Mercury

“Two employees in a mercuric oxide manufacturing plant developed neurologic changes not previously reported from the exposure to inorganic mercury or elemental mercury vapor. The symptoms, physical findings and laboratory studies resembled those found in amyotrophic lateral sclerosis (ALS) and organic mercury intoxication. Nineteen employees are reported who precipitously developed signs and symptoms which may be regarded to be the early onset of a symptom complex of mercury intoxication that would likely have progressed to the ALS-like syndrome if the progression had not been interrupted by removal of the individuals from exposure to mercury. All symptoms, signs, and laboratory findings returned completely to normal after approximately three months in a mercury free work environment.”

“CBA/J mice injected three days beforehand with 203HgCl2 were given ethanol or water by gavage and placed in a chamber designed to collect exhaled mercury. Ethanol treatment led to an eight-fold increase of counts accumulated on a filter over a four-hour period, compared with water-treated mice. The mercury-collection apparatus tested for extracorporeal contribution of volatilised mercury indicated that the counts originated from the air exhaled by the mice.”

“These observations suggest that chronic mercurialism in dentists and others exposed to mercury vapour may be attributable to methyl mercury. Many of the symptoms of chronic poisoning by inorganic mercury, including depression irritability, failure of memory and concentration, and hand tremor are found also in victims of methyl mercury poisoning.”

“This study has demonstrated that the removal of old amalgam restorations with ultraspeed instrumentation has the potential to increase mercury contamination of a dental treatment room. Dry cutting of amalgam produces a transitory, yet significant, increase in mercury vapor at the operator’s breathing level. This increase in mercury vapor can be controlled with the use of central vacuum evacuation or the use of water spray in conjunction with central vacuum suction.”

“A testing procedure is described for the assessment of the toxicological response (e.g., acute toxicity or mutagenicity) of any combination and number of chemical, physical, and biological agents, with no more effort for a particular combination than for a single agent. The method provides a simple, sensitive, and quantitative index of synergism, antagonism, and additivity, and it has been demonstrated experimentally in rats by determining the acute lethality of combinations of cadmium, mercury, and lead salts. In a combination of two metal salts, the dose of one metal of the pair was fixed at or near the no-effect level while the dose of the second metal was increased until the entire dose-response curve was obtained. To evaluate interactions of the three metals, the previous pair of metals were kept fixed at their combined extrapolated LD1 level, and the third metal was increased. The statistical treatment of the data employed a computer program that did not involve probit transformations, but rather the approximate linear relationship between the fractional response and the logarithm of the dose. A particular combination could be synergistic, antagonistic, or additive, depending on the relative doses employed. Generally, a combination was synergistic when the most toxic member was present at or near its LD1 dose in the presence of the much less toxic member; the same combination was protective when the least toxic member was present at or near its LD1 dose. The results clarify apparently contradictory reports regarding the biological effects of metal combinations. The application of the testing procedure to combinations of mutagens is described, and an example is cited involving, for a particular bacterial mutagen, a combination of N-methyl-N’-nitro-N-nitrosoguanidine with ethylmethanesulfonate.”

“Mercury vapor levels associated with grinding amalgam models and mulling amalgams in the palm of the hand following trituration have been measured in a dental laboratory in inhalation position. The threshold limit value of airborne mercury of 0.05 mg/m3 was essentially exceeded in the grinding procedure of amalgam. Levels in excess of seven times this value were recorded. During mulling the mercury vapor level fluctuated around the threshold limit value. The mean mercury concentrations did not essentially exceed the threshold limit value.”

Galvanic currents within the oral cavity may have harmful effects on biological tissues. In the present work 16 patients with different kinds of oral and other discomfort and pain which they attributed to oral galvanism were investigated. The potential and polarization of each metal restoration within reach of a platinum probe were measured versus a reference electrode. A recording of these measured values permits a calculation of the currents which may pass between the teeth. A control group of patients with no subjective symptoms of galvanism in the oral cavity was also investigated. The results of the electrochemical measurements showed that conditions for oral galvanism existed within the individuals of the patient group as well as within the control group. One remarkable observation was that the metallic restorations often consisted of different electrically isolated areas with different electrochemical properties. This and other factors influencing oral galvanism are discussed.

Galvanism or galvanic action is a well known phenomenon in dentistry. Small galvanic currents are generated from the presence of dissimilar metals in most mouths and consequently cause corrosion of fillings.

“A microbial fluctuation test, modified for the detection of environmental mutagens has been evaluated using a number of strains of the yeast Saccharomyces cerevisiae. Auxotrophic diploid cultures of yeast which produce prototrophic colonies by both mitotic gene conversion and mutation have been extensively utilized for the detection and evaluation of chemicals showing genetic activity. A number of the yeast strains utilized were shown to be suitable for use in the fluctuation test although the time scales of the experiments were considerably extended (up to 16 days) compared to those involving bacteria. The yeast strains respond to doses of mutagens at least a 100-fold lower than that required in a conventional short exposure treat and plate experiment. In experiments involving the induction of mitotic gene conversion at the tryptophan-5 and histidine-4 loci in the fluctuation test significant increases in prototrophic cells were produced in the presence of the insecticide Lindex (0.05 microng/ml), the preservative Thiomersal (0.0001 microng/ml), a mahogany hair dye (0.01 microng/ml), the herbicide Paraquat (0.02 microng/ml) and the alkylating agent ethyl methane sulphonate (0.1 microng/ml). The results demonstrate that the fluctuation test provides an extremely sensitive assay for the detection of chemicals which show genetic activity in yeast at non-toxic concentrations.”

A method is described for the measurement of currents generated between dissimilar alloys in die oral cavity. Tests were performed using amalgam fillings versus specimens consisting of a gold alloy, a chromium-cobalt alloy and a stainless sleel alloy. Currents of 0.1-0.3I1Ncm2 of specimen area were measured.