Effects of the real-life metal(oid)s mixture on female reproductive function: Less is different

The current study aimed to examine the effect of toxic metal(oid) mixtures (lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr), and nickel (Ni)) on female reproductive function in Wistar rats after the 28- and 90-day exposure to dose levels calculated on the basis of the previously conducted human study. Experimental groups included: 2 controls (28- and 90-day), treated groups - doses based on: median- F2 (28) and F2(90) and 95th percentile concentrations in the general human population - F3(28) and F3(90); calculated lower Benchmark dose confidence limit (BMDL) for effects on hormone levels - F1(28) and F1(90) and a group given the doses calculated on the basis of the reference values from the literature (F4(28)). Blood and ovarian samples were collected for sex hormones and ovary redox status analysis. After 28-day exposure, changes were present both in prooxidants and antioxidants. However, after the 90-day exposure redox status imbalance was majorly caused by the disturbance of antioxidants. Changes in some parameters were observed even after exposure to the lowest doses. After 28-day exposure, the strongest dose-response relationship was found between hormones: LH and FSH and toxic metal(oid)s and, after 90-day exposure, between investigated redox status parameters: sulfhydryl groups, ischemia-modified albumin and nuclear factor erythroid 2-related factor 2 (Nrf2) and toxic metal(oid)s. Low obtained BMDLs and narrow Benchmark intervals for toxic metal(oid)s and some of the parameters might confirm the "no-threshold" paradigm. This study indicates possible detrimental effects of prolonged exposure to real-life mixtures of toxic metal(oid) on female reproductive function.

Nickel as a potential disruptor of thyroid function: benchmark modelling of human data

Introduction

Nickel (Ni) is one of the well-known toxic metals found in the environment. However, its influence on thyroid function is not explored enough. Hence, the aim of this study was to analyse the potential of Ni to disrupt thyroid function by exploring the relationship between blood Ni concentration and serum hormone levels (TSH, T4, T3, fT4 and fT3), as well as the parameters of thyroid homeostasis (SPINA-GT and SPINA-GD) by using correlation analysis and Benchmark (BMD) concept.

Methods

Ni concentration was measured by ICP-MS method, while CLIA was used for serum hormone determination. SPINA Thyr software was used to calculate SPINA-GT and SPINA-GD parameters. BMD analysis was performed by PROAST software (70.1). The limitations of this study are the small sample size and the uneven distribution of healthy and unhealthy subjects, limited confounding factors, as well as the age of the subjects that could have influenced the obtained results.

Results and discussion

The highest median value for blood Ni concentration was observed for the male population and amounted 8,278 µg/L. Accordingly, the statistically significant correlation was observed only in the male population, for Ni-fT4 and Ni-SPINA-GT pairs. The existence of a dose-response relationship was established between Ni and all the measured parameters of thyroid functions in entire population and in both sexes. However, the narrowest BMD intervals were obtained only in men, for Ni - SPINA-GT pair (1.36-60.9 µg/L) and Ni - fT3 pair (0.397-66.8 µg/L), indicating that even 78.68 and 83.25% of men in our study might be in 10% higher risk of Ni-induced SPINA-GT and fT3 alterations, respectively. Due to the relationship established between Ni and the SPINA-GT parameter, it can be concluded that Ni has an influence on the secretory function of the thyroid gland in men. Although the further research is required, these findings suggest possible role of Ni in thyroid function disturbances.

Environmental exposure to cadmium in breast cancer - association with the Warburg effect and sensitivity to tamoxifen

The association between cadmium and breast cancer remains unexplained due to inconsistent epidemiological data and unknown underlying mechanisms. This study aimed to assess the relationship between environmental exposure to cadmium and the Warburg effect in breast cancer and, thus, its possible interference with breast cancer treatment. The observational study in two groups of breast cancer patients indicated a positive correlation between urinary cadmium concentration and tumor expression of HIF1A (a master regulator of the Warburg effect). Further explanatory research in MCF-7 cells showed no impact of cadmium exposure on molecular and biochemical markers of the Warburg effect. However, long-term exposure to a low and environmentally relevant concentration of cadmium led to the accumulation of the metal in MCF-7 cells and decreased their sensitivity to tamoxifen. To conclude, the association between cadmium and the Warburg effect was suggested in the observational study, although not confirmed in vitro. Nevertheless, cadmium seems to interfere with tamoxifen treatment which deserves further investigation in terms of its possible implication in intrinsic resistance to hormone therapy.

Cadmium dietary exposure assessment in the adult population and pre-school children in the Republic of Serbia

Cadmium (Cd) is a toxic metal, present in all matrices of the environment and a common food contaminant. Human exposure to it may elicit many diverse health impairments. The aim of this study was to assess the dietary exposure to Cd for the adult population and preschool children in Serbia using probabilistic methodology. We measured Cd in 11,227 food samples belonging to 50 food items on the Serbian market. Cd was detected in 90% of the tested food items, and in 30.8% of the overall tested samples. The food item that contributed the most to total dietary Cd intake was potatoes (median Cd concentration of 7 ng/g) in adults, and fruit and vegetable juices in children (median Cd concentration of 19 ng/g). Weekly Cd intake shown as 50th and 95th percentiles were 2.54 and 4.74 µg/kg bw in the adult population, and 3.29 and 4.93 µg/kg bw in children. The results of this study are rather preliminary and should be considered as an indication of the need for further, more refined research, which would contribute to a more realistic risk assessment as a high-priority approach, especially in the case of vulnerable subpopulations such as children. Abbreviations: AT SDR: Agency for Toxic Substances and Disease Registry; EEA: European Environment Agency; EFSA: European Food Safety Authority; FAO/WHO: Food and Agriculture Organization/World Health Organization; HI: hazard index; IARC: International Agency for Research on Cancer; JECFA: Joint FAO/WHO Expert Committee on Food Additives; LOD: limit of detection; Cd: cadmium; TWI: tolerable weekly intake; UNEP: United Nations Environment Program; WI: weekly intake.

Puzzling relationship between levels of toxic metals in blood and serum levels of reproductive hormones: Benchmark dose approach in cross-sectional study

Reproductive disorders and infertility have become more common recently among the general population. Toxic metals are known as endocrine disruptors and as they are widespread in nature they may be linked to reproductive problems. This study was conducted as a cross-sectional study and its aim was to examine the dose–response relationship between cadmium, arsenic, mercury, chromium and nickel and serum hormone levels of testosterone (women) and estradiol and progesterone (men) using the Benchmark dose approach (BMD). Blood samples were collected from 218 women and 217 men digested in a microwave, and the levels of the tested metals were determined by atomic absorption spectrophotometry (AAS) or inductively coupled plasma-mass spectrometry (ICP-MS). Dose–response analysis was performed in PROAST software (version 70.1). The model averaging method was used to calculate the Benchmark dose interval (BMDI). A dose–response relationship has been established between all metals and hormones. The narrowest BMDI was found for the As-testosterone and Hg-testosterone. Levels estimated to produce the extra risk of testosterone serum levels disturbances of 10% were lower than median levels measured in the general population. Moreover, this research suggests the possibility of use of the BMD approach in analyzing data pool generated from extensive human-biomonitoring studies.

Environmental Exposure to Metals, Parameters of Oxidative Stress in Blood and Prostate Cancer: Results from Two Cohorts

We studied the potential role of exposure to various metal(oid)s (As, Cd, Cr, Hg, Ni, and Pb) in prostate cancer. Two cohorts were established: the Croatian cohort, consisting of 62 cases and 30 controls, and the Serbian cohort, consisting of 41 cases and 61 controls. Blood/serum samples were collected. Levels of investigated metal(oid)s, various parameters of oxidative stress, and prostate-specific antigen (PSA) were determined in collected samples. A comparison of the measured parameters between 103 prostate cancer patients and 91 control men from both Croatian and Serbian cohorts showed significantly higher blood Hg, SOD, and GPx levels and significantly lower serum SH levels in prostate cancer patients than in controls. Correlation analyses revealed the significant relationship between certain parameters of oxidative stress and the concentrations of the measured metal(loid)s, pointing to the possible role of metal(oid)-induced oxidative stress imbalance. Furthermore, a significant inverse relationship was found between the blood Pb and the serum PSA in prostate cancer patients, but when the model was adjusted for the impacts of remaining parameters, no significant association between the serum PSA and the measured parameters was found. The results of the overall study indicate a substantial contribution of the measured metal(loid)s to the imbalance of the oxidant/antioxidant system. Although somewhat conflicting, the results of the present study point to the possible role of investigated metal(oid)s in prostate cancer, especially for Hg, since the obtained relationship was observed for both cohorts, followed by the disturbances in oxidative stress status, which were found to be correlated with Hg levels. Nevertheless, further studies in larger cohorts are warranted to explain and confirm the obtained results.

Exposure to mercury and thyroid function: Is there a connection?

Mercury (Hg) is one of the most important environmental pollutants with endocrinedisrupting properties. There is little data from epidemiological studies describing the doseresponse relationship between toxic metal levels and hormone levels. The aim of this study was to use the nearest neighbor matching analysis to determine the difference in Hg concentration in healthy/sick subjects with thyroid disease and to use Benchmark modeling to determine the doseresponse relationship between Hg levels in the blood and thyroid-stimulating hormone (TSH) and thyroid hormones in serum. Blood samples were collected and used for Hg measurement using the ICP-MS method, and separated serum was used for hormone analysis. The study showed the existence of a statistically significant difference in Hg levels measured in healthy and sick subjects and the existence of a dose-response relationship between Hg and all measured hormones, with a narrow interval obtained for the Hg-TSH pair. The results of this research support the use of the Benchmark dose approach for the purpose of analyzing data from human studies, and our further research will be focused on examining the impact of low doses on animal models in order to determine more precise effects of low doses on the organism.