hg-index could be effected, though not in a statistically significant way, by the design of the clinic, the equipment and the routines. Peak readings of mercury vapor at floor level had the greatest influence on Hg-index, which indicates that spillage of mercury is the most important contributor to the dental personnel's exposure to mercury vapor.