Toxic and essential elements in children's blood (<6 years) from Kinshasa, DRC (the Democratic Republic of Congo)

Consequences of Disturbing Manganese Homeostasis

Manganese (Mn) is an essential trace element with unique functions in the body; it acts as a cofactor for many enzymes involved in energy metabolism, the endogenous antioxidant enzyme systems, neurotransmitter production, and the regulation of reproductive hormones. However, overexposure to Mn is toxic, particularly to the central nervous system (CNS) due to it causing the progressive destruction of nerve cells. Exposure to manganese is widespread and occurs by inhalation, ingestion, or dermal contact. Associations have been observed between Mn accumulation and neurodegenerative diseases such as manganism, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. People with genetic diseases associated with a mutation in the gene associated with impaired Mn excretion, kidney disease, iron deficiency, or a vegetarian diet are at particular risk of excessive exposure to Mn. This review has collected data on the current knowledge of the source of Mn exposure, the experimental data supporting the dispersive accumulation of Mn in the brain, the controversies surrounding the reference values of biomarkers related to Mn status in different matrices, and the competitiveness of Mn with other metals, such as iron (Fe), magnesium (Mg), zinc (Zn), copper (Cu), lead (Pb), calcium (Ca). The disturbed homeostasis of Mn in the body has been connected with susceptibility to neurodegenerative diseases, fertility, and infectious diseases. The current evidence on the involvement of Mn in metabolic diseases, such as type 2 diabetes mellitus/insulin resistance, osteoporosis, obesity, atherosclerosis, and non-alcoholic fatty liver disease, was collected and discussed.

Heavy metals in children's blood from the rural region of Popokabaka, Democratic Republic of Congo: a cross-sectional study and spatial analysis

Exposure to heavy metals can affect cell differentiation, neurocognitive development, and growth during early life, even in low doses. Little is known about heavy metal exposure and its relationship with nutrition outcomes in non-mining rural environments. We carried out a community-based cross-sectional study to describe the distribution of four heavy metal concentrations [arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg)] in the serum of a representative population of children aged 12 to 59 months old from the rural region of Popokabaka, Democratic Republic of Congo. The four metals were measured in 412 samples using inductively coupled plasma-mass spectrometry (ICP-MS). Limits of detection (LoD) and quantification (LoQ) were set. Percentiles were reported. Statistical and geospatial bivariate analyses were performed to identify relationships with other nutrition outcomes. Arsenic was quantified in 59.7%, while Cd, Hg, and Pb were quantified in less than 10%, all without toxicities. The arsenic level was negatively associated with the zinc level, while the Hg level was positively associated with the selenium level. This common detection of As in children of Popokabaka requires attention, and urgent drinking water exploration and intervention for the profit of the Popokabaka community should be considered.

Development and Validation of an ICP-MS Method and Its Application to Determine Multiple Trace Elements in Small Volumes of Whole Blood and Plasma

Essential and nonessential element concentrations in human blood provide important information on the nutritional status of individuals and can assist in the screening or diagnosis of certain disorders and their association with other causative factors. A simple and sensitive method, suitable for use with small sample volumes, for quantification of multiple trace element concentrations in whole blood and plasma has been developed using inductively coupled plasma-mass spectrometry. Method validation was performed using standard reference materials of whole blood and serum using varying sample treatments with nitric acid, water and hydrogen peroxide. The method was applied to quantify the trace element concentrations in whole blood and plasma samples (0.1 mL) from 50 adult blood donors in Queensland. The whole blood sample (5 mL) was collected in Vacutainer tubes with K2EDTA as anticoagulant. The developed method was able to quantify, in blood and plasma samples over a wide range of concentrations, several essential elements: cobalt, copper, zinc, iron, manganese and selenium; the nutritionally probably essential elements vanadium and strontium; and nonessential elements including lead, cadmium, arsenic, caesium, barium, thallium and uranium. Significant differences (P < 0.0001) were observed between whole blood and plasma concentrations for 13 elements; 5 of the measured elements, cobalt (0.49 vs. 0.36 μg/L), copper (1.0 vs. 0.75 mg/L), strontium (28 vs. 16 μg/L), barium (1.5 vs. 0.64 μg/L) and thallium (0.06 vs. 0.03 μg/L), had higher mean concentrations in plasma than in blood. Whole blood concentrations of nine trace elements were significantly correlated (P < 0.0001) with plasma concentrations. The distribution of the trace elements between human blood and plasma varied considerably for the different elements. These results indicate that, using a small sample volume, this assay is suitable for the evaluation of nutritional status as well as in monitoring human toxic elemental exposures.

Environmental exposure to metal mixtures and linear growth in healthy Ugandan children

BACKGROUND

Stunting is an indicator of poor linear growth in children and is an important public health problem in many countries. Both nutritional deficits and toxic exposures can contribute to lower height-for-age Z-score (HAZ) and stunting (HAZ < -2).

OBJECTIVES

In a community-based cross-sectional sample of 97 healthy children ages 6-59 months in Kampala, Uganda, we examined whether exposure to Pb, As, Cd, Se, or Zn were associated with HAZ individually or as a mixture.

METHODS

Blood samples were analyzed for a mixture of metals, which represent both toxins and essential nutrients. The association between HAZ and metal exposure was tested using multivariable linear regression and Weighted Quantile Sum (WQS) regression, which uses mixtures of correlated exposures as a predictor.

RESULTS

There were 22 stunted children in the sample, mean HAZ was -0.74 (SD = 1.84). Linear regression showed that Pb (β = -0.80, p = 0.021) and Se (β = 1.92, p = 0.005) were significantly associated with HAZ. The WQS models separated toxic elements with a presumed negative effect on HAZ (Pb, As, Cd) from essential nutrients with presumed positive effect on HAZ (Se and Zn). The toxic mixture was significantly associated with lower HAZ (β = -0.47, p = 0.03), with 62% of the effect from Pb. The nutrient WQS index did not reach statistical significance (β = -0.47, p = 0.16).

DISCUSSION

Higher blood lead and lower blood selenium level were both associated with lower HAZ. The significant associations by linear regression were reinforced by the WQS models, although not all associations reached statistical significance. These findings suggest that healthy children in this neighborhood of Kampala, Uganda, who have a high burden of toxic exposures, may experience detrimental health effects associated with these exposures in an environment where exposure sources are not well characterized.

Selenium deficiency risks in sub-Saharan African food systems and their geospatial linkages

Selenium (Se) is an essential element for human health. However, our knowledge of the prevalence of Se deficiency is less than for other micronutrients of public health concern such as iodine, iron and zinc, especially in sub-Saharan Africa (SSA). Studies of food systems in SSA, in particular in Malawi, have revealed that human Se deficiency risks are widespread and influenced strongly by geography. Direct evidence of Se deficiency risks includes nationally representative data of Se concentrations in blood plasma and urine as population biomarkers of Se status. Long-range geospatial variation in Se deficiency risks has been linked to soil characteristics and their effects on the Se concentration of food crops. Selenium deficiency risks are also linked to socio-economic status including access to animal source foods. This review highlights the need for geospatially-resolved data on the movement of Se and other micronutrients in food systems which span agriculture-nutrition-health disciplinary domains (defined as a GeoNutrition approach). Given that similar drivers of deficiency risks for Se, and other micronutrients, are likely to occur in other countries in SSA and elsewhere, micronutrient surveillance programmes should be designed accordingly.

Determination of toxic and essential trace elements in serum of healthy and hypothyroid respondents by ICP-MS: A chemometric approach for discrimination of hypothyroidism

Inductively coupled plasma-mass spectrometry ((ICP-MS)) was used to determine three toxic (Ni, As, Cd) and six essential trace elements (Cr, Mn, Co, Cu, Zn, Se) in blood serum of patients with hypothyroidism (Hy group) and healthy people (control group), in order to set the experimental conditions for accurate determination of a unique profile of these elements in hypothyroidism. Method validation was performed with standard reference material of the serum by varying the sample treatment with both standard and collision mode for analysis of elements isotopes. Quadratic curvilinear functions with good performances of models and the lowest detection limits were obtained for ⁵²Cr, ⁶⁶Zn, ⁷⁵As, ¹¹²Cd in collision mode, and ⁵⁵Mn, ⁵⁹Co, ⁶⁰Ni, ⁶⁵Cu, ⁷⁸Se in standard mode. Treatment of serum samples with aqueous solution containing nitric acid, Triton X-100 and n-butanol gave the best results. Chemometric tools were applied for discrimination of patients with hypothyroidism. All nine elements discriminated Hy group of samples with almost the same discriminating power as indicated by their higher values for this group of patients. Statistically significant correlation (p < 0.01) was observed for several elements. Results indicated clear differences in element profile between Hy and control group and it could be used as a unique profile of hypothyroid state.

Biomonitoring of 29 trace elements in whole blood from inhabitants of Cotonou (Benin) by ICP-MS

This study aimed to investigate the blood concentration of 29 trace elements, metals or metalloids, in a healthy population of Cotonou not directly exposed to metals in order to propose reference values. Blood samples from 70 blood donors were collected in K2 EDTA tubes for trace elements during September 2015 and a questionnaire was used to assess lifestyle exposure. Blood metal concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) equipped with a quadrupole-based reaction cell. Among the selected blood donors 51.4% were aged from 18 to 36 years and 49.6% from 37 to 65 years. Among the 29 elements analyzed As, Pb, Mn, Pd, Sb, Co, Se, Sr showed blood concentrations higher than the reference values found in the literature for non-exposed healthy European populations and their geometric means were respectively 5.81; 47.39; 19.71; 1.91; 7.50; 0.66; 163.01; 30.53μg/L. This study provides the first reference value (5th-95th percentiles) for each element in Cotonou, which enables us to carry out further investigations on environmental and occupational exposure.

Sociocultural factors associated with fish consumption in Lake Albert fishing community: Guidelines for lead and mercury

Fish consumption in subsistence fishing community is a life style associated with lead and mercury uptake for humans. Fish consumption is influenced by sociocultural factors, exposure and health risks. Unfortunately, no sociocultural study in the Lake Albert fishing community in light of lead and mercury exists. A cross-sectional sociocultural study was carried out between March and June 2015. A total of 270 household heads in four landing sites in Hoima district completed structured questionnaires and data analyzed using SPSS version 20. The majority of the households (74.8%) had primary education or below, 51.1% drank unboiled water, and 30% perceived lake water safe for drinking. Children under five ate soup (15%) and middle piece of the fish (29%). The Poisson general linear model predicting weekly fish consumption amounts against sociocultural factors showed that household size (p = 0.047), male child presence (p = 0.007), methods of preparation i.e. salting (p < 0.0001), fish parts consumed by adults (p < 0.0001), fish preference (p < 0.0001), awareness about the beach management unit (p < 0.0001), and income from charcoal selling (p < 0.0001) were positive predictors. The negative predictors of weekly fish consumption amounts were awareness about fish consumption benefits (p < 0.0001), eating young fish (p = 0.002), donor agency presence (p < 0.0001), and frying as the method of fish preparation (p = 0.002). In conclusion, knowledge of the sociocultural factors associated with fish consumption determines the amounts and frequency of the predominant fish eaten. Therefore, to establish and adopt fish consumption guidelines for lead and mercury in the Lake Albert, the sociocultural factors should be integrated in the message disseminated.

Lead exposure and early child neurodevelopment among children 12-24 months in Kinshasa, the Democratic Republic of Congo

Childhood lead exposure remains a problem in developing countries, and little is known about its effects on early child neurodevelopment and temperament in the Democratic Republic of Congo (DRC). We, therefore, conducted this study to determine the association between lead exposure and the neurodevelopment and behaviour of children aged 12-24 months in Kinshasa, DRC. A cross-sectional study was conducted between February and June 2012, and parents of 104 children were invited to participate. Blood lead levels (BLLs) of each child were tested using the flame atomic spectrophotometry method. All children were subject to a clinical examination and assessed with two selected early child neurodevelopmental tools, the Gensini-Gavito and the baby characteristics questionnaire, to measure their neurodevelopment and temperament. Detectable BLLs ranged from 1 to 30 μg/dl with a geometric mean of 6.9 (SD 4.8) μg/dl. BLLs at 5-9 and ≥10 μg/dl were significantly associated with the child temperament (p <0.05). Perinatal and maternal factors did not seem to affect early child neurodevelopment and temperament. Children exposed to lead were reported with more temperament difficulties at even blood lead levels <10 μg/dl, suggesting the need for preventive and intervention measures to reduce lead exposure among children in Kinshasa, DRC.

Metallic Profile of Whole Blood and Plasma in a Series of 99 Healthy Children

In recent years, special emphasis has been put on heavy metals. Children are very sensitive to accumulation of metals. Furthermore, as regards elements, the reference values in children are scarce in the literature as it is difficult to obtain the large quantity of blood necessary to analyze many metals by the conventional atomic absorption spectrometry technique. An inductively coupled plasma mass spectrometry (ICP-MS) procedure that uses a reduced sample of 0.3 mL whole blood or plasma is adapted to multielemental determinations. We applied a previously validated technique for adults that simultaneously quantifies 25 elements by ICP-MS in whole blood and 23 in plasma in a series of 99 healthy children ranging from under 5 years to <18 years, without exposure to metal or drug-containing metals. The aims of the study were to compare metallic concentrations according to the age among children and metallic concentration differences between children and adults. The blood and plasma pediatric metallic profile is a practical useful tool for many purposes in clinical toxicology, forensic toxicology and any cases of metal environmental exposure.

Cognitive deficits and ALA-D-inhibition in children exposed to multiple metals

Children are especially vulnerable to adverse effects of multiple metals exposure. The aim of this study was to assess some metals concentrations such as lead (Pb), arsenic (As), chromium (Cr), manganese (Mn) and iron (Fe) in whole blood, serum, hair and drinking water samples using inductively coupled plasma-mass spectrometry (ICP-MS) in rural and urban children. In addition, evaluate the adverse effects of multiple metals exposure on cognitive function and δ-aminolevulinate dehydratase (ALA-D) activity. The cognitive ability assessment was performed by the Raven's Colored Progressive Matrices (RCPM) test. The ALA-D activity and ALA-D reactivation index (ALA-RE) activity with DTT and ZnCl2 also were determined. Forty-six rural children and 23 urban children were enrolled in this study. Rural children showed percentile IQ scores in the RCPM test significantly decreased in relation to urban children. According to multiple linear regression analysis, the Mn and Fe in hair may account for the cognitive deficits of children. Manganese and Fe in hair also were positively correlated with Mn and Fe in drinking water, respectively. These results suggest that drinking water is possibly a source of metals exposure in children. ALA-D activity was decreased and ALA-RE with DTT and ZnCl2 was increased in rural children in comparison to urban children. Moreover, ALA-D inhibition was correlated with Cr blood levels and ALA-RE/DDT and ALA-RE/ZnCl2 were correlated with levels of Cr and Hg in blood. Thus, our results indicated some adverse effects of children's exposure to multiple metals, such as cognitive deficits and ALA-D inhibition, mainly associated to Mn, Fe, Cr and Hg.