adam, Author at IAOMT Library

Heavy metal toxicity and the environment.

Heavy metals are naturally occurring elements that have a high atomic weight and a density at least 5 times greater than that of water. Their multiple industrial, domestic, agricultural, medical and technological applications have led to their wide distribution in the environment; raising concerns over their potential effects on human health and the environment. Their toxicity depends on several factors including the dose, route of exposure, and chemical species, as well as the age, gender, genetics, and nutritional status of exposed individuals. Because of their high degree of toxicity, arsenic, cadmium, chromium, lead, and mercury rank among the priority metals that are of public health significance. These metallic elements are considered systemic toxicants that are known to induce multiple organ damage, even at lower levels of exposure. They are also classified as human carcinogens (known or probable) according to the U.S. Environmental Protection Agency, and the International Agency for Research on Cancer. This review provides an analysis of their environmental occurrence, production and use, potential for human exposure, and molecular mechanisms of toxicity, genotoxicity, and carcinogenicity.

By Tchounwou PB, Yedjou CG, Patlolla AK, Sutton DJ.|2018-08-02T21:27:12+00:00January 1st, 2012|Mercury|

Hidden tooth infections may predispose people to heart disease.

An infection of the root tip of a tooth increases the risk of coronary artery disease, even if the infection is symptomless. Hidden dental root tip infections are very common: as many as one in four in Finland suffer from at least one. Such infections are usually detected by chance from Xrays.

By University of Helsinki|2019-05-28T21:21:33+00:00January 1st, 2012|Other|

The toxicology of mercury and its compounds.

A concentrated review on the toxicology of inorganic mercury together with an extensive review on the neurotoxicology of methylmercury is presented. The challenges of using inorganic mercury in dental amalgam are reviewed both regarding the occupational exposure and the possible health problems for the dental patients. The two remaining “mysteries” of methylmercury neurotoxicology are also being reviewed; the cellular selectivity and the delayed onset of symptoms. The relevant literature on these aspects has been discussed and some suggestions towards explaining these observations have been presented.

By Syversen T, Kaur P.|2018-08-02T21:10:57+00:00January 1st, 2012|Mercury|

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 Richardson GM.|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 Chou HN, Anglen J.|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 Knepper TP, Lange FT, editors.|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.

By Miller FW, Alfredsson L, Costenbader KH, Kamen DL, Nelson LM, Norris JM, De Roos AJ.|2018-07-26T18:49:13+00:00January 1st, 2012|Mercury, Other|

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.

By Etminan M, Forooghian F, Brophy JM, Bird ST, Maberley D.|2018-07-20T18:48:29+00:00January 1st, 2012|Fluoride|

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 Richardson GM.|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 Mikulewicz M, Chojnacka K, Woźniak B, Downarowicz P.|2018-07-26T18:32:49+00:00January 1st, 2012|Other|

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About Tchounwou PB, Yedjou CG, Patlolla AK, Sutton DJ.