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Background:This study evaluated Thimerosal-containing childhood vaccines and the risk of a diagnosis called disturbance of emotions specific to childhood and adolescence (ED). Thimerosal is an organic-mercury (Hg)-containing compound used in some vaccines.

Methods: A hypothesis-testing prospective, longitudinal case-control study evaluated Hg exposure from Thimerosal in hepatitis B vaccines administered at specific times within the first 6 months of life and its association with medically diagnosed ED (313.xx) (n = 517) in children born between 1991–2000 in comparison to controls (n = 27 491) in the Vaccine Safety Datalink (VSD) database.

Results: Cases diagnosed with ED were significantly more likely than controls to have received increased Hg exposure within the first month of life (odds ratio (OR) = 1.3384), the first 2 months of life (OR = 1.3367) and the first 6 months of life (OR = 2.37). When the data were separated by gender, similar significant adverse effects were observed for males, but not females. On a per microgram Hg basis, cases diagnosed with ED were significantly more likely than controls to have received increased exposure within the first 6 months of life (OR = 1.025 per microgram Hg).

Conclusions: The results show a significant relationship between Hg exposure from Thimerosal-containing childhood vaccines and the subsequent risk of an ED diagnosis.

Methods
Kidney cortex biopsies and urine and blood samples were collected from 109 living kidney donors. Total Hg concentrations were determined and the relationships between K-Hg, U-Hg, P-Hg, and B-Hg were investigated in regression models. The half-time of K-Hg was estimated from the elimination constant.

Results
There were strong associations between K-Hg and all measures of U-Hg and P-Hg (rp = 0.65–0.84, p < 0.001), while the association with B-Hg was weaker (rp = 0.29, p = 0.002). Mean ratios between K-Hg (in μg/g) and U-Hg/24h (in μg) and B-Hg (in μg/L) were 0.22 and 0.19 respectively. Estimates of the biological half-time varied between 30 and 92 days, with significantly slower elimination in women. Adjusting overnight urine samples for dilution using urinary creatinine resulted in less bias in relation to K-Hg or U-Hg/24h, compared with other adjustment techniques.

Conclusions
The relationship between K-Hg and U-Hg is approximately linear. K-Hg can be estimated using U-Hg and gender. Women have longer half-time of Hg in kidney compared to men. Adjusting overnight urine samples for creatinine concentration resulted in less bias.”

This study focused on the evaluation of the levels of total mercury in hair among 120 breastfeeding mothers aged 20 to 45 -. The concentrations of Hg ranged from 0.07 to 6.87 μg/g with a geometric mean (GM) of 1.22 μg/g. This GM is six times higher than the average internal exposure of mothers from other 17 European countries (0.225 μg/g). Near 70% of mothers presented levels of Hg above the USA EPA internal exposure guideline of 1 μg/g, and 27% exceeded the EFSA health-based guidance value of 1.9 μg/g. The multivariate regression analysis revealed that age, smoking and fish consumption (sword fish, small fat fish, small lean fish) were the major predictors of mercury in hair.

The research conducted on humans in this area is diverse in study design and the results are conflicting. There is currently no evidence to implicate a role for Hg0 exposure from dental amalgams in the development or perpetuation of autoimmune disease, apart from some suggestion of individual sensitivity. Several studies have consistently shown a positive correlation between iHg exposure and serum autoantibody concentrations in gold miners, although the clinical impact of iHg remains unknown. Furthermore, a limited number of studies have reported individuals with autoimmune disease have higher concentrations of blood Hg compared to healthy controls. In summary, it appears that iHg perpetuates markers of autoimmunity to a greater extent than oHg, albeit the impact on clinical outcomes in humans is yet to be elucidated.

Considerable effort has been made to address the issue of occupational health and environmental exposure to mercury. This review reports on the current literature of mercury exposure and health impacts on dental personnel. Citations were searched using four comprehensive electronic databases for articles published between 2002 and 2015. All original articles that evaluated an association between the use of dental amalgam and occupational mercury exposure in dental personnel were included. Fifteen publications from nine different countries met the selection criteria. The design and quality of the studies showed significant variation, particularly in the choice of biomarkers as an indicator of mercury exposure. In several countries, dental personnel had higher mercury levels in biological fluids and tissues than in control groups; some work practices increased mercury exposure but the exposure levels remained below recommended guidelines. Dental personnel reported more health conditions, often involving the central nervous system, than the control groups. Clinical symptoms reported by dental professionals may be associated with low-level, long-term exposure to occupational mercury, but may also be due to the effects of aging, occupational overuse, and stress. It is important that dental personnel, researchers, and educators continue to encourage and monitor good work practices by dental professionals

Historically, entities with a vested interest in a product that critics have suggested is harmful have consistently used research to back their claims that the product is safe. Prominent examples are: tobacco, lead, bisphenol A, and atrazine. Research literature indicates that about 80-90% of studies with industry affiliation found no harm from the product, while only about 10-20% of studies without industry affiliation found no harm. In parallel to other historical debates, recent studies examining a possible relationship between mercury (Hg) exposure and autism spectrum disorder (ASD) show a similar dichotomy. Studies sponsored and supported by industry or entities with an apparent conflict of interest have most often shown no evidence of harm or no “consistent” evidence of harm, while studies without such affiliations report positive evidence of a Hg/autism association. The potentially causal relationship between Hg exposure and ASD differs from other toxic products since there is a broad coalition of entities for whom a conflict of interest arises. These include influential governmental public health entities, the pharmaceutical industry, and even the coal burning industry. This review includes a systematic literature search of original studies on the potential relationship between Hg and ASD from 1999 to August 2015, finding that of the studies with public health and/or industry affiliation, 86% reported no relationship between Hg and ASD. However, among studies without public health and/or industry affiliation, only 21% find no relationship between Hg and ASD. The discrepancy in these results suggests a bias indicative of a conflict of interest.

All types of dental amalgams contain mercury, which partly is emitted as mercury vapor. All types of dental amalgams corrode after being placed in the oral cavity. Modern high copper amalgams exhibit two new traits of increased instability. Firstly, when subjected to wear/polishing, droplets rich in mercury are formed on the surface, showing that mercury is not being strongly bonded to the base or alloy metals. Secondly, high copper amalgams emit substantially larger amounts of mercury vapor than the low copper amalgams used before the 1970s. High copper amalgams has been developed with focus on mechanical strength and corrosion resistance, but has been sub-optimized in other aspects, resulting in increased instability and higher emission of mercury vapor. This has not been presented to policy makers and scientists. Both low and high copper amalgams undergo a transformation process for several years after placement, resulting in a substantial reduction in mercury content, but there exist no limit for maximum allowed emission of mercury from dental amalgams. These modern high copper amalgams are nowadays totally dominating the European, US and other markets, resulting in significant emissions of mercury, not considered when judging their suitability for dental restoration.

In conclusion, we found that younger people with six or more amalgam restorations exhibited a 20%-fold elevated risk of future ADHD in the univariate Cox model, relative to those who received composite resin or glass ionomer restorations. However, that the association disappeared after adjustment for age may indicate that those with six or more amalgam restorations were slightly older and may have had a longer exposure period in which to develop/be diag-nosed with ADHD. This demonstrates the difficulty in interpreting findings from large observational studies such as this where con-founding may be subtle but important. Thus, the current findings revealed that the receipt of amalgam restorations in young patients was not associated with a higher risk of future diagnosis of ADHD.