Gender differences in the disposition and toxicity of metals

Effects of Environmental Cadmium Exposure on the Liver in Korean Adults: Cross-Sectional and Longitudinal Studies

Cadmium (Cd) is a ubiquitous environmental pollutant with an exceptionally long biological half-life. The liver is a major organ for Cd metabolism, but the toxicity of Cd is unclear. This study sought to determine whether blood Cd (BCd) level (representing recent exposure [months] to Cd) was associated with liver function in Korean adults, both cross-sectionally and longitudinally. The baseline cross-sectional study involved 2,086 adults (male: 908, female: 1,178) in 2010 - 2011, and 503 of them (male: 207, female: 296) were followed up in 2014 - 2015. BCd was measured by graphite-furnace atomic absorption spectrometry, and liver function indices (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and γ-glutamyltransferase [GGT]) were determined. Liver damage was defined as an abnormal elevation of more than one liver function index. The geometric mean of BCd (1.07 μg/L) was higher in females than in males (1.16 vs. 0.96 μg/L). Liver function indices increased significantly in a dose-dependent manner according to the BCd levels, except for ALT in males, and were higher in males than in females. BCd level was also associated with the risk of liver damage in both sexes. No significant changes in BCd were observed between baseline and follow-up. The liver function indices in 2014 - 2015 were comparable to those in 2010 - 2011 in males, while ALT and GGT were significantly increased in 2014 - 2015 compared to 2010 - 2011 in females with relatively high BCd. These findings suggest that even a low level of environmental Cd exposure, short- and long-term, may affect liver function, and females appear more susceptible than males.

Could a city-dwelling bat (Pipistrellus kuhlii) serve as a bioindicator species for trace metals pollution?

Bats are an endangered group of mammals that are very sensitive to environmental stresses. One of such stress factor is trace metals pollution which threatens populations of insectivorous bats due to their top position in the food webs and exceptionally long life span. In our research Pipistrellus kuhlii was tested as a promising indicator species (urban-dwelling, sedentary, with limited daily home-range) for trace metal exposure of bats. We measured concentrations of Pb, Cu, Zn and Cd in internal and external tissues of bats from the industrial city Mariupol and the village Karlovka, Ukraine, to answer the following questions: (1) Do metal concentrations in soil samples differ between urban and rural areas, and between populations of P. kuhlii from those areas? (2) Does metal contamination differ between individuals of different sexes and ages? (3) Whether fur and/or wing membrane, the two tissues that can be collected from live bats, can be used as proxies of metal contamination in internal tissues (liver, kidney, lung, forearm bones) of P. kuhlii? Metal concentrations in soil samples were significantly higher in the city. Bats from the city accumulated significantly more Cd, Pb and Zn in external tissues than those from the rural area. Females accumulated more Cd than males, and this-year-born did not differ significantly from adult individuals. We did not find, however, significant positive correlations between metal concentrations in external and internal tissues, indicating that external tissues cannot serve as an indicator of the metal contamination of internal tissues in P. kuhlii.

Sex Differences in Copper Concentrations during a Sports Season in Soccer Players

Physical training produces changes in the concentrations of trace mineral elements. Sex differences in copper (Cu) concentrations in athletes are scarce. The objectives of this study were (i) to analyze changes in intracellular (erythrocytes and platelets) and extracellular (plasma and urine) Cu concentrations during a sports season in soccer players and (ii) to analyze sex differences. A total of 46 soccer players (22 men and 24 women) participated in the study. Three assessments were performed throughout the sports season. Anthropometry, body composition, nutritional intake, physical condition, female hormones (menstrual cycle) and hematology were evaluated, as well as Cu determination (plasma, urine, erythrocytes, and platelets). Regarding longitudinal differences, there were discrepancies in plasma, urine, absolute erythrocyte, and absolute platelet Cu concentrations (p < 0.05). There were differences between sexes in Cu concentrations in urine, erythrocytes relative to cell number and in platelets relative to cell number (p < 0.05). During a sports season, there are changes in Cu concentrations in soccer players. Likewise, there could be sex differences in urinary, erythrocyte and platelet Cu concentrations.

Heterozygous disruption of beclin 1 alleviates neurotoxicity induced by sub-chronic exposure of arsenite in mice

Arsenite is a well-documented neurotoxicant that widely exists in the environment. However, the detailed mechanisms of arsenite neurotoxicity are not fully clarified. Autophagy has been reported to be involved in many neurological problems induced by arsenite. Since beclin 1 is an essential mediator of autophagy, we herein used both adult wild-type (beclin 1^+/+) and heterozygous disruption of beclin 1 (beclin 1^+/-) mice for chronic administration of 50 mg/L arsenite via drinking water for 3 months. Our results demonstrated that exposure of arsenite caused the working memory deficit, anxiety-like behavior and motor coordination disorder in beclin 1^+/+ mice, accompanied with pathological changes in morphology and electrophysiology in the cortical tissues. This treatment of arsenite significantly reduced the number of neuronal cells and induced microglia activation and synaptic transmission disorders in the wild-type mice as compared with vehicle controls. Intriguingly, by using beclin 1^+/- mice, we found that heterozygous disruption of beclin 1 profoundly attenuated these neurotoxic effects induced by arsenite, mainly manifested by improvements in the neurobehavioral impairments, abnormal electrophysiologic alterations as well as dysregulation of synaptic transmission. These findings together indicate that regulation of autophagy via beclin 1 would be a potential strategy for treatment against arsenite neurotoxicity.

Associations of blood lead, cadmium, and mercury with resistant hypertension among adults in NHANES, 1999-2018

BACKGROUND

Resistant hypertension (RHTN), a clinically complex condition with profound health implications, necessitates considerable time and allocation of medical resources for effective management. Unraveling the environmental risk factors associated with RHTN may shed light on future interventional targets aimed at reducing its incidence. Exposure to heavy metal has been linked to an increased risk of hypertension, while the relationship with RHTN remains poorly understood.

METHODS

Using the 1999-2018 National Health and Nutrition Examination Survey (NHANES) data, we examined the association of blood lead (Pb), cadmium (Cd), and mercury (Hg) with RHTN using a multinomial logistic regression model. The combined effects of the metals and the contribution of each metal were assessed using a weighted quantile sum (WQS) analysis.

RESULTS

A total of 38281 participants were included in the analysis. Compared with no resistant hypertension (NRHTN), per 1 µg/dL increase in blood Pb concentration, the proportion of RHTN increased by 16% [adjusted odds ratio (aOR), 1.16; 95% confidence interval (CI) 1.01-1.32]. When analyzed by quartiles (Q), the aOR [95% CI] for Pd was 1.30[1.01,1.67] (Q4 vs. Q1); there was a significant dose-response relationship (p < 0.05). Likewise, as a continuous variable, each 1 µg/dL increase in blood Cd level was associated with a 13% increase in the proportion of RHTN (aOR: 1.13; 95%CI: [1.00,1.27]); when analyzed as quartile, aOR [95% CI] for Cd were 1.30[1.01,1.69] (Q3 vs. Q1), and 1.35[1.03,1.75] (Q4 vs. Q1); the dose-response relationship was significant (p < 0.05). WQS analysis showed a significant combined effects of Pb, Cd, and Hg on RHTN, with Pb as the highest weight (0.64), followed by Cd (0.25) and Hg (0.11). Stratified analysis indicated that the associations for the two heavy metals were significant for participants who were male, ≼ 60 years old, and with kidney dysfunction.

CONCLUSION

Findings of this study with national data provide new evidence regarding the role of environmental heavy metal exposure in RHTN. The prevention strategies aimed at reducing heavy metal exposure should particularly focus on Americans who are middle-aged, male, and afflicted with kidney dysfunction.

Prenatal exposure to opioids and neurodevelopment in infancy and childhood: A systematic review

Aim

This systematic review aims to estimate the relationship between prenatal exposure to opioids and neurodevelopmental outcomes and examines potential sources of heterogeneity between the studies.

Methods

We searched four databases through May 21st, 2022: PubMed, Embase, PsycInfo and the Web of Science according to a specified search strings. Study inclusion criteria include: (1) cohort and case-control peer-reviewed studies published in English; (2) studies comparing neurodevelopmental outcomes among children with prenatal opioid-exposure (prescribed or used non-medically) vs. an unexposed group. Studies investigating fetal alcohol syndrome or a different primary prenatal exposure other than opioids were excluded. Two main performed data extraction using "Covidence" systematic review platform. This systematic review was conducted in accordance with PRISMA guidelines. The Newcastle-Ottawa-Scale was used for quality assessment of the studies. Studies were synthesized based on the type of neurodevelopmental outcome and the instrument used to assess neurodevelopment.

Results

Data were extracted from 79 studies. We found significant heterogeneity between studies due to their use of different instruments to explore cognitive skills, motor, and behavioral outcomes among children of different ages. The other sources of heterogeneity included: procedures to assess prenatal exposure to opioids; period of pregnancy in which exposure was assessed; type of opioids assessed (non-medical, medication used for opioid use dis-order, prescribed by health professional), types of co-exposure; source of selection of prenatally exposed study participants and comparison groups; and methods to address lack of comparability between exposed and unexposed groups. Cognitive and motor skills as well as behavior were generally negatively affected by prenatal opioid exposure, but the significant heterogeneity precluded a meta-analysis.

Conclusion

We explored sources of heterogeneity in the studies assessing the association between prenatal exposure to opioids and neurodevelopmental outcomes. Sources of heterogeneity included different approaches to participant recruitment as well as exposure and outcome ascertainment methods. Nonetheless, overall negative trends were observed between prenatal opioid exposure and neuro-developmental outcomes.

Lead and Other Trace Element Levels in Brains of Croatian Large Terrestrial Carnivores: Influence of Biological and Ecological Factors

Trace element pollution can adversely affect the brains of individuals and thus impact the entire population of apex predators, such as large European carnivores. We assessed exposure to prominent neurotoxicants As, Cd, Hg and Pb by measuring their brain stem levels in brown bears (n = 114), grey wolves (n = 8), Eurasian lynx (n = 3), and golden jackals (n = 2) sampled in 2015-2022 in Croatia. The highest of the non-essential elements was the Pb level in the bears' brains (median, Q1-Q3; 11.1, 7.13-24.1 μg/kg wet mass), with 4% of animals, all subadults, exceeding the established normal bovine levels (100 μg/kg wet mass). Species-specific differences were noted for Ca, Cd, Cu, Fe, Pb and Se brain levels. Female brown bears had higher As brain levels than males. Cubs and yearlings had lower brain Cd, but higher Zn, while subadults had higher Cu than adult bears. Hepatic As, Cd, Cu and Hg levels were shown to be a moderate proxy for estimating brain levels in bears (r_S = 0.30-0.69). Multiple associations of As, Cd, Hg and Pb with essential elements pointed to a possible interaction and disturbance of brain Ca, Cu, Fe, Se and Zn homeostasis. Non-essential element levels in the brains of four studied species were lower than reported earlier for terrestrial meso-carnivores and humans. The age and sex of animals were highlighted as essential factors in interpreting brain element levels in ecotoxicological studies of large carnivores.

Exploring the relationship between blood toxic metal(oid)s and serum insulin levels through benchmark modelling of human data: Possible role of arsenic as a metabolic disruptor

The major goal of this study was to estimate the correlations and dose-response pattern between the measured blood toxic metals (cadmium (Cd), mercury (Hg), chromium (Cr), nickel (Ni))/metalloid (arsenic (As)) and serum insulin level by conducting Benchmark dose (BMD) analysis of human data. The study involved 435 non-occupationally exposed individuals (217 men and 218 women). The samples were collected at health care institutions in Belgrade, Serbia, from January 2019 to May 2021. Blood sample preparation was conducted by microwave digestion. Cd was measured by graphite furnace atomic absorption spectrophotometry (GF-AAS), while inductively coupled plasma-mass spectrometry (ICP-MS) was used to measure Hg, Ni, Cr and As. BMD analysis of insulin levels represented as quantal data was done using the PROAST software version 70.1 (model averaging methodology, BMD response: 10%). In the male population, there was no correlation between toxic metal/metalloid concentrations and insulin level. However, in the female population/whole population, a high positive correlation for As and Hg, and a strong negative correlation for Ni and measured serum insulin level was established. BMD modelling revealed quantitative associations between blood toxic metal/metalloid concentrations and serum insulin levels. All the estimated BMD intervals were wide except the one for As, reflecting a high degree of confidence in the estimations and possible role of As as a metabolic disruptor. These results indicate that, in the case of As blood concentrations, even values higher than BMD (BMDL): 3.27 (1.26) (male population), 2.79 (0.771) (female population), or 1.18 (2.96) μg/L (whole population) might contribute to a 10% higher risk of insulin level alterations, meaning 10% higher risk of blood insulin increasing from within reference range to above reference range. The obtained results contribute to the current body of knowledge on the use of BMD modelling for analysing human data.

Associations between biomarkers of prenatal metals exposure and non-nutritive suck among infants from the PROTECT birth cohort in Puerto Rico

Background/Aim

Infant non-nutritive suck (NNS) has been used as an early marker of neonatal brain function. Although there is an established relationship between prenatal exposure to certain metals and brain development, the association between metal exposure and NNS has not been explored. Therefore, in this study we assessed associations between maternal urinary metal(loid) concentrations and NNS measurements among infants from the Puerto Rico PROTECT birth cohort. We hypothesized that maternal urinary metal(loid) concentrations are significantly associated with infant NNS measures in a sex-dependent manner.

Methods

We measured urinary concentrations of 14 metal(loid)s in pregnant women at up to three time points in pregnancy. The geometric mean of each metal(loid) for each pregnant woman was calculated and used as an exposure measurement across gestation. NNS measurements (duration, frequency, amplitude, bursts/min, cycles/burst, cycles/min) were collected from infants between 4 and 6 (±2 weeks) weeks of age using our custom research pacifier. Linear regression was used to estimate associations between urinary metal(loid) concentrations across pregnancy and continuous NNS variables. Sex-specific effects were estimated using interaction terms between NNS variables and infant sex.

Results

We observed significant positive associations between mercury, manganese, and tin with NNS duration (mercury: %Δ = 1.08, 95% CI: 0.42, 1.74; manganese: %Δ = 0.67, 95% CI: 0.15, 1.20; tin: %Δ = 0.83, 95% CI: 0.17, 1.49) and NNS cycles/burst (mercury: %Δ = 1.85, 95% CI: 0.58, 3.11; manganese: (%Δ = 1.37, 95% CI: 0.40, 2.34; tin: %Δ = 1.68, 95% CI: 0.46, 2.91). Furthermore, the association between NNS cycles/min with cadmium (%Δ = 8.06, 95% CI: 3.33, 12.78), manganese (%Δ = 4.44, 95% CI: 1.40, 7.47), and tin (%Δ = 4.50, 95% CI: 0.81, 8.18) were in the opposite direction from its association with zinc (%Δ = -9.30, 95% CI: -14.71, -3.89), as well as with copper (%Δ = -6.58, 95% CI: -12.06, -1.10). For the sex-stratified analysis, the negative associations between metal(loid)s and NNS duration were predominantly driven by male infants; however, the negative associations between metal(loid)s and NNS bursts/min were mainly driven by female infants.

Conclusion

We observed significant associations between prenatal metal(loid) exposure and NNS measurements among infants from the ongoing Puerto Rico PROTECT cohort. Similar to previous studies that have demonstrated associations between NNS and subsequent neurodevelopment, this study highlights the potential of NNS as a quantitative index to measure altered neurodevelopment from prenatal metal(loid) exposures. We believe this study will inform future efforts aimed at reducing health risks related to early life metal exposures, such as developing early identification of metal-induced adverse outcomes in child neurodevelopment.

Gene Expression Profiling as a New Real-Time Assay in Human Biomonitoring of Waste-to-Energy Plant Workers

Exposure to heavy metals represents one of the most important risk factors for the health of incinerator workers. Indeed, heavy metals can determine increased generation of reactive oxygen species (ROS). In this work, we introduced the use of transcription profiling of detoxifying genes, involved in redox balance and genome integrity, as a highly sensitive assay of heavy metal exposure and subsequent oxidative stress. For this purpose, blood mRNA levels of OGG1, ST13, NQO1 and MT1A genes, as well as urinary concentrations of nine heavy metals and the oxidized base 8-OHdG of 49 subjects (26 controls and 23 employees in the waste-to-energy plant of San Zeno, Arezzo, Italy) were determined. No significant difference between the two populations was observed, thus highlighting, as far as the biomarkers analysed are concerned, the absence of occupational exposure to heavy metals and systemic oxidative stress induction in the workers of the waste-to-energy plant of San Zeno. Correlation analyses underline a close association between heavy metals exposure and changes in expression levels of a number of genes, even at low exposure doses, thus remarking the greater capacity of detection of transcription profiling compared to other biomarkers and the importance of its introduction in future human biomonitoring programs.

Levels of trace elements in human hair samples of adolescents living near petrochemical plants

The aim of the study is a comparative analysis to investigate human hair metal profiles of adolescents residing near petrochemical plants (Sicily, Italy). We selected the small town of Augusta, Gela, and Pace del Mela, and a control area made up of the towns characterized by low anthropogenic activity. Twenty trace elements were measured in samples of scalp hair from adolescents (11-14 years old) of both genders. Hair samples were cleaned using a rigorous cleaning method, mineralized, and processed for analyses by inductively coupled plasma-mass spectrometry (ICP-MS). In industrial sites, zinc was always the most abundant element, ranging from186 to 217 μg g^-1. Following zinc, the elements Al, Ba, Cu, Fe, and Sr were in the range 1-20 μg g^-1. The remaining elements had concentrations < 1 μg g^-1. The comparison with adolescents living in suburban area highlighted that As, Ba, Mn, Sr, U, and V have the highest median concentrations in an industrial location. An industrial factor (As, Mn, Sr, U, and V) and an urban factor (Cd, Cr, Cu, Mo, Ni, and Sb) were distinguished by the multivariate statistical analysis between a cohort residing in urban and industrial areas. Statistically significant differences (Kruskal-Wallis test, p < 0.05) between the genders were found for Ba, Mn, Ni, Sr, and V in all industrial sites with median concentrations higher in females' hair than males'. The data confirm that the study areas are heavily affected by industrial and urban emissions of metals and metalloids, representing a potential hazard to the local population.

Multi-matrix biomonitoring approach to assess exposure to metals and trace elements in the Lebanese population and associations with drinking water consumption

This study is the first attempt to assess exposure to metals and trace elements in subgroups of the Lebanese population using a multi-matrix biomonitoring approach. Concentrations of 11 metals and trace elements (aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), selenium (Se), uranium (U), zinc (Zn)) were measured in urine, hair and toenails. Biological levels were compared according to age, sex, smoking status, socioeconomic status, geographical area and drinking water source. While most urinary and toenail concentrations of metals and trace elements were not different between males and females, measured concentrations of several elements in hair were higher in females compared to males. Urinary concentrations of some metals (Al, Cu, Se and Zn) were higher in children compared to teenagers and adults. Hair and toenail concentrations of several elements (As, Cd, Pb, Mn, Se in hair and toenails plus Al, Fe in toenails) were also significantly higher in children compared to teenagers and/or adults. Smoking status had no influence on metal and trace element concentrations. Levels of Cd, Pb and Mn were also higher in samples from subgroups with lower economic status (Cd and Pb in the three matrices and Mn in hair and toenails). Very few correlations were identified between sources of drinking water and urine, hair, and toenail concentrations of metals and trace elements. However, a correlation was observed between hair and toenails levels of As, Cd and Pb. Overall, results highlight that a special attention should be given to metal and trace element exposure in this population (including Pb, As, Cd, Mn, and Se). It could be relevant to scale up this kind of investigation with a large human biomonitoring initiative in the Lebanese population in order to generalize results, and assess trends over time.

Determinants of blood and saliva lead concentrations in adult gardeners on urban agricultural sites

Soil Pb concentrations at urban agriculture sites (UAS) commonly exceed recommended safe levels. There is a lack of evidence regarding uptake of Pb by gardeners using such sites for food crops. Our study aimed to elucidate whether gardening in soil with raised Pb levels results in Pb body burdens of concern to health, and to assess confounding factors influencing Pb body burden. Our cross-sectional case study measured Pb in saliva and blood of UAS gardeners (n = 43), soil and produce samples from their UAS, and home tap water. Blood and saliva Pb concentrations were compared with those from non-UAS gardener controls (n = 29). A health risk threshold of 5 µg dL^-1 blood Pb level (BLL) was selected in keeping with international guidance. Detailed surveys investigated individuals' anthropometrics and potential Pb exposures from diet, and historic and everyday activities. Saliva was not found to be a suitable biomarker of adult Pb exposure in this context. Predictors of higher BLLs were being older, being male and eating more root vegetables and shrub fruit. Eating more green vegetables predicted a lower BLL, suggesting a protective effect against Pb uptake. UAS gardeners' BLLs (geometric mean 1.53; range 0.6-4.1 µg dL^-1) were not significantly higher (p = 0.39) than the control group (geometric mean 1.43; range 0.7-2.9 µg dL^-1). All BLLs were below 5 µg dL^-1 except one resulting from occupational exposure. Having paired the UAS gardeners with closely matched controls, we found Pb in UAS soils (with range 62-1300 mg kg^-1from common urban sources) unlikely to pose an additional risk to adult health compared to their neighbours who did not access UAS. As such, other Pb sources may be the dominant factor controlling BLL.

A critical review on microbes-based treatment strategies for mitigation of toxic pollutants

Contamination of the environment through toxic pollutants poses a key risk to the environment due to irreversible environmental damage(s). Industrialization and urbanization produced harmful elements such as petrochemicals, agrochemicals, pharmaceuticals, nanomaterials, and herbicides that are intentionally or unintentionally released into the water system, threatening biodiversity, the health of animals, and humans. Heavy metals (HMs) in water, for example, can exist in a variety of forms that are inclined by climate features like the presence of various types of organic matter, pH, water system hardness, transformation, and bioavailability. Biological treatment is an important tool for removing toxic contaminants from the ecosystem, and it has piqued the concern of investigators over the centuries. In situ bioremediation such as biosparging, bioventing, biostimulation, bioaugmentation, and phytoremediation and ex-situ bioremediation includes composting, land farming, biopiles, and bioreactors. In the last few years, scientific understanding of microbial relations with particular chemicals has aided in the protection of the environment. Despite intensive studies being carried out on the mitigation of toxic pollutants, there have been limited efforts performed to discuss the solutions to tackle the limitations and approaches for the remediation of heavy metals holistically. This paper summarizes the risk assessment of HMs on aquatic creatures, the environment, humans, and animals. The content of this paper highlights the principles and limitations of microbial remediation to address the technological challenges. The coming prospect and tasks of evaluating the impact of different treatment skills for pollutant remediation have been reviewed in detail. Moreover, genetically engineered microbes have emerged as powerful bioremediation capabilities with significant potential for expelling toxic elements. With appropriate examples, current challenging issues and boundaries related to the deployment of genetically engineered microbes as bioremediation on polluted soils are emphasized.

Complex Profile of Altered Heavy Metals Accumulation in Multiple Sclerosis, a Relationship with Copper and Zinc Homeostasis

BACKGROUND: Multiple sclerosis (MS) is a demyelinating inflammatory disease of the central nervous system white matter. Both of environmental and genetic factors have been implicated in its pathogenesis. Heavy metals generate free radicals causing alteration in genetic material and blood-brain barrier damage. In addition, intracellular accumulation of certain heavy metals can trigger autoimmune reaction against myelin proteins and nerves cytoskeletal proteins. AIM: We aimed to analyse complex profile of altered heavy metals accumulation in multiple sclerosis and relationship with copper and zinc homeostasis. METHODS: The present study was carried out in the period between September 2019 and May 2021 on 86 MS Egyptian patients and 86 age and gender matched healthy controls. Whole blood levels of lead (Pb), mercury (Hg), and Cadmium (Cd) in microgram/liter (μg/L) in addition to Zinc (Zn) and Copper (Cu) in milligram/liter (mg/L) were quantitated using the Agilent ICP-MS-MS. The current study also discussed physiological-toxic metals interactions in these patients. RESULTS: We demonstrated significant relations between toxic heavy metals levels and MS suggested by significantly higher levels of Pb, Hg, and Cd and significantly lower levels of Zn and Cu as well as Cu/ Zn in MS patients than controls. Besides, it could be assumed that; physiological heavy metals homeostasis limits the accumulation of toxic heavy metals that share absorption and transport binding sites, suggested by the significant negative correlations between whole blood levels of Cu and both of Hg and Pb. CONCLUSION: A complex profile of altered elements rather than a single element imbalance in MS pathogenesis is suggested.

Associations between lead, cadmium, mercury, and arsenic exposure and alanine aminotransferase elevation in the general adult population: an exposure-response analysis

Cadmium, lead, mercury, and arsenic are among the most toxic environmental contaminants. Serum alanine aminotransferase (ALT) is the most common liver biomarker. This analysis aimed to explore the associations between blood cadmium, lead, mercury, urinary total arsenic, and dimethylarsinic acid and ALT elevation in adults. Data were extracted from 5 National Health and Nutrition Examination Survey cycles (NHANES) 2007-2016. Patients with chronic viral hepatitis and excessive alcohol consumption were excluded. ALT elevation was defined according to the 2017 American College of Gastroenterology Clinical Guideline. Logistic models and restricted cubic splines were adopted to assess the exposure-response relationships. Comparing the highest to lowest quintile of exposure, the multivariable-adjusted odds ratios (95% confidence intervals) of ALT elevation were 1.38 (1.07-1.78) for blood lead (P_{for trend} = 0.01), 1.37 (1.16-1.62) for blood mercury (P_{for trend} < 0.01), 0.94 (0.78-1.14) for blood cadmium (P_{for trend} = 0.64), 1.07 (0.79-1.45) for urinary total arsenic (P_{for trend} = 0.81), and 1.25 (0.94-1.66) for urinary dimethylarsinic acid (P_{for trend} = 0.18). The associations between blood lead and mercury and ALT elevation were only observed in women. In addition, the associations between urinary total arsenic [1.53 (1.02-2.29), P_{for trend} = 0.02] and dimethylarsinic acid [2.17 (1.05-4.49), P_{for trend} = 0.02] and ALT elevation were also observed in women. Dose-response analysis showed that there was no safe exposure threshold of blood lead and mercury's toxic effect on ALT elevation, respectively. In conclusion, lead, mercury and arsenic were associated with ALT elevation in adults, and the associations were mainly observed in women.

Racial/ethnic and neighborhood disparities in metals exposure during pregnancy in the Northeastern United States

Despite the unequal burden of environmental exposures borne by racially minoritized communities, these groups are often underrepresented in public health research. Here, we examined racial/ethnic disparities in exposure to metals among a multi-ethnic sample of pregnant women. The sample included women enrolled in the PRogramming of Intergenerational Stress Mechanisms (PRISM) pregnancy cohort (N = 382). Urinary metal concentrations (arsenic [As], barium [Ba], cadmium [Cd], cesium [Cs], chromium [Cr], lead [Pb], antimony [Sb]) were measured during mid-pregnancy and information on individual- and neighborhood-level characteristics was ascertained during an in-person interview and from publicly available databases, respectively. Linear regression was used to examine individual and neighborhood characteristics in relation to metal concentrations. Black/Black-Hispanic women had Cd, Cr, Pb, and Sb levels that were 142.0%, 10.9%, 35.0%, and 32.1% higher than White, non-Hispanic women, respectively. Likewise, White-Hispanic women had corresponding levels that were 141.5%, 108.2%, 59.9%, and 38.3% higher. These same metals were also higher among women residing in areas with higher crime, higher diversity, lower educational attainment, lower household income, and higher poverty. Significant disparities in exposure to metals exist and may be driven by neighborhood-level factors. Exposure to metals for pregnant women can be especially harmful. Understanding exposure inequalities and identifying factors that increase risk can help inform targeted public health interventions.

Cadmium acute exposure induces metabolic and transcriptomic perturbations in human mature adipocytes

Obesity is considered as a major public health concern with strong economic and social burdens. Exposure to pollutants such as heavy metals can contribute to the development of obesity and its associated metabolic disorders, including type 2 diabetes and cardiovascular diseases. Adipose tissue is an endocrine and paracrine organ that plays a key role in the development of these diseases and is one of the main target of heavy metal accumulation. In this study, we determined by inductively coupled plasma mass spectrometry cadmium concentrations in human subcutaneous and visceral adipose tissues, ranging between 2.5nM and 2.5µM. We found a positive correlation between cadmium levels and age, sex and smoking status and a negative correlation between Cd and body mass index. Based on cadmium adipose tissue concentrations found in humans, we investigated the effects of cadmium exposure, at concentrations between 1nM and 10µM, on adipose-derived human mesenchymal stem cells differentiated into mature adipocytes in vitro. Transcriptomic analysis highlighted that such exposure altered the expression of genes involved in trace element homeostasis and heavy metal detoxification, such as Solute Carrier Family transporters and metallothioneins. This effect correlated with zinc level alteration in cells and cellular media. Interestingly, dysregulation of zinc homeostasis and transporters has been particularly associated with the development of obesity and type 2 diabetes. Moreover, we found that cadmium exposure induces the pro-inflammatory state of the adipocytes by enhancing the expression of genes such as IL-6, IL-1B and CCL2, cytokines also induced in obesity. Finally, cadmium modulates various adipocyte functions such as the insulin response signaling pathway and lipid homeostasis. Collectively, our data identified some of the cellular mechanisms by which cadmium alters adipocyte functions, thus highlighting new facets of its potential contribution to the progression of metabolic disorders.

Prenatal metal(loid) mixtures and birth weight for gestational age: A pooled analysis of three cohorts participating in the ECHO program

BACKGROUND

A growing number of studies have identified both toxic and essential metals which influence fetal growth. However, most studies have conducted single-cohort analyses, which are often limited by narrow exposure ranges, and evaluated metals individually. The objective of the current study was to conduct an environmental mixture analysis of metal impacts on fetal growth, pooling data from three geographically and demographically diverse cohorts in the United States participating in the Environmental Influences on Child Health Outcomes program.

METHODS

The pooled sample (N = 1,002) included participants from the MADRES, NHBCS, and PROTECT cohorts. Associations between seven metals (antimony, cadmium, cobalt, mercury, molybdenum, nickel, tin) measured in maternal urine samples collected during pregnancy (median: 16.0 weeks gestation) and birth weight for gestational age z-scores (BW for GA) were investigated using Bayesian Kernel Machine Regression (BKMR). Models were also stratified by cohort and infant sex to investigate possible heterogeneity. Chromium and uranium concentrations fell below the limits of detection for most participants and were evaluated separately as binary variables using pooled linear regression models.

RESULTS

In the pooled BKMR analysis, antimony, mercury, and tin were inversely and linearly associated with BW for GA, while a positive linear association was identified for nickel. The inverse association between antimony and BW for GA was observed in both males and females and for all three cohorts but was strongest for MADRES, a predominantly low-income Hispanic cohort in Los Angeles. A reverse j-shaped association was identified between cobalt and BW for GA, which was driven by female infants. Pooled associations were null for cadmium, chromium, molybdenum, and uranium, and BKMR did not identify potential interactions between metal pairs.

CONCLUSIONS

Findings suggest that antimony, an understudied metalloid, may adversely impact fetal growth. Cohort- and/or sex-dependent associations were identified for many of the metals, which merit additional investigation.

The associations of urinary DEHP metabolite levels, serum thyroid hormones, and thyroid-related genes among the adolescent students from China: a cross-sectional study

Our study aimed to investigate the associations between DEHP exposure and serum thyroid hormone levels in 347 adolescents and young adults. We measured DEHP metabolites including mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono(2-carboxymethyl)hexyl phthalate (MCMHP) in their urine. Total thyroxine (TT4), total triiodothyronine, free triiodothyronine, free thyroxine (FT4), thyroid-stimulating hormone and the mRNA levels of thyroid peroxidase (TPO), thyroglobulin (TG), sodium iodide symporter (NIS), thyroid transcription factor 1 (TTF-1), and paired box gene 8 (PAX-8) in serum were measured. The results of statistical analysis showed that urinary DEHP metabolites were generally negatively associated with TT4 levels in serum. In the males, the FT4 levels showed positive associations with urinary MEHP, MECPP, MCMHP, and ∑DEHP. The mRNA level of TG was significantly positively correlated with the levels of MECPP, MCMHP, and ∑DEHP, while the levels of TTF-1 and PAX-8 mRNA were significantly positively correlated with the levels of DEHP metabolites. Taken together, DEHP may affect the synthesis of TG by altering the normal transcription of TTF-1 and PAX-8, leading to decreased TT4 levels in Chinese adolescents.

Urinary Cadmium and Incident Heart Failure: A Case-Cohort Analysis Among Never-Smokers in Denmark

BACKGROUND

Epidemiologic studies suggest cadmium exposure is associated with cardiovascular disease risk, including heart failure. However, prior findings may be influenced by tobacco smoking, a dominant source of cadmium exposure and risk factor for heart failure. The present study leverages up to 20 years of follow-up in the Danish Diet, Cancer and Health cohort to examine the relationship between urinary cadmium and incident heart failure among people who never smoked.

METHODS

Between 1993 and 1997, 19,394 never-smoking participants (ages 50-64 years) enrolled and provided a urine sample. From this sample, we randomly selected a subcohort of 600 men and 600 women and identified 958 incident heart failure cases occurring between baseline and 2015. Using a case-cohort approach, we estimated adjusted hazard ratios (aHR) for heart failure in Cox proportional hazards models with age as the time scale.

RESULTS

Participants had relatively low concentrations of urinary cadmium, as expected for never smokers (median = 0.20; 25th, 75th = 0.13, 0.32 μg cadmium/g creatinine). In adjusted models, we found that higher urinary cadmium was associated with a higher rate of incident heart failure overall (aHR = 1.1 per interquartile range difference [95% CI = 1.0, 1.2). In sex-stratified analyses, the association seemed restricted to men (aHR = 1.5 [95% CI = 1.2, 1.9]).

CONCLUSIONS

In this cohort of people who never smoked tobacco, environmental cadmium was positively associated with incident heart failure, especially among men.

Gender difference in arsenic biotransformation is an important metabolic basis for arsenic toxicity

BACKGROUND

Arsenic metabolism enzymes can affect the toxic effects of arsenic. However, the effects of different genders on the metabolites and metabolic enzymes in liver arsenic metabolism is still unclear. This study analyzed the gender differences of various arsenic metabolites and metabolic enzymes and further explored the effects of gender differences on arsenic metabolism in liver tissues of rats.

METHODS

Rats were treated with high/medium/low doses of iAs³⁺ or iAs⁵⁺. Liver pathological changes were observed with electron microscopy. The monomethyl aracid (MMA) and dimethyl aracid (DMA) was determined by high performance liquid chromatography-hydride generation atomic fluorescence spectroscopy. S-adenosylmethionine (SAM), arsenate respiratory reductase (ARR), nicotinamide adenine dinucleotide (NAD), purine nucleoside phosphorylase (PNP), pyruvate kinase (PK), and myeloperoxidase (MPO) SAM, ARR, NAD, PNP, PK, and MPO were determined by enzyme-linked immunoassay. RT-qPCR was used to determine Arsenic (+ 3 oxidation state) methyltransferase (AS3MT).

RESULTS

The iAs³⁺ and iAs⁵⁺ at high doses induced pathological changes in the liver, such as increased heterochromatin and lipid droplets. Compared within the same group, MMA and DMA were statistically significant in iAs^{3 +} high, iAs^{3 +} medium and iAs⁵⁺ low dose groups (P < 0.05). MMA of male rats in iAs³⁺ high and medium groups was higher than that of female rats, and the DMA of male rats was lower than that of female rats. As3MT mRNA in the male iAs³⁺ high group was higher than that of females. Besides, compared between male and female, only in iAS³⁺ low dose, iAS³⁺ medium dose, iAS⁵⁺ low dose, and iAS⁵⁺ medium dose groups, there was significant difference in SAM level (P < 0.05). Compared within the same group, male rats had significantly higher PNP and ARR activities while lower PK activity than female rats (P < 0.05). Between the male and female groups, only the iAS³⁺ high dose and medium dose group had a statistically significant difference (P < 0.05). The NAD activity of females in iAS³⁺ high dose group was higher than that of males.

CONCLUSION

The gender differences in the arsenic metabolism enzymes may affect the biotransformation of arsenic, which may be one of the important mechanisms of arsenic toxicity of different sexes and different target organs.

Sex differences in the effects of whole-life, low-dose cadmium exposure on postweaning high-fat diet-induced cardiac pathogeneses

We previously showed the development of cardiac remodeling (hypertrophy or fibrosis) in mice with either post-weaning high-fat diet (HFD, 60% kcal fat) feeding or exposure to chronic low-dose cadmium. Here, we determined whether whole-life exposure to environmentally relevant, low-dose cadmium affects the susceptibility of offspring to post-weaning HFD-induced cardiac pathologies and function. Besides, we also determined whether these effects are sex-dependent. Male and female mice were exposed to cadmium-containing (0, 0.5, or 5 parts per million [ppm]) drinking water before breeding; the pregnant mice and dams with offspring continually drank the same cadmium-containing water. After weaning, the offspring were continued on the same regime as their parents and fed either a HFD or normal fat diet for 24 weeks. Cardiac function was examined with echocardiography. Cardiac tissues were used for the histopathological and biochemical (gene and protein expression by real-time PCR and Western blotting) assays. Results showed a dose-dependent cadmium accumulation in the hearts of male and female mice along with decreased cardiac zinc and copper levels only in female offspring. Exposure to 5 ppm, but not 0.5 ppm, cadmium significantly enhanced HFD cardiac effects only in female mice, shown by worsened cardiac systolic and diastolic dysfunction (ejection fraction, mitral E-to-annular e' ratio), increased fibrosis (collagen, fibronectin, collagen1A1), hypertrophy (cardiomyocyte size, atrial natriuretic peptide, β-myosin heavy chain), and inflammation (intercellular adhesion molecule-1, tumor necrosis factor-α, plasminogen activator inhibitor type 1), compared to the HFD group. These synergistic effects were associated with activation of the p38 mitogen-activated protein kinases (MAPK) signaling pathway and increased oxidative stress, shown by 3-nitrotyrosine and malondialdehyde, along with decreased metallothionein expression. These results suggest that whole-life 5 ppm cadmium exposure significantly increases the susceptibility of female offspring to HFD-induced cardiac remodeling and dysfunction. The underlying mechanism and potential intervention will be further explored in the future.

A U-Turn for Mercury Concentrations over 20 Years: How Do Environmental Conditions Affect Exposure in Arctic Seabirds?

Mercury (Hg) is highly toxic in its methylated form (MeHg), and global change is likely to modify its bioavailability in the environment. However, it is unclear how top predators will be impacted. We studied blood Hg concentrations of chick-rearing black-legged kittiwakes Rissa tridactyla (2000-2019) in Svalbard (Norway). From 2000 to 2019, Hg concentrations followed a U-shaped trend. The trophic level, inferred from nitrogen stable isotopes, and chlorophyll a (Chl a) concentrations better predicted Hg concentrations, with positive and U-shaped associations, respectively. As strong indicators of primary productivity, Chl a concentrations can influence production of upper trophic levels and, thus, fish community assemblage. In the early 2000s, the high Hg concentrations were likely related to a higher proportion of Arctic prey in kittiwake's diet. The gradual input of Atlantic prey in kittiwake diet could have resulted in a decrease in Hg concentrations until 2013. Then, a new shift in the prey community, added to the shrinking sea ice-associated release of MeHg in the ocean, could explain the increasing trend of Hg observed since 2014. The present monitoring provides critical insights about the exposure of a toxic contaminant in Arctic wildlife, and the reported increase since 2014 raises concern for Arctic seabirds.

Trace elements in whole blood in the general population in Trøndelag County, Norway: The HUNT3 Survey

BACKGROUND

Biomonitoring of a cohort within a large health survey can provide reliable information on trace element status. The main aims of this study were 1) to determine the concentrations of 28 trace elements in whole blood samples from the general population of the Nord-Trøndelag region, Norway, and 2) to investigate how trace element concentrations vary with geographical area, lifestyle, and socio-demographic factors.

METHODS

Whole blood samples were collected in the third survey of the Trøndelag Health Survey (HUNT3), a large population-based study in Norway. In total, 1011 whole blood samples from individuals aged 20-91 years were analyzed using high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS). We compared trace element concentrations (As, B, Be, Br, Ca, Cd, Cr, Cs, Cu, Ga, Au, In, Fe, Pb, Hg, Tl, Mg, Mn, Mo, Ni, Rb, Sc, Se, Ag, Sr, Sn, W and Zn) between three geographical areas (coastal, fjord/town, inland/mountain) using multivariable linear regression and assessed differences in trace element concentrations with socio-demographic and lifestyle factors using general linear models.

RESULTS

Trace element concentrations were generally comparable to levels reported in other recent studies and suggest low exposure to toxic trace elements in the region. We found geographical differences in concentrations of 19 trace elements. As, Br, Hg, and Se concentrations were higher on the coast compared to the fjord/town and inland/mountain areas, suggesting that the marine environment is an important source of exposure for these trace elements. In addition, socio-demographic and lifestyle characteristics, particularly age and sex, were associated with differences in trace element concentrations.

CONCLUSIONS

We report concentrations of 28 trace elements in the general population of a rural region with low exposure to pollution. Whole blood concentrations of trace elements varied with geographical area, the participants' lifestyle, and socio-demographic characteristics, highlighting the importance of considering these factors when evaluating trace element status in a population.

Maternal exposure to arsenic in drinking water and risk of congenital heart disease in the offspring

INTRODUCTION

Prenatal exposure to arsenic is suspected to impair fetal health, including congenital malformations. Few studies investigated an association between maternal exposure to arsenic and congenital heart disease.

OBJECTIVE

To examine the association between maternal exposure to arsenic through drinking water and congenital heart disease among offspring.

METHODS

This nationwide cohort study included all liveborn children in Denmark, 1997-2014. Maternal addresses at fetal age 4 weeks were linked to drinking water supply areas. Exposure was arsenic concentration in drinking water in first trimester in four categories (<0.5 μg/L, 0.5-0.9 μg/L, 1.0-4.9 μg/L, ≥5.0 μg/L). Outcomes were defined as congenital heart disease diagnosed within the first year of life, with sub-categorization of severe, septal defects and valvular heart defect. Associations between arsenic levels and congenital heart disease were analysed using logistic regression, presented as odds ratios (OR) with 95% confidence interval (CI), and adjusted for year of birth, mother's educational level and ethnicity.

RESULTS

A total of 1,042,413 liveborn children were included of whom 1.0% had a congenital heart disease. The OR of congenital heart disease was higher among children exposed to all levels of arsenic above 0.5 μg/L; the OR was 1.13 (95% CI: 1.08-1.19) for exposure of 0.5-0.9 μg/L, 1.33 (95% CI: 1.27-1.39) for 1.0-4.9 μg/L and 1.42 (95% CI: 1.24-1.63) for ≥5.0 μg/L. Similar associations were observed for congenital septal defects. The OR was also higher for severe congenital heart disease but at the same level among all exposure levels ≥0.5 μg/L. The OR of congenital valvular heart defects was only higher among children with maternal exposure to arsenic in drinking water ≥5.0 μg/L. The associations were similar for boys and girls.

CONCLUSION

The findings indicate that maternal exposure to arsenic in drinking water even at low concentrations (i.e., 0.5-0.9 μg/L) increased the risk of congenital heart disease in the offspring.

Gender Difference in the Associations among Heavy Metals with Red Blood Cell Hemogram

This study aimed to investigate gender differences in the association between heavy metals and hemograms including hemoglobin (Hgb), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC). A health survey of 2447 participants was conducted in southern Taiwan between June 2016 and September 2018. Seven heavy metals were measured: blood lead (Pb), urine nickel (Ni), urine chromium (Cr), urine manganese, urine arsenic (As), urine copper and urine cadmium (Cd). The results show that in females, Pb and Ni were significantly negatively associated with Hgb. In addition, As and Cd were significantly positively, and Pb and Ni were significantly negatively, associated with MCV, in males and females, respectively. The interactions between gender and Ni and gender and Cd in MCV were statistically significant. Further, Pb, in males, and Pb, Ni and Cr, in females, were significantly negatively associated with MCHC. In conclusion, in females, associations of red blood cell (RBC) hemograms with heavy metals such as Pb and Ni were found. In males, heavy metals such as Pb, As and Cd were found to associate with RBC hemograms. Further research is warranted to discuss the mechanism behind these associations.

Urinary cadmium in relation to bone damage: Cadmium exposure threshold dose and health-based guidance value estimation

Cadmium (Cd) is a widespread heavy metal with osteotoxicity, and bone mineral density (BMD) is often used as an early sensitive biomarker of bone damage. This study retrieved worldwide epidemiological studies to conduct a systematic meta-analysis to explore the association between Cd exposure and bone damage. A random effect model was used to establish the relationship between urinary Cd (U-Cd) and BMD and explore the influence of covariate factors. The benchmark dose method was used to calculate the safety threshold of U-Cd when the BMD decrease within an acceptable range. Toxicokinetic (TK) model was used to estimate the health-based guidance value (HBGV) of dietary Cd exposure based on the U-Cd threshold. The 95% lower confidence interval of benchmark dose of U-Cd derived in this study was 1.71 μg/g Cr, and the HBGV of dietary Cd exposure was determined to be 0.64 μg/kg bw/day. Gender had the greatest influence on BMD, followed by body mass index (BMI), age, and race. This study conducted a comprehensive systematic analysis of global research and was the first exploration to quantify the decreased BMD caused by Cd exposure in a large-scale population. The results provided reference for the risk assessment of Cd exposure and the formulation of dietary exposure standards.

Soil Metal Immobilization in Agricultural Land Contaminated with Cadmium and Lead: A Case Study of Effectiveness Evaluation in Lanping, Southwest China

The growth of edible crops on land that is highly polluted with potentially toxic elements is prohibited in many developed countries, but the growth of fiber or energy crops may be permitted. Here, we have evaluated metal immobilization in a maize field polluted with cadmium (Cd) and lead (Pb) to determine the thresholds of soil CaCl₂-extractable Cd and Pb and to assess management options designed to maximize food safety. Based on geographical and statistical methods we found that when the soil pH was increased from 5.24 to 6.24, the soil CaCl₂-extractable Cd and Pb values decreased by 47.8 and 74.7%, respectively. Soil CaCl₂-extractable Pb concentrations need to be < 2.14 mg kg^-1 in order to comply with the Chinese maximum permissible grain Pb concentration (< 0.2 mg kg^-1). Immobilization increased the percentage of samples that were below permissible levels from 77.4% to 96.2% (grain Cd) and 90.6% to 96.2% (grain Pb) during the period 2017 to 2019. To avoid excessive or inadequacy immobilization, the spatial distribution of correlation coefficients of soil pH, CaCl₂-extractable or grain Cd/Pb may be helpful in the precise management of immobilization for long-term remediation.

Accumulation of selected metals and concentration of macroelements in liver and kidney tissues of sympatric golden jackal (Canis aureus) and red fox (Vulpes vulpes) in Somogy County, Hungary

This study examined the concentrations of Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn in the liver and kidney samples of golden jackals (n = 163) and red foxes (n = 64). Additionally, we studied how sex affected element concentration in both species, and in the case of golden jackals, how concentration levels were affected by age.Liver was the most important storage organ for Cu, Fe, Mn, and Zn, while kidney for Cd and Na in jackals and foxes.We found no sex-related differences in concentration of any of the selected elements in fox samples. In jackals, the mean concentrations of Al, Mn, and Zn were significantly higher in kidneys of males, while Zn and Cu had higher concentrations in female livers. Our results suggest bioaccumulation processes do not occur in mesocarnivores.Lead and Cd concentrations fell within ranges accepted as normal for canine species and were below toxic levels in the organs of the examined species. Concentrations of Cr, Cu, Fe, Mn, and Zn were far below the toxic levels in both organs of both species, with a slight sign of deficiency of Fe, Mn, and Zn in jackal and fox kidneys. In comparison with toxicity levels and results from other European study sites, the current study demonstrated that species living in the examined area of Somogy County, Hungary, are generally exposed to low levels of environmental contamination.

The Risk Factors of Blood Cadmium Elevation in Chronic Kidney Disease

Low-level cadmium exposure has adverse effects on chronic kidney disease (CKD); however, the risk factors for elevated blood cadmium levels (BCLs) have not been studied in CKD. We conducted a cross-sectional investigation in 200 CKD patients and stratified them by the tertiles of BCL to compare their demographic, environmental, and biochemical data. The factors associated with BCL were identified, and their effects were examined in subgroups. In the analyses, female sex, smoking, and CKD stage 5D were associated with high BCL, and statin was inversely correlated with BCL (odds ratio [95% confidence interval, CI], 6.858 [2.381–19.746], p < 0.001, 11.719 [2.843–48.296], p = 0.001, 30.333 [2.252–408.520], p = 0.010, and 0.326 [0.122–0.873], p = 0.026; deviations of BCL [nmol/L, 95% CI], 2.66 [1.33–4.00], p < 0.001, 3.68 [1.81–5.56], p < 0.001, 3.38 [0.95–5.82], p = 0.007, and −2.07 [−3.35–−0.78], p = 0.002). These factors were also independently correlated with BCL in subgroups, including non-dialysis CKD, hypertensive patients, non-smokers, and male patients. In conclusion, female sex, smoking, and CKD stage 5D were the major risk factors for elevated BCL; additionally, statins were negatively associated with BCL in CKD.

Exposure of the residents around the Three Gorges Reservoir, China to chromium, lead and arsenic and their health risk via food consumption

Hydrological management of the Three Gorges Dam has resulted in the interception of heavy metals in the Three Gorges Reservoir (TGR). However, the exposure to heavy metals and health risks among local residents remained poorly understood. Here we collected 208 biomarker samples (hair) and 20 food species from typical regions in the TGR to assess the exposure levels of three toxic metals (Cr, Pb and As) in residents of the TGR, and subsequently investigated their health risk via dietary intake. Results indicated that hair Cr and As levels were below the reference value for normal people and threshold of skin lesions, respectively, whereas about 22% hair Pb exceeded the reference for clinical medicine, indicating a potential Pb exposure of local residents. Smoking habit and fish consumption were found to be predictors for hair Pb. In addition, the concentrations of heavy metals in all investigated food samples were below the limits of contaminants in food in China, except for Pb in the sweet potato and fish. The estimated daily intake of metals (DIMs) revealed that the intakes of Cr and As from studied food were under the recommended thresholds of Cr and As. However, the intake of Pb via diet exceeded the limit of the prevalence of chronic kidney disease and closed to the threshold for cardiovascular, which was probably associated with the high Pb concentrations of fish and sweet potato. Overall, residents around the TGR were at low exposure to Cr and As, but Pb exposure may need more attention.

Prenatal metal exposure, cord blood DNA methylation and persistence in childhood: an epigenome-wide association study of 12 metals

BACKGROUND

Prenatal exposure to essential and non-essential metals impacts birth and child health, including fetal growth and neurodevelopment. DNA methylation (DNAm) may be involved in pathways linking prenatal metal exposure and health. In the Project Viva cohort, we analyzed the extent to which metals (As, Ba, Cd, Cr, Cs, Cu, Hg, Mg, Mn, Pb, Se, and Zn) measured in maternal erythrocytes were associated with differentially methylated positions (DMPs) and regions (DMRs) in cord blood and tested if associations persisted in blood collected in mid-childhood. We measured metal concentrations in first-trimester maternal erythrocytes, and DNAm in cord blood (N = 361) and mid-childhood blood (N = 333, 6-10 years) with the Illumina HumanMethylation450 BeadChip. For each metal individually, we tested for DMPs using linear models (considered significant at FDR < 0.05), and for DMRs using comb-p (Sidak p < 0.05). Covariates included biologically relevant variables and estimated cell-type composition. We also performed sex-stratified analyses.

RESULTS

Pb was associated with decreased methylation of cg20608990 (CASP8) (FDR = 0.04), and Mn was associated with increased methylation of cg02042823 (A2BP1) in cord blood (FDR = 9.73 × 10-6). Both associations remained significant but attenuated in blood DNAm collected at mid-childhood (p < 0.01). Two and nine Mn-associated DMPs were identified in male and female infants, respectively (FDR < 0.05), with two and six persisting in mid-childhood (p < 0.05). All metals except Ba and Pb were associated with ≥ 1 DMR among all infants (Sidak p < 0.05). Overlapping DMRs annotated to genes in the human leukocyte antigen (HLA) region were identified for Cr, Cs, Cu, Hg, Mg, and Mn.

CONCLUSIONS

Prenatal metal exposure is associated with DNAm, including DMRs annotated to genes involved in neurodevelopment. Future research is needed to determine if DNAm partially explains the relationship between prenatal metal exposures and health outcomes.

RELATIONSHIP BETWEEN LEAD AND CADMIUM LEVELS IN BLOOD AND REFRACTORY CHRONIC CONSTIPATION AMONG IRANIAN CHILDREN

BACKGROUND

There is limited research examining reasons causing refractory chronic constipation (RCC) in children. The effects of lead (Pb) and cadmium (Cd) exposures on this condition have been even less clear. However, some related factors may contribute to evaluation of blood lead levels (BLLs) and blood cadmium levels (BCLs).

OBJECTIVE

The present study aimed to examine the relationship between Pb and Cd exposures and RCC in children living in the city of Ahvaz, Khuzestan Province, in Southwestern Iran.

METHODS

This study was performed on a total number of 48 children aged 2-13 years, including 36 medically-diagnosed RCC cases and 12 controls referring to a pediatric clinic in the city of Ahvaz. Their BLLs and BCLs were then determined using a graphite furnace atomic absorption spectrophotometer. The data from the researcher-designed questionnaire were also recoded and the related risk factors were analyzed through Spearman's correlation and logistic regression analysis.

RESULTS

The findings revealed that the geometric means of Pb and Cd in blood samples in the control group were 58.95 µg/dL and 0.45 µg/dL; respectively. These values in the case group were equally 45.26 µg/dL and 0.26 µg/dL; respectively. A significant difference was additionally observed between BCLs in the case and control groups (P<0.01). All children in both groups also had BLLs greater than the permissible limit endorsed by the World Health Organization (WHO) (≤10 µg/dL). On the other hand, 8.3% of the individuals in the case group and 33.3% of those in the control group had BCLs higher than the acceptable range mentioned by WHO (≤0.5 µg/dL).

CONCLUSION

Pb and Cd exposures due to environmental pollution and susceptibility to heavy metals may not be associated with RCC in children living in the city of Ahvaz. Although this research was the first one providing data on BLLs and BCLs in children with RCC, the findings could be useful for designing future epidemiologic studies.

Sex affects the response of Wistar rats to polyvinyl pyrrolidone (PVP)-coated silver nanoparticles in an oral 28 days repeated dose toxicity study

BACKGROUND

Silver nanoparticles (AgNPs) are widely used in biomedicine due to their strong antimicrobial, antifungal, and antiviral activities. Concerns about their possible negative impacts on human and environmental health directed many researchers towards the assessment of the safety and toxicity of AgNPs in both in vitro and in vivo settings. A growing body of scientific information confirms that the biodistribution of AgNPs and their toxic effects vary depending on the particle size, coating, and dose as well as on the route of administration and duration of exposure. This study aimed to clarify the sex-related differences in the outcomes of oral 28 days repeated dose exposure to AgNPs.

METHODS

Wistar rats of both sexes were gavaged daily using low doses (0.1 and 1 mg Ag/kg b.w.) of polyvinylpyrrolidone (PVP)-coated small-sized (10 nm) AgNPs. After exposure, blood and organs of all rats were analysed through biodistribution and accumulation of Ag, whereas the state of the liver and kidneys was evaluated by the levels of reactive oxygen species (ROS) and glutathione (GSH), catalase (CAT) activity, superoxide dismutase (SOD) and glutathione peroxidase (GPx), expression of metallothionein (Mt) genes and levels of Mt proteins.

RESULTS

In all animals, changes in oxidative stress markers and blood parameters were observed indicating the toxicity of AgNPs applied orally even at low doses. Sex-related differences were noticed in all assessed parameters. While female rats eliminated AgNPs from the liver and kidneys more efficiently than males when treated with low doses, the opposite was observed for animals treated with higher doses of AgNPs. Female Wistar rats exposed to 1 mg PVP-coated AgNPs/kg b.w. accumulated two to three times more silver in the blood, liver, kidney and hearth than males, while the accumulation in most organs of digestive tract was more than ten times higher compared to males. Oxidative stress responses in the organs of males, except the liver of males treated with high doses, were less intense than in the organs of females. However, both Mt genes and Mt protein expression were significantly reduced after treatment in the liver and kidneys of males, while they remained unchanged in females.

CONCLUSIONS

Observed toxicity effects of AgNPs in Wistar rats revealed sex-related differences in response to an oral 28 days repeated exposure.

Dietary Heavy Metal Exposure among Finnish Adults in 2007 and in 2012

For the non-smoking and non-occupationally exposed population in Europe, food is the main source of heavy metal exposure. The aim of the study was to estimate the dietary exposure of the Finnish adult population to cadmium, lead, inorganic arsenic, inorganic mercury and methyl mercury as well as nickel using governmental as well as industry data on heavy metal occurrence in foodstuffs and the data from two national food consumption surveys conducted in 2007 and 2012. The sources of heavy metal exposure were estimated for the working-age population (25 to 64 years) and for the elderly (65 to 74 years). Exposure differences between years and between population groups were compared statistically. The mean exposure of women aged 25 to 45 years to cadmium and lead was statistically significantly (p < 0.001) higher, and the methyl mercury exposure lower (p = 0.001) than that of women aged 46 to 64 years. For nickel and inorganic arsenic the differences were lower but still statistically significant (p < 0.05). Between genders, significant difference (p < 0.05) was only seen for lead and nickel. Mean cadmium exposure was significantly higher in 2012 than in 2007. For at least 95% of the adult population, the risk of health damage from mercury or nickel exposure is negligible, but the margin of exposure for lead and inorganic arsenic is small and shows a possible risk of cancer or neurotoxic effects.

Maternal gestational mercury exposure in relation to cord blood T cell alterations and placental gene expression signatures

The immunotoxic impacts of mercury during early life is poorly understood. We investigated the associations between gestational mercury exposure and frequency of cord blood T cells as well as placental gene expression. Frequency of natural Treg cells was positively associated with prenatal and postpartum mercury toenail concentrations. Frequency of NKT and activated naïve Th cells was positively associated with prenatal toenail mercury concentrations and number of maternal silver-mercury dental amalgams, respectively. Placental gene expression analyses revealed distinct gene signatures associated with mercury exposure. Decreased placental expression of a histone demethylase, KDM4DL, was associated with both higher prenatal and postpartum maternal toenail mercury levels among male infants and remained statistically significant after adjustment for fish and seafood consumption. The results suggest that gestational exposure to mercury concentrations contribute to alterations in both T cells and gene expression in placenta at birth. These alterations may inform mechanisms of mercury immunotoxicity.

Sex-specific neurotoxic effects of heavy metal pollutants: Epidemiological, experimental evidence and candidate mechanisms

The heavy metals lead (Pb), mercury (Hg), and cadmium (Cd) are ubiquitous environmental pollutants and are known to exert severe adverse impacts on the nervous system even at low concentrations. In contrast, the heavy metal manganese (Mn) is first and foremost an essential nutrient, but it becomes neurotoxic at high levels. Neurotoxic metals also include the less prevalent metalloid arsenic (As) which is found in excessive concentrations in drinking water and food sources in many regions of the world. Males and females often differ in how they respond to environmental exposures and adverse effects on their nervous systems are no exception. Here, we review the different types of sex-specific neurotoxic effects, such as cognitive and motor impairments, that have been attributed to Pb, Hg, Mn, Cd, and As exposure throughout the life course in epidemiological as well as in experimental toxicological studies. We also discuss differential vulnerability to these metals such as distinctions in behaviors and occupations across the sexes. Finally, we explore the different mechanisms hypothesized to account for sex-based differential susceptibility including hormonal, genetic, metabolic, anatomical, neurochemical, and epigenetic perturbations. An understanding of the sex-specific effects of environmental heavy metal neurotoxicity can aid in the development of more efficient systematic approaches in risk assessment and better exposure mitigation strategies with regard to sex-linked susceptibilities and vulnerabilities.

Arsenic Secondary Methylation Capacity Is Inversely Associated with Arsenic Exposure-Related Muscle Mass Reduction

Skeletal muscle mass reduction has been implicated in insulin resistance (IR) that promotes cardiometabolic diseases. We have previously reported that arsenic exposure increases IR concomitantly with the reduction of skeletal muscle mass among individuals exposed to arsenic. The arsenic methylation capacity is linked to the susceptibility to some arsenic exposure-related diseases. However, it remains unknown whether the arsenic methylation capacity affects the arsenic-induced reduction of muscle mass and elevation of IR. Therefore, this study examined the associations between the arsenic methylation status and skeletal muscle mass measures with regard to IR by recruiting 437 participants from low- and high-arsenic exposure areas in Bangladesh. The subjects' skeletal muscle mass was estimated by their lean body mass (LBM) and serum creatinine levels. Subjects' drinking water arsenic concentrations were positively associated with total urinary arsenic concentrations and the percentages of MMA, as well as inversely associated with the percentages of DMA and the secondary methylation index (SMI). Subjects' LBM and serum creatinine levels were positively associated with the percentage of DMA and SMI, as well as inversely associated with the percentage of MMA. HOMA-IR showed an inverse association with SMI, with a confounding effect of sex. Our results suggest that reduced secondary methylation capacity is involved in the arsenic-induced skeletal muscle loss that may be implicated in arsenic-induced IR and cardiometabolic diseases.

Prenatal methylmercury exposure is associated with decrease heart rate variability in children

BACKGROUND

Although several epidemiological studies have suggested mercury (Hg) might be associated with cardiotoxicity, the impact of Hg exposure on cardiac autonomic activity and blood pressure in children has not been investigated at Hg exposure levels equivalent to the Environmental Protection Agency (EPA) reference dose.

OBJECTIVE

To investigate the association between low dose prenatal and recent methylmercury (MeHg) exposures and cardiac autonomic function and blood pressure with adjustment for factors such as fish consumption among children from a high fish consumption coastal city.

METHODS

Children aged 7-8 years were recruited from the birth cohort of our previous study. Heart rate variability (HRV), resting heart rate (RHR) and blood pressure were measured as surrogate markers of cardiac autonomic function. Cord blood and current whole blood Hg concentration were used as biomarkers of prenatal and recent MeHg exposure, respectively. Recent fish consumption information was estimated with a food frequency questionnaire.

RESULTS

Among 604 children, median cord blood and whole blood Hg concentrations were 45.9 nmol/L (IQR: 32.8-65.03 nmol/L) and 13.57 nmol/L (IQR: 9.29-19.72 nmol/L), respectively. Our results demonstrated that prenatal MeHg exposure was associated with decreased HRV (i.e. low CVRR, SDRR, and RMSSD), reflecting reduced parasympathetic activity (i.e. low CCV_HF and HF), and a sympathovagal balance shift toward sympathetic predominance (i.e. high %LF and LF/HF ratio). Adjustment of recent fish consumption further increased the significance and magnitude of the adverse associations of MeHg.

CONCLUSION

The results of this study suggest that prenatal MeHg exposure is associated with decreased parasympathetic modulation of cardiac autonomic function in children.

Maternal seafood intake during pregnancy, prenatal mercury exposure and child body mass index trajectories up to 8 years

BACKGROUND

Maternal seafood intake during pregnancy and prenatal mercury exposure may influence children's growth trajectories.

METHODS

This study, based on the Norwegian Mother, Father and Child Cohort Study (MoBa), includes 51 952 mother-child pairs recruited in pregnancy during 2002-08 and a subsample (n = 2277) with maternal mercury concentrations in whole blood. Individual growth trajectories were computed by modelling based on child's reported weight and length/height from 1 month to 8 years. We used linear mixed-effects regression analysis and also conducted discordant-sibling analysis.

RESULTS

Maternal lean fish was the main contributor to total seafood intake in pregnancy and was positively but weakly associated with child body mass index (BMI) growth trajectory. Higher prenatal mercury exposure (top decile) was associated with a reduction in child's weight growth trajectory, with the estimates ranging from -130 g [95% Confidence Intervals (CI) = -247, -12 g] at 18 months to -608 g (95% CI = -1.102, -113 g) at 8 years. Maternal fatty fish consumption was positively associated with child weight and BMI growth trajectory, but only in the higher mercury-exposed children (P-interaction = 0.045). Other seafood consumption during pregnancy was negatively associated with child weight growth compared with no intake, and this association was stronger for higher mercury-exposed children (P-interaction = 0.004). No association was observed between discordant maternal seafood intake and child growth in the sibling analysis.

CONCLUSIONS

Within a population with moderate seafood consumption and low mercury exposure, we found that maternal seafood consumption in pregnancy was associated with child growth trajectories, and the direction of the association varied by seafood type and level of prenatal mercury exposure. Prenatal mercury exposure was negatively associated with child growth. Our findings on maternal seafood intake are likely non-causal.

Cadmium and cardiovascular disease: An overview of pathophysiology, epidemiology, therapy, and predictive value

Cadmium is a widely distributed toxic heavy metal that has been associated with many diseases including chronic renal dysfunction, osteomalacia, acute heart failure, secondary hypertension, and atherosclerosis. Although several studies have suggested that cadmium may affect multiple systems by inducing lipid per oxidation in cells and disturbing the antioxidant system, the mechanism by which cadmium affects the cardiovascular system remains unclear. Recent studies on heart failure and acute myocardial infarction have shown that cadmium has good predictive ability for mortality in patients with cardiovascular disease. In this study, we briefly review the role of cadmium in cardiovascular disease, which may prompt further studies to investigate the potential association between cadmium and mortality in patients with cardiovascular disease.

Global and gene-specific promoter methylation, and micronuclei induction in lead-exposed workers: A cross-sectional study

Perturbation of epigenetic regulation is a well-established mechanism for cancer but its role for lead (Pb)-associated toxicity has not been adequately investigated. We aimed to investigate whether occupational Pb exposure is associated with micronuclei (MN) frequency and to further explored the mediating roles of epigenetic gene regulation. All the Pb-exposed workers recruited from a Chinese acid battery factory, blood lead levels (BLLs) and MN frequency in lymphocytes were measured. In addition, methylation levels of seven genes (Line-1, RASSF1A, RUNX3, p16, CYP26C1, hMLH1, p15) were examined among 230 workers. Robust Poisson regression model was used to investigate the association between BLLs and MN frequency. Mediation analysis was used to explore the mediating role of specific DNA methylation. Among total 677 participants, 71% were male, median BLLs was 229.1 μg/L (P₂₅  = 155.5, P₇₅  = 319.3; ranged from 8.9 to 647.7 μg/L), mean MN frequency was 2.5‰ (SD = 1.8‰; ranged from 0 to 9‰). Results from base model, adjusted for age, sex, and body mass index, showed that MN frequency would increase 1.38 (95%confidential interval: 1.34, 1.43) per 100 μg/L increment in BLLs. Using categorized exposure variable analyses, a BLLs dose-response increase in MN frequency was observed: 2.74 (2.13, 3.51), 3.43 (2.73, 4.32), 4.41 (3.89, 5.01) to 6.86 (6.02, 7.81). Mediation analysis indicated that Line-1 methylation significantly mediated 3.6% of the association of BLLs with MN frequency. Occupational Pb exposure induces MN frequency in a dose-response relationship. Part of this association was mediated by Line-1 promotor methylation.

Cadmium disturbs epigenetic modification and induces DNA damage in mouse preimplantation embryos

Cadmium is an environmental pollutant that has extensive deleterious effects on the reproductive system. However, the mechanisms underlying the effects of cadmium on preimplantation embryos are unclear. Here, we used a mouse model to investigate the effects of maternal cadmium (32 mg/l) exposure in drinking water for 2 days on early embryonic development, and studied the mechanisms associated with epigenetic modifications and DNA damage induced by oxidative stress. We observed that maternal cadmium exposure impaired preimplantation embryo development by inducing embryo death, fragmentation, or developmental blockade. After cadmium exposure, the most survived embryos were at the 8-cell stage, which were used for all measurements. Histone acetylation, not methylation, was disturbed by increasing histone deacetylase 1 (HDAC1) levels after cadmium exposure. Cadmium also disrupted DNA methylation of H19; however genomic DNA methylation can be normally reprogrammed in embryos. Furthermore, cadmium increased reactive oxygen species (ROS) levels and DNA damage, and partly inhibited gene expression related to DNA repair. The distribution and activity of mitochondria was increased; therefore, embryos maintain intracellular homeostasis for survival. Collectively, our findings revealed that maternal cadmium exposure impairs preimplantation embryo development by disturbing the epigenetic modification and inducing DNA damage.

Effects of Gadolinium Deposits in the Cerebellum: Reviewing the Literature from In Vitro Laboratory Studies to In Vivo Human Investigations

Gadolinium (Gd)-based contrast agents (GBCAs) are chemicals injected intravenously during magnetic resonance imaging (MRI) to enhance the diagnostic yield. The repeated use of GBCAs can cause their deposition in the brain, including the cerebellum. Such deposition may affect various cell subsets in the brain and consequently cause behavioral alterations due to neurotoxicity. Caution should thus be exercised in using these agents, particularly in patients who are more likely to have repeated enhanced MRIs during their lifespan. Further studies are required to clarify the toxicity of GBCAs, and potential mechanisms causing neurotoxicity have recently been reported. This review introduces the effects of GBCAs in the cerebellum obtained from in vitro and in vivo studies and considers the possible mechanisms of neurotoxicity involved.

Bayesian toxicokinetic modeling of cadmium exposure in Chinese population

Cadmium (Cd) is a toxic heavy metal widely present in the environment. Estimating its internal levels for a given external exposure using toxicokinetic (TK) models is key to the human health risk assessment of Cd. In this study, existing Cd TK models were adapted to develop a one-compartment TK model and a multi-compartment physiologically based toxicokinetic (PBTK) model by estimating the characteristics of Cd kinetics based on Cd exposure data from 814 Chinese residents. Both models not only considered the effect of gender difference on Cd kinetics, but also described the model parameters in terms of distributions to reflect individual variability. For both models, the posterior distributions of sensitive parameters were estimated using the Markov chain-Monte Carlo method (MCMC) and the approximate Bayesian computation-MCMC algorithm (ABC-MCMC). Validation with the test dataset showed 1.4-22.5% improvement in the root mean square error (RMSE) over the original models. After a systematic literature search, the optimized models showed acceptable prediction on other Chinese datasets. The study provides a method for parameter optimization of TK models under different exposure environment, and the validated models can serve as new quantitative assessment tools for the risk assessment of Cd in the Chinese population.

Cadmium and cardiovascular disease: An overview of pathophysiology, epidemiology, therapy, and predictive value

Cadmium is a widely distributed toxic heavy metal that has been associated with many diseases including chronic renal dysfunction, osteomalacia, acute heart failure, secondary hypertension, and atherosclerosis. Although several studies have suggested that cadmium may affect multiple systems by inducing lipid per oxidation in cells and disturbing the antioxidant system, the mechanism by which cadmium affects the cardiovascular system remains unclear. Recent studies on heart failure and acute myocardial infarction have shown that cadmium has good predictive ability for mortality in patients with cardiovascular disease. In this study, we briefly review the role of cadmium in cardiovascular disease, which may prompt further studies to investigate the potential association between cadmium and mortality in patients with cardiovascular disease.

Damage to the Testicular Structure of Rats by Acute Oral Exposure of Cadmium

Cadmium (Cd) is one of the most important heavy metal toxicants, used throughout the world at the industrial level. It affects humans through environmental and occupational exposure and animals through the environment. The most severe effects of oral exposure to Cd on the male reproductive system, particularly spermatogenesis, have not been discussed. In this study, we observed the damage to the testes and heritable DNA caused by oral exposure to Cd. Adult male Sprague–Dawley rats were divided into four groups: a control group and three groups treated with 5, 10, and 15 mg Cd/kg/day for 17 days by oral gavage. Our results revealed that Cd significantly decreases weight gain in 10 and 15 mg/kg groups, whereas the 5 mg/kg groups showed no difference in weight gain. The histopathology showed adverse structural effects on the rat testis by significantly reducing the thickness of the tunica albuginea, the diameter of the tubular lumen, and the interstitial space among seminiferous tubules and increasing the height of the epithelium and the diameter of the seminiferous tubules in Cd treated groups. Comet assay in epididymal sperms demonstrated a significant difference in the lengths of the head and comet in all the 3 Cd treated groups, indicating damage in heritable DNA, although variations in daily sperm production were not significant. Only a slight decrease in sperm count was reported in Cd-treated groups as compared to the control group, whereas the tail length, percentage of DNA in head, and tail showed no significant difference in control and all the experimental groups. Overall, our findings indicate that Cd toxicity must be controlled using natural sources, such as herbal medicine or bioremediation, with non-edible plants, because it could considerably affect heritable DNA and induce damage to the reproductive system.

Nickel Content in Human Internal Organs

With the growing interest in new applications of metals in modern technologies, an increase in their concentration in the environment can be observed, which, in consequence, may constitute a hazard to human health. That is why it is of a great importance to establish "reference" levels of particular elements (essential or toxic) in human biological samples.The aim of this paper was to determine nickel in autopsy tissues of non-occupationally exposed subjects in Southern Poland (n = 60). Measurements were performed by means of electrothermal atomic absorption spectrometry after microwave-assisted acid digestion according to previously optimized and validated procedure. The results obtained indicate that data cover the wide range of concentrations and generally are consistent with other published findings. Nickel levels in the brain, stomach, liver, kidneys, lungs and heart (wet weight) were between 2.15-79.4 ng/g, 0.5-44.2 ng/g,7.85-519 ng/g, 12.8-725 ng/g, 8.47-333 ng/g and 2.3-97.7 ng/g, respectively. Females had generally lower levels of nickel in tissues than males (statistically significant relationships were found for the liver, kidneys and lungs), and median nickel concentrations in all studied material within all age groups had very similar values, with the exception of stomach.