revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY 295
2. HEALTH EFFECTS
controversy will only be satisfactorily resolved with better toxicity and pharmacokinetic data for chronic low
level mercury exposure from amalgams.
People who are concerned that their mercury exposure may be causing adverse effects can be tested for
allergies to mercury or to other metals, or for the amount of mercury in their body. Tests that measure the
amounts of mercury in hair and urine are available and provide some indication of the potential for adverse
effects from mercury. For more information about the tests that are available, see Section 2.7, Biomarkers of
Exposure and Effects.
The following studies supporting or refuting the adverse health effects from exposure to dental amalgam
provide some examples from the recent literature of effects being evaluated and the procedures that are being
used. Some of the studies depend upon the self-reporting of symptoms or may be weakly blinded (i.e., the
patients were not completely unaware of the assignment to different exposure groups) which could bias the
outcome, especially with respect to some of the end points. An exhaustive analysis of the results presented
below, however, is beyond the scope of this profile, and the reader is referred to the cited references for a
more complete discussion of the issues concerning the potential adverse effects from exposure to dental
amalgam.
Studies reporting no association between adverse effects and mercury amalgam.
Berglund and Molin (1996) evaluated whether a group of patients with symptoms, self-related to their
amalgam restorations, experienced an exposure to mercury vapor from their amalgam restorations that
reached the range at which subtle symptoms have been reported in the literature. They further evaluated
whether the mercury exposure for these patients was significantly higher than for controls with no reported
health complaints. The symptom group consisted of 10 consecutively selected patients from a larger group.
The larger group consisted of patients who were referred by their physicians for an investigation of a
correlation between subjective symptoms and amalgam restorations. The control group consisted of
8 persons with no reported health complaints. The intra-oral release of mercury vapor was measured
between 7:45 a.m. and 9:00 p.m. at intervals of 30–45 minutes, following a standardized schedule. The
mercury levels in plasma, erythrocytes, and urine were also determined. The calculated daily uptake of
inhaled mercury vapor, released from the amalgam restorations, was less than 5% of the daily uptake
calculated at the lower concentration range given by the WHO (1991), at which subtle symptoms have been
found in particularly sensitive individuals. The symptom group had neither a higher estimated daily uptake