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

MERCURY 299
2. HEALTH EFFECTS
Siblerud and Kienholz (1997) investigated whether mercury from silver dental fillings (amalgam) may be an
etiological factor in multiple sclerosis (MS). Blood findings were compared between MS subjects who had
their amalgams removed (n=50) and MS subjects with amalgams (n=47). All subjects filled out a health
survey, an MS health questionnaire, and a psychological profile; the MS amalgam removal group completed
a health questionnaire comparing their health before and after amalgam removal. MS subjects with
amalgams were found to have significantly lower levels of red blood cells, hemoglobin, and hematocrit
compared to MS subjects with amalgam removal. Thyroxine (T-4) levels were also significantly lower in
the MS amalgam group, which had significantly lower levels of total T-lymphocytes and T-8 (CD8)
suppressor cells. The MS amalgam group had significantly higher blood urea nitrogen (BUN) and
BUN/creatinine ratio, and lower serum IgG. Hair mercury was significantly higher in the MS subjects
compared to the non-MS control group (2.08 versus 1.32 ppm). A health questionnaire found that MS
subjects with amalgams had significantly more (33.7%) exacerbations during the past 12 months compared
to the MS volunteers with amalgam removal: 31% of MS subjects felt their MS got better after amalgam
removal, 7% felt it was eliminated, 33% felt no change, and 29% believed the condition got worse. In
addition, 17% of the MS with amalgam group had more neuromuscular symptoms compared to the amalgam
removal group.
Björkman et al. (1997) examined the mercury concentrations in saliva, feces, urine, whole blood, and
plasma before and after removal of dental amalgam fillings in 10 human subjects. Before removal, the
median mercury concentration in feces was more than 10 times higher than in samples taken from an
amalgam-free reference group of 10 individuals. Two days following removal of all amalgams, a
considerable increase in mercury appeared in the feces. This initial increase was followed by a significant
decrease. In saliva, there was an exponential decline in the mercury concentration during the first 2 weeks
after amalgam removal (t1/2 of 1.8 days). The authors concluded that while mercury amalgam fillings are a
significant source of mercury in saliva and feces, those levels decrease considerably following amalgam
removal. Further, the gastrointestinal uptake of mercury seen in conjunction with removal of amalgam
fillings appears to be low. Of 108 patients (all with amalgam dental fillings) presenting to an
environmental toxicology service, the average salivary mercury level was 11 µg/L (range, 100 µg/L. Of 58 patients with suspected allergic disease, an epicutaneous test for
amalgam was positive in 32 of them; however, direct involvement of dental amalgams in these sensitivities
was not mentioned. Seventy-five of the total patients presenting with symptoms felt that amalgam fillings