The interpretable machine learning model associated with metal mixtures to identify hypertension via EMR mining method.

There are limited data available regarding the connection between hypertension and heavy metal exposure. The authors intend to establish an interpretable machine learning (ML) model with high efficiency and robustness that identifies hypertension based on heavy metal exposure. Our datasets were obtained from the US National Health and Nutrition Examination Survey (NHANES, 2013-2020.3). The authors developed 5 ML models for hypertension identification by heavy metal exposure, and tested them by 10 discrimination characteristics. Further, the authors chose the optimally performing model after parameter adjustment by Genetic Algorithm (GA) for identification. Finally, in order to visualize the model's ability to make decisions, the authors used SHapley Additive exPlanation (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME) algorithm to illustrate the features. The study included 19 368 participants in total. A best-performing eXtreme Gradient Boosting (XGB) with GA for hypertension identification by 16 heavy metals was selected (AUC: 0.774; 95% CI: 0.772-0.776; accuracy: 87.7%). According to SHAP values, Barium (0.02), Cadmium (0.017), Lead (0.017), Antimony (0.008), Tin (0.007), Manganese (0.006), Thallium (0.004), Tungsten (0.004) in urine, and Lead (0.048), Mercury (0.035), Selenium (0.05), Manganese (0.007) in blood positively influenced the model, while Cadmium (-0.001) in urine negatively influenced the model. Study participants' hypertension associated with heavy metal exposure was identified by an efficient, robust, and interpretable GA-XGB model with SHAP and LIME. Barium, Cadmium, Lead, Antimony, Tin, Manganese, Thallium, Tungsten in urine, and Lead, Mercury, Selenium, Manganese in blood are positively correlated with hypertension, while Cadmium in blood is negatively correlated with hypertension.

Level-specific associations of urinary antimony with cognitive function in US older adults from the National Health and Nutrition Examination Survey 2011-2014.

BACKGROUND: We have looked at antimony (Sb) as a new neurotoxin which causes neuronal apoptosis in animal studies. At the population level, however, there is no direct evidence for a relationship between Sb exposure and cognitive performance. METHOD: The study comprehensively assessed the correlation between urinary antimony levels and cognitive test scores in 631 creatinine-corrected older persons using data from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014. RESULTS: Using logistic regression, the study looked at the prevalence of cognitive impairment at different levels of urine antimony concentrations and found that, after controlling for covariates, higher doses of urinary antimony were positively associated with cognitive function compared to controls, odds ratio (ORs) with 95% confidence interval (CI) were 0.409 (0.185-0.906) and 0.402 (0.186-0.871) respectively. Restricted cubic spline curves showed a non-linear and dose-specific correlation between urinary antimony and cognitive performance, with lower doses associated with better cognitive performance, while higher doses may be associated with cognitive impairment. CONCLUSIONS: Our data provide evidence for a correlation between Sb and cognitive function at the population level, although the specific mechanisms need to be investigated further.

Antimony and sleep health outcomes: NHANES 2009-2016.

OBJECTIVES: Following an earlier National Health and Nutrition Examination Survey (NHANES) 2005-2008 analysis, we investigated the association between urine antimony and sleep health using more recent data, new measures of sleep health, and multiple measures of urine density adjustment in NHANES 2009-2016. DESIGN: A cross-sectional study. SETTING: United States, national population-based survey. MEASUREMENTS: Multinomial logistic regression (sleep duration) and a generalized linear model with log-binomial regression (OSA, daytime sleepiness, sleep problems) were used to analyze the association of urinary antimony with sleep health outcomes. Urine creatinine and osmolality were considered, combined with statistical adjustment and standardization to account for urine density. PARTICIPANTS: A total of 8133 adult participants over 20 years of age were used using NHANES 2009-2016. RESULTS: We did not observe associations between urine antimony and short sleep duration or sleep problems. We observed mixed results for long sleep duration; there was a negative association in NHANES 2015-2016 and no association in NHANES 2009-2014. For self-reported symptoms of OSA, which were only available in 2015-2016, we observed a positive association for upper quartile urine antimony compared with the first quartile (RR = 1.24; 95% CI: 1.03, 1.50) and a test for trend, P= .02. CONCLUSION: Urinary antimony was not consistently associated with short sleep duration, long sleep duration, or sleep problems, despite the findings from a relatively recent scientific article using earlier waves of NHANES. We observed a positive association between antimony and symptoms of OSA; this cross-sectional analysis requires confirmation.

Toxic Metals and Subclinical Atherosclerosis in Carotid, Femoral, and Coronary Vascular Territories: The Aragon Workers Health Study.

OBJECTIVE: Studies evaluating the association of metals with subclinical atherosclerosis are mostly limited to carotid arteries. We assessed individual and joint associations of nonessential metals exposure with subclinical atherosclerosis in 3 vascular territories. Approach and Results: One thousand eight hundred seventy-three Aragon Workers Health Study participants had urinary determinations of inorganic arsenic species, barium, cadmium, chromium, antimony, titanium, uranium, vanadium, and tungsten. Plaque presence in carotid and femoral arteries was determined by ultrasound. Coronary Agatston calcium score ≥1 was determined by computed tomography scan. Median arsenic, barium, cadmium, chromium, antimony, titanium, uranium, vanadium, and tungsten levels were 1.83, 1.98, 0.27, 1.18, 0.05, 9.8, 0.03, 0.66, and 0.23 µg/g creatinine, respectively. The adjusted odds ratio (95% CI) for subclinical atherosclerosis presence in at least one territory was 1.25 (1.03-1.51) for arsenic, 1.67 (1.22-2.29) for cadmium, and 1.26 (1.04-1.52) for titanium. These associations were driven by arsenic and cadmium in carotid, cadmium and titanium in femoral, and titanium in coronary territories and mostly remained after additional adjustment for the other relevant metals. Titanium, cadmium, and antimony also showed positive associations with alternative definitions of increased coronary calcium. Bayesian Kernel Machine Regression analysis simultaneously evaluating metal associations suggested an interaction between arsenic and the joint cadmium-titanium exposure. CONCLUSIONS: Our results support arsenic and cadmium and identify titanium and potentially antimony as atherosclerosis risk factors. Exposure reduction and mitigation interventions of these metals may decrease cardiovascular risk in individuals without clinical disease.

Antimony in urine during early pregnancy correlates with increased risk of gestational diabetes mellitus: A prospective cohort study.

BACKGROUND: Antimony (Sb) has been associated with type 2 diabetes in previous studies. However, the role of Sb in the incidence of Gestational diabetes mellitus (GDM) remains unclear. OBJECTIVES: We investigated the association between Sb exposure during early pregnancy and the risk of GDM. METHODS: We performed a prospective study of 2093 pregnant women from the Tongji Maternal and Child Health Cohort (TMCHC). Sb concentrations were measured in urine samples during early pregnancy by ICP-MS. The association between urinary Sb concentration and GDM incidence was assessed using robust Poisson regression model after adjustment for confounders. RESULTS: The 95th percentile value of creatinine-corrected Sb (CC-Sb) concentration in the urine of all pregnant women was 1.33 µg/g. The CC-Sb concentrations were significantly higher in women with GDM than those without GDM (median value: 0.49 µg/g vs. 0.38 µg/g, p = 0.001). After adjustment for potential confounders, for each one natural logarithmic unit increase in Sb concentration, there was 29% [adjusted relative risk (RR) = 1.29; 95% confidence interval (CI): 1.06, 1.57] increase in the risk of GDM. Women in the highest tertile for CC-Sb had a 1.92-fold (95% CI: 1.42, 2.60) higher risk of GDM compared with women in the lowest tertile (p-value for trend <0.001). CONCLUSION: To our knowledge, this is the first research of an association between urinary Sb levels during pregnancy and GDM. Our study suggests that pregnant women with higher Sb exposure levels may have a higher risk of GDM and this association remains consistent even after stratification.

Heavy Metals' Effect on Susceptibility to Attention-Deficit/Hyperactivity Disorder: Implication of Lead, Cadmium, and Antimony.

Background: Heavy metals are known to be harmful for neurodevelopment and they may correlate to attention deficit/hyperactivity disorder (ADHD). In this study, we aim to explore the relationships between multiple heavy metals (manganese, lead, cadmium, mercury, antimony, and bismuth), neurocognitive function, and ADHD symptoms. Methods: We recruited 29 patients with ADHD inattentive type (ADHD-I), 47 patients with ADHD hyperactivity/impulsivity type (ADHD-H/I), and 46 healthy control children. Urine samples were obtained to measure the levels of the aforementioned heavy metals in each child. Participants’ cognitive function and clinical symptoms were assessed, respectively. Results: We found ADHD-H/I patients demonstrated the highest antimony levels (p = 0.028), and ADHD-I patients demonstrated the highest cadmium levels (p = 0.034). Antimony levels were positively correlated with the severity of ADHD symptoms that were rated by teachers, and cadmium levels were negatively correlated with the Full Scale Intelligence Quotient. Lead levels were negatively correlated with most indices of the Wechsler Intelligence Scale for Children⁻Fourth Edition (WISC-IV), but positively correlated with inattention and hyperactivity/impulsivity symptoms (p < 0.05). Conclusion: Lead, cadmium and antimony were associated with susceptibility to ADHD and symptom severity in school-age children. Eliminating exposure to heavy metals may help to prevent neurodevelopmental disorders in children.

Risk due to exposure to metallic elements in a birdshot factory.

The contribution of biological and environmental monitoring to the risk assessment of occupational exposure to lead (Pb), arsenic (As), and antimony (Sb) was studied in 18 workers at a birdshot factory (Exposed) and in 18 control workers (Controls) by the determination of both airborne Pb (PbA) and airborne As (AsA) only in the exposed workers and blood Pb (PbB), erythrocytic zinc protoporphyrin (ZPP), urinary Sb (SbU), and the urinary As species in exposed workers and controls. PbA (12-42 µg/m3) and AsA (1-4 µg/m3) were strongly correlated (r = .95). PbB, ZPP, and the sum of As3+As5+MMA were significantly higher in the exposed workers. As3 was higher than the limit of detection in 14 exposed workers and 1 control, As5 only in 1 exposed worker, SbU in all the exposed workers and in 4 controls. Monitoring for more metallic elements reveals a wider spectrum of exposures than can be achieved by lead surveillance alone and is preferable for characterizing occupational risk wherever possible.

Assessment of Industrial Antimony Exposure and Immunologic Function for Workers in Taiwan.

This study investigated antimony exposure among employees in industries in Taiwan and evaluated whether their immunologic markers were associated with antimony exposure. We recruited 91 male workers and 42 male office administrators from 2 glass manufacturing plants, 1 antimony trioxide manufacturing plants, and 2 engineering plastic manufacturing plants. Air samples were collected at worksites and administrative offices, and each participant provided specimens of urine, blood, and hair to assay antimony levels. We also determined white blood cells, lymphocyte, and monocyte, IgA, IgE, and IgG in blood specimens. The mean antimony concentration in the air measured at worksites was much higher in the antimony trioxide plant (2.51 ± 0.57 mg/m³) than in plastic plants (0.21 ± 0.06 mg/m³) and glass plants (0.14 ± 0.01 mg/m³). Antimony levels in blood, urine, and hair measured for participants were correlated with worksites and were higher in workers than in administrators. The mean serum IgG, IgA, and IgE levels were lower in workers than in administrators (p < 0.001). Serum IgA and IgE levels in participants were negatively associated with antimony levels in air samples of workplaces, and in blood, urine, and hairs of participants. Serum IgG and IgE of all participants were also negatively associated with antimony levels in their hairs. In conclusion, the antimony exposure is greater for workers employed in the five industrial plants than for administrators. This study suggests serum IgG, IgA, and IgE levels are negatively associated with antimony exposure.

Antimony and sleep-related disorders: NHANES 2005-2008.

BACKGROUND: Antimony is used as a flame-retardant in textiles and plastics, in semiconductors, pewter, and as pigments in paints, lacquers, glass and pottery. Subacute or chronic antimony poisoning has been reported to cause sleeplessness. The prevalence of short sleep duration (<7h/night) has been reported to be 37.1% in the general US population, and obstructive sleep apnea (OSA) affects 12-28 million US adults. Insufficient sleep and OSA have been linked to the development of several chronic conditions including diabetes, cardiovascular disease, obesity and depression, conditions that pose serious public health threats. OBJECTIVE: To investigate whether there is an association between antimony exposure and sleep-related disorders in the US adult population using the National Health and Nutrition Examination Survey (NHANES) 2005-2008. METHODS: We performed multivariate logistic regression to analyze the association of urinary antimony with several sleep disorders, including insufficient sleep and OSA, in adult (ages 20 years and older) participants of NHANES 2005-2008 (n=2654). RESULT: We found that participants with higher urinary antimony levels had higher odds to experience insufficient sleep (≤6h/night) (OR 1.73; 95%CI; 1.04, 2.91) as well as higher odds to have increased sleep onset latency (>30min/night). Furthermore, we found that higher urinary antimony levels in participants were associated with OSA (OR 1.57; 95%CI; 1.05, 2.34), sleep problems, and day-time sleepiness. CONCLUSION: In this study, we found that urinary antimony was associated with higher odds to have insufficient sleep and OSA. Because of the public health implications of sleep disorders, further studies, especially a prospective cohort study, are warranted to evaluate the association between antimony exposure and sleep-related disorders.

Relationships between urinary antimony levels and both mortalities and prevalence of cancers and heart diseases in general US population, NHANES 1999-2010.

The effects of antimony (Sb) exposure on mortalities, cancers and cardiovascular diseases were controversial in occupational workers, and the evidence from the general population is limited. The objective of this study is to investigate the relationships between Sb exposure and specific health events in the general population. Totally, 7781 participants aged ≥20years were selected from the National Health and Nutrition Examination Survey (NHANES) 1999-2010 and were followed for an average of 6.04years. The Cox and logistic regression models were applied to evaluate the effects of urinary Sb (U-Sb) levels on the risks of all-cause and cause-specific mortalities, and the likelihoods of self-reported cancers and heart diseases, respectively. When setting quartile 1 of U-Sb levels as reference, the hazard ratios (HRs) [95% confidence intervals (CIs)] of the quartile 2 through 4 for all-cause mortality were 1.21 (0.84, 1.74), 1.49 (1.08, 2.04) and 1.66 (1.20, 2.28). The HR of quartile 3 of U-Sb levels for heart disease mortality was 2.18 (1.24, 3.86). Furthermore, increased odds ratios (ORs) from quartile 2 to 4 were 1.69 (1.05, 2.74), 1.42 (0.79, 2.55) and 2.11 (1.26, 3.55) for self-reported congestive heart failure, and 1.37 (0.95, 1.99), 1.96 (1.37, 2.82) and 1.81 (1.16, 2.83) for heart attack. Elevated U-Sb levels were not significantly related to mortality of malignant neoplasms, and self-reported cancers. The data demonstrated associations of increased U-Sb levels with all-cause and heart diseases mortalities, and prevalent congestive heart failure and heart attack, suggesting public concerns on the health hazards of Sb exposure in the general population.

Urinary antimony and leukocyte telomere length: An analysis of NHANES 1999-2002.

Telomeres are repetitive DNA sequences (TTAGGG) at the end of chromosomes. Cells with critically short telomeres enter replicative senescence and apoptosis. Several in vitro studies report that antimony causes cell apoptosis in human leukocyte cell lines. The goal of this analysis was to investigate whether there is an association between antimony exposure and leukocyte telomere length (LTL) among US adults aged 20 and older based on the National Health and Nutrition Examination Survey (NHANES) 1999-2002. We used multivariate linear regression to analyze the association of urinary antimony with LTL. LTL was log-natural transformed and the results were re-transformed and presented as percent differences. After adjustment for potential confounders, individuals in the 3rd and 4th quartiles of urinary antimony had statistically significantly shorter LTL (-4.78%, 95% CI: -8.42,-0.90; and -6.11%, 95% CI: -11.04,-1.00, respectively) compared to the lowest referent quartile, with evidence of a dose-response relationship (p-value for trend =0.03). Shorter LTL with antimony was driven by middle aged (40-59 years) and older (60-85 years) adult groups. The association may be biologically plausible because of reported oxidative stress and apoptosis effects of antimony on blood cells, effects known to shorten telomere length.

People with diabetes, respiratory, liver or mental disorders, higher urinary antimony, bisphenol A, or pesticides had higher food insecurity: USA NHANES, 2005-2006.

This study was aimed to examine the prevalence of food insecurity and what social, health, and environmental characteristics could constitute such situation in a national and population-based setting. Data was retrieved from the National Health and Nutrition Examination Survey, 2005-2006. Information on demographics, lifestyle factors, self-reported ever medical conditions in the past and self-reported food security conditions in the last 12 months calculated on the household level was obtained by household interview. Bloods and urines (subsample) were collected at the interview as well. Only adults aged 20 years and above (n = 4979) were included for statistical analysis in the present study. Chi-square test, t test, and survey-weighted logistic regression modeling were performed. Three thousand eight hundred thirty-four (77.9%) people were with full food security, 466 (9.5%) people were with marginal food security and 624 (12.7%) people were with low or very low food security. Being younger, having higher ratios of family income to poverty thresholds (due to low level of education or lack of financial support), having prior asthma, arthritis, chronic bronchitis, depression, diabetes, eczema, emphysema or liver problems, having higher levels of serum cotinine, urinary antimony, bisphenol A, pesticides, or having lower levels of urinary Benzophenone-3 were associated with food insecurity. In addition to socioeconomic and smoking conditions, evidence on people with several prior health conditions and being exposed to environmental chemicals and food insecurity is further provided. Future social, health and environmental policy, and programs protecting people from food insecurity by considering both health and environmental factors mentioned above would be suggested.

Metals in Urine and Diabetes in U.S. Adults.

UNLABELLED: Our objective was to evaluate the relationship of urine metals including barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, tungsten, and uranium with diabetes prevalence. Data were from a cross-sectional study of 9,447 participants of the 1999-2010 National Health and Nutrition Examination Survey, a representative sample of the U.S. civilian noninstitutionalized population. Metals were measured in a spot urine sample, and diabetes status was determined based on a previous diagnosis or an A1C ≥6.5% (48 mmol/mol). After multivariable adjustment, the odds ratios of diabetes associated with the highest quartile of metal, compared with the lowest quartile, were 0.86 (95% CI 0.66-1.12) for barium (Ptrend = 0.13), 0.74 (0.51-1.09) for cadmium (Ptrend = 0.35), 1.21 (0.85-1.72) for cobalt (Ptrend = 0.59), 1.31 (0.90-1.91) for cesium (Ptrend = 0.29), 1.76 (1.24-2.50) for molybdenum (Ptrend = 0.01), 0.79 (0.56-1.13) for lead (Ptrend = 0.10), 1.72 (1.27-2.33) for antimony (Ptrend < 0.01), 0.76 (0.51-1.13) for thallium (Ptrend = 0.13), 2.18 (1.51-3.15) for tungsten (Ptrend < 0.01), and 1.46 (1.09-1.96) for uranium (Ptrend = 0.02). Higher quartiles of barium, molybdenum, and antimony were associated with greater HOMA of insulin resistance after adjustment. Molybdenum, antimony, tungsten, and uranium were positively associated with diabetes, even at the relatively low levels seen in the U.S. POPULATION: Prospective studies should further evaluate metals as risk factors for diabetes.

Use of cloud-point preconcentration for spectrophotometric determination of trace amounts of antimony in biological and environmental samples.

This work presents a cloud-point extraction process using the micelle-mediated extraction method for simultaneous preconcentration and determination of Sb(III) and Sb(V) species in biological and environmental samples as a prior preconcentration step to their spectrophotometric determination. The analytical system is based on the selective reaction between Sb(III) and 3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline (DCHNAQ) in the presence of cetyltrimethylammonium bromide (CTAB) and potassium iodide at pH 4.5. Total Sb concentration was determined after reduction of Sb(V) to Sb(III) in the presence of potassium iodide and ascorbic acid. The optimal reaction conditions and extraction were studied, and the analytical characteristics of the method (e.g., limits of detection and quantification, linear range, preconcentration, improvement factors) were obtained. Linearity for Sb(III) was obeyed in the range of 0.2-20 ng ml(-1). The detection and quantification limits for the determination of Sb(III) were 0.055 and 0.185 ng ml(-1), respectively. The method has a lower detection limit and wider linear range, inexpensive instrument, and low cost, and is more sensitive compared with most other methods. The interference effect of some anions and cations was also studied. The method was applied to the determination of Sb(III) in the presence of Sb(V) and total antimony in blood plasma, urine, biological, and water samples.

Relationship of environmental exposures and ankylosing spondylitis and spinal mobility: US NHAENS, 2009-2010.

It was aimed to study the relationships of different sets of urinary environmental chemical concentrations and ankylosing spondylitis in a national and population-based setting. Data were extracted from United States National Health and Nutrition Examination Surveys, 2009-2010. Information on demographics was obtained by household interview and ankylosing spondylitis clinical measures and urines were taken at examination. People with abnormal occiput-to-wall distance were found to have higher urinary cadmium (OR 2.17, 95 % CI 1.34-3.52, p = 0.004), antimony (OR 1.74, 95 % CI 1.15-2.62, p = 0.012), tungsten (OR 1.91, 95 % CI 1.39-2.64, p = 0.001), uranium (OR 1.49, 95 % CI 1.03-2.15, p = 0.036), and trimethylarsine oxide (OR 5.01, 95 % CI 2.34-10.71, p < 0.001) concentrations. Moreover, people who resided in older households tended to have abnormal ankylosing spondylitis clinical measures, compared to those who resided in households that were built in 1990 or after. The odds were 1.74 for households built in 1978-1989 and 1.81 for those built in 1940 or earlier.

Association of drinking-water source and use characteristics with urinary antimony concentrations.

Environmental factors, such as storage time, frequency of bottle reuse and temperature, have been shown to facilitate antimony (Sb) leaching from water- and food-packaging materials. The globally escalating consumption of water packaged in Sb-containing bottles, such as that of polyethylene terephthalate (PET), could increase human daily Sb doses. This study set out to investigate the relationship between drinking-water source, use characteristics, and urinary Sb concentrations (U-Sb) accompanied with survey responses of a healthy (n=35) Cypriot participant pool. One spot urine sample was collected during administration of questionnaire, while a second spot urine sample was collected from the same individual about 7 days later. Urinary and water Sb concentrations were measured with an inductively coupled plasma mass spectrometer. Survey responses showed that bottled water summed over various volumes and plastic types, such as polycarbonate and PET contributed to an average 61% of daily water consumption. Water sources such as tap, mobile stations (explained in a following section), and well water contributed to 24%, 14%, and 2% of an individual's daily water consumption pattern, respectively. Average daily potable water use of both bottled and tap water by individuals consisted of 65% drinking-water, while the remaining 35% was water used for preparing cold and hot beverages, such as, tea, coffee, and juices. A significant (P=0.02) association between per capita water consumption from PET bottles and urinary creatinine-unadjusted concentrations was observed, but this relationship did not remain after inclusion of covariates in a multivariate regression model. In the creatinine-adjusted regression model, only gender (female) was a significant (P<0.01) predictor of U-Sb, after adjusting for several covariates. It is proposed that consumption data collection on various water uses and sources among individuals could perhaps decrease the uncertainty associated with derivations of acceptable daily Sb intakes.

Associations of multiple metals with kidney outcomes in lead workers.

OBJECTIVES: Environmental exposure to multiple metals is common. A number of metals cause nephrotoxicity with acute and/or chronic exposure. However, few epidemiologic studies have examined the impact of metal coexposure on kidney function. Therefore, the authors evaluated associations of antimony and thallium with kidney outcomes and assessed the impact of cadmium exposure on those associations in lead workers. METHODS: Multiple linear regression was used to examine associations between ln-urine thallium, antimony and cadmium levels with serum creatinine- and cystatin-C-based glomerular filtration measures and ln-urine N-acetyl-ß-D-glucosaminidase (NAG). RESULTS: In 684 participants, median urine thallium and antimony were 0.39 and 0.36 µg/g creatinine, respectively. After adjustment for lead dose, urine creatinine and kidney risk factors, higher ln-urine thallium was associated with higher serum creatinine- and cystatin-C-based estimates of glomerular filtration rate; associations remained significant after adjustment for antimony and cadmium (regression coefficient for serum creatinine-based estimates of glomerular filtration rate =5.2 ml/min/1.73 m2; 95% CI =2.4 to 8.0). Antimony associations with kidney outcomes were attenuated by thallium and cadmium adjustment; thallium and antimony associations with NAG were attenuated by cadmium. CONCLUSIONS: Urine thallium levels were significantly associated with both serum creatinine- and cystatin-C-based glomerular filtration measures in a direction opposite that expected with nephrotoxicity. Given similarities to associations recently observed with cadmium, these results suggest that interpretation of urine metal values, at exposure levels currently present in the environment, may be more complex than previously appreciated. These results also support multiple metal analysis approaches to decrease the potential for inaccurate risk conclusions.

In vivo validation of the unified BARGE method to assess the bioaccessibility of arsenic, antimony, cadmium, and lead in soils.

The relative bioavailability of arsenic, antimony, cadmium, and lead for the ingestion pathway was measured in 16 soils contaminated by either smelting or mining activities using a juvenile swine model. The soils contained 18 to 25,000 mg kg(-1) As, 18 to 60,000 mg kg(-1) Sb, 20 to 184 mg kg(-1) Cd, and 1460 to 40,214 mg kg(-1) Pb. The bioavailability in the soils was measured in kidney, liver, bone, and urine relative to soluble salts of the four elements. The variety of soil types, the total concentrations of the elements, and the range of bioavailabilities found were considered to be suitable for calibrating the in vitro Unified BARGE bioaccessibility method. The bioaccessibility test has been developed by the BioAccessibility Research Group of Europe (BARGE) and is known as the Unified BARGE Method (UBM). The study looked at four end points from the in vivo measurements and two compartments in the in vitro study ("stomach" and "stomach and intestine"). Using benchmark criteria for assessing the "fitness for purpose" of the UBM bioaccessibility data to act as an analogue for bioavailability in risk assessment, the study shows that the UBM met criteria on repeatability (median relative standard deviation value <10%) and the regression statistics (slope 0.8 to 1.2 and r-square > 0.6) for As, Cd, and Pb. The data suggest a small bias in the UBM relative bioaccessibility of As and Pb compared to the relative bioavailability measurements of 3% and 5% respectively. Sb did not meet the criteria due to the small range of bioaccessibility values found in the samples.

Potentiometric stripping analysis of antimony based on carbon paste electrode modified with hexathia crown ether and rice husk.

An electrochemical method based on potentiometric stripping analysis (PSA) employing a hexathia 18C6 (HT18C6) and rice husk (RH) modified carbon paste electrode (HT18C6-RH-CPE) has been proposed for the subnanomolar determination of antimony. The characterization of the electrode surface has been carried out by means of scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and chronocoulometry. By employing HT18C6-RH-CPE, a 12-fold enhancement in the PSA signal (dt/dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/dE (sV(-1)) was proportional to the Sb(III) concentration in the range of 1.42×10(-8) to 6.89×10(-11)M (r=0.9944) with the detection limit (S/N=3) of 2.11×10(-11)M. The practical analytical utilities of the modified electrode were demonstrated by the determination of antimony in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as simple preparation method, high sensitivity, very low detection limit and excellent reproducibility. Moreover, the results obtained for antimony analysis in commercial and real samples using HT18C6-RH-CPE and those obtained by inductively coupled plasma-atomic emission spectrometry (ICP-AES) are in agreement at the 95% confidence level.