Author: Mackert Jr JR, Berglund A.
Source: Critical Reviews in Oral Biology & Medicine.
Year: 1997
Comment: Comment by the late Steve Koral, DDS, MIAOMT: This is the paper in which the claim is made that it would take up to 450 surfaces of amalgam to approach a toxic dose. These authors cited papers that tended to discount the effect of chlorine on absorption of atmospheric mercury, and they used the occupational exposure limit, (derived for adult males exposed eight hours per day, five days per week), of 25 µg-Hg/cubic meter air as their de-facto REL. They did not consider the uncertainty in that number as it would apply to the whole population, including children, who would be exposed 24 hours, seven days a week. {For more on Dr. Koral's comment, visit https://iaomt.org/resources/dental-mercury-facts/understanding-risk-assessment-mercury-dental-amalgam/ }
Abstract / Excerpt:
This review examines the question of whether adverse health effects are attributable to amalgam-derived mercury. The issue of absorbed dose of mercury from amalgam is addressed first. The use of intra-oral Hg vapor measurements to estimate daily uptake must take into account the differences between the collection volume and flow rate of the measuring instrument and the inspiratory volume and flow rate of air through the mouth during inhalation of a single breath. Failure to account for these differences will result in substantial overestimation of the absorbed dose. Other factors that must be considered when making estimates of Hg uptake from amalgam include the accurate measurement of baseline (unstimulated) mercury release rates and the greater stimulation of Hg release afforded by chewing gum relative to ordinary food. The measured levels of amalgam-derived mercury in brain, blood, and urine are shown to be consistent with low absorbed doses (1-3 micrograms/day). Published relationships between the number of amalgam surfaces and urine levels are used to estimate the number of amalgam surfaces that would be required to produce the 30 micrograms/g creatinine urine mercury level stated by WHO to be associated with the most subtle, pre-clinical effects in the most sensitive individuals. From 450 to 530 amalgam surfaces would be required to produce the 30 micrograms/g creatinine urine mercury level for people without any excessive gum-chewing habits. The potential for adverse health effects and for improvement in health following amalgam removal is also addressed. Finally, the issue of whether any material can ever be completely exonerated of claims of producing adverse health effects is considered.
Citation: Mackert Jr JR, Berglund A. Mercury exposure from dental amalgam fillings: absorbed dose and the potential for adverse health effects. Critical Reviews in Oral Biology & Medicine. 1997; 8(4):410-36.