Atmospheric pollution by potentially toxic elements: measurement and risk assessment using lichen transplants

The lichen Usnea articulata collected from an unpolluted area was exposed for 6 months at 26 sites for the sample chosenusing a stratified random design, and the content of potentially toxic elements (PTEs) including As, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sn, V, and Zn, was assessed using ICP-MS. The health risk for both adults and children was then calculated using the PTEs concentrations. The results showed that despite the hostile urban conditions, transplanted lichens depicted clear deposition patterns of airborne PTEs, mostly associated with industrial sites, where As and other elements showed remarkably high values. The cumulative hazard index was below the risk threshold, both for adults and children. For the entire population (particularly children) residing in areas surrounding industrial sites, As and Cr appeared to be potentially carcinogenic elements.

New mechanistic approach of inorganic palladium toxicity: impairment in mitochondrial electron transfer

Human activities have increased the levels of palladium (Pd) that are progressively accumulating in the environment. The growing evidence of Pd toxicity has become the focus of serious concern for the environment, organisms and humans, with little data on the mechanism of Pd toxicity. Recent studies have suggested that mitochondria have a key role in Pd toxicity via mitochondrial membrane potential collapse and depletion of the cellular glutathione (GSH) level. Therefore, it was decided to determine the mechanistic toxicity of Pd towards isolated mitochondria via new and reliable methods. Isolated liver and kidney mitochondria were obtained by differential ultracentrifugation and incubated with different concentrations of Pd (100-400 μM). Our results showed that Pd induced mitochondrial dysfunction via an increase in mitochondrial ROS production and membrane potential collapse, which correlated to cytochrome c release. Also, increased disturbance in oxidative phosphorylation was also shown by the increase in ADP/ATP ratio in Pd-treated mitochondria, which indicates mitochondrial dysfunction in isolated liver and kidney mitochondria. Our results suggest that Pd-induced toxicity is the result of a disruptive effect on the mitochondrial respiratory chain, increasing the chance of cell death signaling. In addition, it is supposed that kidney tissue is more susceptible to Pd exposure than liver tissue.

The Clinical Effectiveness of Various Adhesive Systems: An 18-Month Evaluation

The aim of this clinical trial was to compare the clinical performance of three different adhesive systems over 18 months in noncarious cervical lesions (NCCLs). Thirty patients, with at least three noncarious cervical lesions, were enrolled in the study. One operator randomly restored a total of 90 lesions with resin composite (Herculite XRV). The restorations were bonded with either Optibond FL (OF), three-step total-etch; Optibond Solo Plus (OS), two-step total-etch; or Optibond All-In-One (OA), one step self-etch. The restorations were clinically evaluated at baseline and after six, 12, and 18 months using the eight United States Public Health Services criteria. Data were analyzed using Friedman and Wilcoxon signed ranks tests (p<0.05). After 18 months, the retention rate was (OF) 96.5%, (OS) 93.1%, and (OA) 89.7%. Differences among the three adhesive systems for evaluated criteria were not observed in comparison of the mean Alfa score percentages. There was a significant increase in marginal discoloration for (OA) adhesive after 18 months compared with baseline (p=0.011). Other restoration criteria had no statistically significant differences among the three adhesives (p>0.05). With the exception of marginal discoloration, the clinical effectiveness of three types of adhesive systems in NCCLs was acceptable after 18 months. However, using the one-step self-etch adhesive may lead to some marginal discolorations.

Calculation of total effective dose equivalent and collective dose in the event of a LOCA in Bushehr Nuclear Power Plant

In this research, total effective dose equivalent (TEDE) and collective dose (CD) are calculated for the most adverse potential accident in Bushehr Nuclear Power Plant from the viewpoint of radionuclides release to the environment. Calculations are performed using a Gaussian diffusion model and a slightly modified version of AIREM computer code to adopt for conditions in Bushehr. The results are comparable with the final safety analysis report which used DOZAM code. Results of our calculations show no excessive dose in populated regions. Maximum TEDE is determined to be in the WSW direction. CD in the area around the nuclear power plant by a distance of 30 km (138 man Sv) is far below the accepted limits. Thyroid equivalent dose is also calculated for the WSW direction (maximum 25.6 mSv) and is below the limits at various distances from the reactor stack.