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.

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.

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.

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.

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

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.

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.

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.

Maternal exposure to low-level heavy metals during pregnancy and birth size

We evaluated the effect of environmental, low-level exposure to heavy metals during pregnancy, as estimated by urine analysis, on birth size of the newborns. Spot urine samples were collected from unexposed 78 pregnant women in Tokyo during 2007 and 2008. The urinary concentrations of beryllium (Be), copper (Cu), arsenic (As), zinc (Zn), selenium (Se), molybdenum (Mo), cadmium (Cd), tin (Sn), antimony (Sb), and lead (Pb) were measured by ICP-MS. The birthweight (BW), length (BL) and head circumference (HC) of the newborns delivered to the subjects were measured and relationship with urinary metal concentration was examined. The geometric mean concentration of urinary Be, Cu, As, Zn, Se, Mo, Cd, Sn, Sb, and Pb were 0.031, 12.8, 393, 76.9, 37.6, 79.0, 0.766, 0.232, < 0.21, 0.483 microg g-creatinine(-1), respectively. The mean birth size of the newborn was close to the national average value in Japan. Stepwise multiple regression analysis using birth size as a dependent variable and urinary metal concentrations and covariates as independent variables extracted urinary Cd with a significant negative standardized partial regression coefficient (beta) for BW along with gestational age and maternal BMI. For HC, Sn was selected with a negative beta. The present study suggested that even a low-level Cd body burden of general population has slight but significant negative effect on BW.

Centers for Disease Control and Prevention (CDC). Pseudo-outbreak of antimony toxicity in firefighters - Florida, 2009

Antimony oxides, in combination with halogens, have been used as flame retardants in textiles since the 1960s. Uniforms made from fabric containing antimony are common among the estimated 1.1 million firefighters in the United States. In October 2008, CDC received a report from the fire chief of a fire department in Florida (fire department A) regarding an outbreak of antimony toxicity among 30 firefighters who had elevated antimony levels detected in hair samples. This report summarizes the ensuing health hazard evaluation conducted by CDC to determine the source of antimony exposure. In February 2009, CDC administered questionnaires to and collected urine samples from two groups of firefighters: 20 firefighters from fire department A who did not wear pants made from antimony-containing fabric, and 42 firefighters from fire department B (also located in Florida) who did. All 20 firefighters from fire department A and 41 (98%) from fire department B had urine antimony concentrations below or within the laboratory reference range. CDC concluded that wearing pants made from antimony-containing fabric was not associated with elevated levels of urinary antimony. Only validated methods (e.g., urine testing) should be used for the determination of antimony toxicity. Accurate and timely risk communication during suspected workplace exposures should underscore the importance of using validated tests, thereby refuting an unproven hypothesis, allaying unsubstantiated concerns, and enhancing public trust.

Effects of fluconazole on the pharmacokinetics and pharmacodynamics of antimony in cutaneous leishmaniasis-infected hamsters

Pentavalent antimony (Sb(V)) compounds are the drugs of choice for the treatment of all forms of leishmaniasis. For 20 years there has been an interest in antifungal azoles for treating leishmaniasis, with variable success. In the current study, we examined the effects of co-administration of fluconazole (FLZ) on the pharmacokinetics and pharmacodynamics of Sb(V) in cutaneous leishmaniasis-infected hamsters. Hamsters were divided into four groups. All hamsters were injected with 0.1 mL of 1x10(8)promastigotes/mL into the right foot on Day 1. Treatment was started 5 days after the infection. The antimony group received 80 mg/kg/day of Pentostam intramuscularly whilst the FLZ group received FLZ 20 mg/kg/day orally for 14 days. The combination group received both Pentostam and FLZ at the above mentioned doses for 14 days. Animals in the control group received no treatment. The infected footpads were measured on Days 1 and 14. A pharmacokinetic study was conducted on Days 1 and 14 of treatment, representing single- and multiple-dose pharmacokinetics, respectively. Blood samples were collected at different time intervals up to 24h. Sb(V) was determined using flameless atomic absorption spectrophotometry. Pharmacokinetic parameters were calculated using a non-compartmental analysis. In the single-dose study, there was no statistically significant difference in any of the pharmacokinetic parameters of Sb(V) when given alone or with FLZ. However, on Day 14 a significant increase in peak plasma concentration (C(max)) (three-fold) and area under the concentration-time curve (AUC) (four-fold) of antimony was observed when Sb(V) was co-administered with FLZ. A statistically significant prolongation of the terminal half-life from 1.63 to 8.67 h (P<0.05) was also observed. A significant reduction in clearance was detected. However, FLZ had no effect on the pharmacodynamics of Sb(V) as measured by footpad sizes. In conclusion, FLZ did not improve the therapeutic effect of Sb(V) when given concomitantly despite the significant increase in blood concentration and prolongation of the elimination half-life of Sb(V).

Lipid peroxidation in workers exposed to aluminium, gallium, indium, arsenic, and antimony in the optoelectronic industry

OBJECTIVE

The objective of this study was to investigate whether exposure to aluminum, gallium, indium, arsenic, and antimony induces lipid peroxidation in humans.

METHODS

Whole blood and urine levels of 103 exposed electronic industry workers and 67 referents were analyzed by use of inductively coupled plasma mass spectrometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography.

RESULTS

The mean plasma MDA level in the 103 workers was significantly higher than that in 67 referents. The levels of MDA in the exposed workers were correlated significantly with the levels of urinary gallium and arsenic.

CONCLUSIONS

Malondialdehyde as an index of lipid peroxidation can be induced by gallium and arsenic exposure. By reducing exposure to these metals, biologic effects such as lipid peroxidation may also be diminished.

Uncertainty of inductively coupled plasma mass spectrometry based measurements: an application to the analysis of urinary barium, cesium, antimony and tungsten

The wide use of barium (Ba), cesium (Cs), antimony (Sb) and tungsten (W) in many industrial and agricultural fields causes the increased release of these metals into the environment, laying the basis for health risk. To assess the exposure for the general population, the development of adequate and reliable analytical techniques becomes compulsory. This study refers to the quantification of urinary Ba, Cs, Sb and W levels by both quadrupole (Q) and sector field (SF) inductively coupled plasma mass spectrometry (ICP-MS). The two procedures were compared for their performances and their measurement uncertainties. The limits of detection were (Q and SF) 23.0 and 5.21 ng L(-1) for Ba; 21.1 and 7.52 ng L(-1) for Cs; 1.09 and 0.43 ng L(-1) for Sb; and 0.36 and 0.49 ng L(-1) for W. The trueness was better than 93.3% and the precision less than 12% for both techniques. Relative expanded uncertainties of the analytical procedures, at the median levels found in the general population, were below 5% for all the elements with both ICP-MS techniques. The uncertainties related to the calibration and repeatability were the parameters most influencing the final analytical performance. The urinary median values observed in healthy subjects from central Italy were 1146, 4301, 60.8 and 48.5 ng L(-1) for Ba, Cs, Sb and W, respectively.

Biological monitoring of exposures to aluminium, gallium, indium, arsenic, and antimony in optoelectronic industry workers

The main objective of this study was to investigate aluminum, gallium, indium, arsenic, and antimony exposures on blood and urine levels in the optoelectronic workers. One hundred seventy subjects were enrolled in this cohort study. Whole blood and urine levels were determined by inductively coupled plasma-mass spectrometry. Blood indium and urine gallium and arsenic levels in the 103 workers were significantly higher than that in 67 controls during the follow-up period. In regression models, the significant risk factors of exposure were job title, preventive equipment, Quetelet's index, sex, and education level. The findings of this study suggest that gallium, indium, and arsenic exposure levels may affect their respective levels in blood and urine. The use of clean, preventive equipment is recommended when prioritizing the administration of safety and hygiene in optoelectronics industries.

Monitoring of total antimony and its species by ICP-MS and on-line ion chromatography in biological samples from patients treated for leishmaniasis

Results from a study are reported in which patients with leishmaniasis were monitored by whole blood, blood plasma, urine, and hair analysis, before, during, and after intramuscular administration of N-methyl meglumine antimoniate. Quadrupole ICP-MS was used for the detection of antimony and on-line ion chromatography for the separation of its species. After typically 30 consecutive daily injections of 5 mg antimony per kg of body weight, Sb concentrations of up to 250 microg L(-1) in whole blood and plasma, and 60 mg of Sb per gram of creatinine in urine, were measured 24 h after drug administration. Antimony in hair samples of these patients showed concentrations of up to 24 microg g(-1). Speciation studies of Sb5+ and Sb3+ in drug, urine, and plasma samples were performed by ion chromatography using a Hamilton PRP-100X anion exchange column and EDTA (2 or 20 mM, pH 4.7) as the mobile phases. Repeatability of elution time and peak area measurements for a 0.125 ng spike were <1.2% and <3.5%, respectively. Method detection limits for both species, using a 1:10 diluted urine or plasma sample, were typically 1.6 microg L(-1). The procedure was capable of separating the very intense drug peak from its inorganic species, thus permitting the first studies on the bio-transformation of N-methyl meglumine antimoniate to Sb5+ and Sb3+ in the human body.

Biomonitoring of a worker population exposed to low antimony trioxide levels

Antimony trioxide (Sb2O3) is used as a flame retardant in the textile industry. We carried out a study in a factory for the evaluation of antimony (Sb) occupational exposure and urinary levels in workers exposed to Sb2O3. Urinary levels and airborne Sb2O3 personal exposure values were very low when compared to international occupational standards (500 microg/m3, as Sb). The range of forty-two personal exposures was 0.01-0.55 microg Sb/m3, while twenty-four area samplings ranged from < 0.01 microg Sb/m3 to 1.45 microg Sb/m3. The mean urinary Sb levels at the beginning (n = 39) and end of the shift (n = 39) were 0.31 +/- 0.25 microg/L and 0.35 +/- 0.29 microg/L respectively, without any significant statistical difference. When the workers were divided into two subgroups according to "higher" and 'lower" exposure levels, a statistical difference (P < 0.001) was observed between the mean Sb urinary levels of the two subgroups during the workweek, both at the beginning and end of the shift. A statistical difference was also observed between the above mentioned subgroups and the controls (n = 15). No correlation was found between personal Sb2O3 exposure and the difference in urinary Sb levels at the beginning and end of the workshift on the day the flame retardant was utilized. This lack of correlation could be due to low airborne Sb2O3 levels and Sb dietary intake, estimated as 3 microg/day in UK, but not yet fully investigated in Italy. Any accidental occupational Sb per os exposure however low, could further enhance the lack of correlation.

Antimony excretion in a patient with renal impairment during meglumine antimoniate therapy

Meglumine antimoniate was administered to a patient with visceral leishmaniasis with normal renal function. Soon after the first intramuscular administration of meglumine antimoniate 20 mg/kg, equivalent to 510 mg antimony (Sb), the patient developed septic shock with oliguria. Creatinine clearance decreased to 23 ml/minute. Treatment was discontinued, and Sb urinary excretion was measured. After the initial dose, 500.25 mg Sb was recovered in urine over 8 days, corresponding to 98% of the amount of Sb given intramuscularly (66% eliminated within first 48 hrs). Nine days after the dose, meglumine antimoniate was reintroduced at a dosage of 11.7 mg/kg (equivalent to 300 mg Sb) every 48 hours with good tolerance. At that time creatinine clearance had returned to 87.8 ml/minute. By day 14 of therapy the interval was reduced to daily administration of the same dose; the dosage was increased to 16.6 mg/kg/day (equivalent to 425 mg Sb) from day 17 to day 31. The patient eventually completely recovered and was discharged with normal renal function. Although no specific guidelines exist for dosage adjustment in renal failure, monitoring of Sb urinary excretion indicates that the kidneys are the almost exclusive route of elimination.

Altered serum cytokine and immunoglobulin levels in the workers exposed to antimony

1 Antimony (Sb), an industrial and environmental toxicant, is known to cause dermatitis and pulmonary inflammations, but the immunomodulatory effects of environmental or occupational exposure to Sb have not been reported. To initiate investigation of Sb-induced alterations of the immune system, the concentrations of the IgG subclasses, IgE, interleukin-2, interferon-gamma, and interleukin-4 in sera obtained from workers exposed to Sb through antimony trioxide manufacture were determined and compared with those of control subjects. 2 The serum levels of IgG1, an immunoglobulin involved in host defense against many microbial infections, were significantly lower in the sera of Sb-exposed individuals than the controls. The serum concentrations of IgE, an immunoglobulin mediating allergic hypersensitivity, also were lower in the Sb-exposed workers than the controls. In addition, the levels of interleukin-2 and interferon-gamma, multifunctional cytokines for T-cell mediated immunity, were lowered in the factory workers. 3 A significant positive correlation between IgG4 and urine Sb levels was found among the Sb-exposed workers, indicating a possible role of IgG4 in Sb-mediated pulmonary or skin pathogenesis. 4 The present study provides the first report on immune alterations induced by occupational exposure to Sb and suggests that Sb exposure disturbs immunohomeostasis in humans observed as a function of aberrant serum cytokine and immunoglobulin levels, which could influence health.

Human biomonitoring of antimony

OBJECTIVES

The aim of the study was to test the suitability of 24-h urine, blood, and scalp-hair samples as surrogates for the determination of internal exposure to antimony in case of a strongly elevated soil contamination with antimony.

METHODS

The bio-monitoring was performed using graphite-furnace atomic absorption spectrometry. Blood and scalp-hair samples were decomposed by microwave digestion.

RESULTS

No elevated content of antimony could be detected in 24-h urine, blood, or scalp-hair samples from the study participants geogenically exposed to antimony. The results did not show a correlation between the antimony contents in the soil of the housing area and those in urine, blood, or hair. Surprisingly, the reference group (n = 47) showed a significantly higher median antimony excretion rate than did the exposed group (n = 89; 1.23 versus 0.60 micrograms Sb/24 h). Additionally, the scalp-hair contents of the reference group were also significantly higher than those of the exposed persons (0.045 versus 0.026 mg Sb/kg). Blood contents of the two study groups were 0.57 and 0.48 microgram Sb/l, respectively. The detection limit for urine and blood was 0.5 microgram Sb/l and that for scalp hair was 0.005 mg Sb/kg. Of all samples of urine, blood, and scalp hair analyzed, 31.2%, 49.3%, and 10.3%, respectively, were below the limit of analytical detection.

CONCLUSIONS

The antimony contents recorded for both study groups in urine, blood, and scalp hair can be judged as being within the normal range. The rate of transfer of antimony from the soil to humans in the exposure case described seemed to be very low. With respect to analytical practicability and validity, urine was the surrogate which deemed most useful for determination of internal exposure to antimony.

Antimony in blood and urine of infants

AIM

To establish a reference range for antimony in the serum and urine of infants in the first year of life.

METHODS

100 infants were selected randomly from the population. Each infant had a single blood and urine sample taken. Antimony was assayed using inductively coupled plasma mass spectrometry.

RESULTS

The reference range for antimony in the serum of infants in the first year of life was established as 0.09-0.25 microgram/l. The upper 95% centile for urinary antimony, corrected for creatinine, in the same population was 2.6 ng/mg creatinine. There was a very weak correlation between the serum and urine concentrations.

CONCLUSIONS

This study confirms the presence of low concentrations of antimony in the serum and urine of healthy infants.

[Influence of exposure to mercury, arsenic and antimony on body burden--a biomonitoring study]

Part of the northern Palatinate region in Germany is characterized by elevated levels of mercury, arsenic and antimony in the soil due to the presence of ore sources and former mercury mining activities. Today, the region is characterized by housing and agriculture. In a biomonitoring study, 218 residents (age 1-89 years) were investigated for a putatively increased absorption of these elements from the environment. 76 non-exposed subjects (age 2-84 years) of a region in south lower Saxony (Germany) were chosen as a reference group. Urine and scalp hair samples were obtained as surrogates to determine the internal exposures to mercury, arsenic and antimony. In the northern Palatinate subjects slightly, yet presumably not hazardous, elevated arsenic contents in urine and scalp hair could be correlated to an increased arsenic content in the soil. On the other hand, the results did not show a correlation between the mercury and antimony contents in the soil of the housing area and those in urine and hair. Urinary mercury contents were correlated with the total amalgam area in both study groups. Mercury contents in scalp hair and arsenic contents in urine were correlated with the consumption of seafood. Surprisingly, the geogenically non-exposed reference subjects showed significantly higher internal exposures to arsenic and antimony in urine and scalp hair. However, data of both groups correspond to normal range reference data described by others.

Human biomonitoring of arsenic and antimony in case of an elevated geogenic exposure

Part of the northern Palatinate region in Germany is characterized by elevated levels of arsenic and antimony in the soil due to the presence of ore sources and former mining activities. In a biomonitoring study, 218 residents were investigated for a putative increased intake of these elements. Seventy-six nonexposed subjects in a rural region in south lower Saxony were chosen as the reference group. Urine and scalp hair samples were obtained as surrogates to determine the internal exposures to arsenic and antimony. The analyses were performed using graphite furnace atomic absorption spectrometry except for arsenic in urine, which was determined by the hydride technique. This method does not detect organoarsenicals from seafood, which are not toxicologically relevant. In the northern Palatinate subjects, slightly elevated arsenic contents in urine and scalp hair (presumably not hazardous) could be correlated with an increased arsenic content in the soil. On the other hand, the results did not show a correlation between the antimony contents in the soil of the housing area and those in urine and hair. Except for antimony in scalp hair, age tended to be associated with internal exposures to arsenic and antimony in both study groups. Consumption of seafood had a slight impact on the level of urinary arsenic, which is indicative of the presence of low quantities of inorganic arsenicals and dimethylarsinic acid in seafood. The arsenic and antimony contents in scalp hair were positively correlated with the 24-hr arsenic excretion in urine. However, antimony in scalp hair was not correlated with seafood consumption as was arsenic in scalp hair and in urine. This indicated the existence of unidentified common pathways of exposure contributing to the alimentary body burden. Short time peaks in the 24-hr excretion of arsenic in urine, which could not be assigned to a high consumption of seafood, were detected for six study participants. This suggests that additional factors relevant in the exposure to arsenic are still unidentified.

Determination of antimony in urine, blood and serum and in liver and lung tissues of infants by inductively coupled plasma mass spectrometry

Methods are presented for the determination by ICP-MS of antimony in body fluids and tissues of infants. Urine, serum and whole blood specimens are prepared for analysis by simply diluting 200 microliters sample volumes (1 + 14) with water and adding indium as internal standard. Liver and lung tissues are digested using 16 M HNO3 either in open quartz vessels at 150 degrees C or in sealed vessels with microwave heating. The acid digests are diluted with water and indium is added as internal standard for ICP-MS measurements. All analyses were subjected to stringent internal quality control protocols. Accuracy was assessed by recoveries, repeated analyses and by analysis of NIST SRMs 1577a Bovine Liver and 1566a Oyster Tissue. Precisions of analyses were better than 5-10% in the ranges 0.1-0.3 microgram l-1 for urine, serum and blood; and at 7-25 ng g-1 in tissues. Detection limits were 0.7 ng g-1 in liver, 0.8 ng g-1 in lung, and 0.01 microgram l-1 in urine, serum and blood. The need to employ validated procedures for specimen collection and to give considerable attention to pre-analytical factors in order to avoid adventitious contamination with antimony is demonstrated.

Urinary antimony in infancy

OBJECTIVE

To determine whether antimony may be detected in the urine during infancy and early childhood and its association with passive exposure to tobacco smoke, as assessed by urinary cotinine.

DESIGN

Analysis of spare aliquots of urine collected from infants participating in studies of respiratory function and passive smoking. Urinary antimony was assayed using inductively coupled plasma mass spectroscopy in 201 urine specimens collected at different ages throughout the first two years of life from 122 term and 26 preterm infants. Urinary cotinine was measured using gas liquid chromatography.

MAIN OUTCOME MEASURE

Urinary antimony concentrations.

RESULTS

Absolute antimony concentrations varied widely between infants, being below the laboratory detection limit of 0.02 microgram/l in 7% of samples, below 0.5 microgram/l in 90.5%, and above the reference value of 1 microgram/l reported for non-occupationally exposed UK populations in 4%. Creatinine standardised antimony values were unrelated to postnatal age or urinary cotinine concentrations and were highest in urine collected from preterm infants within 24 hours of birth (geometric mean (95% confidence interval): 2.3 ng/mg (1.5 to 3.4)).

CONCLUSIONS

Although antimony is present at very low concentrations in urine during infancy and early childhood, the relevance to health is uncertain. The higher levels found in preterm infants may reflect prematurity or fetal assimilation of antimony. Tobacco is unlikely to be an important source of environmental exposure to antimony during infancy and early childhood.

The determination of metals (antimony, bismuth, lead, cadmium, mercury, palladium, platinum, tellurium, thallium, tin and tungsten) in urine samples by inductively coupled plasma-mass spectrometry

OBJECTIVE

An analytical method has been established to determine the concentration of antimony (Sb), bismuth (Bi), lead (Pb), cadmium (Cd), mercury (Hg), Palladium (Pd), platinum (Pt), tellurium (Te), tin (Sn), thallium (Tl) and tungsten (W) in urine. The aim was to develop a method which is equally suitable for the determination of environmentally as well as occupationally caused metal excretion.

METHODS

Inductively coupled plasma-mass spectroscopy (ICP-MS) was used for the determination of metals. Calibration was done using aqueous solutions and standard addition respectively.

RESULTS

Urine samples of 14 persons occupationally non-exposed to metals were analysed. With the exception of Pt and Bi all the metals were found in these urine samples. The detection limits for these metals lie between 5 and 50 ng/l.

CONCLUSIONS

For some metals, which are important from an occupational as well as an environmental viewpoint, ICP-MS is more sensitive than atomic absorption spectrometry (AAS). ICP-MS, moreover, is welcome as a reference method for AAS with the additional advantage of multi-element measurement.

Disposition of antimony after the administration of N-methylglucamine antimoniate to dogs

A study was carried out in dogs to define the pharmacokinetic profile of antimony and to define a better therapeutic protocol for the treatment of canine leishmaniasis. Six healthy beagle dogs received 100 mg/kg of N-methylglucamine antimoniate containing 27.2 per cent of antimony intravenously, intramuscularly and subcutaneously. After intravenous administration the plasma concentration of antimony decreased rapidly and after 240 minutes it was lower than the ED50 values suggested for Leishmania donovani. The pharmacokinetic parameters and bioavailability of antimony were calculated after each route of administration in each dog. The curves of plasma concentrations vs time were best described by a triexponential open model with a mean (sd) half life t1/2 alpha of 9.4 (4.4) min, a t1/2 beta of 45.3 (4.5) min and a t1/2 gamma of 618.0 (93.5) min. The mean volume of distribution at steady state was 0.25 (0.03) litres/kg and the total body clearance was 0.25 (0.04) litres/h/kg. The peak plasma concentration (Cmax) after intramuscular administration was 27.2 (3.1) micrograms/ml, and after subcutaneous administration it was 25.5 (4.5) micrograms/ml; they were reached after 73.6 (11.9) min and 85.6 (11.3) min, respectively. The bioavailabilities after intramuscular and subcutaneous administration were 91.7 (7.1) and 92.2 (7.1) per cent, respectively. More than 80 per cent of the antimony was excreted in the urine in the first nine hours.

External and internal antimony exposure in starter battery production

In the production of lead batteries two antimony compounds occur: in the casting of grids antimony trioxide (Sb2O3), and in the formation of lead plates stibine (SbH3). Seven workers from the grid-casting area and 14 workers from the formation area were examined with regard to the antimony concentration in blood (Sb-B) and urine (Sb-U). Antimony air concentrations (Sb-A) were measured by means of personal air samplers. Urine samples were collected at the end of the working week, at the beginning (U1) and the end (U2) of the shift, and at the beginning of work following a weekend without Sb exposure (U3). At U2 among the casters, the median Sb-A exposure was 4.5 (1.18-6.6) micrograms Sb/m3 and among the formation workers, 12.4 (0.6-41.5) micrograms Sb/m3. The exposure in both groups is more than 10 times lower than the present threshold limit values. The median Sb-B concentrations in the preshift samples was 2.6 (0.5-3.4) micrograms Sb/l for the casters and 10.1 (0.5-17.9) micrograms Sb/l for the formation workers. The average Sb-U values (U2) were 3.9 (2.8-5.6) micrograms Sb/g creatinine in the casting area and 15.2 (3.5-23.4) micrograms Sb/g creatinine in the forming area. Our investigation indicates that the two antimony compounds show virtually equal pulmonary absorption and renal elimination. The statistically significant correlations between Sb-A/Sb-B and Sb-A/Sb-U form the basis for proposals regarding appropriate biological exposure limits for occupational antimony exposure.

Pharmacokinetics of N-methylglucamine antimoniate after intravenous, intramuscular and subcutaneous administration in the dog

The pharmacokinetic profile of antimony in dogs was defined by administering it intravenously, intramuscularly and subcutaneously as N-methylglucamine antimoniate at a dose of about 25.65 mg of antimony kg-1 bodyweight. The results showed a different half-life for the three routes of administration: 20.5, 42.1 and 121.6 minutes for the intravenous, intramuscular and subcutaneous routes, respectively; peak time values (Tmax) were also different for the intramuscular (90 to 120 minutes) and subcutaneous (210 to 240 minutes) injection. The apparent bioavailability of antimony was > 100 per cent for the intramuscular and 100 per cent for the subcutaneous routes. The data obtained showed a relevant difference in the behaviour of the drug in the dog in comparison to that in humans.

Blood and urinary levels of metals (Pb, Cr, Cd, Mn, Sb, Co and Cu) in cloisonne workers

Blood and urine samples from cloisonne ware workers were assayed for Pb, Cr, Cd, Mn, Sb, Co and Cu for biological monitoring. Mean blood Pb levels were 47.8 +/- 27.3 micrograms/dl (111-13.3 micrograms/dl) for 49 cloisonne glaze workers, and 0.97 +/- 0.47 microgram/dl (2.4-0.6 microgram/dl) for 62 normal subjects. There was a distinct difference between the 2 groups, and slight differences (p < 0.01) in mean Cr, Cd and Mn levels. There was a distinct difference in mean urinary Pb level between the 2 groups, and slight differences (p < 0.01) in mean Cr, Cd and Mn levels. The correlation coefficient, r, between blood Pb and Cd levels was 0.631 (p < 0.01) for 132 subjects consisting of cloisonne ware workers and normal subjects. r between blood Pb and blood Cr levels was 0.501 (p < 0.01), and that between blood and urinary Pb levels, 0.794 (p < 0.01). The above assays showed that glaze workers at cloisonne plants suffer severe exposure to lead and slight exposure to Cd and Cr.

The distribution of free and non-ionic vesicular sodium stibogluconate in the dog

The pharmacokinetics and tissue distribution of antimony after the administration of sodium stibogluconate in a free form or entrapped in vesicles prepared from non-ionic surfactant were studied in the dog. Animals were given either one or two intravenous bolus injection(s) equivalent to 45 mg Sb kg-1 as free drug or 0.625 or 0.685 mg Sb kg-1 as vesicular drug. Blood samples were taken at various times after dosing and antimony levels in various tissues were determined at 3 h, 48 h and 6 days after dosing. After free stibogluconate antimony clearance from the blood occurred in a rapid elimination phase with a blood half-life of 0.58 +/- 0.08 h. This rapid elimination phase did not occur after vesicular drug. Both drug preparations gave similar antimony levels in the spleen, liver and femur and humerus bone marrow at all time points assessed even though the vesicular dose was one-seventieth of the free drug dose. After the free drug there was marked urinary excretion of antimony and, as a result, increased kidney loading at the expense of other tissue. Vesicle-mediated drug delivery suppressed renal excretion and a much greater proportion of the antimony dose was recovered from tissue than was obtained after free drug. A hypothesis is presented to account for the differences in tissue antimony concentrations produced by the two formulations.

Simultaneous determination of arsenic and antimony species in environmental samples using bis(trifluoroethyl)dithiocarbamate chelation and supercritical fluid chromatography

Simultaneous separation and quantitation of arsenic(III) and antimony(III) can be achieved by extraction with lithium bis(trifluoroethyl)dithiocarbamate followed by supercritical fluid chromatographic (SFC) analysis. Arsenic(V) and antimony(V) are extracted after reduction with potassium iodide and sodium thiosulfate. Detection limits of 7 pg As and 11 pg Sb are achieved using this extraction method and SFC. Application to natural water and biological sample analysis is discussed.

Experimental and human studies on antimony metabolism: their relevance for the biological monitoring of workers exposed to inorganic antimony

Unlike inorganic arsenic, inorganic trivalent antimony (Sb) is not methylated in vivo. It is excreted in the bile after conjugation with glutathione and also in urine. A significant proportion of that excreted in bile undergoes an enterohepatic circulation. In workers exposed to pentavalent Sb, the urinary Sb excretion is related to the intensity of exposure. It has been estimated that after eight hours exposure to 500 micrograms Sb/m3, the increase of urinary Sb concentration at the end of the shift amounts on average to 35 micrograms/g creatinine.

Biological assessment of exposure to antimony and lead in the glass-producing industry

The oxide of trivalent antimony is used in the glass-producing industry as a refining agent and as a glass colouring. The batch contains up to 2% Sb2O3, a substance which has shown carcinogenic properties in animal experiments. The internal levels of antimony and lead in blood (SbB and PbB) as well as the excretion with the urine (SbU and PbU) were determined by hydrid and electrothermal atomic absorption (HY-AAS and ET-AAS), respectively. In addition, measurements of airborne Sb2O3-concentrations were performed. The 109 volunteers were employed in four different fields: melting area, batch bunker, glass-washing area, and transport/maintenance. Differences between the concentrations of antimony and lead in blood and urine with respect to the fields of activity were evaluated statistically. The highest values of airborne Sb2O3, with up to 840 micrograms/m3 (TWA), were detected in the batch bunker. Correspondingly, significantly enhanced SbU-values from 1.5 to 15.7 micrograms/l (median: 5.0 micrograms/l) were found in specimens collected from the batch mixers. In the same group, the lead excretion (PbU) with values from 9 to 110 micrograms/l (median: 43 micrograms/l) was also found to be the highest. Due to the fast renal excretion of antimony, the determination of SbU is useful for biological monitoring.

Pharmacokinetic and toxicological studies of antimony dextran glycoside (RL-712)

1. The absorption, tissue distribution and excretion of antimony dextran glycoside (RL-712) has been studied in normal rodents.2. Some organs in the body, especially liver and spleen, retain large amounts of antimony for considerable periods of time. Excretion of antimony in the urine was low and only about 10-12% of the dose administered was excreted within the first 48 hours.3. Blood levels were maintained for at least 3 days after a single intramuscular dose to rabbits, corresponding to 14 mg Sb/kg body weight.4. Toxicity studies and tests on foetal toxicity in mice and rats, respectively, showed no abnormalities.5. The possible value of RL-712 in the prophylaxis and treatment of leishmaniasis is discussed.

Acute intoxication from antimony trichloride

Seven men were accidentally exposed to the fume of antimony trichloride. Their symptoms included not only the well-recognized upper respiratory irritation from hydrochloric acid but, in five of the men, an additional, slightly delayed onset of gastro-intestinal disturbance including abdominal pain and persistent anorexia. Urine antimony estimations revealed a concentration in excess of 1 mg./litre in these five men. Environmental measurements suggest that they were briefly exposed to air containing up to 146 mg. hydrochloric acid and 73 mg. antimony per m.³ expressed as the metal. These findings are compared with other reports on chronic antimony intoxication. No report could be found in recent literature about acute intoxication from antimony trichloride.