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Concentrations of copper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) in muscle and gills of four Benthic fish species (Brachirus orientalis, Argyrops spinifer, Platycephalus indicus and Sillago sihama) from Shif Island of Iran were analyzed using flame atomic absorption spectrometry. The heavy metal levels observed in tissues varied for Cu: 2.15-820.98, Fe: 24.46-533.26, Mn: 1.80-53.17, Ni: 1.86-65.54 and Zn: 28.77-375.79 mg/kg. Significant differences were found among muscle and gill of the four fish species. Heavy metals concentration were significantly (p < 0.05) higher in the gill than in the muscles of all fish species studied. The metal levels in benthic fish species should be continuously monitored in polluted areas since benthic fish indicated a tendency to bioaccumulate pollutants in their tissues from polluted water. The indices of Estimated Daily Intake, Target Hazard Quotient and Hazard Index suggests no risk while carcinogenic risk for Ni showed unacceptable carcinogenic risk.

Crude oil contamination in soils may result in destructive effects on soil microorganisms and plants and act as a source of groundwater contamination. The objective of this study was to evaluate the biological activities for a better understanding of ecological risks. A couple of biological assays, including soil microbial biomass of carbon (SMBC) and urease activity (UA), were used to evaluate the microbial activities in soils. The chemical analysis demonstrated different values of total petroleum hydrocarbons (TPHs) concentrations (from 0.12 to 2.99 mg/kg of dry soil) and relatively high quantities of Nickel (from 32 to 136.8 mg/kg of dry soil) and cadmium (from 0 to 4 mg/kg of dry soil) in samples. UA and SMBC values were comparatively lower in close distances to oil wells, pipelines, and especially drilling sediments pool. The spatial variability maps using the interpolation module by GIS specified the line from northwest to the southeast of the area as a more affected area by TPHs and Ni + Cd., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Elevated contents of mercury (Hg) and nickel (Ni) in soils and foodstuffs can threaten human health. As contents of these metals in soil, water and food vary from place to place, the associated risks will also be different in various parts of a region and it should be considered for environmental decision making and human health management. The objective of this study was to map the variation of human health risks related to Ni and Hg in soil, water and foodstuffs across an entire region, in province of Hamedan western Iran as an example case. Risks were calculated using the methods proposed by USEPA. The risk maps showed that total non-cancer relative risks of Ni and Hg were much higher than 1 (critical level). Risk of Ni in Razan and Kaboudarahang was higher than other counties. For some areas, relative non-cancer risks associated with exposure to Hg were estimated up to 7 and 11 in children and adults respectively. Consumption of plant foods particularly wheat was found to be the major route of human exposure to Ni and Hg. Soil ingestion was found to be another important route of human exposure to these metals., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Effect of long-term orthodontic treatment on salivary nickel and chromium has not been quite assessed except in few retrospective studies with controversial results. The aim of this prospective study was to measure salivary levels of these ions during 1 year of orthodontic treatment. Saliva samples were collected from 20 orthodontic patients, before treatment (control) and 6 and 12 months later. Nickel and chromium concentrations were determined using atomic absorption spectrophotometry. Data were analyzed using one- and two-way repeated-measures ANOVA, Bonferroni, Friedman (α = 0.05), and Wilcoxon signed-ranks tests (α = 0.016). Average nickel level changed from 9.75 ± 5.02 to 10.37 ± 6.94 and then to 8.32 ± 4.36 μg/L in 1 year. Average chromium concentration changed from 3.86 ± 1.34 to 4.6 ± 6.11 and then to 2.04 ± 1.66 μg/L. Alterations in nickel values were not statistically significant [P = 0.468 (ANOVA)], but fluctuations in chromium levels were [P = 0.021 (Friedman)]. The decrease in chromium concentration after 12 months was significant compared to the control [P = 0.004 (Wilcoxon)]. Although slightly increased after 6 months, the concentration of both ions dropped to levels slightly lower than the control groups after 12 months.

Nickel constitutes about 8-60 % of orthodontic alloys. It is known as an allergenic/cytotoxic trace metal. Therefore, it should be investigated in patients undergoing orthodontic treatment which might last for 2 or 3 years. However, no controlled studies have assessed the influence of orthodontic treatments of longer than 5 months on its systemic levels. Thus, the aim of this retrospective cohort study was to evaluate systemic nickel in patients undergoing orthodontic therapy for a minimum period of 1 year. In this study, urinary nickel concentrations in 20 female and 10 male patients being treated with stainless steel appliances were measured using atomic absorption spectrophotometry. The same procedure was done on a control group of the patients' same-gender near-age siblings (n = 30). The effect of treatment and gender on urinary nickel levels were assessed using a repeated-measures two-way analysis of variance (ANOVA) and a Tukey test (α = 0.05). The mean treatment duration was 17.1 ± 6.4 months (range, 12-21). The mean nickel concentrations in male and female patients were 9.67 ± 3.25 and 9.9 ± 3.83 μg/L, respectively. These statistics for male and female control subjects were 6.65 ± 2.57 and 8.43 ± 2.94 μg/L, respectively. The ANOVA showed a statistically significant difference between the urinary nickel levels of the treatment and the control groups (P = 0.009) but not between the genders (P = 0.194). The interaction between gender and treatment was also nonsignificant (P = 0.337). The Tukey test indicated that the increase in nickel was higher in male patients, in comparison to their brothers (P < 0.05). It could be concluded that orthodontic therapy for longer durations with stainless-steel archwires might elevate slightly, but significantly, urinary nickel levels.

Objective: To determine the effects of water hardness on the toxicities of cobalt (Co) and nickel (Ni) to a freshwater fish, Capoeta fusca., Methods: Toxicity was investigated by static bioassay. Fish were exposed to cobalt (as CoCl(2)) and nickel (as NiCl(2)) for 96 h in waters with two levels of hardness ("hard" and "very hard", nominally 130 mg/L and 350 mg/L as CaCO(3), respectively)., Results: Water hardness had a significant effect on the acute toxicity of both elements. The 96 h LC(50) values for Co were 91.7 mg/L and 204.8 mg/L in hard and very hard waters, respectively, and for Ni the 96 h LC(50) values were 78.0 mg/L and 127.2 mg/L, respectively., Conclusion: The fish were more sensitive to Co and Ni toxicity in hard water than in very hard water; very hard water protects C. fusca against the toxicity of Co and Ni., (Copyright © 2011 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.)