Heavy metals in human teeth dentine: A bio-indicator of metals exposure and environmental pollution

Teeth and alveolar bones as tracers of metals and radionuclides in inhabitants of a uranium region

Biodosimetry can define risks in inhabitants of areas with potential contaminants, ensuring environmental protection and living conditions due to toxic and radioactive effects. This study aimed to evaluate metals and radionuclides in dental structures and alveolar bones in residents of a uranium area in Paraíba and Pernambuco, Brazil. Eighty-nine specimens were pulverized, fractionated, and chemically prepared for analysis by EDXRF, FAAS, and ICP-MS. Levels of Ca, Cu, Fe, Si, Mn, Ni, Pb, Sr, Ti, V, Zn, K, Mn, Th, and U were investigated. Higher concentrations were measured for Ca, with an average of 272,986.4 mg kg-1. Ni presented in lower concentrations, with an average of 30.4 mg kg-1. For U, concentrations ranged from 1.5 to 145.0 mg kg-1, with more than 27% of the samples above the reference value of 8.1 μg kg-1. For Th, almost 38% of the results were above the limit of 3.5 μg kg-1. In the bone spicules, the contents of U and Th ranged from 45.1 to 1451.2 μg kg-1 and from 7.5 to 78.4 μg kg-1, in this order. The levels of radionuclides were more expressive for the teeth collected in São José do Sabugi, suggesting contamination through food and water consumption. In the bone spicules, the levels of U were up to 179 times higher than the safety limit. The results indicate a possible risk of contamination with probable induced radiobiological effects.

Tracking Childhood Lead Exposure in Early Industrial Romanians

Childhood lead exposure has been linked to severe adverse health outcomes throughout life. Measurements of lead in teeth have established that individuals living in contaminated environments show higher levels compared to individuals living further away, although less is known about when individuals are most susceptible to these exposures. We examined lead (Pb208) concentrations (ppm) in teeth over the first 2.5 years of life in 16 children born in the late 19th to early 20th century throughout Romania. This period of intense industrialization was characterized by increases in mining, coal burning, and oil refining-activities that contaminate air, water, and food with Pb. We hypothesized the distance from an operational mine or oil refinery, or being born in a city, would be positively associated with cumulative dentine Pb exposure (CDPE). We also predicted that Pb exposures would peak in the first six months of life when gastrointestinal (GI) absorption of Pb is likely highest. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of sectioned tooth dentine followed by Bayesian statistical analyses revealed that living 30 km or more from a mine or oil refinery did not explain CDPE. However, being born in a city explained 42% of CDPE. All individuals showed maximum Pb exposures after six months of age, likely due to contaminated solid food and/or non-milk liquids. This research demonstrates how tooth formation can be coupled with comprehensive elemental mapping to analyse the context and timing of early-life neurotoxicant exposures, which may be extended to well-preserved teeth from clinical and historic populations.

Permanent and decidua dentition as chronological biomarkers of heavy metal contamination: A review of the forensic literature

STATEMENT OF PROBLEM

Contamination with heavy metals (HM) has great environmental consequences in the environment due to lack of biodegradation, in addition, accumulation in living beings causes defects in tissues and organs, deteriorating their function and inducing a wide spectrum of diseases. Human biomonitoring consists of the periodic measurement of a certain chemical substance or metabolite in a particular population, using matrices that can be acute or chronic. Teeth are chronic matrices that have great characteristics of resistance and chronological storage of information. This review aims to identify the mechanisms, spatial location, and affinity of HM within teeth, along with understanding its applicability as a chronological record matrix in the face of HM contamination.

MATERIAL AND METHODS

A systematic search review was performed using the PubMed/Medline, Web of Science, and Scopus metasearch engines, and the terms "teeth" OR "dental" OR "tooth" AND "heavy metals" were intersected. Complete articles are included in Spanish, English and Portuguese without time restrictions, involving studies in humans or in vitro; Letters to the editor, editorials and those that did not refer to information on the incorporation and relationship of HM with the teeth were excluded.

RESULTS

837 published articles were detected, 91 were adjusted to the search objective, and 6 were manually included. Teeth are structures with a great capacity for information retention in the face of HM contamination due to low physiological turnover and their long processes of marked formations by developmental biorhythm milestones such as the neonatal line (temporal reference indicator). The contamination mechanisms inside the tooth are linked to the affinity of hydroxyapatite for HM; this incorporation can be in the soft matrix during the apposition phase or as part of the chemical exchanges between hydroxyapatite and the elements of the environment.

CONCLUSION

The teeth present unique characteristics of great resistance and affinity for HM, as well as a chronological biomarker for human biomonitoring, so they can be used as means of expertise or evidence to confirm or rule out a fact of environmental characteristics in the legal field.

Lead exposure across the life course and age at death

BACKGROUND

Lead (Pb) exposure has been associated with an increased risk of all-cause mortality, even at low levels. Little is known about how the timing of Pb exposure throughout life may influence these relationships. Quantifying the amount of Pb present in various tissues of the body provides measurements of exposure from different periods of life. These include bone, tooth enamel, which is the hard outer layer of the crown, and tooth cementum, which is the calcified connective tissue covering the tooth root. The purpose of the study was to examine Pb exposure at multiple periods throughout life, including childhood (enamel), adulthood (cementum), and later life (bone), and to estimate their associations with age at death.

METHODS

208 skeleton donors (born 1910-1960) from an ongoing case-control study were included in this study. Pb was measured in tibia (shin), bone using X-Ray Florescence and in teeth using Laser-Ablation Inductively Coupled Plasma Mass Spectroscopy. After excluding unusually high measurements (>2sd), this resulted in a final sample of 111 with all exposure measures. Correlations across measures were determined using partial Spearman correlations. Associations between Pb exposure and age at death were estimated using Multivariable Linear Regression.

RESULTS

Pb measures across exposure periods were all significantly correlated, with the highest correlation between cementum and tibia measures (r = 0.61). Donors were largely female (63.0 %), White (97.3 %), and attended some college (49.5 %). Single exposure models found that higher tooth cementum Pb (-1.27; 95 % CI: -2.48, -0.06) and tibia bone Pb (-0.91; 95 % CI: -1.67, -0.15) were significantly associated with an earlier age at death. When considered simultaneously, only cementum Pb remained significant (-1.51; 95 % CI: -2.92, -0.11). Secondary analyses suggest that the outer cementum Pb may be especially associated with an earlier age at death.

CONCLUSION

Results suggest that higher Pb exposure is associated with an earlier age at death, with adulthood as the life period of most relevance. Additional studies using Pb exposure measures from different life stages should be conducted.

Determination of Major and Trace Metals in Date Palm Fruit (Phoenix dactylifera) Samples Using Flame Atomic Absorption Spectrometry and Assessment of the Associated Public Health Risks

This study aimed to assess the concentrations of major and trace metals (Na, Ca, Fe, Zn, Ni, Mn, Cu, Cd, and Pb) in date palm fruit samples collected from diverse regions, including Afar (Ethiopia), Iraq, and Saudi Arabia, utilizing flame atomic absorption spectrometry (FAAS). The wet acid digestion method was employed for sample treatment, with optimization of the key parameters such as reagent volume ratio, oven temperature, and digestion time for analytical applications. Under the optimized parameters, average metal concentrations in date palm fruit samples ranged from 205-299, 134-320, 38.8-115, 25.1-42.2, 9.27-27.9, 7.11-16.3, and 0.002-1.15 mg/kg for Ca, Na, Fe, Ni, Zn, Mn, and Cu, respectively. Cd and Pb levels were below detection limits within the linear range. Generally, date palm samples exhibited higher Ca and Na contents and lower concentrations of Cu and Mn than other metals. Pearson correlation analysis revealed very strong positive correlations between Fe and Na, Na and Zn, Na and Mn, Ca and Zn, Fe and Ni, Fe and Mn, and Mn and Ni. Strong negative correlations were observed for Ni and Na, Fe and Cu, and Cu and Ni. Weak correlations were noted among Na and Cu, Ca and Fe, Ca and Ni, Ca and Mn, Ca and Cu, Fe and Zn, Ni and Zn, Zn and Mn, and Zn and Cu. A recovery study using the spiking method demonstrated acceptable percentage recoveries ranging from 91.6% to 97.8%. Health risk assessment, including chronic daily intake (CDI), hazard quotient (HQ), total exposure hazard index (HI), and carcinogenic risk (CR), indicated CDI, HQ, and HI values below 1.0, except for the HI value for Ni. This suggests that the metals pose no probable public health risk, with the absence of Cd and Pb in date palm samples affirming no carcinogenic threats associated with their consumption.

Teeth as an Indicator of the Environmental Exposure of Silesia Province's Inhabitants in Poland to Metallic Trace Elements

(1) Background: The elemental composition of teeth can provide an estimate of environmental exposure to heavy metals. The aim of this study was to analyze the possibility of using teeth in the biomonitoring of environmental exposure to heavy metals as an indicator of contaminants present in the human residential environment. (2) Methods: The research materials were 110 samples of extracted teeth. The samples were taken from people living in three areas in the province of Silesia. The concentrations of cadmium, lead, and mercury in the samples were determined. (3) Results: The results of the chemical analysis of the collected samples showed a significant variation in the concentrations of heavy metals (Cd, Pb, and Hg) in the analyzed teeth. Furthermore, the mean concentrations of the analyzed heavy metals in the teeth varied according to the patient's place of residence, the type of tooth analyzed, the presence of caries in the patient, and the smoking or non-smoking status of the patient. (4) Conclusions: The results of the chemical analysis of the teeth of inhabitants of three cities in the most polluted region of Poland indicate that they can be used as an indicator of environmental exposure to cadmium, lead, and mercury.

Drugs in dental biofilm and enamel - A pilot study

Objective

Enamel and dental biofilm might serve as alternative matrices for determination of illicit and medical drugs. Thus, this study aims at evaluating possible correlations between detected drug concentrations in the matrices and simulated drug use in situ.

Design

Eleven subjects wore intraoral splints with embedded demineralized bovine enamel samples. Drug use was simulated by mouth rinsing with a 1.0 μg/ml drug solution three times daily for 1 min (study A) or by incubation of the splints in a 10 μg/ml drug solution once a day for 30 min (study B). Amphetamines, opiates, cocaine and benzoylecgonine were used as drugs. After 11 days, biofilm and enamel samples of the intraoral splints were analyzed by liquid chromatography mass spectrometry after drying and extraction via ultrasonication with acetonitrile (biofilm) or methanol (enamel).

Results

In study A, median and mean drug concentration ± standard deviation were 1.3 pg/mg and 6.4 ± 11 pg/mg in biofilm and 0.2 pg/mg and 0.5 ± 0.9 pg/mg in enamel. In study B, median and mean drug concentration ± standard deviation were 350 pg/mg and 1100 ± 1600 pg/mg in biofilm and 5.8 pg/mg and 9.9 ± 10 pg/mg in enamel.

Conclusions

Overall, there were considerable interindividual concentration differences. Correlations between concentrations in the two sample materials were shown. The results of this pilot study revealed a dependence of concentrations on intensity and duration of drug contact. Thus, important information on past drug use might be provided in forensic cases by analysis of dental biofilm and enamel.

Heavy metals in drinking water and periodontitis: evidence from the national oral health survey from China

BACKGROUND

Periodontitis has become an increasingly important public health issue, coupled with a high economic burden for prevention and treatment. Exposure to essential trace heavy metals has been associated with various diseases; however, the relationships between essential trace heavy metals and periodontitis remain inconclusive.

OBJECTIVES

To investigate the association between essential trace heavy metals in tap water and periodontitis in a nationally representative sample in China.

METHODS

We conducted a nationwide study including 1348 participants from the Fourth National Oral Health Survey in the 2015-2016 period. The trace heavy metals concentration was measured in the local pipeline terminal tap water. Periodontitis was diagnosed according to the classification scheme proposed at the 2018 world workshop on the classification of periodontal and peri-implant diseases and conditions. We used weighted multivariable logistic regression to estimate the association between essential trace heavy metals and the risk of periodontitis. We additionally used spline analysis to explore the possible nonlinear dose-response associations.

RESULTS

Periodontitis patients were exposed to higher concentrations of essential trace heavy metals. In adjusted models, for 1 SD increase in the concentration of iron, manganese, and copper in tap water, the risk of periodontitis increased by 30% (OR: 1.30, 95%CI: 1.12-1.50), 20% (OR: 1.20, 95%CI: 1.03-1.41), and 20% (OR: 1.20, 95%CI: 1.04-1.39), respectively. Stratified analyses demonstrated that the associations between essential trace heavy metals and periodontitis were higher in females, elders, and rural residents. Spline analysis revealed nonlinear exposure-response relationships between periodontitis and exposure to iron, manganese, and copper in tap water.

CONCLUSIONS

Exposures to essential trace heavy metals in drinking water were associated with greater odds of periodontitis. Given the growing burden of periodontitis, our study sheds light on tailored public health policies for improving drinking water standards to alleviate periodontitis impairment.

A State-of-the-Science Review on Metal Biomarkers

PURPOSE OF REVIEW

Biomarkers are commonly used in epidemiological studies to assess metals and metalloid exposure and estimate internal dose, as they integrate multiple sources and routes of exposure. Researchers are increasingly using multi-metal panels and innovative statistical methods to understand how exposure to real-world metal mixtures affects human health. Metals have both common and unique sources and routes of exposure, as well as biotransformation and elimination pathways. The development of multi-element analytical technology allows researchers to examine a broad spectrum of metals in their studies; however, their interpretation is complex as they can reflect different windows of exposure and several biomarkers have critical limitations. This review elaborates on more than 500 scientific publications to discuss major sources of exposure, biotransformation and elimination, and biomarkers of exposure and internal dose for 12 metals/metalloids, including 8 non-essential elements (arsenic, barium, cadmium, lead, mercury, nickel, tin, uranium) and 4 essential elements (manganese, molybdenum, selenium, and zinc) commonly used in multi-element analyses.

RECENT FINDINGS

We conclude that not all metal biomarkers are adequate measures of exposure and that understanding the metabolic biotransformation and elimination of metals is key to metal biomarker interpretation. For example, whole blood is a good biomarker of exposure to arsenic, cadmium, lead, mercury, and tin, but it is not a good indicator for barium, nickel, and uranium. For some essential metals, the interpretation of whole blood biomarkers is unclear. Urine is the most commonly used biomarker of exposure across metals but it should not be used to assess lead exposure. Essential metals such as zinc and manganese are tightly regulated by homeostatic processes; thus, elevated levels in urine may reflect body loss and metabolic processes rather than excess exposure. Total urinary arsenic may reflect exposure to both organic and inorganic arsenic, thus, arsenic speciation and adjustment for arsebonetaine are needed in populations with dietary seafood consumption. Hair and nails primarily reflect exposure to organic mercury, except in populations exposed to high levels of inorganic mercury such as in occupational and environmental settings. When selecting biomarkers, it is also critical to consider the exposure window of interest. Most populations are chronically exposed to metals in the low-to-moderate range, yet many biomarkers reflect recent exposures. Toenails are emerging biomarkers in this regard. They are reliable biomarkers of long-term exposure for arsenic, mercury, manganese, and selenium. However, more research is needed to understand the role of nails as a biomarker of exposure to other metals. Similarly, teeth are increasingly used to assess lifelong exposures to several essential and non-essential metals such as lead, including during the prenatal window. As metals epidemiology moves towards embracing a multi-metal/mixtures approach and expanding metal panels to include less commonly studied metals, it is important for researchers to have a strong knowledge base about the metal biomarkers included in their research. This review aims to aid metals researchers in their analysis planning, facilitate sound analytical decision-making, as well as appropriate understanding and interpretation of results.

Mercury Content in Impacted Wisdom Teeth from Patients of the Legnica-Głogów Copper Area-An In Vitro Pilot Study

The aim of this study was to determine the content of mercury in impacted third molars from Legnica-Głogów Copper Area residents to emphasize the effects of environmental pollution on the human body. A group of 72 patients with an average age of 27.3 ± 6.9 years participated in the study. Within this study, the research group (Legnica-Głogów Copper Area residents) comprised 51 individuals, while the control group (residents of Wrocław) consisted of 21 participants. A higher number of female individuals participated in the research (55). The amount of mercury present in the samples was determined through atomic absorption spectrometry with the use of a SpectraAA atomic absorption spectrometer and a V2 AA240FS flame attachment that utilized an air-acetylene flame. The accumulation of Hg in the teeth of members of the control group residing in Wrocław was studied, with a focus on identifying the risk factors that contribute to this phenomenon. The final model analyzed the presence of various factors, including thyroid and parathyroid gland diseases, cardiac diseases, and interval-scale Vit. D3 concentration. Among these factors, the presence of cardiac diseases was deemed statistically significant in relation to an increase in Hg concentration in third molars (rate ratio = 2.27, p < 0.0001). The concentration of mercury increased with the age and time of residence in the L-G Copper District.

Neonicotinoid insecticides and their metabolites: Specimens tested, analytical methods and exposure characteristics in humans

The use of neonicotinoid insecticides (NEOs) has been rising globally due to their broad-spectrum insecticidal activity, unique mode of neurotoxic action and presumed low mammalian toxicity. Given their growing ubiquity in the environment and neurological toxicity to non-target mammals, human exposure to NEOs is flourishing and now becomes a big issue. In the present work, we demonstrated that 20 NEOs and their metabolites have been reported in different human specimens with urine, blood and hair as the dominance. Sample pretreatment techniques of solid-phase and liquid-liquid extractions coupled with high performance liquid chromatography-tandem mass spectrometry have successfully achieved matrix elimination and accurate analysis. We also discussed and compared exposure characteristics of these compounds among types of specimens and different regions. A number of important knowledge gaps were also identified in order to further facilitate the understanding of health effects of NEO insecticides, which include, but are not limited to, identification and use of neuro-related human biological samples for better elucidating neurotoxic action of NEO insecticides, adoption of advanced non-target screening analysis for a whole picture in human exposure, and expanding investigations to cover non-explored but NEO-used regions and vulnerable populations.

Identification of multi-component metal ion mixtures in complex systems using fluorescence sensor arrays

The growing co-contamination of multiple metal ions seriously influences human health due to their synergistic and additive toxicological effects, whereas the rapid discrimination of multiple heavy metal ions in complex aquatic systems remains a major challenge. Herein, a high- throughput fluorescence sensor array was fabricated based on three gold nanoclusters (GSH-Au NCs, OVA-Au NCs, and BSA-Au NCs) for the direct identification and quantification of seven heavy metal ions (Pb²⁺, Fe³⁺, Cu²⁺, Co²⁺, Ag⁺, Hg²⁺ and As³⁺) from environmental waters without sample pretreatment other than filtration. At the detection system, three gold nanoclusters with various ligands possessed distinct binding capacities against metal ions and induced aggregation-induced fluorescence enhancement and quenching, resulting in a unique pattern of fluorescence variations. Meanwhile, integrated the collected fluorescence fingerprints with linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA), a discrete database was obtained for the accurate recognition and sensitive detection of metal ions. Under the optimized conditions, the limit of detection (LOD) of the proposed fluorescence sensor array for metal ions detection at nM concentration level along with a satisfactory accuracy. Importantly, our study indicated that the fluorescence sensor array could be widely used as a general platform in environmental monitoring against multiple targets at low concentrations.

Teeth and bones micro-slurries introduction to MIP OES for elements simultaneous quantification

This study aims development of new, rapid and direct method for simultaneous multi-elemental determination in micro-volume slurried samples of teeth and bones. The method proposed allow for direct, without prior sample decomposition, injection of 15 μL of slurries (Bone Meal NIST 1486, deciduous human and dog teeth) into microwave induced plasma optical emission spectrometer (MIP OES) and determination of Ca, Cu, Fe, K, Mg, Mn, Na, Pb, Sr and Zn. The optimization procedures were undertaken (univariate and simplex methods) to achieve the best values of parameters influencing the analytical signals. Minimum dead volume, high nebulization and slurry transport efficiency were obtained by using on-axis low-volume spray chamber/v-groove pneumatic nebulizer interface for 15 μL slurry injection in discontinues mode (at 1.2 mL min^-1 pump speed). Analytical parameters of the proposed method were assessed by determination of the limits of detection (LODs), absolute detection limit and precision (RSDs). The obtained LODs were appropriate (in the range of mg/kg) for the determination of the elements in the standard reference material (Bone Meal NIST 1486) for validation procedure and successful application in two real samples (deciduous human and dog teeth).

Characterization of the Toxicological Impact of Heavy Metals on Human Health in Conjunction with Modern Analytical Methods

Increased environmental pollution, urbanization, and a wide variety of anthropogenic activities have led to the release of toxic pollutants into the environment, including heavy metals (HMs). It has been found that increasing concentrations of HMs lead to toxicity, mineral imbalances, and serious diseases, which are occurring more and more frequently. Therefore, testing has become imperative to detect these deficiencies in a timely manner. The detection of traces of HMs, especially toxic ones, in human tissues, various biological fluids, or hair is a complex, high-precision analysis that enables early diagnosis, addressing people under constant stress or exposed to a toxic environment; the test also targets people who have died in suspicious circumstances. Tissue mineral analysis (TMA) determines the concentration of toxic minerals/metals at the intracellular level and can therefore determine correlations between measured concentrations and imbalances in the body. Framing the already-published information on the topic, this review aimed to explore the toxicity of HMs to human health, the harmful effects of their accumulation, the advantages vs. the disadvantages of choosing different biological fluids/tissues/organs necessary for the quantitative measurement of HM in the human body, as well as the choice of the optimal method, correlated with the purpose of the analysis.

Remediation of heavy metal polluted waters using activated carbon from lignocellulosic biomass: An update of recent trends

The use of a cheap and effective adsorption approach based on biomass-activated carbon (AC) to remediate heavy metal contamination is clearly desirable for developing countries that are economically disadvantaged yet have abundant biomass. Therefore, this review provides an update of recent works utilizing biomass waste-AC to adsorb commonly-encountered adsorbates like Cr, Pb, Cu, Cd, Hg, and As. Various biomass wastes were employed in synthesizing AC via two-steps processing; oxygen-free carbonization followed by activation. In recent works related to the activation step, the microwave technique is growing in popularity compared to the more conventional physical/chemical activation method because the microwave technique can ensure a more uniform energy distribution in the solid adsorbent, resulting in enhanced surface area. Nonetheless, chemical activation is still generally preferred for its ease of operation, lower cost, and shorter preparation time. Several mechanisms related to heavy metal adsorption on biomass wastes-AC were also discussed in detail, such as (i) - physical adsorption/deposition of metals, (ii) - ion-exchange between protonated oxygen-containing functional groups (-OH, -COOH) and divalent metal cations (M²⁺), (iii) - electrostatic interaction between oppositely-charged ions, (iv) - surface complexation between functional groups (-OH, O^2-, -CO-NH-, and -COOH) and heavy metal ions/complexes, and (v) - precipitation/co-precipitation technique. Additionally, key parameters affecting the adsorption performance were scrutinized. In general, this review offers a comprehensive insight into the production of AC from lignocellulosic biomass and its application in treating heavy metals-polluted water, showing that biomass-originated AC could bring great benefits to the environment, economy, and sustainability.

Polarography Can Successfully Quantify Heavy Metals in Dentistry

Background and Objectives: Due to the nutritional and behavioral patterns of children, their teeth can be a good indicator of heavy metal uptake from over the years. To determine the amount of Zn, Cu, Cd, and Pb accumulated in the body, primary teeth of children in Zanjan, Iran, were examined with a polarography device. Materials and Methods: Samples were collected from dentistry clinics of Zanjan, Iran, and were prepared for acid digestion, and then were analyzed by a polarography device for determining the concentration of lead, copper, zinc, and cadmium. Results: Data were analyzed by a t-independent test to compare different groups (p < 0.05). Based on the results obtained from this study, the mean concentrations of zinc, lead, copper, and cadmium were 245, 7.66, 5.33, and 0.0879 µg/g, respectively, which shows that the amount of each of the four elements was more than the amounts that have been reported for different countries. The results showed no significant difference between age, tooth type, and jaw groups. Conclusions: We conclude that primary teeth are an important biological indicator to evaluate the concentration of heavy elements in the human body. The high concentrations of these elements in the primary teeth analyzed in this study could be attributed to the high concentrations of these elements in the environment of Zanjan.

Association between heavy metals and metabolic syndrome in drinking water and surface soil: case-control study in Iran

Although obesity is a major risk factor for metabolic syndrome (MetS), not all obese people develop MetS that is directly related to obesity. This suggests that the risk of MetS is influenced by other genetic or environmental agents such as heavy metals. The aim of this study was to investigate the relationship between heavy metals in drinking water and surface soil, and its relationship with the incidence of MetS. To determine the sampling points of drinking water and surface soil, from the location of 150 people selected for inclusion in the study, 16 points were selected randomly for heavy metal concentration analysis. Results were indicated that mean concentrations of V, Mn, Ni, As, Cd, and Sr in drinking water of MetS group were higher than control group. The concentration of heavy metals in drinking water, except for Mn and Sr, did not show a significant difference between case and control groups. The results of this study showed that concentration of heavy metals in drinking water and surface soil was positively associated with the incidence of MetS.

Effects of environmental parameters on Lemna minor growth: An integrated experimental and modelling approach

Pollution of surface waters is a worldwide problem for people and wildlife. Remediation and phytoremediation approaches can offer a solution to deal with specific scenarios. Lemna minor, commonly known as duckweed, can absorb and accumulate pollutants in its biomass. To evaluate if L. minor could be applied for phytoremediation purposes, it is necessary to further investigate its remediation capability and to identify which parameters affect the remediation process. Such a model must include both plant growth and pollutant exchange. A remediation model based on a robust experimental study can help to evaluate L. minor as a proper remediation strategy and to predict the outcome of a L. minor based remediation system. To set up this model, this paper focusses on a detailed experimental study and a comprehensive mathematical modelling approach to represent L. minor growth as a function of biomass, temperature, light irradiation and variable nutrient concentrations. The influence of environmental conditions on L. minor growth was studied, by composing 7 days growth curves. Plants were grown under predefined environmental conditions (25°C, 14h photoperiod, 220 μmol m^-2 s^-1 light intensity and a modified Hoagland solution with 23.94 mg N L^-1 and 3.10 mg P L^-1 (N:P ratio of 7.73)) as standard for all experiments. The influence of different temperatures (6, 10, 15, 20, 25, 30 and 35°C), light intensities (63, 118, 170, 220 and 262 μmol m^-2 s^-1), photoperiods (12h and 14h) and N:P ratios (1.18, 3.36, 7.73 and 29.57) were tested in the model. As a result, a growth model was optimised using separate datasets for temperature, light intensity, photoperiod and nutrients and validated by further integrated testing. The growth model is a stable platform for application in phytoremediation of radionuclides in contaminated water, to be extended in future studies with information of pollutant uptake, pollutant-nutrient interactions and transfer to the biomass.

Elevated Concentrations of Metal(loids) in Seaweed and the Concomitant Exposure to Humans

While the consumption of seaweed and seaweed-based products is very common amongst East Asian nations, forming a notable component of the daily diet, relatively very few studies have concerned the concentrations of heavy metals in these together with potential effects on human health. The present study analyses the concentrations of 17 elements in locally resourced seaweed, also assessing potential noncarcinogenic and carcinogenic risks. The samples were ground, homogenized, and quantified using the ICP-OES technique. It has been found that the essential elements K, Ca, Mg, Zn, and Na typically show concentrations somewhat greater than a number of potentially toxic metals, in particular, Cd, Pb, Ag, and As, with exceptions being Ni, Cr-VI, and Si. Statistical analysis indicates all of the latter to have similar origin, with increased concentration of these metals within the marine ecosystem. While the daily estimated intake of most metals is seen to be within the daily dietary allowance level recommended by various international organizations, the noncarcinogenic risk shows a value greater than unity, estimated via the hazard quotient. This indicates a potential for adverse effects to health arising from consumption of the sampled seaweed. The carcinogenic risk resulting from nonessential elements shows values greater than the United States Environmental Protection Agency (US-EPA) reference limit of 10-4. Considering the nonbiodegradability of heavy metals and metalloids and their potential accumulation in seaweed, there is need for critical examination of metal levels in the seaweeds obtained from the present study locations, together with the introduction of practices of removal of heavy metals via bio-adsorbent techniques.

Toxic Metals Content in Impacted Third Molars and Adjacent Bone Tissue in Different Groups of Patients

The aim of the study was to determine the content of: Pb, Cd, Cr, Ni, Fe, Mn, Cu, Zn in the impacted third molars and a fragment of covering bone. Patients were divided according to following criteria: place of residence, age, gender, anatomical location of the removed tooth. Content of Cd, Pb, and Mn in the samples increases with age of the patient. The content of Cd and Pb in the tooth and bone was higher in patients living in Wroclaw. Residents of the Wroclaw had higher Cu content in the teeth, while they had a lower content in the jawbone. In contrast to Cd and Pb, an average of 68% higher concentration of Zn in the jawbone than in the tooth was noted. The content of Cr in tooth was lower by 33% than in the mandible bone and, similarly to the content of Ni, it decreased with age. In women, the Fe content in bone of the jaw was higher than in the removed tooth. The presence of Pb and Cd aggregates is confirmed in all hard tissues of the tooth and bone, in contrast to bioelements which show a stronger tendency to aggregate, essentially within the dentine.

Effect of humic acids on lead poisoning in bones and on a subcellular level in mitochondria

Humic acids (HA) are natural substances which exhibit a remarkable spectrum of health benefits, such as their role in chelation. This study aims to supplement the current knowledge on the chelating effects of HA in chronic lead intoxication in rat femurs and in liver, heart and kidney mitochondria in an experiment lasting 10 weeks. Lead acetate trihydrate was administered to rats for 5 weeks at a daily dose of 155.5 mg/kg body weight. At the same time, rats were given three concentrations of HA, with their effect measured over the following 5 weeks. Increased Pb concentrations were detected in the femur after the first week, while HA-administered groups showed a tendency towards inhibiting the increase in Pb deposition. After 5 weeks, Pb concentrations dropped significantly in the HA groups. At the same time, however, other elements were redistributed, with a decrease in Se and Zn being particularly noteworthy. While an increase in Pb concentrations was found after 5 weeks of Pb administration, a concentration of 1% HA resulted in the least significant increase in Pb as well as an increase/decrease in Se/Cu, respectively. In mitochondria, an increase in Pb content was detected after the first and fifth weeks with concomitant redistribution of other elements. At the end of the experiment, again in the 1% HA group, Pb concentrations remained higher only in the liver with the other elements sufficiently normalized, indicating this concentration to be useful in the treatment of Pb intoxication.

Seasonal and ontogenic variations of metal content in the European pilchard (Sardina pilchardus) in northwestern African waters

Marine fishes are exposed to great human-induced alterations due to the indiscriminate discharges into the sea, increasing marine pollution. For this study, 324 specimens of Sardina pilchardus from the Canary Islands were analized during a period of 2 years (June 2016 to May 2018). The concentration of 11 metals and trace elements (Al, B, Cd, Cr, Cu, Fe, Li, Ni, Pb, V and Zn) was determined in each individual using the Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique. Statistical analyses were carried out considering the following factors: oceanographic season, maturity of the gonads in the seasons, size of the specimens. Sardina pilchardus specimens captured in the hot season presented higher Ni, Li and Pb levels than the specimens caught in the cold season. Immature specimens had higher concentration in more metals than the mature specimens. This fact may be due to the fact that these specimens require a much higher metabolic rate due to their growth and do not detoxify like mature specimens. Significant differences were found in the concentration of metals in all the analyzes performed.

Transcriptome sequencing reveals the effects of cadmium toxicity on the cold tolerance of the wolf spider Pirata subpiraticus

As the predominant predator of pests in rice fields, spiders have been exposed to cadmium (Cd) pollution for a long time. The livability of spiders during the overwintering period is closely related to population growth in spring, but the effects of Cd on spider's survival of cold hardness and the underlining mechanism remain unclear. In the present study, we found that some growth parameters (body length, width, mass and livability) in the wolf spider Pirata subpiraticus were altered distinctively under Cd stress. To investigate the effects of Cd toxicity on the spider at molecular levels, RNA-sequencing was performed on the spiderlings undergoing ambient temperature alterations. Transcriptome data showed that a total of 807 differentially expressed genes (DEGs) were yielded in the comparison. The obtained DEGs were mainly linked with metabolism-related process, including oxidoreductase activity and lipid transport, and 25 DEGs were associated with the reported cryoprotectants, including glycerol, arginine, cysteine, heat shock protein, glucose and mannose. Growth factors (insulin growth factor, platelet-derived growth factor and transforming growth factor) and cytochrome P450 encoding genes were dramatically expressed in the spider. Furthermore, transcriptional factors (TFs) family were characterized according to the transcriptomic profile, and ZBTB TFs were represented the most distinctive alterations in the characterized genes. Collectively, our study illustrated that Cd poses disadvantageous effects on the growth of P. subpiraticus at cold ambient temperature, and the spiders are capable of responding to the adverse Cd stress by expressing the genes involved in the metabolism of energy substances, cryoprotectants and immune-related components.

Aging and trace elements in human coronal tooth dentine

Teeth are a fundamental tool in forensic odontology for identification in a legal context of those individuals who cannot be identified visually or by other means. Dentine presents physiological exchanges of in trace elements after a period of mineralization and several factors can affect its concentration. The aim of this study was to investigate the concentration of 25 trace elements in the coronal dentine according to sex and type of tooth to determine their relationship with age. A total of 25 trace elements were analyzed in 150 human coronal dentine. Teeth were classified into three age groups, sex and tooth type. The trace elements were grouped as potentially toxic or essential. Inductively Coupled Plasma-Mass Spectrometry and Atomic Emission Spectroscopy were used. The toxic and essential elements were detected in the following order of concentration: Al > Pb > Sn > Li > As > Cd and Ca > P > Mg > Na > S > K > Sr > Zn > Ba > Fe > B > Ti > Mn > Cr > Ni > Cu > Co > Se > V. Our findings show an increase in the concentration of toxic (Pb, Li and Sn) and essential (B, Ba, K, Sr, S and Mg) elements in coronal dentin related to the age of the teeth, regardless of sex. The concentrations of Pb and K in dentin of molars and premolars are the elements that best relate their variations with age. In view of our results, the analysis of these trace elements in dentin in combination with other types of techniques could be established as an element to consider in age dating studies in different forensic situations.

Correlation between urinary chromium level and semen quality in men attending an andrology laboratory

Chromium is an essential element that is required for the normal physiology but can be toxic to humans above a certain level. In spite of growing interest in research on chromium exposure to human health consensus about its effect on human, semen quality has not been achieved. The aim of the present study is to evaluate the impact of chromium exposure on semen parameters. A total of 760 males attending andrology laboratory of Tongji Hospital, Wuhan, for routine semen analysis were enrolled and requested to provide semen and urine samples. The urine level of chromium was evaluated using inductively coupled plasma mass spectrometry (ICP-MS), and computer-assisted semen analysis (CASA) was applied to examine semen parameters. Associations between semen parameters and urinary chromium were analyzed by means of multivariate linear regression analysis. Multivariate analysis showed a negative association between the urinary concentrations of chromium and progressive motility (β = - 0.014, p = 0.040) and total motility (β = - 1.077, p = 0.048), while other semen parameters did not show any statistically significant changes. Urinary chromium could influence semen quality parameters and impair male fecundity.

Morphologic, Structural, and Chemical Properties of Pulp Stones in Extracted Human Teeth

INTRODUCTION

Pulp stones are mineral structures that develop in the pulp tissue triggered by several clinical conditions. The exact biochemical process behind the occurrence of pulp stones is uncertain. This study aimed to perform a structural and crystallographic characterization of pulp stones and dentin from extracted human teeth.

METHODS

The sample consisted of 13 erupted and unerupted permanent human teeth diagnosed with pulp stones. The teeth were analyzed with scanning electron microscopy with secondary and backscattered electrons, energy-dispersive spectroscopy, micro-Raman spectroscopy, micro-X-ray diffraction, and inductively coupled plasma atomic emission spectroscopy.

RESULTS

The pulp stones revealed a heterogeneous morphology and structure compared with each other. Compared with the adjacent dentin, the pulp stones had a similar structure. From a chemical point of view, oxygen, calcium, carbon, and phosphorus were the most prevalent chemical elements in the inner part of the stones, whereas on the surface carbon, nitrogen, sulfur, chlorine, aluminum, potassium, zinc, copper, and lead were the most prevalent. Copper, iron, and zinc were higher in the stones than the dentin (P < .05). Statistically significant differences between the chemical structure of stones from erupted and unerupted teeth were not detected (P > .05).

CONCLUSIONS

Pulp stones have structural and chemical properties that are similar to dentin. Variations in morphology are common.

Role of cotton sticks biochar in immobilization of nickel under induced toxicity condition and growth indices of Trigonella corniculata L

Among various heavy metals, nickel (Ni) is a potential pollutant that accumulates in broad-leaf vegetables and is reported to be carcinogenic. Biochar (BC) is a nutrient-rich and effective organic amendment for immobilization of Ni in soil. Fenugreek (Trigonella corniculata L.), a broad-leaf vegetable, is commonly cultivated due to its all-inclusive composition of nutrients such as calcium and iron and β-carotene and vitamins. Therefore, a field-pot study was conducted to examine the effectiveness of cotton-sticks-waste biochar (BC) for soil immobilization of Ni in fenugreek crop cultivated between early-October to end-November 2015. Fenugreek was grown in a sandy-loam soil experimentally contaminated with various Ni levels (0, 25, 50, and 100 mg Ni kg^-1 soil) under three BC levels (0, 3, and 5%; w/w). Overall, results showed increasing plant lipid peroxidation (assessed via malondialdehyde) and ascorbic-acid concentration with increasing Ni toxicity level without BC application (p ≤ 0.05). Application of 3% BC increased the chlorophyll a (20.0%), chlorophyll b (49.1%), total chlorophyll (27.6%), carotenoids (21.6%), anthocyanin (27.2%), photosynthetic rate (112%), transpiration rate (45.0%), and sub-stomatal CO₂ concentration (19.9%) in fenugreek as compared to control (0% BC) under 50 mg Ni kg^-1 soil. Higher BC application rate (5%) was more effective in increasing the chlorophyll a (33.6%), chlorophyll b (81.1%), total chlorophyll (43.9%), carotenoids (71.7%), anthocyanin (77.8%), photosynthetic rate (127%), transpiration rate (42.2%), and sub-stomatal CO₂ concentration (23.5) over control under 100 mg Ni kg^-1 soil. We suggest that the consistent increases in dry mass, carbon flux rate and, protein, amino acids, and sugar contents of fenugreek (cultivated in a soil toxified with Ni and amended with 5% BC) seems to be caused by the reduction in the mobility of Ni in the presence of BC in a sandy-loam soil.

Metal content in Mullus surmuletus in the Canary Islands (North-West African Atlantic)

The contents of 3 heavy metals (Al, Cd, and Pb) and 10 trace elements (B, Cr, Cu, Fe, Li, Mg, Ni, Sr, V, Zn) were determined by means of atomic emission spectrometry with inductively coupled plasma (ICP-OES) in 117 specimens of red mullet, Mullus surmuletus. The specimens were taken in two of the Canary Islands; two locations on the island of Tenerife: Candelaria on the northeast coast and Punta de Hidalgo on the north coast and Arguineguín, on the south coast of the island of Gran Canaria. No significant differences were found between the two sites in Tenerife regarding the metal content of the specimens studied, but differences were found between the specimens captured in Arguineguín and the two sites in Tenerife, the latter having higher concentrations of the analyzed metals.

The cross-sectional and longitudinal associations of chromium with dyslipidemia: A prospective cohort study of urban adults in China

Chromium exposure can induce altered lipoprotein metabolism in animals, but the health effects of chromium on dyslipidemia in humans have not been fully evaluated. In this study, we aimed to investigate the cross-sectional and longitudinal effects of urinary chromium on lipid levels and dyslipidemia risk among urban adults from two cities in China. A total of 3762 urban adults from the Wuhan-Zhuhai cohort were included in the initial investigation, and followed up three years later. Urinary chromium concentration was measured at baseline and repeated at follow-up. Associations of urinary chromium concentration with lipid levels and risk of dyslipidemia were analyzed by generalized linear and binary logistic regression models, respectively. We found significant relationships between increased urinary chromium concentration and both reduced triglyceride (TG) level and elevated high-density lipoprotein cholesterol (HDL-C) level at baseline and follow-up. In the cross-sectional analysis, each 1-unit increase in log-transformed urinary chromium was associated with a 0.25 mmol/L decrease in TG and a 0.05 mmol/L increase in HDL-C (P < 0.05); also, downward trends for odds ratios of hyperTG (TG level ≥ 1.7 mmol/L) and hypoHDL-C (HDL-C level < 1.0 mmol/L) were significantly associated with increasing quartiles of urinary chromium (P trend < 0.05). In the longitudinal analysis, each 1-unit increase in log-transformed urinary chromium concentration was associated with a 3% and 6% decrease in the risk of developing hyperTG and hypoHDL-C, respectively (P > 0.05). Our study indicated that significant dose-response relationships between urinary chromium concentration and lipid levels were observed at baseline and at follow-up.

Modeling contamination conditions in small-scale industrial areas to estimate health savings benefits associated with remediation

Mercury and dioxin pollution associated with the China Petrochemical Development Corporation's An-shun plant is one of the most severe soil contamination incidents in Taiwan's history. Residents living nearby were exposed to heavy metals and dioxins that led to significant impacts on human health and safety. While many studies related to contamination in large-scale industrial areas have been conducted to evaluate the effects of occupational contaminant exposure, studies related to people who live near small-scale industry areas are less common. In this study, we use the system dynamics modeling to build a media flow pattern for mercury and dioxin in the vicinity of the An-shun plant, simulate the concentrations of the pollutants before and after remediation, and compare the simulated values with the measurements of actual conditions after remediation to evaluate the feasibility and accuracy of the model. This study also estimated the concentration of mercury and dioxin in each food medium to simulate the daily exposure of the human body to these contaminants. Finally, the reduction in mercury and dioxin levels in the study area was used to estimate the total health benefits to the local population. The objective of this study was to evaluate the application of this methodology to small-scale industrial areas as well as improve the decision-making process before, during, and after remediation of contaminated sites. The results of this study revealed the health benefits to residents living in the Annan District after remediation was completed at the An-shun plant were significant.

A possible etiological factor in obesity: element status in blood and tooth of overweight versus normal-weight children

We aimed to assess element status in whole blood and tooth dentin and identify their correlations in overweight or obese children without additional metabolic risk factors. In a case-control study, 40 overweight and 80 normal weight children aged 6-10 years were enrolled. Samples of blood and tooth were collected. While all studied elements were similar in groups in univariate analysis, after adjustment for confounding factors, tooth Mn levels were lower and blood Zn levels were higher in the overweight/obese group (p = 0.049 and p = 0.032, respectively). A significant correlation in blood and tooth dentin levels of Sr and Zn was detected in both groups. In both biological substances, the concentrations of elements did not differ significantly in overweight children without metabolic comorbidities compared to healthy children of normal weight. Presence of low Mn levels in tooth dentin and high Zn levels in blood samples should be explored in further studies.

Unraveling the impact of chronic exposure to metal pollution through human gallstones

This study aims to explore the impact of chronic metal exposure derived from persistent pollution from mining activity using human gallstones as proxies. The samples were obtained from patients residing in geologically and environmentally contrasting areas in the Province of Huelva, SW Spain, allowing for the evaluation of the regional effect of metal pollution. The study group resides in the Iberian Pyrite Belt characterized by natural and anthropogenic metal pollution from mining activities, whereas the control group resides in the Ossa Morena Zone famous for its natural parks. A total of 68 gallstones were first classified based on their phase composition and structure and subsequently their chemical composition was studied using solution Inductively Coupled Plasma-Mass Spectrometry. The metal concentrations increased in the cholesterol-rich gallstones from pure, to mixed and composite cholesterol stones along with the increasing amount of minor phases, such as bilirubinate, carbonate, and phosphate. These cholesterol stones did not show an evident enrichment tendency. On the contrary, pigment stones, composed of bilirubinate, carbonate, and phosphate phases, were rich in a variety of elements and the regional comparison showed that the pigment stones from the study area were enriched in sulfide-associated metal(loid)s, Mn, Fe, Cu, Zn, Sr, As, Ag, Sb, and Pb with respect to the control group. Inhalation of polluted airborne particulate matter is considered as one of the main exposure routes among the residents of the study area. Additionally, consumption of local water and locally produced food products such as fruit and vegetables and dermal contact may be possible sources of exposure, but no direct connection was observed.

New insights into the metal partitioning in different microphases of human gallstones

Chronic metal exposure, e.g. from metal mining, may cause accumulation of metals in soft and hard tissues, and in developing biomineralizations in the human body. Gallstones are biomineralizations formed in the gallbladder which are able to trap trace elements from the bile. Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) was used to analyze gallstone cross-sections to trace the elemental abundances and correlate them with the principal phases constituting gallstones, namely cholesterol, Ca bilirubinate salts, Ca carbonate, and Ca phosphate. Five different types of gallstones (pure, mixed, and composite cholesterol stones, pigment stone, and carbonate stone) were chosen according to a previous classification based on phase characterization by different spectroscopic and microscopic techniques. These data were combined with bulk solution ICP-MS/OES analyses for total elemental concentrations. The results indicated that cholesterol has a zero capacity to retain elements except for Ca. Hence, pure cholesterol stones contained the lowest bulk metal concentrations, and the metals were found in the scarce carbonate and phosphate phases in these calculi. Calcium and trace element concentrations increased in other types of gallstones along with increasing amount of bilirubinate, carbonates and phosphates; pigment stones being the most enriched in metals. Phosphates were the principal carriers of Ca, P, Na, Mg, Mn, Fe, Pb, and Cd, whereas carbonate phases were enriched in Ca, Mg, Na, and Mn in order of decreasing abundance. Bilirubinate on the other hand was enriched in Ca, Cu, Ag, and Ni. The higher trace metal affinities of bilirubinate and phosphate explain the elevated metal concentrations observed in the pigment stones. These results give new insight to the trace metal behavior in the gallstone formation and the metal accumulation in the human body, validating the possible use of these biomineralizations as a proxy for exposure to metal pollution.