Association of Combined Per- and Polyfluoroalkyl Substances and Metals with Chronic Kidney Disease.

Background: Exposure to environmental pollutants such as metals and Per- and Polyfluoroalkyl Substances (PFAS) has become common and increasingly associated with a decrease in the estimated Glomerular Filtration Rate (eGFR), which is a marker often used to measure chronic kidney disease (CKD). However, there are limited studies involving the use of both eGFR and the urine albumin creatinine ratio (uACR), which are more comprehensive markers to determine the presence of CKD and the complexity of pollutant exposures and response interactions, especially for combined metals and PFAS, which has not been comprehensively elucidated. Objective: This study aims to assess the individual and combined effects of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), Cadmium (Cd), Mercury (Hg), and Lead (Pb) exposure on CKD using data from the National Health and Nutritional Examination Survey (NHANES) 2017-2018. Methods: We employed the use of bivariate logistic regression and Bayesian Kernel Machine Regression (BKMR) in our analysis of the data. Results: Logistic regression results revealed a positive association between PFOA and CKD. Our BKMR analysis revealed a non-linear and bi-phasic relationship between the metal exposures and CKD. In our univariate exposure-response function plot, Cd and Hg exhibited a U and N-shaped interaction, which indicated a non-linear and non-additive relationship with both low and high exposures associated with CKD. In addition, the bivariate exposure-response function between two exposures in a mixture revealed that Cd had a U-shaped relationship with CKD at different quantiles of Pb, Hg, PFOA, and PFOS, indicating that both low and high levels of Cd is associated with CKD, implying a non-linear and complex biological interaction. Hg's interaction plot demonstrated a N-shaped association across all quantiles of Cd, with the 75th quantile of Pb and the 50th and 75th quantiles of PFOA and PFOS. Furthermore, the PIP results underscored Cd's consistent association with CKD (PIP = 1.000) followed by Hg's (PIP = 0.9984), then PFOA and PFOS with a closely related PIP of 0.7880 and 0.7604, respectively, and finally Pb (PIP = 0.6940), contributing the least among the five environmental pollutants on CKD, though significant. Conclusions: Our findings revealed that exposure to environmental pollutants, particularly Hg and Cd, are associated with CKD. These findings highlight the need for public health interventions and strategies to mitigate the cumulative effect of PFAS and metal exposure and elucidate the significance of utilizing advanced statistical methods and tools to understand the impact of environmental pollutants on human health. Further research is needed to understand the mechanistic pathways of PFAS and metal-induced kidney injury and CKD, and longitudinal studies are required to ascertain the long-term impact of these environmental exposures.

Cottage industry as a source of high exposure to lead: A biomonitoring study among people involved in manufacturing cookware from scrap metal.

In low-income countries, a widespread but poorly studied type of cottage industry consists of melting scrap metal for making cookware. We assessed the exposure to lead (Pb) among artisanal workers, and their families, involved in manufacturing cookware from scrap metal. In a cross-sectional survey, we compared artisanal cookware manufacturing foundries with carpentry workshops (negative controls) and car battery repair workshops (positive controls), all located in residential areas, in Lubumbashi (DR Congo). We collected surface dust in the workspaces, and blood and urine samples among workers, as well as residents living in the cookware workshops. Trace elements were quantified in the samples by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In surface dust, median Pb concentrations were higher in cookware foundries (347 mg/kg) than in carpentries (234 mg/kg) but lower than in battery repair workshops (22,000 mg/kg). In workers making the cookware (n = 24), geometric mean (GM) Pb blood cencentration was 118 µg/L [interquartile range (IQR) 78.4-204], i.e. nearly twice as high as among carpenters [60.2 µg/L (44.4-84.7), n = 33], and half the concentration of battery repair workers [255 µg/L (197-362), n = 23]. Resident children from the cookware foundries, had higher urinary Pb [6.2 µg/g creatinine (2.3-19.3), n = 6] than adults [2.3 (2.2-2.5), n = 3]. Our investigation confirms the high Pb hazard linked to car battery repair and reveals a high exposure to Pb among artisanal cookware manufacturers and their families, especially children, in residential areas of a city in a low-income country.

Comparison of the accumulation of toxic metal biomarkers in Asian subgroups and other races in the United States: NHANES 2015-2016.

Toxic metals such as lead (Pb), cadmium (Cd), mercury (Hg) and arsenic (As) that lead to many visceral organ and nervous system diseases have attracted global attention due to their gradual accumulation in human bodies. The tolerance levels of exposure to toxic metals among race/ethnic groups are different due to the variance of sociodemographic, dietary, and behavioral characteristics. Few studies focused on investigating the biomarker levels of toxic metals in different race/ethnic groups and the potential mechanisms for controlling the accumulation in human bodies. Therefore, we selected eight biomarkers for four toxic metals from the National Health and Nutrition and Examination Survey (NHANES) in the 2-year data cycle of 2015-2016 to reveal the accumulation levels in different races. According to the NHANES rules, we applied probability sampling weights. The geometric mean levels of these biomarkers were calculated in all five race/ethnic groups (Mexican American, white, black, Asian, and other Hispanic) and two Asian subgroups (U.S.-born Asian, and other-born Asian), and compared with each other. The results showed that all the biomarkers in other-born Asians were 1.1-6.7 times in blood and 1.1-3.6 times in urine higher than other race/ethnic groups. Except Hg and As, the lowest biomarker levels were recorded in U.S.-born Asians, only 0.6-0.9 times of lead and 0.3-0.8 times of cadmium than other race/ethnic groups. Furthermore, the major factors of higher Hg and As biomarker levels in Asians were dietary intake of seafood and rice, indicating different accumulation mechanisms among Asians and other race/ethnic groups, especially for U.S.-born Asians. These findings provided new insight into a deeper understanding the accumulation of toxic metals and human health.

Association of Urinary Lead and Cadmium Levels, and Serum Lipids with Subclinical Arteriosclerosis: Evidence from Taiwan.

BACKGROUND: Exposure to lead and cadmium has been linked to changes in lipid metabolism and the development of arteriosclerosis, but the role of lipoprotein profiles in this relationship is not well understood, including the potential role of novel lipid biomarkers. METHODS: In this study, we enrolled 736 young Taiwanese subjects aged 12 to 30 years to assess the correlation between urine levels of lead and cadmium, lipoprotein profiles, and carotid intima-media thickness (CIMT). RESULTS: Higher levels of lead and cadmium were significantly associated with higher levels of low-density lipoprotein cholesterol (LDL-C), small dense LDL-C (sdLDL-C), LDL-triglyceride (LDL-TG), and CIMT. Participants with higher levels of lead and cadmium had the highest mean values of CIMT, LDL-C, sdLDL-C, and LDL-TG. In a structural equation model, lead had a direct and indirect association with CIMT through LDL-C and sdLDL-C, whereas cadmium had a direct association with CIMT and an indirect association through LDL-C. CONCLUSION: Our results suggest higher levels of lead and cadmium are associated with abnormal lipid profiles and increased CIMT. These heavy metals could have additive effects on lipids and CIMT, and the relationship between them may be mediated by lipoprotein levels. Further research is needed to determine the causal relationship.

Identification of the regulatory network and potential markers for type 2 diabetes mellitus related to internal exposure to metals in Chinese adults.

People intake metals from their environment. This study investigated type 2 diabetes mellitus (T2DM) related to internal exposure to metals and attempted to identify possible biomarkers. A total of 734 Chinese adults were enrolled, and urinary levels of ten metals were measured. Multinomial logistic regression model was used to assess the association between metals and impaired fasting glucose (IFG) and T2DM. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction were used to explore the pathogenesis of T2DM related to metals. After adjustment, lead (Pb) was positively associated with IFG (odds ratio [OR] 1.31, 95% confidence interval [CI] 1.06-1.61) and T2DM (OR 1.41, 95% CI 1.01-1.98), but cobalt was negatively associated with IFG (OR 0.57, 95% CI 0.34-0.95). Transcriptome analysis showed 69 target genes involved in the Pb-target network of T2DM. GO enrichment indicated that the target genes are enriched mainly in the biological process category. KEGG enrichment indicated that Pb exposure leads to non-alcoholic fatty liver disease, lipid and atherosclerosis, and insulin resistance. Moreover, there is alteration of four key pathways, and six algorithms were used to identify 12 possible genes in T2DM related to Pb. SOD2 and ICAM1 show strong similarity in expression, suggesting a functional correlation between these key genes. This study reveals that SOD2 and ICAM1 may be potential targets of Pb exposure-induced T2DM and provides novel insight into the biological effects and underlying mechanism of T2DM related to internal exposure to metals in the Chinese population.

Effects of heavy metals in acute ischemic stroke patients: A cross-sectional study.

ABSTRACT: Cerebrovascular disease is the second commonest cause of mortality globally and among the commonest causes of disability. However, research executed to probe the heavy metal exposure-stroke incidence relationship is scarce. Accordingly, we executed our study to probe the relationship of heavy metal concentrations (ie, concentrations of lead [Pb], mercury [Hg], cadmium [Cd], and arsenic) in the serum and urine of acute ischemic stroke (AIS) patients with several patient variables.For enrollment, we chose patients who had a first AIS within 7 days after the onset of a stroke. Thus, 33 newly diagnosed patients with AIS were recruited. We determined the aforementioned metals' concentrations by executing inductively coupled plasma mass spectrometry. We also gauged the association between such metal concentrations and patient variables by employing Spearman correlation coefficient. To examine the differences in metal concentrations between the different variables, we implemented an independent Mann-Whitney U test.In our cohort analysis, we noted serum Pb and Cd concentrations to be positively correlated with serum creatinine and hemoglobin. Serum and urine Cd concentrations had a negative correlation with impaired HbA1c in AIS patients. Urine Hg had a positive correlation with C-reactive protein in the participants. Participants who smoked or consumed alcohol had significantly higher Pb and Cd levels in serum than did those who neither smoked nor drank. Patients with AIS who smoked or consumed alcohol had high levels of serum Pb and serum Cd than did those who did not. Patients with AIS who consumed alcohol had significantly higher Pb and Hg urine concentrations than did those who did not.Our study indicated that serum Cd and Pb elevation increased the AIS risk in southern Taiwan patients.

Associations between urinary heavy metal concentrations and blood pressure in residents of Asian countries.

BACKGROUND: Previous studies have suggested that exposures to heavy metals (arsenic, cadmium, lead, and selenium) may be associated with differences in blood pressure. However, the findings of these studies have been inconsistent. This study was performed to examine the associations between urinary heavy metal concentrations and blood pressure among residents of four Asian countries (Bangladesh, Indonesia, Nepal, and Vietnam). METHODS: This cross-sectional study examined 1899 adults in four Asian countries. Urinary concentrations of heavy metals were measured by inductively coupled plasma mass spectrometry. A questionnaire survey was administered regarding individual characteristics. Anthropometric measurements (height and weight) were performed. Systolic and diastolic blood pressures were measured after a short rest. Multiple linear regression models were applied to investigate associations between urinary heavy metal concentrations and blood pressure after adjustments for age, sex, and body mass index. RESULTS: The geometric means of the urinary concentrations of arsenic, cadmium, lead, and selenium were 84.6, 0.885, 2.09, and 16.5 µg/g creatinine, respectively. The urinary arsenic concentrations were slightly higher than those typically reported in non-polluted populations, while urinary cadmium, lead, and selenium concentrations were equivalent or slightly lower. The urinary lead concentrations were positively associated with both systolic and diastolic blood pressure, but urinary selenium concentrations were negatively associated with them. CONCLUSIONS: Variations in the urinary concentrations of lead and selenium were associated with blood pressure at low levels of exposure/intake.

Positive Association between Endothelium-Platelet Microparticles and Urinary Concentration of Lead and Cadmium in Adolescents and Young Adults.

(1) Background: In previous research, higher levels of urine heavy metals, especially lead and cadmium, have been associated with increased cardiovascular risk. However, there is no information linking exposure to heavy metal to endothelial and platelet microparticles (EMPs and PMPs), particularly in the younger population, which are novel biomarkers of endothelial dysfunction. (2) Methods: From a nationwide database, which was incepted in 1992-2000, screening for renal health among Taiwanese school children, a total of 789 subjects were recruited. Cross-sectional analysis was performed to evaluate the association between serum EMPs/PMPs and urine iron, nickel, copper, cadmium, lead, chromium, manganese, and zinc levels in the adolescent and young adult population. (3) Results: After we adjusted the conventional cardiovascular risk factors, CD31+/CD42a- and CD31+/CD42a+ counts, in subjects' serum, respective markers of EMP and PMP displayed a significant positive dose-response relationship with urinary lead and cadmium levels. Higher quartiles of urine lead and cadmium levels were associated with an increased risk of higher EMPs/PMPs (≥75th percentile) in a multivariate logistic regression model. (4) Conclusion: Higher urinary lead and cadmium concentrations are strongly associated with endothelium-platelet microparticles in this adolescent and young adult population, which could help explain, in part, the mechanism through which heavy metal exposure results in cardiotoxicity.

Multibiomarker approach to assess the magnitude of occupational exposure and effects induced by a mixture of metals.

Metals and metalloids including lead (Pb), arsenic (As) and manganese (Mn) can occur as mixtures in occupational contexts, such as mines. These chemicals are all known to be neurotoxic and provoke changes in heme metabolism also known to induce neurotoxicity. The objective of this work was to propose a multi-biomarker (BM) methodology to screen subjects exposed to the mixture of Pb, As and Mn and assess the severity of their exposure/effects, in an individual basis. The urinary levels of the metals, dela-aminolevulinic acid (ALA) and porphyrins were determined in Portuguese miners and in a control group. The combination of Pb and As urinary levels had the highest capability to identify subjects occupationally exposed to this mixture in mines, as evaluated through Receiver Operating Characteristic (ROC) (A = 98.2%; p < 0.05), allowing that 94.2% of 86 studied subjects were properly identified and the generation of an equation indicating the odd of a subject be considered as exposed to the metal mixture. The combination of urinary ALA and porphyrins revealed to be best one to be applied in the assessment of subjects with high, intermediate, and low magnitudes of exposure/effects, with 95.7% of 46 miners classified correctly according to their severity sub-group and allowing to generate equations, which can be applied in new subjects. The proposed methodology showed a satisfactory performance, evaluating in an integrated manner the magnitude of exposure/effects of the exposed workers, may contributing to improve the control of their health.

Human biomarkers associated with low concentrations of arsenic (As) and lead (Pb) in groundwater in agricultural areas of Thailand.

Human biomarkers were used to evaluate the lead (Pb) and arsenic (As) exposure of local people who lived in an agricultural area with intense agrochemical usage and who consumed groundwater. Although the heavy metals/metalloids in the groundwater were at low concentrations, they could cause adverse effects due to a high daily water intake rate over the long term. Biomarkers (hair, fingernails and urine) were collected from 100 subjects along with the local shallow groundwater and tap water, which is the treated deep groundwater, and investigated for the concentrations of As and Pb. Shallow groundwater had an average pH of 5.21 ± 1.90, ranging from 3.77 to 8.34, with average concentrations of As and Pb of 1.311 µg/L and 6.882 µg/L, respectively. Tap water had an average pH of 5.24 ± 1.63, ranging from 3.86 to 8.89, with the average concentrations of As and Pb of 0.77 µg/L and 0.004 µg/L, respectively. The levels of both As and Pb in the hair, fingernails and urine of shallow groundwater-consuming residents were greater than those in the hair, fingernails and urine of tap water-consuming residents. Interestingly, the As level in urine showed a linear relationship with the As concentration in groundwater (R2 = 0.91). The average water consumption rate was approximately two-fold higher than the standard; thus, its consumption posed a health risk even at the low As and Pb levels in the groundwater. The hazard index (HI) ranged from 0.01 to 16.34 (average of 1.20 ± 2.50), which was higher than the acceptable level. Finally, the concomitant factors for As and Pb in the urine, hair and nails from both binary logistic regression and odds ratio (OR) analysis indicated that groundwater consumption was the major concomitant risk factor. This study suggested that direct consumption of this groundwater should be avoided and that the groundwater should be treated, especially before consumption. In conclusion, urine is suggested to be a biomarker of daily exposure to As and Pb, while for long-term exposure to these metals, fingernails are suggested as a better biomarker than hair.

Global DNA (LINE-1) methylation is associated with lead exposure and certain job tasks performed by electronic waste workers.

OBJECTIVE: This study assessed the associations between blood and urine levels of toxic metals; cadmium (Cd) and lead (Pb), and methylation levels of the LINE-1 gene among e-waste and control populations in Ghana. METHODS: The study enrolled 100 male e-waste workers and 51 all-male non-e-waste workers or controls. The concentrations of Cd and Pb were measured in blood and urine using inductively coupled plasma mass spectrometry, while LINE1 methylation levels were assessed by pyrosequencing of bisulfite-converted DNA extracted from whole blood. Single and multiple metals linear regression models were used to determine the associations between metals and LINE1 DNA methylation. RESULTS: Blood lead (BPb) and urine lead (UPb) showed higher median concentrations among the e-waste workers than the controls (76.82 µg/L vs 40.25 µg/L, p ≤ 0.001; and 6.89 µg/L vs 3.43 µg/L, p ≤ 0.001, respectively), whereas blood cadmium (BCd) concentration was lower in the e-waste workers compared to the controls (0.59 µg/L vs 0.81 µg/L, respectively, p = 0.003). There was no significant difference in LINE1 methylation between the e-waste and controls (85.16 ± 1.32% vs 85.17 ± 1.11%, p = 0.950). In our single metal linear regression models, BPb was significantly inversely associated with LINE1 methylation in the control group (ßBPb = - 0.027, 95% CI - 0.045, - 0.010, p = 0.003). In addition, a weak association between BPb and LINE1 was observed in the multiple metals analysis in the e-waste worker group (ßBPb = - 0.005, 95% CI - 0.011, 0.000, p = 0.058). CONCLUSION: Continuous Pb exposure may interfere with LINE1 methylation, leading to epigenetic alterations, thus serving as an early epigenetic marker for future adverse health outcomes.

Urinary Heavy Metals and Longitudinal Changes in Blood Pressure in Midlife Women: The Study of Women's Health Across the Nation.

[Figure: see text].

Associations between urinary heavy metal concentrations and blood pressure in residents of Asian countries

BACKGROUND@#Previous studies have suggested that exposures to heavy metals (arsenic, cadmium, lead, and selenium) may be associated with differences in blood pressure. However, the findings of these studies have been inconsistent. This study was performed to examine the associations between urinary heavy metal concentrations and blood pressure among residents of four Asian countries (Bangladesh, Indonesia, Nepal, and Vietnam).@*METHODS@#This cross-sectional study examined 1899 adults in four Asian countries. Urinary concentrations of heavy metals were measured by inductively coupled plasma mass spectrometry. A questionnaire survey was administered regarding individual characteristics. Anthropometric measurements (height and weight) were performed. Systolic and diastolic blood pressures were measured after a short rest. Multiple linear regression models were applied to investigate associations between urinary heavy metal concentrations and blood pressure after adjustments for age, sex, and body mass index.@*RESULTS@#The geometric means of the urinary concentrations of arsenic, cadmium, lead, and selenium were 84.6, 0.885, 2.09, and 16.5 μg/g creatinine, respectively. The urinary arsenic concentrations were slightly higher than those typically reported in non-polluted populations, while urinary cadmium, lead, and selenium concentrations were equivalent or slightly lower. The urinary lead concentrations were positively associated with both systolic and diastolic blood pressure, but urinary selenium concentrations were negatively associated with them.@*CONCLUSIONS@#Variations in the urinary concentrations of lead and selenium were associated with blood pressure at low levels of exposure/intake.

Serum and urinary concentrations of arsenic, beryllium, cadmium and lead after an aerobic training period of six months in aerobic athletes and sedentary people.

AIM: The aim of the present study was to evaluate the possible effect of a period of 6 months of aerobic physical training on serum and urinary concentrations of arsenic (As), beryllium (Be), cadmium (Cd) and lead (Pb), potentially toxic minerals. METHODS: Twenty-four well-trained, long distance runners (AG), were recruited at the start of their training period. They had been performing training regularly for the previous 2 years, recording an average volume of 120 km per week of rigorous aerobic exercise aimed at high-level competitions (1500 and 5000 m race modalities). Twenty-six untrained, sedentary participants constituted the control group (CG). All participants had been living in the same geographic area for at least 2 years before the start of the survey. Serum and urine samples were obtained from each participant at the beginning and at the end of the 6 months of the training program. The values of each mineral were determined by inductively coupled plasma mass spectrometry (ICP-MS). Additionally, the daily intake of each mineral was evaluated at both moments in time. RESULTS: The daily concentrations of trace elements in the diet were similar at the start and the end of the training period without differences between groups. In serum, significant differences between groups were observed in As, Cd and Pb (p < 0.05). Attending to time effects, a significant difference was obtained in Pb (p < 0.05). In urine, significant differences between groups were obtained in all minerals (p < 0.05). According to training period, significant differences were observed in As, Be and Pb (p < 0.05). Finally, the group x time interaction revealed significant differences in As and Be (p < 0.05). CONCLUSIONS: Aerobic training may constitute a possibly effective method for increasing the elimination of Cd and Pb potentially toxic minerals from the body, especially among highly trained individuals.

Urinary heavy metals, DNA methylation, and subclinical atherosclerosis.

PURPOSE: Lead (Pb) or cadmium (Cd) exposure has been linked to atherosclerosis. Co-exposure of these two heavy metals often occurs in humans. Recent evidence has indicated a crucial role of DNA methylation in atherosclerosis, while Pb or Cd exposure has also been shown to alter DNA methylation. However, it is still unknown whether DNA methylation plays a role in the pathological mechanism of these two heavy metals in atherosclerosis. APPROACH AND RESULTS: We enrolled 738 participants (12-30 years) to investigate the association among concentrations of urine Pb or Cd, the 5mdC/dG value (a global DNA methylation marker) and the carotid intima-media thickness (CIMT). When each heavy metal was modeled separately, the results showed urine Pb and Cd concentrations were positively associated with the 5mdC/dG value and CIMT, respectively. When the two heavy metals were analyzed in the same model, urinary Pb concentrations were positively associated with the 5mdC/dG value and CIMT, while urinary Cd concentrations were only positively associated with the CIMT. When Pb and Cd are simultaneously considered in the same logistic regression model, the odds ratios (OR) of thicker CIMT (greater than 75th percentile) with one unit increase in ln-Pb level was 1.67 (95% C.I. = 1.17-2.46, P = 0.005) when levels of 5mdC/dG were above 50th percentile, which is higher than 5mdC/dG bellow the 50th percentile (OR = 1.50 (95% C.I. = 0.96-2.35), P = 0.076). In structural equation model (SEM), Pb or Cd levels are directly associated with CIMT. Moreover, Pb or Cd had an indirect association with CIMT through the 5mdC/dG. When we considered Pb and Cd together, Pb levels had a direct association with CIMT and an indirect association with CIMT through the 5mdC/dG value, while Cd only had a direct association with CIMT. CONCLUSIONS: Our findings imply that Pb and Cd exposure might be associated with subclinical atherosclerosis, and global DNA methylation might mediate Pb-associated subclinical atherosclerosis in this young population. Future effort is necessary to elucidate the causal relationship.

Biological monitoring of urinary lead: Preshift and postshift sampling detects efficiently recent lead exposure and signals the need to review and possibly improve controls at work.

The objective of this study is to highlight the effectiveness of urinary lead as an index of recent lead exposure. In the past scientific literature urinary lead has been studied as a parameter for recent lead exposure. It is a reliable indicator for occupational lead exposure. But, strangely enough, nowadays is scarcely used in the Netherlands and worldwide. We performed six field biological monitoring studies of preshift and postshift urinary lead tests during tank maintenance and bridge repair work. Highest values occurred during bridge repair. Mean urinary values were postshift 1,6-5 times higher than preshift values, indicating clearly recent lead exposure and failing protective measures. This is so far we know the first study combining preshift and postshift sampling of urinary lead. We compared our studies with crossectional and follow-up studies in occupational medicine. Our conclusion is that preshift and postshift urinary lead testing is a worker friendly test, ideally for detecting recent lead exposures in the field. It signals the need to review or possibly improve controls at work. There are no safe lead levels, so we recommend to use a target value for urinary lead of <3 µg/g creatinine for all lead workers in the Netherlands.

Evaluation and updates to the Leggett model for pharmacokinetic modeling of exposure to lead in the workplace - Part I adjustments to the adult systemic model.

California's Division of Occupational Safety and Health has initiated a process to update its standards for exposure to lead in workplaces. In support of this effort, the state's Office of Environmental Health Hazard Assessment evaluated the age-specific, bio-kinetic model of lead metabolism in humans, originally published by R.W. Leggett in 1993. This model was ultimately chosen for its physiologic realism and practicality in characterizing the relationship between air lead concentrations and blood lead levels in chronically exposed worker and its practicality in making necessary adjustments. Leggett's original model systematically under-predicts bone and blood levels in workers such that several adjustments to the parameters are needed to improve predictions for occupational exposure scenarios. The aim of this work is to incorporate new information about the bio-kinetics of lead in workers and to adjust the Leggett model to improve its predictions.The Leggett model was evaluated by comparing its predictions with information on lead concentrations in bone, blood, and urine from workers and other chronically exposed adults. Key model parameters were identified based upon a review of the relevant exposure assessment and modeling literature. Adjustments to the model parameters were made based on empirical evidence. They included reducing the level of lead in blood (BLL) where the rate of decrease in red blood cell binding begins and ends, lead accumulation rate in cortical bone, the rate of lead elimination in trabecular bone, and rate of lead transferred from diffusible plasma to urine. Regression methods and visual inspection of plotted data were used to assess the effect of adjustments on model predictions. When compared with the original, the adjusted Leggett model more accurately predicted lead concentrations observed in active and retired workers. Also, the adjusted Leggett model required less lead uptake to reach the same BLLs for BLLs less than 25 µg/dL and more time for BLLs to decline than the original Leggett model. These findings are important for defining an adequately protective occupational standard for lead exposure.

Effect of exposure to high temperatures in the excretion of cadmium and lead.

OBJECTIVE: This study aims to observe the effect on urine and sweat excretion levels of cadmium (Cd) and lead (Pb) in healthy men in a maximum incremental test until exhaustion and repeated exposure to heat. METHODS: twenty-nine adult men divided into control group (CG; n = 14) and experimental group (EG; n = 15) performing two maximum tests until exhaustion in normothermia (22 °C) and hyperthermia (42 °C). EG experienced 9 sessions of heat exposure at high temperatures (100 °C) (HEHT). After the nine sessions, the initial tests were repeated in both groups. Urine samples were collected before and after each test. After the hyperthermia tests, sweat samples were gathered. RESULTS: Urinary Cd increased after initial tests in GC and in hyperthermia in EG (p < 0.05). Urinary excretion of Pb rose after HEHT (p < 0.05). Pb in sweat was higher in EG than in CG after HEHT (p < 0.05). CONCLUSION: Heat exercise and constant exposure to heat can be a valid method to increase the excretion of toxic metals.

Association between urine lead levels and cardiovascular disease risk factors, carotid intima-media thickness and metabolic syndrome in adolescents and young adults.

BACKGROUND: Environmental lead exposure is a known risk factor of cardiovascular disease (CVD) in animal and human epidemiological studies of adults, but limited research has been conducted in young populations. Moreover, the association between lead level and common carotid artery intima-media thickness (CIMT) has never been documented. DESIGN: and Participants: In this study, 738 subjects were recruited from a cohort of Taiwanese adolescents and young adults to study the relationship between lead levels in urine and CVD risk factors, metabolic syndrome (MS) and CIMT. RESULTS: The geometric mean of the urine lead level was 1.50 µg/g creatinine. We found a significant positive association between urine lead levels and CVD risk factors, including diastolic blood pressure (DBP), mean arterial pressure (MAP), as well as markers of glucose homeostasis, such as serum glucose, serum insulin, homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of ß-cell function (HOMA-ß), body mass index (BMI) z score, and CIMT. Overall, increased urine lead concentrations were positively correlated with the prevalence of MS, specifically the criteria of waist/BMI and serum HDL-C. The relationship between urine lead levels and CIMT remained unchanged in all subgroups. CONCLUSION: In this study, we found that increased urinary levels of lead were positively associated with CVD risk factors, CIMT, and MS in this cohort. Future research to explore the pathogenic basis of exposure to lead and risk of CVDs and their risk factors are warranted.

Preconcentration of Lead in Blood and Urine Samples Among Bladder Cancer Patients Using Mesoporous Strontium Titanate Nanoparticles.

In this work, mesoporous strontium titanate nanoparticles (SrTiO3 NPs) were synthesized through a single-step combustion process and were characterized by FT-IR, XRD, SEM-EDX, and TEM. The effects of main parameters that may influence the extraction process (i.e., pH, sorbent amount, time of extraction, eluting agent, and the presence concomitant ions) were investigated. The optimum extraction was achieved at pH 6, 50 mg of sorbent, 20-min shaking time, and 4.0 mL of 0.1 mol L-1 thiourea as desorption agent. Under these conditions, the maximum adsorption capacity was 155.6 mg g-1 with a preconcentration factor of 250 (for a 1000 mL sample solution). The calibration graph was linear up to 1000 µg L-1 and the limit of detection was 1.75 µg L-1. The precision (as relative standard deviation) was 2.53% (n = 10). The procedure was employed for the preconcentration of Pb2+ from blood and urine samples of bladder cancer patients before its determination by FAAS.