Evaluation of trace metals in thyroid tissues: Comparative analysis with benign and malignant thyroid diseases

The association between trace metals in both cancerous and non-cancerous tissues with the risk of liver and gastric cancer progression in northwest China

Liver cancer and gastric cancer have extremely high morbidity and mortality rates worldwide. It is well known that an increase or decrease in trace metals may be associated with the formation and development of a variety of diseases, including cancer. Therefore, this study aimed to evaluate the contents of aluminium (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), selenium (Se), and zinc (Zn) in cancerous liver and gastric tissues, compared to adjacent healthy tissues, and to investigate the relationship between trace metals and cancer progression. During surgery, multiple samples were taken from the cancerous and adjacent healthy tissues of patients with liver and gastric cancer, and trace metal levels within these samples were analysed using inductively coupled plasma mass spectrometry (ICP-MS). We found that concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn in tissues from patients with liver cancer were significantly lower than those in healthy controls (P < 0.05). Similarly, patients with gastric cancer also showed lower levels of Cd, Co, Cr, Mn, Ni, and Zn-but higher levels of Cu and Se-compared to the controls (P < 0.05). In addition, patients with liver and gastric cancers who had poorly differentiated tumours and positive lymph node metastases showed lower levels of trace metals (P < 0.05), although no significant changes in their concentrations were observed to correlate with sex, age, or body mass index (BMI). Logistic regression, principal component analysis (PCA), Bayesian kernel regression (BKMR), weighted quantile sum (WQS) regression, and quantile-based g computing (qgcomp) models were used to analyse the relationships between trace metal concentrations in liver and gastric cancer tissues and the progression of these cancers. We found that single or mixed trace metal levels were negatively associated with poor differentiation and lymph node metastasis in both liver and gastric cancer, and the posterior inclusion probability (PIP) of each metal showed that Cd contributed the most to poor differentiation and lymph node metastasis in both liver and gastric cancer (all PIP = 1.000). These data help to clarify the relationship between changes in trace metal levels in cancerous liver and gastric tissues and the progression of these cancers. Further research is warranted, however, to fully elucidate the mechanisms and causations underlying these findings.

Association between Heavy Metals and Trace Elements in Cancerous and Non-cancerous Tissues with the Risk of Colorectal Cancer Progression in Northwest China

Alterations in heavy metals and trace element levels may be associated with various cancers. However, the role of this interaction in colorectal cancer (CRC) progression is unclear. In recent years, Principal Component Analysis (PCA) and Bayesian Kernel Machine Regression (BKMR) models have provided new ideas for analyzing the effects of metal mixtures on CRC progression. Herein, we assessed the differences in the levels of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), selenium (Se), and zinc (Zn) in tumors and adjacent healthy tissues, to investigate the relationship between heavy metals/trace elements and CRC progression. Surgical samples of CRC and noncancerous tissues were collected, and trace metal levels were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Logistic regression, PCA, and BKMR models were used to investigate the relationship between heavy metals and trace elements and the degree of tumor differentiation and lymph node metastasis in CRC. Cancer tissues showed lower As, Cd, Co, and Cr concentrations, and higher Se concentrations than healthy tissues (P < 0.05). In addition, CRC patients with poorly differentiated tumors and/or positive lymph node metastases had lower levels of Cd, Zn, Cu, and Se (P < 0.05). Logistic regression showed that single metal concentration was negatively correlated with CRC progression. PCA and BKMR models also showed that the metal mixture concentration was negatively correlated with CRC progression, with Cd contributing the most. Overall, changes in heavy metal and trace element levels may be related to the development of CRC; however, further mechanistic studies are required.

The role of heavy metals in the development of colorectal cancer

OBJECTIVE

To investigate the relationship among 18 heavy metals, microsatellite instability (MSI) status, ERCC1, XRCC1 (rs25487), BRAF V600E and 5 tumor markers and their role in the development of colorectal cancer (CRC).

METHODS

A total of 101 CRC patients and 60 healthy controls were recruited in the present study. The levels of 18 heavy metals were measured by ICP-MS. MSI status and the genetic polymorphism were determined by PCR (FP205-02, Tiangen Biochemical Technology Co., Ltd., Beijing, China) and Sanger sequencing. Spearman's rank correlation was used to analyze the relationship among various factors.

RESULTS

The level of selenium (Se) was lower in the CRC group compared with the control group (p < 0.01), while vanadium (V), arsenic (As), tin (Sn), barium (Ba) and lead (Pb) were higher (p < 0.05), chromium (Cr) and copper (Cu) were significantly higher (p < 0.0001) in the CRC group than those in the control group. Multivariate logistic regression analysis indicated that Cr, Cu, As and Ba were the risk factors for CRC. In addition, CRC was positively correlated with V, Cr, Cu, As, Sn, Ba and Pb, but negatively correlated with Se. MSI was positively correlated with BRAF V600E, but negatively correlated with ERCC1. BRAF V600E was positively correlated with antimony (Sb), thallium (Tl), CA19-9, NSE, AFP and CK19. XRCC1 (rs25487) was found to be positively correlated with Se but negatively correlated with Co. The levels of Sb and Tl were significantly higher in the BRAF V600E positive group compared to the negative group. The mRNA expression level of ERCC1 was significantly higher (P = 0.035) in MSS compared to MSI. And there was a significant correlation between XRCC1 (rs25487) polymorphism and MSI status (P<0.05).

CONCLUSION

The results showed that low level of Se and high levels of V, As, Sn, Ba, Pb, Cr, and Cu increased the risk of CRC. Sb and Tl may cause BRAF V600E mutations, leading to MSI. XRCC1 (rs25487) was positively correlated with Se but negatively correlated with Co. The expression of ERCC1 may be related to MSS, while the XRCC1 (rs25487) polymorphism is related to MSI.

The Role of Selected Trace Elements in Oxidoreductive Homeostasis in Patients with Thyroid Diseases

Impaired levels of selenium (Se), zinc (Zn), copper (Cu), iron (Fe), manganese (Mn) and iodine (I) in the organism may adversely affect the thyroid endocrine system. These trace elements play a role in the fight against oxidative stress as components of enzymes. Oxidative-antioxidant imbalance is considered a possible factor in many pathological conditions, including various thyroid diseases. In the available literature, there are few scientific studies showing a direct correlation of the effect of supplementation of trace elements on slowing down or preventing the occurrence of thyroid diseases in combination with the improvement of the antioxidant profile, or through the action of these elements as antioxidants. Among the available studies, it has been shown that an increase in lipid peroxidation levels and a decrease in the overall antioxidant defense status occur during such thyroid diseases as thyroid cancer, Hashimoto's thyroiditis and dysthyroidism. In studies in which trace elements were supplemented, the following were observed: a decrease in the level of malondialdehyde after supplementation with Zn during hypothyroidism and reduction in the malondialdehyde level after Se supplementation with a simultaneous increase in the total activity status and activity of antioxidant defense enzymes in the course of autoimmune thyroiditis. This systematic review aimed to present the current state of knowledge about the relationship between trace elements and thyroid diseases in terms of oxidoreductive homeostasis.

Comparison of Thyroid Function in Lead-Poisoned Patients and Healthy Individuals in Eastern Iran

Lead (Pb) is a prevalent environmental toxic metal that may harmfully affect the function of the thyroid gland. Our information about the effects of lead on thyroid function in lead poisoning is limited. The present study aimed to evaluate thyroid function in lead-poisoned patients compared with the healthy group. In this study, two groups of lead poisoning subjects (lead concentrations ≥ 25 μg/dL) (n = 56) (HBLC group) and randomly selected age and gender-matched healthy individuals with lower blood lead concentrations (BLC < 10 μg/dL) (n = 58) (LBLC group) were included. Thyroid function tests, including thyroxine (T4), triiodothyronine (T3), and thyroid-stimulating hormone (TSH) concentration, were measured for each patient in both groups (for the HBLC group, it was taken on admission). The linear regression model was used to investigate the effects of lead poisoning on thyroid function tests. A p-value of less than 0.05 was considered significant. Our study showed no significant difference between the two groups in terms of age and gender. The mean concentration of T3 and TSH in the HBLC group was significantly lower than the LBLC group, but the mean levels of T4 were significantly higher in the HBLC group (p < 0.05). Based on the linear regression model results, the T3 and TSH levels in the LBLC group were significantly higher by 13.86 and 0.43 units than the HBLC group, respectively. The current study results showed that lead poisoning affects thyroid function, reduces TSH, and increases T4.

Recent advances in the application of metallomics in diagnosis and prognosis of human cancer

Metals play a critical role in human health and diseases. In recent years, metallomics has been introduced and extensively applied to investigate the distribution, regulation, function, and crosstalk of metal(loid) ions in various physiological and pathological processes. Based on high-throughput multielemental analytical techniques and bioinformatics methods, it is possible to elucidate the correlation between the metabolism and homeostasis of diverse metals and complex diseases, in particular for cancer. This review aims to provide an overview of recent progress made in the application of metallomics in cancer research. We mainly focuses on the studies about metallomic profiling of different human biological samples for several major types of cancer, which reveal distinct and dynamic patterns of metal ion contents and the potential benefits of using such information in the detection and prognosis of these malignancies. Elevated levels of copper appear to be a significant risk factor for various cancers, and each type of cancer has a unique distribution of metals in biofluids, hair/nails, and tumor-affected tissues. Furthermore, associations between genetic variations in representative metalloprotein genes and cancer susceptibility have also been demonstrated. Overall, metallomics not only offers a better understanding of the relationship between metal dyshomeostasis and the development of cancer but also facilitates the discovery of new diagnostic and prognostic markers for cancer translational medicine.

Ovaries and testes of Lithobius forficatus (Myriapoda, Chilopoda) react differently to the presence of cadmium in the environment

Proper reproduction depends on properly functioning gonads (ovaries and testes). Many xenobiotics, including heavy metals, can cause changes in somatic and germ line cells, thus damaging the reproductive capacity. The aim of this study was to investigate the effect of the heavy metal cadmium on the gonads, including germ line and somatic cells. It is important to determine whether cell death processes are triggered in both types of cells in the gonads, and which gonads are more sensitive to the presence of cadmium in the environment. The research was conducted on the soil-dwelling arthropod Lithobius forficatus (Myriapoda, Chilopoda), which is common for European fauna. Animals were cultured in soil supplemented with Cd for different periods (short- and long-term treatment). Gonads were isolated and prepared for qualitative and quantitative analysis, which enabled us to describe all changes which appeared after both the short- and long-term cadmium treatment. The results of our study showed that cadmium affects the structure and ultrastructure of both gonads in soil-dwelling organisms including the activation of cell death processes. However, the male germ line cells are more sensitive to cadmium than female germ line cells. We also observed that germ line cells are protected by the somatic cells of both gonads.

The role of heavy metals in thyroid cancer: A meta-analysis

INTRODUCTION

Metal ions are known to accumulate in the thyroid and some play an important role in the function and homeostatic mechanisms of the thyroid gland. Certain metal ions are known endocrine disruptors while others are classified to be carcinogenic. Although higher thyroid cancer incidence rates have been reported in regions with high metal levels in soil and drinking water, including volcanic regions, the effect of heavy metals on the thyroid is still poorly understood. To investigate the association between heavy metals and thyroid cancer, a comprehensive meta-analysis was performed to draw a more evidence-based conclusion for individual metal ions.

MATERIAL AND METHODS

Nineteen studies were included in this meta-analysis, of which 9 studies reported blood metal ion levels, 8 studies reported tissue metal ion levels and 2 studies reported blood and tissue metal ion levels. The standardized mean difference (SMD) was calculated between thyroid cancer patients group and a control group (benign thyroid patients group or healthy controls group) per study.

RESULTS

A significant positive SMD in manganese tissue levels between thyroid cancer patients and benign thyroid patients (SMD: 0.56 (95 % CI: 0.16, 0.95)) and a significant negative SMD in cobalt blood levels between thyroid cancer patients and healthy controls (SMD: -2.03 (95 % CI: -3.95, -0.10)) was found. No difference in levels of other metals in blood or thyroid tissue between thyroid cancer patients and non-thyroid cancer patients was noted.

DISCUSSION AND CONCLUSION

The present meta-analysis therefore demonstrates the urgent need for future studies, especially given the increasing exposure of the general population to various environmental pollutants, including metal ions, and the thyroid cancer burden worldwide.

Trace elements and the thyroid

Trace elements, such as iodine and selenium (Se), are vital to human health and play an essential role in metabolism. They are also important to thyroid metabolism and function, and correlate with thyroid autoimmunity and tumors. Other minerals such as iron (Ir), lithium (Li), copper (Co), zinc (Zn), manganese (Mn), magnesium (Mg), cadmium (Cd), and molybdenum (Mo), may related to thyroid function and disease. Normal thyroid function depends on a variety of trace elements for thyroid hormone synthesis and metabolism. These trace elements interact with each other and are in a dynamic balance. However, this balance may be disturbed by the excess or deficiency of one or more elements, leading to abnormal thyroid function and the promotion of autoimmune thyroid diseases and thyroid tumors.The relationship between trace elements and thyroid disorders is still unclear, and further research is needed to clarify this issue and improve our understanding of how trace elements mediate thyroid function and metabolism. This paper systematically reviewed recently published literature on the relationship between various trace elements and thyroid function to provide a preliminary theoretical basis for future research.

Alteration of Trace Elements in Multinodular Goiter, Thyroid Adenoma, and Thyroid Cancer

Modest progress has been made in understanding the role of trace elements as endocrine disruptors. The aim of this study was to examine whether there is a change in the content of trace elements in thyroid disease, as well as whether the ratio of elements could be considered a blood marker for thyroid disease. In addition, this study examined the influence of biological and clinical/pathological parameters on the elemental profile. Blood samples from patients diagnosed with multinodular goiter (MNG), thyroid adenoma (TA), and thyroid cancer (TC) were examined and compared with control samples using chemometric analysis. The concentrations of essential (Mn, Co, Cu, Zn, Se) and toxic elements (Ni, As, Cd, Pb, U) were determined by ICP-MS. This study showed for the first time that the content of Mn, Co, Ni, Cu, Zn, Se, and Pb in pathological blood samples was significantly lower compared to the control, while opposite results were obtained for As, Cd, and U. Based on the classification model, the most important trace metals for discrimination of MNG and TC from the control group (CG) were Co and Zn, while Co, Zn, and Mn influenced the distinction of CG from TA. Moreover, it was found that Cu/Zn and U/Se ratios had significantly increased values in pathological blood samples leading to the possibility of establishing new circulating screening markers. These findings can represent significant translational information since these diseases are widespread and the diagnostic procedure is still difficult in many cases.

Possible zinc deficiency in the Serbian population: examination of body fluids, whole blood and solid tissues

Studies indicate that the soil, water and consequently foodstuffs in Serbia are significantly poor in zinc (Zn), and thus, it is likely that there is a Zn deficiency in the Serbian population. This study examined the Zn status in multiple clinical samples, including body fluids (serum, cerebrospinal fluid), whole blood and Zn-rich solid tissues (thyroid and brain tissue). Differences between sex and age were also considered, and comparative analysis of Zn status with other world populations was performed. Serum samples from a large number of Serbian adults approximately had twofold lower Zn amounts when compared to other populations. A similar trend was obtained for whole blood. Males had significantly higher amounts of Zn in serum, whole blood and thyroid tissue samples than females. Higher amounts of Zn were observed in the group older than 50 years. Importantly, in thyroid and brain tissues, Zn was 10- and 20-fold lower, respectively, than reported in the literature. Our results indicate that the population in Serbia could be considered Zn deficient. Therefore, adequate oral Zn supplementation and/or foodstuff fortification should be considered to prevent the deleterious effects caused by Zn deficiency.

Current applications and future perspectives on elemental analysis of non-invasive samples for human biomonitoring

Humans are continuously exposed to numerous environmental pollutants including potentially toxic elements. Essential elements play an important role in human health. Abnormal elemental levels in the body, in different forms that existed, have been reported to be correlated with different diseases and environmental exposure. Blood is the conventional biological sample used in human biomonitoring. However, blood samples can only reflect short-term exposure and require invasive sampling, which poses infection risk to individuals. In recent years, the number of research evaluating the effectiveness of non-invasive samples (hair, nails, urine, meconium, breast milk, placenta, cord blood, saliva and teeth) for human biomonitoring is increasing. These samples can be collected easily and provide extra information in addition to blood analysis. Yet, the correlation between the elemental concentration in non-invasive samples and in blood is not well established, which hinders the application of those samples in routine human biomonitoring. This review aims at providing a fundamental overview of analytical methods of non-invasive samples in human biomonitoring. The content covers the sample collection and pretreatment, sample preparation and instrumental analysis. The technical discussions are separated into solution analysis and solid analysis. In the last section, the authors highlight some of the perspectives on the future of elemental analysis in human biomonitoring.

Health risk assessment of heavy metals in selected Ethiopian spices

A total of 144 spice samples (ajwain, black cumin, coriander and fenugreek) were collected from three districts. For the determination of heavy metals (Cd, Cr, Cu, Pb and Zn) concentrations and human health risks, the spice samples were digested in a mixture of HNO₃ and HClO₄. The highest concentrations of Cr (24.85 ± 1.673 mg/kg) and Cu (32.267 ± 7.355 mg/kg) were investigated in ajwain and Zn (54.13 ± 6.122 mg/kg) in fenugreek. However, lowest concentration of Cr and Cu were detected in fenugreek; and Zn in coriander. Cd and Pb were not detected in all spice samples. A positive correlation was observed among Cr, Cu and Zn in fenugreek; Zn with Cr and Cu in black cumin and Zn with Cu in ajwain and coriander. However, negative correlation was observed Cr with Cu and Zn in ajwain and coriander; Cr with Cu in black cumin. THQ values of Cu, Zn and 75% of Cr in all spices were less than 1. About 66.7% of the HI values of the samples under study were less than 1, indicated that the consumers will not experience potential health risks from the intake of individual metals through spices consumption.

Associations between essential microelements exposure and the aggressive clinicopathologic characteristics of papillary thyroid cancer

Aim of this study was to evaluate the association between multiple essential microelements exposure and the aggressive clinicopathologic characteristics of papillary thyroid carcinoma (PTC). The concentrations of 10 essential microelements in urine [cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), strontium (Sr), zinc (Zn), and iodine (I)] were measured in 608 patients newly diagnosed with PTC, including 154 males and 454 females. Chi square test and Wilcoxon rank sum test were used to compare general characteristics among males and females. Multivariate logistic regression was used to evaluate the associations between essential microelements and PTC clinicopathologic characteristics in single- and multi-microelement models. In this study, we only observed that the frequency of lymph node metastasis in males was higher than in females, and males had higher levels of zinc than females, but males had lower levels of iodine than females. It was found that high levels of Fe were associated with decreased risk of PTC tumor size > 1 cm, capsular invasion, and advanced T stage (T3/4a/4b). High levels of Co and Mo were associated with decreased risk of capsular invasion and lymph node metastasis, respectively. However, high levels of Mn and Sr were associated with increased risk of capsular invasion and multifocality respectively, and both were associated with increased risk of advanced T stage (T3/4a/4b). These findings indicated that certain essential microelements might have potential effects on PTC progression and aggressiveness. Further studies are required to confirm these findings.

Urinary Biomarkers of Phthalates Exposure, Blood Lead Levels, and Risks of Thyroid Nodules

Thyroid nodules (TNs) are becoming increasingly prevalent. However, few studies have reported the effects of phthalates and lead (Pb) on TNs. In this study, we aimed to explore the associations of phthalates and Pb with the risks of TN. We sex-age-matched 220 TNs patients and 220 healthy controls from Zhejiang Shangyu, China. We measured 13 phthalate metabolites in spot urine samples. Blood lead levels (BLLs) were determined by atomic absorption spectrometry. The multivariable logistic regression models were used to assess the associations between urinary phthalate metabolites and BLLs and the risks of TNs. We found BLLs were associated with increased risk of TNs in total population. Female-specific positive associations of mono-2-ethyl-5-carboxypentylphthalate (MECPP), mono-2-ethyl-5-hydroxyhexylphthalate (MEHHP), mono-2-ethyl-5-oxohexylphthalate (MEOHP), mono-2-carboxymethyl-hexyl phthalate (MCMHP), and mono-isononyl phthalate (MiNP) with increased risk of TNs were also observed. Moreover, the positive association between phthalates and TNs was modified by BLLs. At the highest tertile of BLLs, monoethylphthalate (MEP), MECPP, MEHHP, MEOHP, and MiNP were significantly associated with increased risk of TNs. Our results indicated that certain phthalate metabolites and BLLs may contribute to increased risks of TNs.

A case-control study on the association of mineral elements exposure and thyroid tumor and goiter

Thyroid tumor and thyroid goiter are prevalent disease around the world. In this case-control study, we investigated the association between exposure to a total of twelve mineral elements and thyroid disease as well as thyroid functions. Participants with thyroid tumor or goiter (N = 197) were matched with a healthy population (N = 197) by age (± 2 years old) and same sex. Questionnaires were used to collect data about the demographic characteristics and information of subjects. Serum and urine samples were collected simultaneously for each of the subjects. Mineral elements, iodine level of urine and levels of the total seven thyroid function indexes in serum were detected respectively. Conditional logistic regression was applied to estimate the associations between mineral elements and the risk of thyroid tumor and goiter through single-element models and multiple-element models. Multiple linear regression was used to evaluate relationships between mineral elements and percentage changes of thyroid functions. Higher concentrations of mineral elements in the recruited population were found in this study than other comparable studies, and the levels of chromium (Cr), manganese (Mn), nickel (Ni), arsenic (As), cadmium (Cd), selenium (Se), antimony (Sb), thallium (Tl) and lead (Pb) in the case group were lower than the control group. According to the single-element models, Cr, Mn, Ni, Sb and Tl showed significant negative associations with the risk of thyroid tumor and goiter, and, Cd showed nonmonotonic dose response. Cd and mercury (Hg) showed a nonmonotonic percentage change with T4, while Tl was associated with the increased FT4 in the control group. Therefore, Cd, Hg and Tl may disturb the balance of thyroid function to some extent, and Cr, Mn, Ni, Cd, Sb, and Tl may become potential influencing factors for the risk of thyroid tumor and goiter.

The first insight into the trace element status of human adrenal gland accompanied by elemental alterations in adrenal adenomas

BACKGROUND

The baseline status of trace metals in adrenal tissue is unresolved, while the elemental profile for any adrenal pathology has not been examined so far. This study aimed to determine the baseline status of important toxic (Ni, As, Cd, Pb, Th, U) and essential trace elements (Mn, Co, Cu, Zn, Se) in healthy adrenal tissues (HATs) as well as to examine whether there are alterations in the elemental composition of adenomatous adrenal tissues (AATs). Furthermore, this study aimed to find potential trace metals that could play a role in the pathogenesis of adrenal adenoma (AA).

METHODS

The study included 45 patients diagnosed with AA. Impacts of relevant parameters such as gender, age, smoking habits and nodular sizes were considered. All samples were subjected to microwave digestion and the trace elements were determined by inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

This is the first study that provided an insight into the elemental status of HATs. It was also shown that AATs had altered trace metal contents. Compared to HATs, the most significant findings were related to the high content of essential (Cu, Mn, Se, Zn) and Pb as a non-essential metal. Although gender, age and smoking habits had a modest effect on metal profiles, the most significant alterations were related to the nodular diameter above 4 cm, indicating that the growth of benign tumor could influence changes in elemental composition.

CONCLUSION

For the first time the baseline contents of essential and toxic trace metals in HATs were determined. The results of this study may highlight the role of toxic and essential trace metals in AAs and could provide new insights into the molecular basis of pathophysiological changes caused by the hazardous effects of trace metals on adrenal structure and function.

Incidence of Thyroid Cancer in Italian Contaminated Sites

Some human literature suggests a possible role of endocrine disruptors (EDs) exposure in thyroid cancer (TC) development. We investigated TC incidence in selected Italian National Priority Contaminated Sites (NPCS) with documented presence of EDs considered thyroid carcinogens. Adjusted Standardized Incidence Ratios (SIRs), with their 90% confidence intervals, were computed by gender, and age-specific groups (aged 15-39 years, and 40 years or over) for each NPCS in the period 2006 to 2013. In the age group of 15-39 years, a significant excess of TC risk was found in two NPCSs in males; non-significant excess risks were observed in four NPCSs in males, and in five in females. In the age group of 40 years and over, significant excess risks were found in six NPCSs in males and in seven NPCSs in females; non-significant excess risks were identified in two NPCSs in males and females. The findings of several excesses in incidence, mainly observed in adults aged 40 years or over, are suggestive of a possible adverse effect associated with residence in NPCSs, even if a role of other factors cannot be excluded, due to the adoption of an ecological study design. Future analytical studies are needed to clarify if EDs are a TC risk factor for individuals living in NPCSs.

Significance of arsenic and lead in Hashimoto's thyroiditis demonstrated on thyroid tissue, blood, and urine samples

Our previous investigation showed significantly increased arsenic (As) content in thyroid tissue samples of patients with Hashimoto's thyroiditis (HT). This research aimed to extend previous findings and provide reliable insight into the close relationship between As and other trace elements with HT by considering a greater number of thyroid tissue samples, accompanied by blood and urine samples. The essential trace elements for thyroid homeostasis (Mn, Cu, Zn, Se) and the main threatening toxic trace elements (Ni, As, Pb, Cd, U) was analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). Relevant parameters that could affect the concentration of trace elements were considered. This research showed that there was a difference in the elemental profile between HT and control samples. The most important findings were related to the elevated As and Pb content in the thyroid tissue and HT blood samples. The obtained negative correlations between As and Pb with Se may explain the antagonistic effect of As and Pb on the extrusion of essential Se from the HT tissue. The reduced Se content in the blood and its increased content in urine samples may further confirm this hypothesis and explain the lack of Se in HT. Furthermore, the reported results may highlight the unresolved molecular basis of HT and could indicate the role of trace element effects on thyroid homeostasis.

Assessment of trace metal alterations in the blood, cerebrospinal fluid and tissue samples of patients with malignant brain tumors

The pathogenesis of malignant brain tumors (MBTs) should be better understood due to the evident association between prolonged exposure to metals and increased risk of MBTs. The present research aimed to find trace metals that could contribute to the pathogenesis of MBTs. Essential trace elements (Mn, Co, Zn, Cu, Se) and relevant toxic metals (Al, Ni, As, Sr, Cd, Ce, Pt, Pb, U) in the serum, cell fraction (CF), cerebrospinal fluid (CSF) and cancerous tissue (CT) samples of MBT patients were analyzed. The results were compared with sex- and age-matched control groups. For the first time, this research showed that elemental profiles of serum, CF, CSF and CT samples in MBT patients were significantly altered compared to the appropriate controls, as well as that higher contents of trace elements (particularly Mn, Se, and Pb) could be involved in the pathogenesis of MBTs. However, the most noticeable change found was the elevated U content, indicating its considerable role as a major cerebral discriminator of the presence/absence of MBTs. The U/Se ratio could be considered as an appropriate blood marker in diagnostic MBT evaluation. The reported results could contribute to better understanding of the poorly understood pathogenesis of MBTs. Furthermore, the reported results could highlight a molecular basis for the pathophysiological changes caused by the hazardous effects of trace metals on brain homeostasis.

Thyroid dysfunction: how concentration of toxic and essential elements contribute to risk of hypothyroidism, hyperthyroidism, and thyroid cancer

This study was conducted to evaluate the levels of trace metals Fe, Cr, Co, Cd, Cu, Ni, Hg, Zn, and Pb in healthy individuals and patients with thyroid disease (hyperthyroidism, hypothyroidism, and cancerous). The serum levels of 110 participants living in Birjand City, east of Iran, were collected and analyzed using ICP-MS (Agilent 7900). Results showed that the concentration levels of Cr, Co, Zn, Cd, and Pb were significantly higher at case-patients (p < 0.05), but the levels of Fe, Ni, and Hg were similar between healthy and patient subjects (p > 0.05). In patients with high or low thyroid activity, strong mutual correlations between Cr, Ni, and Fe were noticeable (p < 0.05). In hypothyroid patients, no significant correlation between Zn and Hg, Co, and Cd was found, but Zn was moderately and positively correlated with other trace metals. The moderate negative correlations between Cd-Cr (p = - 0.46) and Cd-Fe (p = - 0.43) were also observed. Logistic regression analysis showed that the effect of Cr, Co, Pb, Cu, Zn, and Cd was significant in developing hyperthyroidism and hypothyroidism; whereas, in patients with thyroid cancer, the effect of Cr, Cd, and Pb was found to be significant. In conclusion, our findings suggest that toxic metals such as Pb, Cd, and Cr can increase the risk of developing hypothyroidism and thyroid cancer, but more research is needed to evaluate the potential toxicity mechanisms of Pb, Cd, and Cr.