Levels Of Toxic Metals Research Articles

Strength development and microstructure of sustainable geopolymers made from alkali-activated ground granulated blast-furnace slag, calcium carbide residue, and red mud

Red mud (RM) and calcium carbide residue (CCR) are waste generated from alumina refining and acetylene gas producing, respectively. This study utilized alkali-activated ground granulated blast-furnace slag (GGBS) and wet-basis CCR stabilized RM to prepare geopolymers material. The alkali activator solution was composed of CCR supernatant, sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). CCR supernatant was used to reduce the amount of strong alkali. The effects of alkali activator on chemical composition and microstructure of geopolymers were studied by X-ray diffraction (XRD), thermogravimetric-derivative thermogravimetric (TG-DTG) analysis, and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). The results show that the utilization of alkali activator improved the compressive strength and especially significantly improved the flexural strength of geopolymers. The strength was negatively correlated with the RM content: the geopolymers containing 30 % RM achieved a maximum 28-day compressive and flexural strength value of 20.3 MPa and 4.3 MPa, respectively. The microstructural analysis revealed that the strength increased due to the formation of calcium aluminate hydrates (C-A-H) and calcium silicate hydrates (CSH). The toxic heavy metals (Cr, Ni, Cu, Pb, Sb, and Zn) from RM formed some complex compounds and were combined in the geopolymers. The 28-day leaching experiment showed that the toxic heavy metals levels were below the test limits. In summary, this study confirmed the safety and feasibility of preparing RM-GGBS-CCR based geopolymers via alkali-activated method.

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

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

Water quality implications of the neutralization of acid mine drainage with coal fly ash from India and the United States

Subsurface coal mining often induces the formation of acid mine drainage (AMD) in active and abandoned coal mines while coal combustion generates coal combustion residuals (CCR), including fly ash (FA), with elevated levels of toxic metals. Decades of AMD and CCR production have caused major environmental and human health impacts. Given the typically elevated level of oxides in FA, previous studies have examined its potential to neutralize AMD and remove the associated metals. While the neutralization of AMD through reaction with FA has been demonstrated to successfully remove cationic metals, the fate of oxyanion forming elements are less well studied and is the focus of this study. Here we conducted 49 different experiments in which simulated AMD solutions were interacted with representative U.S. (n = 7) and Indian (n = 6) FA samples through controlled liquid to solid ratios in short-term (24 h) and long-term (up to 5 weeks) lab-scale experiments. We show that Class-F FA, originating from Gondwana and Northeastern Tertiary coals in India, has limited neutralization capacity, while Class-C FA, with high CaO and MgO contents from Powder River coals in the U.S. has the greatest AMD neutralization capacity among the studied fly ashes. The neutralization experiments show that AMD-FA reactions cause the removal of cationic elements (i.e., Fe, Mn, and Al) from solution, while at the same time, leaching oxyanion forming elements (i.e., As, Se, Mo, Cr, B, Tl, and Sb) from the FA, increasing the potential environmental risks from the treated leachates. The magnitude of mobilization of these elements depends on their concentrations in the FA and the pH conditions. We show that using FA from the Appalachian and Illinois coals efficiently neutralizes AMD, but also results in secondary contamination of the treated effluents with oxyanion forming elements to levels exceeding drinking water and ecological standards, which could contaminate the ambient environment, whereas neuralization with Powder River Basin Class-C FA induces only limited contamination.

Spatial distribution and ecological risk evaluation of toxic metals in the southern Black Sea coastal sediments

Spatial distribution and ecological risk levels of toxic metals (Cu, Pb, Zn, Ni, Co, As, Sr, V, and La) in sediments from the southern Black Sea coastal (Türkiye) were evaluated. The sediment samples were taken in April and May 2019 from thirty-one stations, from depths ranged between 16 and 65 m. The average metal concentrations (in dry weight) varied from 59.4 ± 4.8 to 102.5 ± 12.3 for Cu, 39.3 ± 4,1 to 46.1 ± 2.9 for Pb, 104.5 ± 4.7 to 126 ± 6.9 for Zn, 21.2 ± 1.8 to 24.9 ± 1.4 for Ni, 9.8 ± 0.4 to 16.6 ± 1.5 for As, 16.7 ± 0.5 to 18.2 ± 0.9 for Co, 68.2 ± 11.4 to 123.3 ± 13.5 for Sr, 82.7 ± 13.1 to 97.3 ± 4.3 for V, and 16.2 ± 1.8 to 23.6 ± 1.8 μg g−1 for La. Geoaccumulation index (IGEO), Sediment enrichment factor (SEF), and pollution load index (PLI) indicated that Cu and Pb are above the pollution limits. Thus, continuous pollution monitoring programs should be established. Moreover, measures should be implemented more effectively to prevent pollution.

Health Risk Assessment and Comparative Studies on Some Fish Species Cultured in Traditional and Biofloc Fish Farms.

The present study aimed at (a) determining the concentration of macro-minerals and toxic metals in fish species collected from biofloc and traditional fish farms; (b) assessing the contribution of macro-minerals to our daily diet; and (c) evaluating the health risks of children and adults based on the US Environmental Protection Agency (USEPA) deterministic model. Significantly higher concentrations of macro-minerals and significantly lower levels of toxic metals (at < 0.05 level) were found in most of the biofloc fish species compared to the market fish samples. The values of the target hazard quotient (THQ) were less than 1.0 for all individual trace metals in all species, which indicated that there were no noncarcinogenic health risks. Furthermore, the value of the hazard index (HI) in three samples of Tilapia from the market exceeded the recommended value of 1.0, while all samples from the biofloc fish tank were within the maximum tolerable limit, which suggested that the daily consumption of Tilapia fishes from the market may result in considerable harmful effects. Target cancer risk (TCR) for Pb in all of the studied samples was within the range of 10-6 and 10-4, hence the adults and children would not experience any kinds of carcinogenic effects. The result obtained from this comparative study revealed that the consumption of fish species from both local market and biofloc fish farms was almost safe, but the value of TCR in Pb was higher in traditional fish samples than that of biofloc tanks, hence fish samples from biofloc farms were more suitable for consumption.

Heavy metals research in Nigeria: a review of studies and prioritization of research needs.

Nigeria is experiencing continuous economic and industrial transformations, typical of many developing nations. In addition to its well-established oil industry, which is infamous for exuding various kinds of pollutants, there are increased mining operations, indiscriminate disposal and burning of wastes, illegal oil refinery and terroristic insurgency, all poised to increase the levels of heavy metal contaminants in the Nigerian environment. A recent revelation indicates that about 2 million people in South-western Nigeria alone could potentially be poisoned by lead (Pb) and mercury (Hg), emanating from illegal mining operations. This further underscores the importance of investigations of toxic trace metal levels in the country. The current review of 148 research articles was conducted to provide an understanding of the scope of heavy metals research in Nigeria and to prioritize needed research. The review recognized that the scope of heavy metals studies has been wide, covering matrices such as cosmetics, human blood, hair, medicines, foods, beverages, water, air, soil and crude oil. However, important toxic metals, especially mercury (Hg), arsenic (As) and antimony (Sb), are largely under-investigated. Also, there is a need for more studies to be conducted in the northern part of the country. Furthermore, studies need to focus on marine environments rather than the freshwater ecosystems alone. Techniques such as the inductively coupled plasma-optical emission spectrometry (ICP-OES) and particle-induced X-ray emission (PIXE) analyses are herein recommended to bridge the data gap and to overcome limitations in trace metals analyses in the Nigerian total environment.

Supercritical carbon dioxide extraction of squalene rich cod liver oil: Optimization, characterization and functional properties

Cod liver oil (CLO) was extracted using conventional hexane and pressing methods or ecofriendly supercritical carbon dioxide (SC-CO2). The extraction main parameters including temperature (A), pressure (B), and CO2 flow rate (C) were optimized using response surface methodology. The oil chemical composition, safety, thermostability, and biological properties were characterized. The optimized SC-CO2 extraction conditions were A = 49 °C, B = 29.9 MPa, and C = 4.97 mL/min. Time-dependent extraction curves revealed a 68%, 85%, and 89% CLO recovery in 5, 15, and 20 h, respectively. SC-CO2-extracted oil contained the highest squalene (≈150 µg/mL) and vitamins D and K concentrations and the lowest toxic heavy metal levels. Thermogravimetric analysis indicated that SC-CO2-extracted oil was more susceptible to thermal degradation because of its high purity. SC-CO2-extracted CLO exhibited radical scavenging and antimicrobial functions and was cytotoxic for cancer cells suggesting its potential use in the nutraceutical industry and novel functional material designs.

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.

An Investigation for Heavy Metals’ Contamination in Farmers’ Fingernails: Case Study in Libya

This study aims to assess the concentration levels of heavy metals, which are associated with health hazards: arsenic (As), cadmium (Cd), and lead (Pb) among Libyan farmers using fingernails as a biomarker. Factors that may contribute for accumulation of these toxic heavy metals in the farmers’ fingernails were also evaluated. This cross-sectional study involved 127 farmers and 25 high school teachers living in the same geographical area as the farmers (served as the control group). Fingernail samples of the participants were collected, treated, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS) for As, Cd, and Pb contents after microwave acid digestion. Results of this study indicated that the concentration levels of the investigated heavy metals in fingernail samples of both participating farmers and control group were in order of Pb &gt; Cd &gt; As. Also, the results showed that As, Cd, and Pb levels in the farmers’ fingernails were found to be higher than in the control group by about 9-, 5-, and 2-fold, respectively. This difference for all heavy metals analyzed was found to be statistically significant P &lt; 0.05 . As a conclusion, the results of this study clearly indicated that Libyan farmers have been exposed to high levels of toxic heavy metals as a result of their agricultural activities compared with the general population living in the same geographical area as farmers, which, in turn, pose a high risk to their health. Thus, toxicological, epidemiological, and clinical studies for the Libyan farmers are strongly recommended.

Comparison of the ICP OES viewing modes efficiency in the estimation of cadmium (Cd) and lead (Pb) in whole blood samples

In forensic toxicology, precise determination of toxic trace metals in biological samples is critical. Inductively coupled plasma optical emission spectrometry (ICP OES), which has a low limit of detection, high sensitivity, accurate testing, and high analytical efficiency, is one of the most widely used techniques for determining the level of toxic trace metals in biological samples. This study aimed to assess the efficiency of ICP-OES in estimating cadmium (Cd) and lead (Pb) in whole blood samples when viewed axially, dual, and radially. All the samples that were analyzed were digested in 1.5 ml HNO3 and 2 ml H2O2. Selectivity, linearity, recovery, limits of detection (LOD), and quantification (LOQ) were used to validate the system. Cd-axial and radial recovery values were between 82–96 and 84–97%, while Pb-axial and radial recovery values were between 85–94 and 83–99%. Dual Cd-axial and radial recovery values were between 80–92 and 82–94%, while dual Pb-axial and radial recovery values were between 77–92 and 75–96%. The results demonstrated that the axillary and radially view is preferable to the dual view when using separate axially and radially view inductively coupled plasmas (ICP). In axillary and radially views, Cd's recovery rates were better than Pb's in the separate mode, but overall they were satisfactory. The recovery values for Cd and Pb in the dual view were acceptable but not sufficient.

Genome-Wide Association Mapping of Grain Metal Accumulation in Wheat

Increasing wheat grain yield while ignoring grain quality and metal accumulation can result in metal deficiencies, particularly in countries where bread wheat accounts for the majority of daily dietary regimes. When the accumulation level exceeds a certain threshold, it becomes toxic and causes various diseases. Biofortification is an effective method of ensuring nutritional security. We screened 200 spring wheat advanced lines from the wheat association mapping initiative for Mn, Fe, Cu, Zn, Ni, and Cd concentrations. Interestingly, high-yielding genotypes had high essential metals, such as Mn, Fe, Cu, and Zn, but low levels of toxic metals, such as Ni and Cd. Positive correlations were found between all metals except Ni and Cd, where no correlation was found. We identified 142 significant SNPs, 26 of which had possible pleiotropic effects on two or more metals. Several QTLs co-located with previously mapped QTL for the same or other metals, whereas others were new. Our findings contribute to wheat genetic biofortification through marker-assisted selection, ensuring nutritional security in the long run.

Molecular Regulation and Evolution of Cytokinin Signaling in Plant Abiotic Stresses.

The sustainable production of crops faces increasing challenges from global climate change and human activities, which leads to increasing instances of many abiotic stressors to plants. Among the abiotic stressors, drought, salinity and excessive levels of toxic metals cause reductions in global agricultural productivity and serious health risks for humans. Cytokinins (CKs) are key phytohormones functioning in both normal development and stress responses in plants. Here, we summarize the molecular mechanisms on the biosynthesis, metabolism, transport and signaling transduction pathways of CKs. CKs act as negative regulators of both root system architecture plasticity and root sodium exclusion in response to salt stress. The functions of CKs in mineral-toxicity tolerance and their detoxification in plants are reviewed. Comparative genomic analyses were performed to trace the origin, evolution and diversification of the critical regulatory networks linking CK signaling and abiotic stress. We found that the production of CKs and their derivatives, pathways of signal transduction and drought-response root growth regulation are evolutionarily conserved in land plants. In addition, the mechanisms of CK-mediated sodium exclusion under salt stress are suggested for further investigations. In summary, we propose that the manipulation of CK levels and their signaling pathways is important for plant abiotic stress and is, therefore, a potential strategy for meeting the increasing demand for global food production under changing climatic conditions.

The trial to assess chelation therapy 2 (TACT2): Rationale and design

BackgroundIntravenous edetate disodium-based infusions reduced cardiovascular events in a prior clinical trial. The Trial to Assess Chelation Therapy 2 (TACT2) will replicate the initial study design. MethodsTACT2 is an NIH-sponsored, randomized, 2x2 factorial, double masked, placebo-controlled, multicenter clinical trial testing 40 weekly infusions of a multi-component edetate disodium (disodium ethylenediamine tetra-acetic acid, or Na2EDTA)-based chelation solution and twice daily oral, high-dose multivitamin and mineral supplements in patients with diabetes and a prior myocardial infarction (MI). TACT2 completed enrollment of 1000 subjects in December 2020, and infusions in December 2021. Subjects are followed for 2.5 to 5 years. The primary endpoint is time to first occurrence of all-cause mortality, MI, stroke, coronary revascularization, or hospitalization for unstable angina. The trial has >;85% power to detect a 30% relative reduction in the primary endpoint. TACT2 also includes a Trace Metals and Biorepository Core Lab, to test whether benefits of treatment, if present, are due to chelation of lead and cadmium from patients. Design features of TACT2 were chosen to replicate selected features of the first TACT, which demonstrated a significant reduction in cardiovascular outcomes in the EDTA chelation arm compared with placebo among patients with a prior MI, with the largest effect in patients with diabetes. ResultsResults are expected in 2024. ConclusionTACT2 may provide definitive evidence of the benefit of edetate disodiumbased chelation on cardiovascular outcomes, as well as the clinical importance of longitudinal changes in toxic metal levels of participants.

Contamination of breast milk with lead, mercury, arsenic, and cadmium in Iran: a systematic review and meta-analysis.

Breast milk is a complete food for the development of the newborn, but it can also be an important route for environmental pollutants transmission to the infants. This study was aimed to evaluate the status of heavy metals including lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As) in the breast milk of Iranian mothers. The international databases including Scopus, PubMed, Web of Science and the Persian electronic databases including Scientific Information Database, IranMedex and Magiran were examined to find relevant articles published until July 2021. A total of 23 studies examined the levels of toxic metals in Iranian breast milk samples. According to the findings, the pooled average concentrations (µg/L) of Pb, Cd, Hg and As were 25.61, 2.40, 1.29 and 1.16, respectively. The concentration of Hg and Pb in colostrum milk was more than twice of mature milk. The Hg mean concentration in the breast milk of mothers with at least one amalgam-filled tooth was approximately three times that of mothers without amalgam-filled teeth. Risk assessment analysis indicated that the intake of Pb and Hg by infants through breastfeeding can be considered a health concern in Iran. It seems necessary to reduce the Pb exposure of pregnant and lactating women in Iran. However, more extensive studies are needed to clarify the toxic metals' exposure status of infants through breast milk in other parts of the country.

Concentrations of metal residues in domestically produced and imported milk in Kosovo

The aim of this study was to investigate the concentration of metal residues in cows’ milk and the health risks to humans from its consumption. In total 37 milk samples were analysed, namely 32 raw milk samples from domestic rural milk collection centres, and 5 imported sterilized milk samples from markets. The concentrations of chromium (Cr), manganese (Mn), nickel (Ni), and copper (Cu) in the milk samples were from 0.06 to 20.3 μg/kg, 4.7 to 64.8 μg/kg, 2.16 to 65.99 μg/kg and 0.21 to 44.7 μg/kg, respectively. Concentrations of iron (Fe), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) ranged from 157.52 to 989.95 μg/kg, 1429.63 to 5718.71 μg/kg, 0.12 to 2.01 μg/kg, 0.22 to 2.28 μg/kg, 0.00 to 0.29 μg/kg, and 0.17 to 4.29 μg/kg, respectively. The concentrations of Mg, Fe and Zn were slightly higher in domestic milk samples than in imported milk. The concentrations of Cr, Ni, Cu, As, Cd, Hg, and Pb were higher in imported milk samples than in the samples of domestic milk. Overall concentrations of minor elements had good nutritional values and the levels of the heavy toxic metals including As, Cd, Hg, and Pb were lower than the recommended limits and did not pose any threat to consumers.

W152 Oxidative stress, trace and toxic metal levels in Alzheimer’s disease in an African population

W152 Oxidative stress, trace and toxic metal levels in Alzheimer’s disease in an African population

Assessment of Metal Intake by Selected Food Supplements Based on Beehive Products.

The aim of this study was to determine the quantity of particular toxic metals (Pb, Cd, As, Hg) and micronutrients (Cr, Fe, Co, Ni, Cu, Zn, Se) in the recommended daily dose of 51 food supplements based on beehive products. Samples taken from the Croatian market were submitted for the identification/quantification of studied metals and micronutrients. It was carried out by means of inductively coupled plasma mass spectrometry (ICP-MS). Eleven samples (21.57%) showed an increased concentration of total arsenic, three samples (5.88%) contained an increased concentration of total iron, and eight samples (15.68%) had an increased concentration of total nickel. Three samples (5.88%) contained an increased concentration of zinc, while one sample (1.96%) contained an increased concentration of selenium. Increased levels of certain toxic metals and micronutrients do not pose a danger to human health because the amount identified was less than what can cause toxic effects in humans. All other analysed metals and micronutrients fell within the defined literature values. Despite certain increases in particular parameters, all samples met the established toxicity criteria. This study evidenced their safety if consumed in the recommended daily dose.

Impacts of Smoking and Stomach Disorders on Essential Elements in Biological Samples of Cement and Glass Industrial Workers.

The infection caused by Helicobacter pylori (H. pylori) disrupts the metabolism and absorption of essential trace elements. Stomach disorders are related to changes in essential trace element metabolism caused by increased toxic metal exposure and H. pylori infection. The aim of the work is to link the development of stomach-related illnesses to an imbalance of essential trace and toxic metals. We have investigated the variations in essential trace elements such zinc (Zn), iron (Fe), and copper and toxic metals like lead (Pb) and cadmium (Cd) in biological (scalp hair, blood) samples of glass and cement workers. The study participants are further divided into smokers and nonsmokers, as well as diseased (gastric ulcer, irritable bowel syndrome, and chronic ulcer) and exposed referents (non-diseased industrial workers). Biological samples of age-matched (40-60years) male subjects living in non-industrial areas were gathered for comparative purposes. After a pre-concentration method, the drinking water of industrial and domestic areas was analysed for both toxic metals. Microwave-aided acid digestion was used to oxidise the matrices of biological samples before atomic absorption spectrometer analysis of selected metals. Toxic metal levels in both industries' drinking water were much higher than those found in domestically treated water (p < 0.01). Industrial workers suffering different types of stomach disorders have two to three times higher Pb and Cd concentrations than age-matched referents. Toxic metals are found in higher concentrations in smoker referents and diseased patients' biological samples than in nonsmoker subjects. The findings of this study suggested that Pb and Cd toxicity's immunological effects may be associated to an increased vulnerability to chronic infections.

Optimization of Pb2+, Cd2+, Ni2+ and Ba2+ adsorption onto light expanded clay aggregate (LECA)

The possibility of Pb2+, Cd2+, Ni2+ and Ba2+ ions removal from aqueous solution using light expanded clay aggregate (LECA) was investigated in this work. The central composite design (CCD) in response surface methodology (RSM) was used to optimize the operating parameters (adsorbent granulometry, absorption time and initial metal ions concentration) to reach the maximum ions removal in single and multi-elemental solutions. After optimization, the results shows that the removal efficiency decrease following the ion sequence Pb2+ &gt; Ba2+ &gt; Cd2+ &gt; Ni2+ ions. The better efficiency (~95%) is observed for the Pb2+. The Langmuir and Freundlich isotherm models were applied to the equilibrium data at room temperature. The results revealed that data on LECA was very well fitted with Langmuir equations. The real interest of this work is to demonstrate that a simple material such as LECA can be used to remove extremely small levels of toxic metals, such as those found in drinking water. So our results could be the starting point for the development of a low-cost filtration system to remove toxic metals.

Environmental thallium exposure and the risk of early embryonic arrest among women undergoing in vitro fertilization: thallium exposure and polymorphisms of mtDNA gene interaction and potential cause exploring.

Early embryonic arrest (EEA) leads to cancelation of fresh cycles among infertile women undergoing in vitro fertilization (IVF), bringing a great challenge for IVF. Whether exposure to thallium (Tl) is associated with an increased risk of EEA, especially its interaction with polymorphisms of mitochondria DNA (mtDNA) gene, is worthy of study. A case-control design was performed, including 74 EEA cases with 123 IVF cycles and 157 age and BMI-matched controls with 180 IVF cycles. Levels of Tl and other toxic metals (lead (Pb), (mercury) Hg, and (arsenci) As) were assessed by measuring them in blood samples collected on the day of oocyte retrieval; PCR amplification and sequencing were performed to screen the polymorphic sites of mtDNA gene in D-loop region. Bayesian kernel machine regression (BKMR) was used to confirm that Tl played a leading role in the situation of combined exposure; generalized estimating equation (GEE) models were used to evaluate the associations of Tl concentrations, polymorphisms of mtDNA gene, and their interactions with the risk of EEA. The impact of Tl exposure or polymorphisms of mtDNA gene on the oogenesis and embryonic development was also evaluated. BKMR analysis revealed that PIP (posterior inclusion probability) value of T1 was 0.9096, indicating that it played a leading role in the situation of combined exposure. Compared to the first quartile of Tl, the adjusted ORs (95% CIs) of EEA risk were 0.66 (0.26, 1.70), 1.18 (0.52, 2.64), and 4.53 (2.11, 9.69) for the second, third, and fourth quartile, respectively (p trend < 0.001). Compared to the wild type of mtDNA 16,519 gene (T 16,519T), the adjusted OR (95% CI) of EEA risk for the variant type (T 16,519 C) was 3.11 (1.70, 5.72), and the variant types of the other sites with a minor allele frequency > 10% were not significantly related with the risk of EEA after FDR (False Discovery Rate)correction. With respect to interaction, compared to women at low Tl exposure level & wild type of mtDNA 16,519 gene group, the adjusted OR (95% CI) of EEA risk for women at high Tl exposure level & variant type of mtDNA 16,519 gene group was 9.28 (3.33, 25.81). Additionally, Tl exposure and polymorphisms of mtDNA 16,519 gene are inversely associated with the outcomes of oogenesis and embryonic development significantly. Our study indicated that high Tl exposure level was associated with the increased risk of EEA and Tl played a leading role in the situation of combined exposure; the strength of association was much higher when Tl exposure interacted with polymorphism of 16,519 mtDNA gene. These relationships might originate from the impact of Tl exposure or polymorphism of 16,519 mtDNA gene on the oogenesis and early embryonic development in vitro. Infertile women should keep high vigilant against Tl exposure especially those with variant type of mtDNA 16,519 gene.