Niacin prevents mitochondrial oxidative stress caused by sub-chronic exposure to methylmercury.

Humans and animals can be exposed to different chemical forms of mercury (Hg) in the environment. For example, methylmercury (MeHg)-contaminated fish is part of the basic diet of the riparian population in the Brazilian Amazon Basin, which leads to high total blood and plasma Hg levels in people living therein. Hg induces toxic effects mainly through oxidative stress. Different compounds have been used to prevent the damage caused by MeHg-induced reactive oxygen species (ROS). This study aims to investigate the in vivo effects of sub-chronic exposure to low MeHg levels on the mitochondrial oxidative status and to evaluate the niacin protective effect against MeHg-induced oxidative stress. For this purpose, Male Wistar rats were divided into four groups: control group, treated with drinking water on a daily basis; group exposed to MeHg at a dose of 100 µg/kg/day; group that received niacin at a dose of 50 mg/kg/day in drinking water, with drinking water being administered by gavage; group that received niacin at a dose of 50 mg/kg/day in drinking water as well as MeHg at a dose of 100 µg/kg/day. After 12 weeks, the rats, which weighed 500-550 g, were sacrificed, and their liver mitochondria were isolated by standard differential centrifugation. Sub-chronic exposure to MeHg (100 µg/kg/day for 12 weeks) led to mitochondrial swelling (p < 0.05) and induced ROS overproduction as determined by increased DFCH oxidation (p < 0.05), increased gluthatione oxidation (p < 0.05), and reduced protein thiol content (p < 0.05). In contrast, niacin supplementation inhibited oxidative stress, which counteracted and minimized the toxic MeHg effects on mitochondria.

Arsenic, cadmium, and mercury-induced hypertension: mechanisms and epidemiological findings.

Arsenic (As), cadmium (Cd), and mercury (Hg) are toxic elements widely distributed in the environment. Exposure to these elements was attributed to produce several acute and chronic illnesses including hypertension. The aim of this review is to provide a summary of the most frequently proposed mechanisms underlying hypertension associated with As, Cd, and Hg exposure including: oxidative stress, impaired nitric oxide (NO) signaling, modified vascular response to neurotransmitters and disturbed vascular muscle Ca2+ signaling, renal damage, and interference with the renin-angiotensin system. Due to the complexity of the vascular system, a combination rather than a singular mechanism needs to be considered. In addition, epidemiological findings showing the relationship between various biomarkers of metal exposure and hypertension are described. Given the complex etiology of hypertension, further epidemiological studies evaluating the roles of confounding factors such as age, gender, and life style are still necessary.

Evaluation of distribution, redox parameters, and genotoxicity in Wistar rats co-exposed to silver and titanium dioxide nanoparticles.

The increasing production of silver nanoparticles (AgNPs) and titanium dioxide nanoparticles (TiO2NPs) has resulted in their elevated concentrations in the environment. This study was, therefore, aimed at determining the distribution, redox parameters, and genotoxic effects in male Wistar rats that were treated with either AgNP or TiO2NP individually, as well as under a co-exposure scenario. Animals were exposed via oral gavage to either sodium citrate buffer (vehicle), 0.5 mg/kg/day TiO2NP, 0.5 mg/kg/day AgNP or a mixture of TiO2NPs and AgNPs. Exposure lasted 45 days after which rats were sacrificed, and tissue biodistribution of Ag and Ti measured. The blood concentration of glutathione (GSH) and activities of glutathione peroxidase (GPx) and catalase (CAT) were determined while the genotoxicity was analyzed using the comet assay in peripheral blood and liver cells. The tissue concentrations of Ag followed the order; blood > liver > kidneys while for Ti the order was kidneys > liver > blood. There was no significant change in the measured redox parameters in animals that were exposed to TiO2NPs. However, there was a significant increase in GSH levels accompanied by a reduction in the GPx activity in AgNP-treated and co-exposed groups. The individual or co-exposure to TiO2NP and AgNP did not markedly induce genotoxicity in blood or liver cells. Data showed that TiO2NP did not produce significant oxidative stress or genotoxicity in rats at the dose used in this study while the same dose level of AgNPs resulted in oxidative stress, but no noticeable adverse genotoxic effects.

Protective effects of niacin against methylmercury-induced genotoxicity and alterations in antioxidant status in rats.

This study investigates the potential beneficial effects of niacin (NA; vitamin B3) supplementation in rats chronically exposed to methylmercury (MeHg). Animals were randomly assigned to one of 4 groups (n = 6): Group I, control, received distilled water by gavage; Group II, received MeHg (100 µg/kg/d) by gavage; Group III, received NA (50 mg/kg/d) in drinking water; Group IV, received MeHg (100 µg/kg/d) by gavage + NA (50 mg/kg/d) in drinking water. Biochemical parameters levels of glucose, triglycerides, total cholesterol and fractions, and enzyme activities aspartate transaminase (AST) and alanine transaminase (ALT) were determined. Further, oxidative stress markers activity of glutathione peroxidase (GPx) and catalase (CAT) activity, as well as levels of reduced glutathione (GSH), malondialdehyde (MDA), and nitric oxide, were examined, and the comet assay was performed, using blood/plasma. Hg levels were measured in blood, brain, and kidneys of animals. Our results demonstrated that NA reduced adverse effects produced by MeHg. The mechanism underlying these effects appears to be related to the intrinsic antioxidant potential of NA. Considering the beneficial effects attributed to NA following MeHg exposure and that fish are the main source of both NA and MeHg, future studies need to evaluate the potential counteractive effect of NA against the adverse consequences of MeHg exposure in fish-eating populations.

Thimerosal induces apoptotic and fibrotic changes to kidney epithelial cells in vitro.

Thimerosal is an ethyl mercury-containing compound used mainly in vaccines as a bactericide. Although the kidney is a key target for mercury toxicity, thimerosal nephrotoxicity has not received the same attention as other mercury species. The aim of this study was to determine the potential cytotoxic mechanisms of thimerosal on human kidney cells. Human kidney proximal tubular epithelial (HK2) cells were exposed for 24 h to thimerosal (0-2 µM), and assessed for cell viability, apoptosis, and cell proliferation; expression of proteins Bax, nuclear factor-κB subunits, and transforming growth factor-ß1 (TGFß1); mitochondrial health (JC-1, MitoTracker Red CMXRos); and fibronectin levels (enzyme-linked immunosorbent assay). Thimerosal diminished HK2 cell viability and mitosis, promoted apoptosis, impaired the mitochondrial permeability transition, enhanced Bax and TGFß1 expression, and augmented fibronectin secretion. This is the first report about kidney cell death and pro-fibrotic mechanisms promoted by thimerosal. Collectively, these in vitro results demonstrate that (1) thimerosal induces kidney epithelial cell apoptosis via upregulating Bax and the mitochondrial apoptotic pathway, and (2) thimerosal is a potential pro-fibrotic agent in human kidney cells. We suggest that new evidence on toxicity as well as continuous surveillance in terms of fibrogenesis is required concerning thimerosal use.

A systematic study of the disposition and metabolism of mercury species in mice after exposure to low levels of thimerosal (ethylmercury).

Thimerosal (TM) is an ethylmercury (etHg)-containing preservative used in some vaccines despite very limited knowledge on the kinetics and direct interaction/effects in mammals׳ tissues after exposure. Thus, this study aimed to evaluate the kinetics of Hg species in mice in a time course analysis after intramuscular injection of TM, by estimating Hg half-lives in blood and tissues. Mice were exposed to one single intramuscular dose of 20 µg of Hg as TM. Blood, brain, heart, kidney and liver were collected at 0.5 hour (h), 1 h, 8 h, 16 h, 144 h, 720 h and 1980 h after TM exposure (n=4). Hg species in animal tissues were identified and quantified by speciation analysis via liquid chromatography hyphenated with inductively coupled mass spectrometry (LC-ICP-MS). It was found that the transport of etHg from muscle to tissues and its conversion to inorganic Hg (inoHg) occur rapidly. Moreover, the conversion extent is modulated in part by the partitioning between EtHg in plasma and in whole blood, since etHg is rapidly converted in red cells but not in a plasma compartment. Furthermore, the dealkylation mechanism in red cells appears to be mediated by the Fenton reaction (hydroxyl radical formation). Interestingly, after 0.5 h of TM exposure, the highest levels of both etHg and inoHg were found in kidneys (accounting for more than 70% of the total Hg in the animal body), whereas the brain contributed least to the Hg body burden (accounts for <1.0% of total body Hg). Thirty days after TM exposure, most Hg had been excreted while the liver presented the majority of the remaining Hg. Estimated half-lives (in days) were 8.8 for blood, 10.7 for brain, 7.8 for heart, 7.7 for liver and 45.2 for kidney. Taken together, our findings demonstrated that TM (etHg) kinetics more closely approximates Hg(2+) than methylmercury (meHg) while the kidney must be considered a potential target for etHg toxicity.

Inorganic and methylmercury levels in plasma are differentially associated with age, gender, and oxidative stress markers in a population exposed to mercury through fish consumption.

This study aimed to determine the concentrations of plasma methylmercury (Me-Hg) and inorganic mercury (I-Hg) in a population exposed to Me-Hg. In addition, associations between each form of mercury (Hg) and gender, age, plasma selenium (Se), and oxidative stress markers were also investigated. The mean plasma I-Hg level was 5.7 µg/L while the mean for plasma Me-Hg was 3.6 µg/L, representing approximately 59 and 41% of the total Hg in blood, respectively. However, several plasma samples contained higher percentages of Me-Hg. Age displayed a direct linkage with plasma I-Hg levels, whereas gender did not correlate with any of the Hg species. In addition, fish intake was only correlated with and a predictor of plasma Me-Hg, suggesting that plasma I-Hg levels originated endogenously through a demethylation reaction that needs to be verified. Further, plasma Me-Hg was markedly correlated with adverse effects to a greater extent than plasma I-Hg and may be considered a valuable, reliable internal dose biomarker for Hg in chronically Me-Hg- exposed individuals.

Manioc flour consumption as a risk factor for lead poisoning in the Brazilian Amazon.

Recent studies reported elevated blood lead (Pb) levels in riparian populations of the Amazon. For this reason, the aim of the present study was to assess the risk to riparians in the Brazilian Amazon to Pb exposure due to the intake of contaminated manioc flour. Lead levels were determined in whole blood (n = 74) and in manioc flour samples (n = 30) in three different communities. Mean blood Pb levels were 16.8 µg/dl, with individuals living in Açaituba presenting the highest mean blood Pb level (22.4 µg/dl), followed by Nova Canaã (17.3 µg/dl) and Santa Cruz (9.8 µg/dl). The minimum blood Pb level found was 0.83 µg/dl and the maximum was 44.3 µg/dl. The estimated daily intake (EDI) was calculated and compared to the benchmark dose lower confidence limit (BMDL) for neurotoxicity. Mean Pb in manioc flour was 0.34 µg/g while EDI was 79 µg/d, corresponding to 260% of the BMDL (varying from 168 to 308%). This finding is of great importance since this high EDI may exert adverse effects on the nervous system of this population. Manioc flour intake may thus present considerable risk of Pb exposure in this region. Risk management strategies and further studies on adverse effects in this population are needed.

Evaluation of biochemical and redox parameters in rats fed with corn grown in soil amended with urban sewage sludge.

The increased production of urban sewage sludge requires alternative methods for final disposal. A very promising choice is the use of sewage sludge as a fertilizer in agriculture, since it is rich in organic matter, macro and micronutrients. However, urban sewage sludge may contain toxic substances that may cause deleterious effects on the biota, water and soil, and consequently on humans. There is a lack of studies evaluating how safe the consumption of food cultivated in soils containing urban sewage sludge is. Thus, the aim of this paper was to evaluate biochemical and redox parameters in rats fed with corn produced in a soil treated with urban sewage sludge for a long term. For these experiments, maize plants were grown in soil amended with sewage sludge (rates of 5, 10 and 20 t/ha) or not (control). Four different diets were prepared with the corn grains produced in the field experiment, and rats were fed with these diets for 1, 2, 4, 8 and 12 weeks. Biochemical parameters (glucose, total cholesterol and fractions, triglycerides, aspartate aminotransferase and alanine aminotransferase) as well the redox state biomarkers such as reduced glutathione (GSH), malondialdehyde (MDA), catalase, glutathione peroxidase and butyrylcholinesterase (BuChE) were assessed. Our results show no differences in the biomarkers over 1 or 2 weeks. However, at 4 weeks BuChE activity was inhibited in rats fed with corn grown in soil amended with sewage sludge (5, 10 and 20 t/ha), while MDA levels increased. Furthermore, prolonged exposure to corn cultivated in the highest amount per hectare of sewage sludge (8 and 12 weeks) was associated with an increase in MDA levels and a decrease in GSH levels, respectively. Our findings add new evidence of the risks of consuming food grown with urban sewage sludge. However, considering that the amount and type of toxic substances present in urban sewage sludge varies considerably among different sampling areas, further studies are needed to evaluate sludge samples collected from different sources and/or undergoing different types of treatment.

Evaluation of the concentration of nonessential and essential elements in chicken, pork, and beef samples produced in Brazil.

Food safety is a global concern. Meat represents the most important protein source for humans. Thus, contamination of meat products by nonessential elements is a ready source of human exposure. In addition, knowledge of the concentration of essential elements is also relevant with respect to human nutrition. The aim of the present study was to determine the concentration of 17 elements in pork, beef, and chicken produced in Brazil. Meat samples were analyzed by inductively coupled plasma mass spectrometry. The estimated daily intake for nonessential elements including arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), and antimony (Sb) through meat consumption is below the toxicological reference values. However, high levels were detected for the nonessential element cesium (Cs), mainly in beef samples, an observation that deserves future studies to identify the source of contamination and potential adverse consequences.

Gold-Coated Superparamagnetic Iron Oxide Nanoparticles Attenuate Collagen-Induced Arthritis after Magnetic Targeting.

The aim of the study was to evaluate if gold-coated superparamagnetic iron oxide nanoparticles (AuSPION) magnetic-targeted to the arthritic articulation of collagen induced arthritis (CIA) rats are able to ameliorate rheumatoid arthritis without producing significant biological adverse effects in comparison to colloidal Au nanoparticles (AuC) and metotrexate (MTX). Male Wistar rats were divided into control; arthritic; AuSPION (150 µg kg-1); AuC (150 µg kg-1) and MTX (2.5 µg kg-1). Treatments were administered thrice every other day by the intraperitoneal route 15 min after all groups had a neodymium magnet coupled to the right ankle joint (kept for 1 h). Paw edema and body weight were measured weekly. Joint sections were evaluated by Haematoxylin & Eosin and immunohistochemistry (TNF-α, IL-1ß). Biomarkers of oxidative stress were used to evaluate toxicity. Among the evaluated treatments, AuSPION led to significant clinical improvements (decreased edema and infiltration by leukocytes as well as less positively immunostained cells for both TNF-α and IL-1ß in synovium) accompanied by a lack of toxicity as indicated by redox state and genotoxicity assays. Our results clearly indicate that the magnetic targeting of AuSPION suppresses joint edema and inflammation, cytokine expression as well as the redox imbalance, thereby contributing to an amelioration of arthritis severity in CIA rats. The results demonstrate for the first time the potentiality of AuSPION administration under a magnetic field as an attractive alternative for future treatments of rheumatic diseases.

Long-Term Excessive Selenium Supplementation Induces Hypertension in Rats.

Selenium (Se) is an essential trace element involved in several biological pathways, naturally found in rocks, soils, and food. Even though the daily requirement of Se is achieved through a balanced diet, the use of Se supplements has been frequent. Due to the risk of toxic effects of having Se in excess, supplementation is still under debate. The aim was to evaluate the effects of long-term Se supplementation upon systolic blood pressure (SBP) and redox status of rats exposed to sodium selenite. Male Wistar rats were exposed to 2 and 6 mg/L of sodium selenite in drinking water for 85 days. SBP and body weight were evaluated weekly; oxidative stress biomarkers were measured in blood or plasma; and Se levels were assessed in blood, plasma, kidney, and liver. Se supplementation (2 and 6 mg/L) induced significant increase in the SBP in rats from the 42nd day until the end of the study. This increase on SBP was not associated with significant changes in oxidative stress biomarkers. A significant increase in Se levels was found in whole blood, kidney, and liver from both groups of rats receiving Se supplementation when compared to control. Although the exact mechanisms underlying this augment in SBP are not clear, they are potentially related to other Se biological routes besides the synthesis of selenoproteins, such as GSH-Px. Due to the negative effects upon blood pressure, precautionary measures are advised, since the selling of supplements does not require a medical prescription.

The impact of occupational exposure to traffic-related air pollution among professional motorcyclists from Porto Alegre, Brazil, and its association with genetic and oxidative damage.

Vehicles play an important role in modern life; however, they also generate hazards. Occupational exposed subjects are in long-term contact with harmful products, which sets these professionals in a susceptible group to air pollutant damage. The aims of this study were to quantify individual exposure to pollutant gases and chemical elements and to evaluate oxidative and genetic damage in professional motorcyclists and office workers. We recruited professional motorcyclists and office workers from Porto Alegre, Brazil, between January and December 2016. Individual exposure to air pollutants was assessed by passive monitoring. Fingernail trace elements were determined by using inductively coupled plasma mass spectrometry. Oxidative stress biomarkers were quantified spectrophotometrically, and genotoxicity was evaluated by micronuclei assay. Individual exposure to NO2 and O3, trace element content (Sb, Pt, As, Cd, V, Mn, and Co), oxidative stress factors, and genetic damage were statistically higher in professional motorcyclists (p < 0.05). Moreover, NO2 and O3 levels showed very strong positive correlation with plasmatic lipid peroxidation (p < 0.001 and r = 0.8849 and 0.8995) and strong positive correlation with micronuclei frequency (p < 0.001 and r = 0.7683 and 0.7280). Results suggest that professional motorcyclists are at high risk due to long-term air pollution exposure, which implies in the onset of several harmful effects and worsening of pre-existent diseases.

The use of tree barks and human fingernails for monitoring metal levels in urban areas of different population densities of Porto Alegre, Brazil.

The aim of this study was to evaluate the use of tree barks as a bioindicator of atmospheric pollution in areas of contrasting population densities and to associate the levels of elements found in this bioindicator with those obtained in fingernail samples collected from students living in the same study areas. Tree bark samples were collected from urban areas near highways in regions with high (Area A), intermediate (Area B), and low (Area C) population densities of Porto Alegre, Brazil, and evaluated for chemical elements concentration. Since these areas also differed in traffic density, NO2 was measured by passive sampling. For a comparative purpose, the elements were also determined in fingernail samples collected from students living in the same areas. Accumulated elements were determined by inductively coupled plasma mass spectrometry (ICP-MS) and principal component analysis (PCA) was used as a tool in exploratory data analysis to identify possible sources. We found that Ba, Cd, Co, Cu, Mg, Mn, Ni, Pb, Sb, Sr, V, and Zn were at higher concentrations in tree barks in Area A, while Cd, Co, Cu, Mg, Mn, Ni, and Sr were at higher levels in students' fingernails of Area A as well. Furthermore, concentrations of elements found in barks were associated with those identified in fingernails collected from students living in the same areas. PCA demonstrated that vehicular traffic explained 66.4 % of the variance in tree bark and 50.8 % of the variance in fingernails. NO2 levels were significantly different among the areas, what is consistent with their respective vehicular flow and population density. In conclusion, we found conformance of elements levels accumulated in barks and fingernails at three monitoring areas with different profiles. The amount of traffic-related elements accumulated appears to be associated with the degree of urbanization and vehicular flow. Overall, data suggests a relationship between fingernails and tree bark as bioindicators of exposure to metals from air pollution.

Monitoring an outdoor smoking area by means of PM2.5 measurement and vegetal biomonitoring.

The extension of pollutant accumulation in plant leaves associated with its genotoxicity is a common approach to predict the quality of outdoor environments. However, this approach has not been used to evaluate the environmental quality of outdoor smoking areas. This study aims to evaluate the effects of environmental tobacco smoke (ETS) by assessing particulate matter 2.5 µm (PM2.5) levels, the pollen abortion assay, and trace elements accumulated in plant leaves in an outdoor smoking area of a hospital. For this, PM2.5 was measured by active monitoring with a real time aerosol monitor for 10 days. Eugenia uniflora trees were used for pollen abortion and accumulated element assays. Accumulated elements were also assessed in Tradescantia pallida leaves. The median concentration of PM2.5 in the smoking area in all days of monitoring was 66 versus 34 µg/m3 in the control area (P < 0.001). In addition, the elements Al, Cd, Cu, Ni, Pb, Rb, Sb, Se, and V in Tradescantia pallida and Al, Ba, Cr, Cu, Fe, Mg, Pb, and Zn in Eugenia uniflora were in higher concentration in the smoking area when compared to control area. Smoking area also showed higher rate of aborted grains (26.1 ± 10.7 %) compared with control (17.6 ± 4.5 %) (P = 0.003). Under the study conditions, vegetal biomonitoring proved to be an effective tool for assessing ETS exposure in outdoor areas. Therefore, vegetal biomonitoring of ETS could be a complement to conventional analyses and also proved to be a cheap and easy-handling tool to assess the risk of ETS exposure in outdoor areas.

Trace elements concentration in nails and association with airway inflammation in adolescents.

Asthma is a multifactorial disease and its severity varies with the inflammatory status of the patient. It has been hypothesized that deficiency of trace elements has an important role in the etiology of asthma. The aim of the study was to evaluate the concentration of trace elements in nails of adolescents with different degrees of airway inflammation. We assessed the prevalence of active and severe asthma in adolescents (n = 106) through the ISAAC questionnaire. Subjects were allocated into two different groups according to the value of fraction exhaled nitric oxide (FeNO) measured. Also, nail specimens were collected in order to determine the concentration of accumulated trace elements (Cu, Zn, Mn, Se) by ICP-MS. It was performed Student's t test to evaluate statistical differences between inflammatory groups considering normally distributed data. On the other hand, when data presented non-normal distribution, Mann-Whitney U test was utilized. Spearman coefficients were calculated to investigate correlations between FeNO and mineral concentrations. Exhaled NO was increased in male subjects. We found association between active asthma and elevated exhaled NO. There was no significant difference in Cu (4.40 vs. 4.52), Zn (84.66 vs. 79.48), Mn (0.59 vs. 0.76), and Se (0.18 vs. 0.19) concentrations (µg/g) among distinct FeNO groups as well as was not observed correlation between exhaled NO levels and any element. Deficiency of trace elements in nails were not associated with increased FeNO.

Low concentrations of selenium and zinc in nails are associated with childhood asthma.

The purpose of this study was to investigate possible associations between Zn, Se, Cu, Mn, and Co concentrations in nails and asthma in a young population from a Southern Brazil city. Additionally, correlations between these chemical elements among asthmatic and non-asthmatic children were evaluated. Before nail collection (n = 165), children were asked to complete the International Study of Asthma and Allergies in Childhood questionnaire. The concentrations of trace elements were determined by inductively coupled plasma mass spectrometry. The chi-square test was used to evaluate the association between element concentrations in nails and the respiratory outcome. To evaluate correlations between the elements, we used the Spearman correlation test. For all tests, the significance level was set at 95% (P ≤ 0.05). Children included in the highest quartile of nail Se and Zn concentration presented a fivefold decrease in the prevalence ratio of asthma while children in the lowest Se range presented an almost 2.5-fold increase in the asthma prevalence ratio. There were weak to strong correlations between Cu vs. Zn, Cu vs. Co, Cu vs. Se, Zn vs. Se, Zn vs. Mn, and Mn vs. Co in both asthmatic and non-asthmatic children. Interestingly, non-asthmatics also presented correlations between Co vs. Se and Zn. Taken together, our results clearly demonstrated an association between concentrations of selenium and zinc and childhood asthma and the usefulness of nail as a noninvasive matrix to detect minerals imbalance in asthma patients.

Background values for essential and toxic elements in children's nails and correlation with hair levels.

Human nails are an attractive matrix for assessing environmental exposures to toxic elements as well as the deficiency of essential elements since it is noninvasively collected and can be stored at room temperature. However, reference or baseline levels in nonexposed and healthy populations are not yet established. Then, the aims of this study were (a) to estimate background values for essential and toxic elements in nails from a healthy young population in southern Brazil and (b) to evaluate possible correlations between essential and toxic elements in nails. Furthermore, this report took part of a recent study of background values in the hair of a young population. Thus, correlations between chemical elements in nails and hair were also evaluated. Nails were collected from healthy children (n = 126), and element concentrations were determined by inductively coupled plasma mass spectrometry. This study provides new and reliable reference concentrations for toxic and essential elements in children's nails. The results can be used as reference values for epidemiological or clinical investigations based on trace elements in nails. Additionally, we also showed weak to strong correlations between Cu, Mg, Mn, Se, and Zn levels in nails and hair.

Assessment of trace elements in scalp hair of a young urban population in Brazil.

The aim of this study was to establish background values for toxic and essential elements in hair, interelement correlations and the differences in levels between genders in a healthy young population from Southern Brazil. Hair samples (n=167) were collected from healthy students aged 12-18 years. Trace element concentrations in hair were determined by inductively coupled plasma mass spectrometry. The study provided relatively low values for toxic elements and balanced concentrations for the essential elements in the adolescents' hair with reliable reference data. Interestingly, this study also demonstrated statistical correlations considered newfound between the elements in hair. Hair mercury levels were influenced by gender; with males presenting higher values. The overall findings of the present study, with respect to the estimated chemical elements, are of prime importance in the evaluation of reference values for determining environmental effects on children living in urban areas.