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MERCURY 226
2. HEALTH EFFECTS
nonsteady-state conditions was influenced by both the age of the amalgam and the amalgam type, the
steady-state value of the mercury dose released by the amalgam was only 0.03 µg/day.
Sandborgh-Englund et al. (1998) evaluated the absorption, blood levels, and excretion of mercury in nine
healthy volunteers (2 males, 7 females) exposed to 400 µg /m3 mercury vapor in air for 15 minutes. This
exposure corresponded to a dose of 5.5 nmol Hg/kg body weight. Samples of exhaled air, blood and urine
were collected for 30 days after exposure. The median retention of elemental Hg was 69% of the inhaled
dose. To evaluate the chronic exposure to mercury from dental amalgam in the general population, the
daily Hg dose from fillings was estimated based on the plasma Hg levels of subjects with amalgam fillings
and the plasma clearance obtained in this study. The daily dose was estimated to be from 5 to 9 µg/day in
subjects with an “average” number (20–35 amalgam surfaces) of amalgam fillings (Sandborgh-Englund et
al. 1998)
Halbach (1994) examined the data from 14 independent studies and concluded that the probable mercury
dose from amalgam is less than 10 µg/day. When combined with the 2.6 µg/day background intake
estimated by WHO (1990) for persons without amalgam fillings and with an estimated methylmercury
intake of 5 µg/day from food, Halbach noted that the sum of all those inputs still falls within the WHO's
40 µg/day acceptable daily intake (ADI) level for total mercury. For the ADI of 40 µg total mercury
exposure inhaled, approximately 30 µg would be absorbed, assuming 80% absorption (Halbach 1994;
WHO 1976).
Whether adverse health effects result from exposure to mercury from amalgams at the levels reported above
is currently a topic of on-going research and considerable discussion. A thorough review of this subject is
beyond the scope of this profile. Readers are referred to the end of this section (see More on the Effects of
Dental Amalgam) for a discussion of some recent reviews of this topic, and a few examples of studies on
the putative toxic effects or the lack thereof from continued use of amalgam.
Other Uses of Metallic Mercury
A less well-documented source of exposure to metallic mercury among the general population is its use in
ethnic religious, magical, and ritualistic practices, and in herbal remedies. Mercury has long been used for
medicinal purposes in Chinese herbal preparations and is also used in some Hispanic practices for medical
and/or religious reasons. Espinoza et al. (1996) analyzed 12 types of commercially produced herbal ball
preparations used in traditional Chinese medicine. Mercury levels were found to range from 7.8 to