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So far Richardson GM. has created 991 blog entries.

Mercury exposure and risks from dental amalgam in Canada: the Canadian health measures survey 2007–2009. Human and Ecological Risk Assessment

Dental amalgam is 50% metallic mercury (Hg) by weight and Hg vapour continuously evolves from in-place dental amalgam, causing increased Hg content with increasing amalgam load in urine, faeces, exhaled breath, saliva, blood, and various organs and tissues including the kidney, pituitary gland, liver, and brain. The Hg content also increases with maternal amalgam load in amniotic fluid, placenta, cord blood, meconium, various foetal tissues including liver, kidney and brain, in colostrum and breast milk. Based on 2001 to 2004 population statistics, 181.1 million Americans carry a grand total of 1.46 billion restored teeth. Children as young as 26 months were recorded as having restored teeth. Past dental practice and recently available data indicate that the majority of these restorations are composed of dental amalgam. Employing recent US population-based statistics on body weight and the frequency of dentally restored tooth surfaces, and recent research on the incremental increase in urinary Hg concentration per amalgam-filled tooth surface, estimates of Hg exposure from amalgam fillings were determined for 5 age groups of the US population. Three specific exposure scenarios were considered, each scenario incrementally reducing the number of tooth surfaces assumed to be restored with amalgam. Based on the least conservative of the scenarios evaluated, it was estimated that some 67.2 million Americans would exceed the Hg dose associated with the reference exposure level (REL) of 0.3 μg/m(3) established by the US Environmental Protection Agency; and 122.3 million Americans would exceed the dose associated with the REL of 0.03 μg/m(3) established by the California Environmental Protection Agency. Exposure estimates are consistent with previous estimates presented by Health Canada in 1995, and amount to 0.2 to 0.4 μg/day per amalgam-filled tooth surface, or 0.5 to 1 μg/day/amalgam-filled tooth, depending on age and other factors.

By |2019-06-21T18:08:42+00:00January 1st, 2012|Mercury|

An evaluation of amalgam separators.

The ADA Laboratories purchased and evaluated nine amalgam separators available in the United States to determine their efficiency of amalgam removal. Table 1 lists all amalgam separators tested with product information provided by each manufacturer.

By |2018-07-19T20:34:38+00:00January 1st, 2012|Mercury|

Polyfluorinated Chemicals and Transformation Products.

With this edition of The Handbook of Environmental Chemistry “Polyfluorinated Chemicals and Transformation Products” we aim to give an overview of the recent state of the art. Polyfluorinated chemicals (PFC) are widespread substances with effective and measurable effects to environment and economy. Topics, such as synthesis and application, analysis and degradation as well as environmental aspects, food and toxicity are spotlighted.

By |2018-07-24T19:42:04+00:00January 1st, 2012|Fluoride|

Epidemiology of environmental exposures and human autoimmune diseases: findings from a National Institute of Environmental Health Sciences Expert Panel Workshop.

Autoimmune diseases (AID) are a collection of many complex disorders of unknown etiology resulting in immune responses to self-antigens and are thought to result from interactions between genetic and environmental factors. Here we review the epidemiologic evidence for the role of environmental factors in the development of human AID, the conclusions that can be drawn from the existing data, critical knowledge gaps, and research needed to fill these gaps and to resolve uncertainties. We specifically summarize the state of knowledge and our levels of confidence in the role of specific agents in the development of autoimmune diseases, and we define the areas of greatest impact for future investigations. Among our consensus findings we are confident that: 1) crystalline silica exposure can contribute to the development of several AID; 2) solvent exposure can contribute to the development of systemic sclerosis; 3) smoking can contribute to the development of seropositive rheumatoid arthritis; and 4) an inverse association exists between ultraviolet radiation exposure and the risk of development of multiple sclerosis. We suggest that more studies of phenotypes, genotypes, and multiple exposures are needed. Additional knowledge gaps needing investigation include: defining important windows in the timing of exposures and latencies relating to age, developmental state, and hormonal changes; understanding dose-response relationships; and elucidating mechanisms for disease development. Addressing these essential issues will require more resources to support research, particularly of rare AID, but knowledge of the risks conferred by environmental factors in specific genetic contexts could pave the way for prevention of AID in the future.

Oral fluoroquinolones and the risk of retinal detachment.

CONTEXT:
Fluoroquinolones are commonly prescribed classes of antibiotics. Despite numerous case reports of ocular toxicity, a pharmacoepidemiological study of their ocular safety, particularly retinal detachment, has not been performed.

OBJECTIVE:
To examine the association between use of oral fluoroquinolones and the risk of developing a retinal detachment.

DESIGN, SETTING, AND PATIENTS:
Nested case-control study of a cohort of patients in British Columbia, Canada, who had visited an ophthalmologist between January 2000 and December 2007. Retinal detachment cases were defined as a procedure code for retinal repair surgery within 14 days of a physician service code. Ten controls were selected for each case using risk-set sampling, matching on age and the month and year of cohort entry.

MAIN OUTCOME MEASURE:
The association between retinal detachment and current, recent, or past use of an oral fluoroquinolone.

RESULTS:
From a cohort of 989,591 patients, 4384 cases of retinal detachment and 43,840 controls were identified. Current use of fluoroquinolones was associated with a higher risk of developing a retinal detachment (3.3% of cases vs 0.6% of controls; adjusted rate ratio [ARR], 4.50 [95% CI, 3.56-5.70]). Neither recent use (0.3% of cases vs 0.2% of controls; ARR, 0.92 [95% CI, 0.45-1.87]) nor past use (6.6% of cases vs 6.1% of controls; ARR, 1.03 [95% CI, 0.89-1.19]) was associated with a retinal detachment. The absolute increase in the risk of a retinal detachment was 4 per 10,000 person-years (number needed to harm = 2500 computed for any use of fluoroquinolones). There was no evidence of an association between development of a retinal detachment and β-lactam antibiotics (ARR, 0.74 [95% CI, 0.35-1.57]) or short-acting β-agonists (ARR, 0.95 [95% CI, 0.68-1.33]).

CONCLUSION:
Patients taking oral fluoroquinolones were at a higher risk of developing a retinal detachment compared with nonusers, although the absolute risk for this condition was small.

Evidence that bisphenol a exposure is not associated with composite resin dental fillings.

In their recent article, Maserejian et al.(1) propose bisphenol-a (BPA) exposure as a hypothesis to explain apparent psychosocial effects in children of the New England Children’s Amalgam Trial (NECAT) who received composite resin fillings. The authors rightly point out that a “thorough investigation considering exposure levels is important to substantiate these findings”. Within the NECAT, no direct measure of BPA exposure, such as BPA concentration in urine, was reported. Data from Cycle 1 of the Canadian Health Measures Survey (2,3) (CHMS, 2007-2009) suggests that exposure to BPA is not associated with the presence of composite resin fillings.

By |2018-07-30T18:48:01+00:00January 1st, 2012|Other|

Release of metal ions from orthodontic appliances: an in vitro study.

In this paper, we report the results of an in vitro experiment on the release of metal ions from orthodontic appliances composed of alloys containing iron, chromium, nickel, silicon, and molybdenum into artificial saliva. The concentrations of magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel, and chromium were significantly higher in artificial saliva in which metal brackets, bands, and wires used in orthodontics were incubated. In relation to the maximum acceptable concentrations of metal ions in drinking water and to recommended daily doses, two elements of concern were nickel (573 vs. 15 μg/l in the controls) and chromium (101 vs. 8 μg/l in the controls). Three ion release coefficients were defined: α, a dimensionless multiplication factor; β, the difference in concentrations (in micrograms per liter); and γ, the ion release coefficient (in percent). The elevated levels of metals in saliva are thought to occur by corrosion of the chemical elements in the alloys or welding materials. The concentrations of some groups of dissolved elements appear to be interrelated.

By |2018-07-26T18:32:49+00:00January 1st, 2012|Other|

Blood cadmium, mercury, and lead in children: an international comparison of cities in six European countries, and China, Ecuador, and Morocco.

Children’s blood-lead concentration (B-Pb) is well studied, but little is known about cadmium (B-Cd) and mercury (B-Hg), in particular for central Europe. Such information is necessary for risk assessment and management. Therefore, we here describe and compare B-Pb, B-Cd and B-Hg in children in six European, and three non-European cities, and identify determinants of these exposures. About 50 school children (7-14 years) from each city were recruited (totally 433) in 2007-2008. Interview and questionnaire data were obtained. A blood sample was analyzed: only two laboratories with strict quality control were used. The European cities showed only minor differences for B-Cd (geometric means 0.11-0.17 μg/L) and B-Pb (14-20 μg/L), but larger for B-Hg (0.12-0.94 μg/L). Corresponding means for the non-European countries were 0.21-0.26, 32-71, and 0.3-3.2 μg/L, respectively. For B-Cd in European samples, traffic intensity close to home was a statistically significant determinant, for B-Hg fish consumption and amalgam fillings, and for B-Pb sex (boys higher). This study shows that European city children’s B-Cd and B-Pb vary only little between countries; B-Hg differs considerably, due to varying tooth restoration practices and fish intake. Traffic intensity seemed to be a determinant for B-Cd. The metal concentrations were low from a risk perspective but the chosen non-European cities showed higher concentrations than the cities in Europe.

Perception of patients with amalgam fillings about toxicity of mercury in dental amalgam.

OBJECTIVE:
The objective of this study is to evaluate the awareness of patients with dental fillings about the toxicity of mercury in dental amalgam.

MATERIALS AND METHODS:
Adult patients having at least one amalgam filling in their mouth were recruited in the Oral Diagnosis Department of OAUTHC, Ile-Ife Dental Hospital. Participants were recruited consecutively as they report in the clinic. Data were collected using a structured questionnaire developed based on standard questions from relevant publications. They were asked to indicate the type of filling material in their mouth, ingredients of the material, previous knowledge of mercury in dental amalgam and ailments due to mercury. They were to indicate their level of agreement with filling their cavities with dental amalgam despite prior information about its mercury content.

RESULTS:
There were about 446 respondents analyzed; male, 194 (43.5%); female 252 (56.5%). Six (1.4%) and 21 (4.7%) respondents were primary and secondary schools students respectively; 15(3.4%) had no formal education while about 410 (91.9%) were either undergraduate or graduate. All of them had at least one amalgam filling. 249 (55%) participants know the type of filling on their teeth; 156 (34.5%) had the knowledge of the presence of mercury in dental amalgam while 26.1% believed mercury can cause problems in human beings. About 90 (19.9%) participants claimed to have heard about adverse reactions to dental amalgams and 34 (7.5%) of them have heard about people recovering from an illness after removal of their filling. The level of agreement with filling their cavities with amalgam despite prior knowledge of its mercury content was 74% while 60% was observed for allowing just any material to be placed on their teeth.

CONCLUSION:
Awareness of toxicity of mercury in dental amalgam was slightly low among the respondents studied. This may be suggested to be a reflection of nonexistent of global amalgam controversy in Nigeria.

By |2018-07-18T19:31:57+00:00January 1st, 2012|Mercury|

Practical issues for purchasing, installing and maintaining dental amalgam separators.

OVERVIEW:
The authors review factors related to office infrastructure and operation that dentists should consider when investing in an amalgam separator. They also provide a cost-analysis worksheet and checklist that may be useful to dentists who are considering purchasing a separator.

CONCLUSIONS AND CLINICAL IMPLICATIONS:
Before purchasing or installing an amalgam separator, dentists should consider factors specific to the available models, including size and maintenance requirements. In addition, office-specific actors should be considered (such as the plumbing configuration, available space for installation and subsequent access to that space for equipment replacement and maintenance). Dentists also should research whether any local or state regulations exist that might influence product selection or installation. Dentists should consider the effect an amalgam separator could have on existing suction equipment. Finally, dentists will want to consider the short- and long-term costs (including maintenance and parts replacement) of the available options.

By |2018-07-26T16:34:55+00:00January 1st, 2012|Mercury|
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