Neurobehavioral effects from exposure to dental amalgam Hg ^o : new distinctions between recent exposure and Hg body burden

Abstract

Potential toxicity from exposure to mercury vapor (Hg(o)) from dental amalgam fillings is the subject of current public health debate in many countries. We evaluated potential central nervous system (CNS) toxicity associated with handling Hg-containing amalgam materials among dental personnel with very low levels of Hg(o) exposure (i.e., urinary Hg <4 microg/l), applying a neurobehavioral test battery to evaluate CNS functions in relation to both recent exposure and Hg body burden. New distinctions between subtle preclinical effects on symptoms, mood, motor function, and cognition were found associated with Hg body burden as compared with those associated with recent exposure. The pattern of results, comparable to findings previously reported among subjects with urinary Hg >50 microg/l, presents convincing new evidence of adverse behavioral effects associated with low Hg(o) exposures within the range of that received by the general population.

Mercury concentrations in urine, scalp hair, and saliva in children from Germany

“…There is some evidence for adverse behavioral effects associated with low mercury exposures ( Echeverria et al, 1998 ) and cognitive deficits in children due to methylmercury (Grandjean et al, 1997 ). On the other hand, there is no reasonable suspicion for health impairment caused by correctly posed amalgam fillings (Harhammer, 2001).…”

Neuropsychological effects associated with exposure to mercury vapor among former chloralkali workers

“…Several studies have reported neurobehavioral effects related to motor and cognitive functions (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) in humans during ongoing exposure to mercury vapors. Contrary to the large number of studies on currently exposed workers, few epidemiologic studies have focused on the long-term effects on workers who are no longer exposed.…”

“…These tests mainly measure attention, motor speed, visual scanning and visuomotor tracking. They were not applied in the 2 neuropsychological studies of previously exposed workers (26,27), but poorer performance has been reported for currently exposed populations (16,18). It is an interesting observation that workers with high acute intensive exposure showed a substantial improvement in the test results of parts A and B after chelation with 2,3-dimercaptosuccinic acid (20).…”

“…Neurobehavioral effects of occupational exposure have been described as falling into the 3 major groups of alterations in emotional state, effects on cognitive functions, and effects on motor functions (1,2). Ongoing exposure to lower concentrations of mercury vapors has been associated with increased hand or finger tremor, subclinical changes in coordination, neuromuscular functions, and deficits in memory and attention (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Magos (21) suggested that it may be a mistake to relate defects to exposure estimates valid at a time when the possibility of higher exposure in the past cannot be excluded.…”

Thirty-five year review of a mercury monitoring service for Scottish dental practices

“…6,7 Chronic exposure to lower concentrations of mercury can result in milder symptoms as well as detectable effects on motor function and behaviour, and previous studies have shown that relatively low levels of mercury exposure may be detrimental to health. 8,9 However, it is difficult to designate a threshold of exposure below which can be considered to be safe. For this reason and because local cases of symptomatic mercury poisoning of dentists had been detected, an occupational mercury monitoring programme was introduced in 1975 for dental practices in Scotland.…”