Mercury

“Introduction
Autism is a severe developmental disorder, which involves social withdrawal, communication deficits, and stereotypic repetitive behavior. The possible etiologies that precipitate autism symptoms remain controversial in many cases, but both genetic and environmental factors have been implicated. Mercury has gained much attention for a considerable period of time before other exacerbating or protective factors were suggested. The aim of this study was to investigate the relationship between autism and the level of some metals (namely mercury, lead, and copper) or zinc as a counteracting antioxidant element.
Methods
The study recruited 32 autistic children and 32 normal controls and all of them were subjected to KID-SCID, Childhood Autism Rating Scale (CARS), Stanford Binet intelligence test, and biochemical analysis of hair samples for the level of mercury, copper, lead and zinc.
Results
There were highly significant differences between the level of these substances in the hair of children with autism compared with controls, positive correlation of CARS score with both mercury and copper, while intelligence quotient has significant negative correlation with the level of lead in the hair. The level of zinc does not correlate with either CARS score or intelligence quotient.
Conclusion
These preliminary results suggest a complementary role for the studied elements in the pathogenesis of autistic disorder, which should be considered in the management plane.”

“The Food and Drug Administration (FDA) convened a meeting on December 14 and 15, 2010 to consider FDA policy regarding the safety of dental amalgam.(1-12) Dental amalgam, commonly called “silver filling” material, is composed of about 50% mercury mixed with other metals including silver, tin and copper. At the meeting, the FDA Dental Products Panel of the Medical Devices Advisory Committee considered whether a 2009 FDA rule(13) adequately addressed the health risks posed by the mercury contained in the fillings. The meeting included scientific and public testimony, as well as panel deliberation, providing a forum to present information pertinent to the dental amalgam debate.”

“Previous studies noted specific changes in urinary porphyrin excretion patterns associated with exposure to mercury (Hg) in animals and humans. In our study, urinary porphyrin concentrations were examined in normal children 8-18 years-old from a reanalysis of data provided from a randomized, prospective clinical trial that was designed to evaluate the potential health consequences of prolonged exposure to Hg from dental amalgam fillings (the parent study). Our analysis examined dose-dependent correlations between increasing Hg exposure from dental amalgams and urinary porphyrins utilizing statistical models with adjustments for the baseline level (i.e. study year 1) of the following variables: urinary Hg, each urinary porphyrin measure, gender, race, and the level of lead (Pb) in each subject’s blood. Significant dose-dependent correlations between cumulative exposure to Hg from dental amalgams and urinary porphyrins associated with Hg body-burden (pentacarboxyporphyrin, precoproporphyrin, and coproporphyrin) were observed. Overall, 5-10% increases in Hg-associated porphyrins for subjects receiving an average number of dental amalgam fillings in comparison to subjects receiving only composite fillings were observed over the 8-year course of the study. In contrast, no significant correlations were observed between cumulative exposure to Hg from dental amalgams and urinary porphyrins not associated with Hg body-burden (uroporphyrin, heptacarboxyporphyrin, and hexacarboxyporphyrin). In conclusion, our study, in contrast to the no-effect results published from the parent study, further establishes the sensitivity and specificity of specific urinary porphyrins as a biomarker for low-level Hg body-burden, and also reveals that dental amalgams are a significant chronic contributor to Hg body-burden.”

“The notion that dental amalgam is a potential source of mercury exposure remains a controversial issue. However, there are few epidemiological analyses that have addressed whether this occurs in children. We aimed in our current study to identify the relationship between dental amalgam filling surfaces and the blood mercury levels in a cohort of 711 South Korean children aged between 8-9 years. Oral examinations were conducted to detect the number of amalgam filling surfaces on the teeth of these individuals. Blood samples were also taken from these children to assess the levels of mercury accumulation in the body. The amalgam filling surfaces were classified into four groups based on their number: 0 (n = 368), 1-5 (n = 219), 6-10 (n = 89), and 11+ (n = 35). The blood mercury levels in the children with more than 10 amalgam surfaces was 0.47 microg/L higher on average than those with no amalgam surfaces after adjusting for the frequency of fish or seafood consumption, age, and gender (P < 0.05). We found from our data that a higher number of dental amalgam fillings correlated with a higher blood mercury level in Korean children. Further studies are needed to investigate whether these elevated mercury levels exert neurotoxic or nephrotoxic effects.”

“Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders characterized by social and language deficits, stereotypic behavior, and abnormalities in motor functions. The particular set of behavioral impairments expressed in any given individual is variable across the spectrum. These behavioral abnormalities are consistent with our current understanding of the neuropathology of ASD which suggests abnormalities in the amygdala, temporal and frontal cortexes, hippocampus, and cerebellum. However, regions unrelated to these behavioral deficits appear largely intact. Both genetic predisposition and environmental toxins and toxicants have been implicated in the etiology of autism; the impact of these environmental triggers is associated with increases in oxidative stress, and is further exacerbated when combined with genetic susceptibility. We have previously reported increased levels of 3-nitrotyrosine (3-NT), a marker of oxidative stress, in ASD cerebella.We have also shown that this increase was associated with an elevation in neurotrophin-3 (NT-3) levels. The objectives of the current study were to determine whether the increase in oxidative stress in ASD is brain region-specific, to identify the specific brain regions affected by oxidative stress, and to compare brain regionspecific NT-3 expression between ASD and control cases. The levels of 3-NTand NT-3 were measured with specific ELISAs in individual brain regions of two autistic and age- and postmortem interval (PMI)–matched control donors…”

Background. The authors conducted a study to identify factors associated with the materials that dentists in The Dental Practice-Based Research Network (DPBRN) use when placing the first restoration on permanent posterior tooth surfaces.

Methods. A total of 182 DPBRN practitioner-investigators provided data regarding 5,599 posterior teeth with caries. Practitioner-investigators completed an enrollment questionnaire that included the dentist’s age, sex, practice workload, practice type and number of years since graduation. When patients who had provided informed consent to participate in the investigation sought treatment for a previously unrestored carious surface, the practitioner-investigator recorded patient and tooth characteristics.

Results. Practitioner-investigators used amalgam more often than they used direct resin-based composite (RBC) for posterior carious lesions. Practitioner and practice characteristics (years since graduation and type of practice); patient characteristics (sex, race, age and dental insurance status); and lesion characteristics (tooth location and surface, preoperative and postoperative lesion depth) were associated with the type of restorative material used.

Conclusions. Several practitioner and practice, patient and lesion characteristics were associated significantly with use of amalgam and RBC: geographical region, years since dentist’s graduation, patient’s dental insurance status, tooth location and surface, and preoperative and postoperative lesion depth.

Clinical Implications. Despite advances in esthetic dentistry, U.S. dentists still are placing amalgam on posterior teeth with carious lesions. Amalgam was used more often than RBC in older patients, who may have had deeper carious lesions.”

“Orofacial granulomatosis is a clinicopathologic entity characterized by chronic swelling of the lip and possible soft tissues in the orofacial region owing to granulomatous inflammation of unknown cause. We present 3 cases of orofacial granulomatosis associated with allergic contact dermatitis to dental materials. Previous treatment with corticosteroids did not have any therapeutic effect. Patch testing revealed a positive reaction to several allergens, including dental amalgam and mercury in 2 cases. A lymphocyte transformation test modified for metals was used to evaluate lymphocyte reactivity. After the removal of the suspected allergens, all patients experienced recovery within 1 month, with the exception of the lip swelling, which gradually subsided over several months.”

“OBJECTIVES:

For many years an amalgam containing metallic mercury, which has been associated with neurological and renal diseases, has been used in dentistry. In this nationwide study we compared hospital admissions due to neurological and renal diseases among dentists and dental assistants to admissions in controls.

METHODS:

This register-based cohort study included all Danish workers employed in dental clinics, general practitioners’ clinics or lawyers’ offices between 1964 and 2006. We compared dentists with general practitioners and lawyers, and dental assistants with medical secretaries, nurses and legal secretaries. We also compared dentists and dental assistants employed during periods with high occupational mercury exposure with dentists and dental assistants employed during periods with less mercury exposure. We followed all subjects in a nationwide register of hospital admissions. We analysed risk of neurological diseases, Parkinson’s disease and renal diseases using a Cox regression model.

RESULTS:

The cohort consisted of 122,481 workers including 5371 dentists and 33,858 dental assistants. For neurological diseases, no association was observed for dental assistants, while for dentists an increasing risk for periods with less mercury exposure was observed. Among dental assistants, a negative association between employment length and risk of neurological disease was observed. Admissions for renal disease among dental assistants were increased during periods with less mercury exposure compared with controls. For dentists a non-significant increased risk was observed between employment length and renal disease risk.

CONCLUSIONS:

Our nationwide study does not indicate that occupational exposure to mercury increases the risk of hospital admissions for neurological, Parkinson’s or renal diseases.”

“Environmental pollution is a product of urbanization and technology, and other attendant factors of population density, industrialization and mechanization that serve to provide the necessities of the population. For example, in cities of developing countries, the rural-urban migration activated by the search for increased incomes has resulted in the concentration of large populations in relatively small areas under poor conditions of sanitation. Traffic jams and the legendary ‘go-slow’ of automobiles are everyday occurrences in these cities. The impact of pollution in the vicinity of overcrowded cities and from industrial effluents and automobile exhausts has reached a disturbing magnitude and is arousing public awareness. At present, no enough data are available on the extent of environmental pollution because there are no agencies charged with the routine monitoring and protection of the environment. This chapter therefore focuses on the critical issues of heavy metals (HMs) pollution in rapidly developing nations. Once emitted from their sources, they have the property of accumulating in the environment for many years. They enter the human body through inhalation, ingestion, and dermal. They also can accumulate in the bodies of animals and humans before they even cause damage. However; HMs such as Lead (Pb), Cadmium (Cd), Arsenic (As), Manganese (Mn) Nickel (Ni), Chromium (Cr) and Mercury (Hg), are also metabolized in the body in a similar way to nutrient metals. Environmental exposure to HMs can occur through air, soil, drinking water and food stuff. The neurotoxic effects of exposure HMs in the environment, though insufficiently recognized, remains a topic of sub stantial current concern and interest as it could be considered an early endpoint for health effects induced by exposure to heavy metals.In addition, they can adversely affect the quality of life, and have broad health, social and economic implications. Special concern is directed to children as they are the most sensitive population exposed to environmental pollution in general and heavy metals in specific. Finally, the magnitude and potential severity of neurotoxicity problems make it imperative to direct researches towards preventive intervention, and focus on the development of new biomarkers for neurotoxicity at the individual and population levels with emphasis on health education about HMs exposure and their potential for neurotoxicity. The establishment of comprehensive monitoring systems and information gathering should be given priority by governments of the developing countries in the sub-region with support and encouragement from international agencies.”

“The experimental and analytical difficulties associated with the measurement of mercury vapor in the oral cavity are considerable. In the present paper, the objective was to measure the amount of intra-oral mercury vapor in subjects with amalgams, by means of two sets of equipment based on different functional principles. In addition, it was found that the type of mercury source prevalent in the oral cavity had to be evaluated. The measuring technique used to obtain correct results is discussed, and an evaluation of the conditions for the application of the measuring equipment available was made. It was found that the amount of mercury released from the oral cavity was time-dependent. Furthermore, the amount of mercury released with the time kept constant was almost independent of the pumping flow rate up to 8 L/min. It was found that the tissue, saliva, and the amalgam restorations were not depleted of mercury during the measuring time. The results of the Mercollector-Mercometer measurements carried out on seven subjects with nine or more occlusal surfaces restored with dental amalgam and on three subjects without any amalgam restorations revealed that the rate of mercury release was in the range 0.03-0.34 ng/sec in the former group and less than 0.01 ng/sec in the latter. Based on the experimental results and on theoretical considerations, it was concluded that the amount of mercury released per time unit is the only quantity measurable.”