Evaluation of Arsenic and Cobalt Levels in Pediatric Patients Receiving Long-Term Parenteral Nutrition.

This study continues the research in which we determined the concentration of aluminum in children receiving long-term parenteral nutrition (LPN). Since our results were interesting, we decided to assay arsenic (As) and cobalt (Co) in the collected material, which, like aluminum, constitute contamination in the mixtures used in parenteral nutrition. Excesses of these trace elements in the human body are highly toxic, and deficiencies, particularly in the case of Co, can lead to various complications. The aim of this study was to determine the impact of LPN in children on their serum levels of As and Co, as well as the excretion of these elements in urine, and to compare them with a control group of healthy children. The study group consisted of 83 children receiving home parenteral nutrition from two Polish centers, while the control group included 121 healthy children. In both groups, the levels of As and Co in serum and urine were measured. The elemental compositions of the samples were determined using inductively coupled plasma mass spectrometry (ICP-MS). It was demonstrated that the children receiving LPN did not have increased As exposure compared to the controls. Greater exposure compared to the control group was shown for Co. In conclusion, children receiving LPN are not exposed to As, and even though the concentrations of Co in serum and urine were higher in the LPN group than in the healthy controls, neither trace element poses a health threat to children requiring LPN.

Coordination chemistry applied to anti-doping analysis: Cobalt quantification as its diethyldithiocarbamate complex by liquid chromatography coupled to high resolution tandem mass spectrometry.

Cobalt was included on the World Anti-Doping Agency Prohibited List in 2015 due to its effect on stimulus of erythropoiesis via stabilization of hypoxia-inducible factor. Although it has proven benefits for performance enhancement, the unavailability of inductively coupled plasma-mass spectrometry on routine of the accredited laboratories is a factor that reduces its applicability in anti-doping analysis. Therefore, an analytical method for quantification of urinary cobalt as its diethyldithiocarbamate complex by liquid chromatography coupled with high-resolution tandem mass spectrometry was developed and validated. Palladium was proposed as internal standard and rhodium as a complexation control. A microwave-assisted acid digestion of the urine samples was essential, not only to eliminate the matrix effect but mainly to avoid the non-specific bond of cobalt to endogenous molecules. A linear method was obtained over the studied range from a negative urine control to a spiked concentration of 25 ng/mL, with an estimated limit of quantification of 2.5 ng/mL, and an adequate combined standard uncertainty of 11.4%. Considering that all reagents are commercially available, the proposed strategy is feasible to be included on routine sample preparation. Monitoring urinary cobalt concentrations globally opens the perspective to support the anti-doping system to define a suitable threshold value and to understand its potential misuse by athletes seeking for performance improvement.

The association between the essential metal mixture and fasting plasma glucose in Chinese community-dwelling elderly people.

BACKGROUND: Epidemiological studies about the effect of essential metal mixture on fasting plasma glucose (FPG) levels among elderly people are sparse. The object of this study was to examine the associations of single essential metals and essential metal mixture with FPG levels in Chinese community-dwelling elderly people. METHODS: The study recruited 2348 community-dwelling elderly people in total. Inductively coupled plasma-mass spectrometry was adopted to detect the levels of vanadium (V), selenium (Se), magnesium (Mg), cobalt (Co), calcium (Ca), and molybdenum (Mo) in urine. The relationships between single essential metals and essential metal mixture and FPG levels were evaluated by linear regression and Bayesian kernel machine regression (BKMR) models, respectively. RESULTS: In multiple-metal linear regression models, urine V and Mg were negatively related to the FPG levels (ß = - 0.016, 95 % CI: - 0.030 to - 0.003 for V; ß = - 0.021, 95 % CI: - 0.033 to - 0.009 for Mg), and urine Se was positively related to the FPG levels (ß = 0.024, 95 % CI: 0.014-0.034). In BKMR model, the significant relationships of Se and Mg with the FPG levels were also found. The essential metal mixture was negatively associated with FPG levels in a dose-response pattern, and Mg had the maximum posterior inclusion probability (PIP) value (PIP = 1.0000), followed by Se (PIP = 0.9968). Besides, Co showed a significant association with decreased FPG levels in older adults without hyperlipemia and in women. CONCLUSIONS: Both Mg and Se were associated with FPG levels, individually and as a mixture. The essential metal mixture displayed a linear dose-response relationship with reduced FPG levels, with Mg having the largest contribution to FPG levels, followed by Se. Further prospective investigations are necessary to validate these exploratory findings.

Development of an interpretable machine learning model associated with heavy metals' exposure to identify coronary heart disease among US adults via SHAP: Findings of the US NHANES from 2003 to 2018.

Limited information is available on the links between heavy metals' exposure and coronary heart disease (CHD). We aim to establish an efficient and explainable machine learning (ML) model that associates heavy metals' exposure with CHD identification. Our datasets for investigating the associations between heavy metals and CHD were sourced from the US National Health and Nutrition Examination Survey (US NHANES, 2003-2018). Five ML models were established to identify CHD by heavy metals' exposure. Further, 11 discrimination characteristics were used to test the strength of the models. The optimally performing model was selected for identification. Finally, the SHapley Additive exPlanations (SHAP) tool was used for interpreting the features to visualize the selected model's decision-making capacity. In total, 12,554 participants were eligible for this study. The best performing random forest classifier (RF) based on 13 heavy metals to identify CHD was chosen (AUC: 0.827; 95%CI: 0.777-0.877; accuracy: 95.9%). SHAP values indicated that cesium (1.62), thallium (1.17), antimony (1.63), dimethylarsonic acid (0.91), barium (0.76), arsenous acid (0.79), total arsenic (0.01) in urine, and lead (3.58) and cadmium (4.66) in blood positively contributed to the model, while cobalt (-0.15), cadmium (-2.93), and uranium (-0.13) in urine negatively contributed to the model. The RF model was efficient, accurate, and robust in identifying an association between heavy metals' exposure and CHD among US NHANES 2003-2018 participants. Cesium, thallium, antimony, dimethylarsonic acid, barium, arsenous acid, and total arsenic in urine, and lead and cadmium in blood show positive relationships with CHD, while cobalt, cadmium, and uranium in urine show negative relationships with CHD.

Association between urine cobalt and prevalence of kidney stones in Americans aged ≥ 20 years old.

To determine whether urine cobalt (Co) is associated with the prevalence of kidney stones, we conducted a cross-sectional study of participants (≥ 20 years) involved in the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018. The urine Co level was divided into four groups: 0.02-0.22, 0.22-0.36, 0.36-0.58, and 0.58-37.40 µg/L. The independent correlation between urine Co and prevalence of kidney stones was determined by logistic regression analyses. A total of 10,744 participants aged over 20 years that were not pregnant were eligible. Among them, 1041 participants reported ever having developed kidney stones. Patients with kidney stones developed significantly higher urine Co than the non-stone participants. The kidney stone patients were more likely to have been smoking ≥ 100 cigarettes in life; have hypertension, diabetes, and cancer; and engage in heavy activity. Multivariate logistic regression indicated a significantly positive relationship between the urine Co level and occurrence of kidney stones (OR 1.059, 95% CI 1.018-1.102, P = 0.00430). Moreover, the outcome remained unchanged after some sophisticated factors were adjusted (OR 1.059, 95% CI 1.001-1.120, P = 0.04635), and kidney stones were significantly related to a higher level of Co (OR (95% CI) = 0.22-0.36 µg/L: 1.111 (0.869, 1.421); 0.36-0.58 µg/L: 1.392 (1.095, 1.770); 0.58-37.40 µg/L: 1.712 (1.351, 2.170), and P for trend < 0.00001). So, urine Co concentration is positively associated with the prevalence of kidney stones. However, more high-quality prospective studies are needed to elucidate the causal correlation between Co level and kidney stones.

Measurement of urinary cobalt as its complex with 2-(5-chloro-2-pyridylazo)-5-diethylaminophenol by liquid chromatography-tandem mass spectrometry for the purpose of anti-doping control.

Cobalt is well known for its ability to stimulate erythropoiesis via stabilization of hypoxia-inducible factors. In sports, this can provide a competitive benefit to athletes, so the World Anti-Doping Agency prohibits the use of cobalt in any form except its cobalamin vitamers. As of now, cobalt in biological fluids is detected by inductively coupled plasma mass spectrometry (ICP-MS), a technique which has very limited availability in anti-doping laboratories. Therefore, a quantitative method based on liquid chromatography-tandem mass spectrometry capable of measuring urinary cobalt in the form of its complex with 2-(5-chloro-2-pyridylazo)-5-diethylaminophenol (5-Cl-PADAP) has been developed and validated. A cobalt complex with deuterium-labeled 5-Cl-PADAP was used as internal standard. The method was found linear over the concentration range of 5-500 ng/ml with a combined standard uncertainty less than 10% at 15, 200, and 450 ng/ml. Stability of cobalt ions in urine was investigated over the course of 2 months; the concentration of free Co2+ was observed to decline by approximately 50% but restored upon hydrolysis with hydrochloric acid. Unlike ICP-MS, this method is practically unaffected by the presence of cyanocobalamin as the latter is resistant to acid hydrolysis. Notwithstanding the lack of formalized threshold concentration of cobalt in urine, it is highly desirable that more anti-doping laboratories engage in testing for cobalt levels to better understand the prevalence of cobalt misuse in athletes. Given that cobalt salts are inexpensive and easily obtainable, the risk of such abuse should not be underestimated.

Dermal and inhalable cobalt exposure-Uptake of cobalt for workers at Swedish hard metal plants.

PURPOSE: Cobalt exposure is known to cause adverse effects on health. A major use of cobalt is in the manufacture of hard metal. Exposure can lead to asthma, hard metal lung disease, contact allergy and increased risk of cancer. Cobalt is mainly absorbed from the pulmonary tract, however penetration through skin may occur. The relationships between exposure to inhalable cobalt in air and on skin and the uptake in blood and urine will be investigated, as well as the association between dermal symptoms and dermal exposure. METHODS: Cobalt exposure in 71 workers in hard metal production facilities was measured as inhalable cobalt in the breathing zone and cobalt found on skin with acid wash. Uptake of cobalt was determined with concentrations in blood and urine. Correlations between exposure and uptake were analysed. RESULTS: Inhalable cobalt in air and cobalt in blood and urine showed rank correlations with coefficients 0.40 and 0.25. Cobalt on skin and uptake in blood and urine presented correlation coefficients of 0.36 and 0.17. Multiple linear regression of cobalt in air and on skin with cobalt in blood showed regression coefficients with cobalt in blood (ß = 203 p < 0.0010, and ß = 0.010, p = 0.0040) and with cobalt in urine (ß = 5779, p = 0.0010, and ß = 0.10, p = 0.60). CONCLUSIONS: Our data presents statistically significant correlations between exposure to cobalt in air with uptake of cobalt in blood and urine. Cobalt on skin was statistically significant with cobalt in blood but not with urine.

Occupational low-level exposure to hard metals: cobalt and tungsten biomonitoring as an effective tool to evaluate the effectiveness of industrial hygiene interventions for risk management.

Purpose: The aim of the study was to assess the exposure to Cobalt (Co) and Tungsten (W) in a group of hard metal tool sharpeners through a combined approach of air and biological monitoring, and to evaluate the effectiveness of a control and improvement intervention carried out in collaboration with the medical officers of the local Health Protection Agency, by biomonitoring.Methods: We enrolled 132 workers from 17 companies of the province of Brescia, northern Italy. The study was performed in two phases: (1) an environmental and biomonitoring survey to assess the workers' exposure to Co and W at their usual working conditions; (2) a further biomonitoring survey 3 months after the enforcement of a control and improvement intervention, to assess its effectiveness.Results: Workers were found to be exposed to low concentration of airborne dust containing Co and W but after the intervention we recorded a significant decrease of the urinary concentrations of both Co and W. The extent of the decrease was correlated to the number of preventive industrial hygiene interventions that were carried out.Conclusions: Biological monitoring of Co and W in the hard metal tools manufacturing industry is a sensitive and effective method to evaluate the effectiveness of prevention practices.

Urinary cobalt and ferritin in four-years-old children.

Cobalt (Co) is an essential trace element but may cause toxic effects upon occupational or environmental exposure. The present study is aimed to determine the urine concentrations of Co in four years-old children in the INMA-Asturias cohort (Spain) and to assess the factors determining the observed levels. This cohort is located in a heavily industrialized zone with strong potential for metal exposure. Some diet components such as consumption of sweets were meaningfully associated with higher urine Co concentrations. Traffic pollution also showed a noteworthy positive association with Co levels. Family tobacco consumption did not show substantial association with the urine concentrations of this metal in the INMA-Asturias children. A significant inverse association between urine Co and venous blood ferritin was found. Iron deficiency anemic children had significantly higher concentrations of Co than those with normal levels, e.g. median values 1.9 µg/g creatinine and 1.0 µg/g creatinine, respectively. This association could be explained by an increased expression of DMT1, a divalent metal transporter that captures higher levels of iron in deficiency states of this metal. This transporter is non-specific and not only captures iron but also other divalent metals such as Co. The presence of this metal in iron deficiency anemic children may represent an additional disturbing health factor that must be considered during treatment.

Cobalt accumulation in horses following repeated administration of cobalt chloride.

OBJECTIVE: To monitor cobalt concentrations in urine, red blood cells and plasma after chronic parenteral administration of cobalt chloride evaluate these results against the current International Federation of Horseracing Authorities thresholds for detecting cobalt misuse. DESIGN: Eight mares were randomly assigned to four treatment groups, with two mares in each group: Group 1 - control group, Group 2 - 25 milligrams cobalt intravenously as CoCl2 weekly, Group 3 - 50 milligrams cobalt intravenously as CoCl2 weekly, and Group 4 - 25 milligrams cobalt intravenously mid-week and at the end of the week. Urine and blood samples were collected before each weekly administration so that trough levels were assessed. In the group receiving two doses per week, urine and blood were collected prior to the dose given at the end of each week. Samples were initially collected at time zero then weekly for 10 weeks. Three further collections of urine and blood were made at days 81, 106 and 127. METHODS: Urine creatinine measurements to assess horse hydration status were performed by the Jaffe reaction method. Cobalt determinations in plasma, blood and urine were by inductively coupled plasma-mass spectrometry. Haematocrit concentrations, used to calculate red cell cobalt levels, were performed using a microhematocrit centrifuge. Statistical analyses were conducted in Genstat (v17, VSNi). RESULTS: Marked cobalt accumulation was evident with increasing cobalt concentrations for all sample matrices in specimens collected immediately prior to cobalt administration. Correlation between the sample matrices improved when urine cobalt concentration was adjusted for creatinine level. Red cell cobalt levels remained elevated for at least 12 weeks after cessation of administration, consistent with the lifespan of the red cell. There was no significant change in haematocrit concentrations for the duration of the study. CONCLUSION: The current urine cobalt threshold was only effective at detecting acute cobalt exposure while the plasma cobalt threshold was able to consistently identify chronic high-level cobalt exposure and potential cobalt misuse. The threshold values legislated for urine cobalt do not correlate with those set for plasma. The acute nature of urinary cobalt excretion provides a relatively small window through which cobalt administration is detected. Plasma and red cell cobalt concentrations can provide a clearer picture of potential cobalt misuse.

A monolithic copolymer prepared from N-(4-vinyl)-benzyl iminodiacetic acid, divinylbenzene and N,N'-methylene bisacrylamide for preconcentration of cadmium(II) and cobalt(II) from biological samples prior to their determination by ICP-MS.

A capillary monolith consisting of poly[N-(4-vinyl)-benzyl iminodiacetic acid-co-divinylbenzene-co-N,N'-methylene bisacrylamide), referred to as poly(VBIDA-DVB-Bis), has been prepared. It is shown to be an efficient sorbent for the enrichment of Co(II) and Cd(II). The two ions are completely retained by the monolith in the pH range from 4.0 to 9.0. The breakthrough curve tests were adopted to evaluate the adsorption performance of the monolith towards Co(II) and Cd(II). A dose-response model was used to describe the breakthrough curves of the two ions at different initial concentrations. The adsorption capacities for Co(II) and Cd(II) are 1.54 and 1.73 mg·m-1 at a concentration level of 2.5 mg·L-1, respectively. The enrichment factor is 100, and the required sample volume is 5 mL. Following elution of the two ions with 0.5 M HNO3, they were quantified by ICP-MS. The limits of detection in a 1 mL sample are 0.35 ng·L-1 for Co(II) and 0.44 ng·L-1 for Cd(II). The method was applied to the determination of Co(II) and Cd(II) in spiked rice, human urine and seawater samples. Graphical abstract Schematic representation of a monolithic copolymer prepared from N-(4-vinyl)-benzyl iminodiacetic acid (VBIDA), divinylbenzene (DVB) and N,N'-methylene bisacrylamide (Bis) and its application for selective capturing of cadmium(II) and cobalt(II) from complex sample matrices prior to their determination by ICP-MS.

Urinary metal/metalloid levels in relation to hypertension among occupationally exposed workers.

Occupational exposure to metals can have an adverse effect on the cardiovascular system. However, epidemiological studies of the associations of metals expose with hypertension among occupationally exposed workers were limited. The aim of this study was to investigate the potential association between urinary metal levels and the risk of hypertension among molybdenum miners and iron and steel foundry workers. The cross-sectional study had 395 participants. Urinary metal levels were determined by inductively coupled plasma mass spectrometry. Log-binomial regression model and two-piece-wise regression model were applied to assess the dose-response relationship between metal exposure and hypertension. We observed that increased prevalence ratios for hypertension among the quartile of urinary concentrations of molybdenum, arsenic and lead were positive (all P for trend <0.05). Compared with the lowest quartiles, participants in the highest quartiles of molybdenum, arsenic and lead had a 2.58-fold, 4.30-fold and 4.85-fold increased probability of having hypertension, respectively. In the threshold effect analyses, we found the relationship was nonlinear between urinary molybdenum, cobalt, cadmium, arsenic and lead concentrations and the prevalence of hypertension. In addition, Pb, Mo, As and Co may have joint effect, and a strong positive correlation with the prevalence of hypertension. Conversely, the association between the joint effect of Cd, Pb and Mo versus the prevalence of hypertension is not significant. We provide reference levels of molybdenum, cobalt, cadmium, arsenic and lead that can be used to assess the effects of occupational metal exposure on hypertension.

Levels and temporal variations of urinary lead, cadmium, cobalt, and copper exposure in the general population of Taiwan.

Toxic metal contamination in food products and the environment is a public health concern. Therefore, understanding human exposure to cadmium (Cd), lead (Pb), cobalt (Co), and copper (Cu) levels in the general population of Taiwan is necessary and urgent. We aimed to establish the human biomonitoring data of urine toxic metals, exposure profile changes, and factors associated with metal levels in the general population of Taiwan. We randomly selected 1601 participants older than 7 years of age (36.9 ± 18.7 years (7-84 years)) from the Nutrition and Health Survey in Taiwan (NAHSIT) conducted during 1993-1996 (93-96) and 2005-2008 (05-08) periods and measured the levels of four metals in the participants' urine samples using inductively coupled plasma-mass spectrometry. The median (range) levels of urinary Cd, Pb, Co, and Cu in participants from the NAHSIT 93-96 (N = 821)/05-08 (N = 780) were 0.60 (ND-13.90)/0.72 (ND-7.44), 2.28 (ND-63.60)/1.09 (0.04-48.88), 0.91 (0.08-17.30)/1.05 (0.05-22.43), and 16.87 (2.62-158.28)/13.66 (1.67-189.70) µg/L, respectively. We found that the urinary median levels of Pb and Cu in our participants were significantly lower in the NAHSIT 05-08 (Pb 1.09 µg/L, Cu 13.66 µg/L) than in the NAHSIT 93-96 (Pb 2.28 µg/L, Cu 16.87 µg/L; P < 0.01), whereas those of Cd and Co were significantly higher in the NAHSIT 05-08 (Cd 0.72 µg/L, Co 1.05 µg/L; P < 0.01). Youths had higher exposure levels of Pb, Co, and Cu than adults. Participants with alcohol consumption, betel quid chewing, or cigarette smoking had significantly higher median levels of urinary Pb or Cu (P < 0.01) than those without. Principal components and cluster analysis revealed that sex had different exposure profiles of metals. We concluded that levels of urinary Cd, Pb, Co, and Cu exposure in the general Taiwanese varied by age, sex, and lifestyles.

Effect of an Acute Exercise Until Exhaustion on the Serum and Urinary Concentrations of Cobalt, Copper, and Manganese Among Well-Trained Athletes.

The current information about the effect of physical exercise on the body concentrations of several minerals is still limited, both in the acute (short-term) and adaptive (long-term) responses. So, this manuscript aims, on the one hand, to assess the possible differences on basal levels of cobalt (Co), copper (Cu), and manganese (Mn) concentrations in serum and urine between athletes and sedentary participants and, on the other hand, to evaluate the effect of an acute progressive physical exercise until voluntary exhaustion on the serum and urinary concentrations of Co, Cu, and Mn. Two groups participated in this survey, one was formed by untrained, sedentary males (CG; n = 26), and the other group was constituted by national endurance (long and middle distances) athletes (AG; n = 21). All participants were from the same region of Spain. Participants of both groups performed a physical test on a treadmill, reaching voluntary exhaustion. Blood and urine samples of each participant were collected before and at after the tests. Once obtained and processed, the concentrations of Co, Cu, and Mn elements were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The differences in the studied variables were evaluated using a mixed model by means of an ANOVA and Bonferroni post hoc tests. In the comparison of the pre-test values between groups, the results showed that serum concentrations of Mn were significantly lower in CG than in AG (p < 0.01). In urine, Co and Mn levels were significantly higher among CG participants (p < 0.01) than among AG ones, while in the case of Cu, the values were lower (p < 0.01) in the CG than in the AG. Regarding the effects of the effort tests, no significant changes were found among the participants of the CG. It was observed that the serum concentrations of Co (p < 0.05) and Cu (p < 0.01) decreased after the test among the AG participants. Also, the results showed that there were no statistical differences in Co and Mn values (expressed in µg/g creatinine). However, the urinary post-test Cu concentrations were lower (p < 0.05) among AG participants. In basal conditions, serum concentrations of Mn were significantly lower in CG than in AG. In urine, Co and Mn levels were significantly higher among CG participants and Cu level was significantly lower in CG, a fact which may reflect adaptive responses to exercise. An incremental exercise to exhaustion in AG produces a decrease in Co and Cu serum concentrations, as well as in urinary excretion of Cu.

Erythropoietic effects of low-dose cobalt application.

Cobaltous ions (Co2+ ) stabilize HIFα, increase endogenous erythropoietin (EPO) production, and may, therefore, be used as a performance-enhancing substance. To date, the dosage necessary to stimulate erythropoiesis is unknown. The aim of this study was, therefore, to determine the minimum dosage necessary to increase erythropoietic processes. In a first double-blind placebo-controlled study (n = 5), single oral Co2+ dosages of 5 mg (n = 6) and 10 mg (n = 7) were administered to healthy young men. Cubital venous blood and urine samples were collected before and up to 24 hours after Co2+ administration. In a second study, the same daily Co2+ dosages were administered for five days (placebo: n = 5, 5 mg: n = 9, 10 mg: n = 7). Blood and urine samples were taken the day before administration and at day 3 and day 5. Plasma [EPO] was elevated by 20.5 ± 16.9% at 5 hours after the single 5-mg administration (p < 0.05) and by 52.8 ± 23.5% up to 7 hours following the 10-mg Co2+ administration (p < 0.001). Urine [Co2+ ] transiently increased, with maximum values 3-5 hours after Co2+ ingestion (5 mg: from 0.8 ± 1.1 to 153.6 ± 109.4 ng/mL, 10 mg: from 1.3 ± 1.7 to 338.0 ± 231,5 ng/mL). During the five days of Co2+ application, 5 mg showed a strong tendency to increase [EPO], while the 10-mg application significantly increased [EPO] at day 5 by 27.2 ± 26.4% (p < 0.05) and the immature reticulocyte fraction by 49.9 ± 21.7% (p < 0.01). [Ferritin] was decreased by 12.4 ± 10.4 ng/mL (p < 0.05). An oral Co2+ dosage of 10 mg/day exerts clear erythropoietic effects, and 5 mg/day tended to increase plasma EPO concentration.

Neglected exposure route: cobalt on skin and its associations with urinary cobalt levels.

OBJECTIVES: Cobalt (Co) exposure is associated with adverse health effects including skin sensitisation, asthma and interstitial lung fibrosis. Exposure to Co in industrial settings is often assessed using air samples or biomonitoring in urine. Skin exposure is rarely measured. Aim of this study was to quantify and compare the importance of Co skin exposure and respiratory exposure in determining urinary Co concentrations. METHODS: Co skin exposure was measured in 76 hard metal workers by acid wipe sampling before and at the end of work shifts. Spot urine was collected during a 24-hour period from the start of a shift. Respiratory exposure was measured by personal inhalable dust sampling during a shift in 30 workers. Co was analysed by inductively coupled plasma mass spectrometry. RESULTS: Quantile regression modelling showed that a doubling of Co on skin before or at the end of shift increased the median urinary concentration of Co by 70% (p<0.001) or 32% (p<0.001), respectively. A doubling of Co in air increased median urinary Co by 38% (p<0.001). Co skin exposures were still significantly associated with urinary Co after excluding a group of workers with high respiratory exposure (33%, p=0.021 and 17%, p=0.002). CONCLUSIONS: The results indicate an association between Co skin exposure and urinary Co concentrations. This should be considered when using urinary Co as a biomarker of exposure.

Assessing exposure to metals using biomonitoring: Achievements and challenges experienced through surveys in low- and middle-income countries.

In this narrative account based on a keynote presentation on exposure biomonitoring of metals in low- and middle-income countries (LMIC), we first briefly address practical issues that have arisen from our experience during the conduct of various surveys in LMIC. These have included the statistical handling of multiple pollutants in the same subject, the problem of correctly adjusting for urinary flow in spot samples of urine, and the possible external contamination of samples when doing field surveys in challenging environments. We then review and present selected results from surveys conducted in the mining area of Katanga in the Democratic Republic of Congo (DR Congo), where we documented high urinary levels of cobalt and other trace metals (arsenic, uranium) in people living close (<3 km) to mining or smelting operations (Banza et al., 2009). Consumption of contaminated foodstuffs (maize, legumes, fish) and, especially among children, dust ingestion proved to be the main sources of exposure to cobalt (Cheyns et al., 2014). Urinary biomonitoring studies among artisanal workers involved in mining cobalt, craftsmen working malachite, and workers processing gold ore revealed high to extremely high values of cobalt (largely exceeding the Biological Exposure Index of 15 µg/L), as well as other trace metals such as uranium, manganese, lead or mercury, depending on the type of jobs. This abundant biomonitoring data has been valuable to argue for improved enforcement of legislation to protect workers and citizens against the hazards posed by the mining activities in the area. Epidemiological studies have been undertaken and are ongoing to assess the human health impact of this pollution.