Elemental Mercury Sources<br><br>Silver "amalgam"
dental fillings typically weigh between 1.5-2.0 g, with
approximately 50 percent of the material being elemental
mercury. When no chewing occurs, individuals with amalgam
fillings on occlusal surfaces have been found to have oral
levels of mercury vapor nine times greater than those
without amalgams. Upon chewing, the same individuals had
a six-fold increase in oral elemental mercury
levels, resulting in a 54-times greater level of mercury
vapor in their oral cavities than persons without
amalgams.15 Serial measurements of these individuals found
mercury concentrations remained elevated during 30
minutes of continuous chewing, and then declined slowly
over 90 minutes after chewing ceased.16 Based on the
relatively small size of the trial (35 subjects), the
researchers concluded individuals with 1-4 occlusal amalgams
would be exposed to an average daily dose of 8 µg
elemental mercury; those with 12 or more occlusal amalgams
were estimated to receive 29 µg per day, and the
average of all 35 subjects was estimated at 20 µg per
day. Individual cases have been published showing
urinary mercury excretion to be 23-60 µg/Hg/day (25-54
µg/g creatinine) indicating a daily intake as high as
100 µg.17 In these individuals, bruxism and gum
chewing were noted as probable causes of the high mercury
output, which fell back to normal levels with amalgam
removal. Higher levels of mercury release from dental
amalgams have also been found with tooth brushing18 and
after consuming hot drinks.19<br><br>Mercury vapor is
highly lipid soluble and enters the blood from both the
lungs and oral mucosa. It traverses cell membranes
(including the blood-brain and placental barriers), rapidly
partitions between plasma and red blood cells, and becomes
widely distributed. As much as 40 percent of mercury
vapor is excreted through the feces.20 Once in the
cell, elemental mercury is oxidized by
catalase-hydrogen peroxide and becomes divalent Hg2+, which then
combines covalently with sulfhydryl groups in molecules
such as hemoglobin, reduced glutathione, and cysteine
residues in proteins. Thus, individuals exposed to mercury
have been found to have lower levels of reduced
glutathione.<br><br>Blood mercury concentrations have been positively
correlated with the number and surface area of amalgam
restorations, and are significantly higher in individuals with
amalgams than those without.22 Amalgams are also
associated with higher urinary mercury output,23 as well as
higher levels in breast milk, although not hair.24 When
examining the association between mercury presence and
breast milk it was found the total and inorganic mercury
levels in blood and milk did correlate with the number
of amalgam fillings. In this study, when seafood was
not the main dietary staple, there was no association
found between dietary methylmercury intake and milk
levels. Exposure of the breastfed infant to mercury from
the mother's amalgams was calculated up to 0.3µg/kg
(one-half of the tolerable daily intake for adults
recommended by the World Health
Organization).<br><br>Thimerosal in Vaccines - an Interim Report to Clinicians
<br><br>INTRODUCTION <br><br>On July 8, 1999, the American Academy of
Pediatrics (AAP) issued with the Public Health Service a
joint statement alerting clinicians and the public of
concern about thimerosal, a mercury-containing
preservative used in some vaccines. That statement was
disseminated widely, including on the AAP e-mail list and is
posted on the Members Only Channel on the AAP Web site
at <a href=http://www.aap.org/moc target=new>http://www.aap.org/moc</a>
<br><br><a href=http://fahc.vtmednet.org/~g125393/thimero.htm
target=new>http://fahc.vtmednet.org/~g125393/thimero.htm</a><br><br><br><br><a
href=http://www.thorne.com/altmedrev/fulltext/enviro5-3.html
target=new>http://www.thorne.com/altmedrev/fulltext/enviro5-3.html</a>