Determination of total arsenic concentrations in nails by inductively coupled plasma mass spectrometry

Arsenic modifies the effect of folic acid in spina bifida prevention, a large hospital-based case-control study in Bangladesh

Background Spina bifida, a developmental malformation of the spinal cord, is associated with high rates of mortality and disability. Although folic acid-based preventive strategies have been successful in reducing rates of spina bifida, some areas continue to be at higher risk because of chemical exposures. Bangladesh has high arsenic exposures through contaminated drinking water and high rates of spina bifida. Methods We conducted a hospital-based case-control study at the National Institute of Neurosciences & Hospital (NINS&H) in Dhaka, Bangladesh, between December 2016 and December 2022. Cases were infants under age one year with spina bifida and further classified using data from observations by neurosurgeons and available imaging. Controls were drawn from children who presented to NINS&H or Dhaka Shishu Hospital (DSH) during the same study period. Mothers reported folic acid use during pregnancy, and we assessed folate status with serum assays. Arsenic exposure was estimated in drinking water using graphite furnace atomic absorption spectrophotometry (GF-AAS) and in toenails using inductively coupled plasma mass spectrometry (ICP-MS). Results We evaluated data from 294 cases of spina bifida and 163 controls. We did not find a main effect of mother's arsenic exposure on spina bifida risk. However, in stratified analyses, folic acid use was associated with lower odds of spina bifida (adjusted odds ratio [OR]: 0.50, 95% confidence interval [CI]: 0.25-1.00, p = 0.05) among women with toenail arsenic concentrations below the median, and no association was seen among mothers with toenail arsenic concentrations higher than median (adjusted OR: 1.09, 95% CI: 0.52-2.29, p = 0.82). Conclusions Mother's arsenic exposure modified the protective association of folic acid with spina bifida. Increased surveillance and additional preventive strategies, such as folic acid fortification and reduction of arsenic, are needed in areas of high arsenic exposure.

Quantitative analysis of human hairs and nails

Hair and nails are human biomarkers capable of providing a continuous assessment of the concentrations of elements inside the human body to indicate the nutritional status, metabolic changes, and the pathogenesis of various human diseases. Laser-induced breakdown spectroscopy (LIBS) and X-ray fluorescence (XRF) spectrometry are robust and multi-element analytical techniques able to analyze biological samples of various kinds for disease diagnosis. The primary objective of this review article is to focus on the major developments and advances in LIBS and XRF for the elemental analysis of hair and nails over the last 10-year period. The developments in the qualitative and quantitative analyses of human hair and nail samples are discussed in detail, with special emphasis on the key aspects of elemental imaging and distribution of essential and non-essential elements within the hair and nail tissue samples. Microchemical imaging applications by LIBS and XRF (including micro-XRF and scanning electron microscopy, SEM) are also presented for healthy as well as diseased tissue hair and nail samples in the context of disease diagnosis. In addition, main challenges, prospects, and complementarities of LIBS and XRF toward analyzing human hair and nails for disease diagnosis are also thoroughly discussed here.

Assessment of disease burden in the arsenic exposed population of Chapar village of Samastipur district, Bihar, India, and related mitigation initiative

Fast growing arsenic menace is causing serious health hazards in Bihar, India, with an estimated 10 million people at risk. The exposed population is often unaware of the problem, which only amplifies the burden of arsenic health effects. In the present study, we have assessed the current situation of arsenic exposure in Chapar village of Samastipur district, Bihar. The health of the inhabitants was assessed and correlated with (1) arsenic concentrations in the groundwater of individual wells and (2) arsenic concentration found in their hair and urine. Altogether, 113 inhabitants were assessed, and 113 hair, urine and groundwater samples were collected. The health study reveals that the exposure to arsenic has caused serious health hazard amongst the exposed population with pronounced skin manifestations, loss of appetite, anaemia, constipation, diarrhoea, general body weakness, raised blood pressure, breathlessness, diabetes, mental disabilities, diabetes, lumps in the body and few cancer incidences. It was found that 52% of the total collected groundwater samples had arsenic levels higher than the WHO limit of 10 µg/l (with a maximum arsenic concentration of 1212 µg/l) and the reduced arsenite was the predominant form in samples tested for speciation (N = 19). In the case of hair samples, 29% of the samples had arsenic concentrations higher than the permissible limit of 0.2 mg/kg, with a maximum arsenic concentration of 46 µg/l, while in 20% exposed population, there was significant arsenic contamination in urine samples > 50 µg/l. In Chapar village, the probability of carcinogenic-related risk in the exposed population consuming arsenic contaminated water is 100% for children, 99.1% for females and 97.3% for male subjects. The assessment report shared to the government enabled the village population to receive two arsenic filter units. These units are currently operational and catering 250 households providing arsenic-free water through piped water scheme. This study therefore identified a significant solution for this arsenic-exposed population.

Exposure to e-cigarette aerosol over two months induces accumulation of neurotoxic metals and alteration of essential metals in mouse brain

Despite a recent increase in e-cigarette use, the adverse human health effects of exposure to e-cigarette aerosol, especially on the central nervous system (CNS), remain unclear. Multiple neurotoxic metals have been identified in e-cigarette aerosol. However, it is unknown whether those metals accumulate in the CNS at biologically meaningful levels. To answer this question, two groups of mice were whole-body exposed twice a day, 5 days a week, for two months, to either a dose of e-cigarette aerosol equivalent to human secondhand exposure, or a 5-fold higher dose. After the last exposure, the olfactory bulb, anterior and posterior frontal cortex, striatum, ventral midbrain, cerebellum, brainstem, remaining brain tissue and spinal cord were collected for metal quantification by inductively coupled plasma mass spectrometry and compared to tissues from unexposed control mice. The two-month exposure caused significant accumulation of several neurotoxic metals in various brain areas - for some metals even at the low exposure dose. The most striking increases were measured in the striatum. For several metals, including Cr, Cu, Fe, Mn, and Pb, similar accumulations are known to be neurotoxic in mice. Decreases in some essential metals were observed across the CNS. Our findings suggest that chronic exposure to e-cigarette aerosol could lead to CNS neurotoxic metal deposition and endogenous metal dyshomeostasis, including potential neurotoxicity. We conclude that e-cigarette-mediated metal neurotoxicity may pose long-term neurotoxic and neurodegenerative risks for e-cigarette users and bystanders.

Assessment of arsenic exposure in the population of Sabalpur village of Saran District of Bihar with mitigation approach

Arsenic poisoning through groundwater is the world's greatest normal groundwater catastrophe which got an immense effect on worldwide general wellbeing. India is confronting the outcomes of arsenic poisoning in the zone of Ganga Brahmaputra alluvial plains. In Bihar, out of 38 districts, 18 districts are exceptionally influenced with groundwater arsenic defilement. In the present study, we have assessed the current situation of arsenic exposure in Sabalpur village of Saran district of Bihar after reporting of breast, renal, skin and thyroid cancer cases from this village along with typical symptoms of arsenicosis. Such cancer patients were identified at our institute and were taken for the study. The present investigation deals with the quantification of arsenic in groundwater, hair and nail samples of subjects as well as the survey of entire village to know the overall health status of the village people. A total of n=128 household handpump water samples as well as n=128 human hair and nail samples were collected from over n=520 households. Using the graphite furnace atomic absorption spectrophotometer (GF-AAS), all the samples were analysed. The investigation resulted that the 61% of the analysed samples particularly the groundwater had the arsenic levels more than the permissible limit of WHO (> 10 μg/L) with 244.20 μg/L as the highest arsenic contamination in one of the handpump water sample. The exposure effect of hair sample was worst as 88% of all the collected samples were having high arsenic levels more than the permissible limit (> 0.2 mg/Kg). In case of nail samples, 92% of the samples were having high arsenic concentration more than the permissible limit (> 0.5 mg/Kg). The health survey study revealed high magnitude of disease burden in the exposed population with symptoms such as asthma, anaemia, hepatomegaly, diabetes, cardiac problem, skin fungal infections, breathlessness and mental disability. Few cancer cases of renal, skin, breast and cervix were also found among the exposed population of this village. The percentage of cancer cases in this village was 0.94% that was low, but it would be an aggravated situation in the near future if people will continue drinking arsenic-contaminated water. Therefore, a mitigation intervention was carried out in March 2020 by installing an arsenic filter plant. The health situation in the village in the present scenario is hope to improve in the coming years. However, motivation and awareness among the village population are still required.

Structure of human GABAB receptor in an inactive state

The human GABAB receptor-a member of the class C family of G-protein-coupled receptors (GPCRs)-mediates inhibitory neurotransmission and has been implicated in epilepsy, pain and addiction1. A unique GPCR that is known to require heterodimerization for function2-6, the GABAB receptor has two subunits, GABAB1 and GABAB2, that are structurally homologous but perform distinct and complementary functions. GABAB1 recognizes orthosteric ligands7,8, while GABAB2 couples with G proteins9-14. Each subunit is characterized by an extracellular Venus flytrap (VFT) module, a descending peptide linker, a seven-helix transmembrane domain and a cytoplasmic tail15. Although the VFT heterodimer structure has been resolved16, the structure of the full-length receptor and its transmembrane signalling mechanism remain unknown. Here we present a near full-length structure of the GABAB receptor, captured in an inactive state by cryo-electron microscopy. Our structure reveals several ligands that preassociate with the receptor, including two large endogenous phospholipids that are embedded within the transmembrane domains to maintain receptor integrity and modulate receptor function. We also identify a previously unknown heterodimer interface between transmembrane helices 3 and 5 of both subunits, which serves as a signature of the inactive conformation. A unique 'intersubunit latch' within this transmembrane interface maintains the inactive state, and its disruption leads to constitutive receptor activity.

Association between chronic arsenic exposure and the characteristic features of asthma

Widespread contamination of arsenic (As) has become a global public health concern. Exposure to As causes respiratory complications. Asthma, a major respiratory complication, is increasing worldwide. However, the effect of chronic As exposure on the risk of asthma remains to be clarified. This study aims to examine the associations between As exposure (water, hair and nail As) and the risk of asthma among 842 individuals exposed to a wide range of As concentrations through drinking water in Bangladesh. Subjects' As exposure levels were measured with ICP-MS. Lung function was examined by a handheld spirometer. Characteristic features of asthma were evaluated by bronchodilator-mediated reversibility in airway obstruction and asthma-like symptoms through a structured questionnaire. Total serum immunoglobulin E (sIgE) levels were measured by immunoassay. As exposure metrics showed inverse associations with lung function measures (FEV1, FEV6, and FEV1/FEV6 ratio) and positive associations with the risks of airway obstruction (AO), reversible airway obstruction (RAO), and asthma-like symptoms. The majority of AO patients (70 of 97) were RAO with one or more characteristic symptoms of asthma. Intriguingly, subjects' As exposure levels showed positive associations with total sIgE levels. Total sIgE in RAO patients was significantly (p < 0.001) higher than that in the control group. Thus the results revealed that chronic As exposure was associated with the risk of the characteristic features of asthma. Additionally the association between As exposure and subjects' total sIgE levels and an elevated level of total sIgE in RAO group suggested that As exposure-related asthma might be allergic in nature.

Development and characterization of reference materials for trace element analysis of keratinized matrices

Biomonitoring for human exposure to lead, arsenic, mercury, and other toxic metal(loid)s often relies on analyzing traditional biospecimens such as blood and urine. While biomonitoring based on blood and urine is well-established, non-traditional biospecimens such as hair and nails can offer the potential to explore past exposures as well as the advantages of non-invasive collection and ease of storage. The present study describes the production of four reference materials (NYS RMs 18-01 through 18-04) based on caprine horn, a keratinized tissue similar to human hair and nails, intended to serve as a resource for calibration, quality control, and method validation purposes. The elemental content and homogeneity of these candidate reference materials were characterized for 17 elements using inductively coupled plasma mass spectrometry (ICP-MS). Commutability between two or more of the NYS caprine horn RMs and human nails was established for 8 elements (Ba, Ca, Cr, Cu, Mn, Pb, Sr, and Zn) based on analysis by ICP-MS/MS and ICP-optical emission spectrometry. The development and optimization of an ICP-MS/MS instrumental method for the determination of 17 elements in keratinized tissues is described. The method was validated against three certified reference materials based on human hair showing good accuracy and method repeatability better than 25% for all analytes. This study also describes sample preparation issues and addresses common challenges including surface contamination, microwave digestion, matrix effects, and spectral interferences in inorganic mass spectrometry. New York State Department of Health Keratin Matrix Reference Materials. Graphical abstract.

Living near an active U.S. military base in Iraq is associated with significantly higher hair thorium and increased likelihood of congenital anomalies in infants and children

In Iraq, war contamination is the result of dispensed bombs, bullets, detonation of chemical and conventional weapons, and burn-pit emissions by US bases. Increases in congenital anomalies were reported from Iraqi cities post-2003. These cities were heavily bombed and encircled by US bases with burn-pits. Thorium is a radioactive compound and a direct depleted-uranium decay-product. Radioactive materials, including depleted uranium, are routinely stored in US bases and they have been shown to leak into the environment. We conducted a case-control study to investigate associations of residential proximity to Tallil Air Base, a US military base near Nasiriyah, as well as levels of uranium and thorium in hair and deciduous teeth with congenital anomalies. The study was based on a sample of 19 cases and 10 controls who were recruited during late Summer and early Fall of 2016. We developed mixed effects logistic regression models with village as the random effect, congenital anomaly as the outcome and distance to the US base and hair metal levels (one at a time) as the predictor variable, controlling for child's age, sex and paternal education. We also explored the mediation of the association between proximity to the base and congenital anomalies by hair metal levels. We found an inverse association between distance to Tallil Air Base and risk of congenital anomalies and hair levels of thorium and uranium. The results of our mediation analyses were less conclusive. Larger studies are necessary to understand the scope of war contamination and its impact on congenital anomalies in Iraq.

Environmental Arsenic Contamination and Its Effect on Intelligence Quotient of School Children in a Historic Gold Mining Area Hutti, North Karnataka, India: A Pilot Study

Context:

Arsenic is a rare crystal element that naturally occurs in all environmental media. A combination of regional and site-specific biogeochemical and hydrological factors governs its dispersion in the environment. It has far reaching consequences on human health. Exposure to arsenic in drinking water has been associated with a decline in intellectual function in children.

Aim:

The aim of this study is to assess the relationship between exposure to arsenic by drinking water and children's intelligence in Karnataka state, India.

Settings and Design:

Twenty school children of age 10–14 years from Sandur, Bellary, Karnataka, and from Hutti, Raichur, Karnataka, were categorized as control and study group, respectively.

Subjects and Methods:

Water samples were collected from both the villages for the analysis of arsenic and fluoride levels. Hair and nail samples were collected from the participants, and the arsenic levels were determined. Intelligence quotient (IQ) assessment was done using the Raven's Standard Progressive Matrices.

Statistical Analysis Used:

Chi-square test, Mann–Whitney U-test, and Fisher's exact test. P < 0.05 was considered statistically significant.

Results:

There was a significant increase in the arsenic content in the hair and nail samples of children in the study group. The mean IQ tests score in the control group and study group was 30.55 and 17.95, respectively, and this difference was statistically significant.

Conclusion:

Chronic arsenic exposure could be a possible cause for the reduced IQ scores seen in children residing in Hutti, Raichur District, North Karnataka.

A case-control analysis of maternal diet and risk of neural tube defects in Bangladesh

OBJECTIVES

Mothers need a nutrient-rich diet for healthy neural tube development. Neural tube defect risk can be reduced through fortifying grain products with folic acid and taking folic acid supplements. Fortification is not required in Bangladesh. Maternal supplement use rates are low, similar to other countries. This study evaluates maternal dietary intake during pregnancy to identify possible interventions.

METHODS

A food frequency questionnaire (FFQ) assessed maternal diet. The primary aim compared dietary intake (calories, fat, carbohydrate, protein, fiber, vitamins, and minerals) between mothers of infants with myelomeningocele (cases) and mothers of controls. Secondary aims included (i) comparing foods consumed and (ii) evaluating if rice intake correlated with arsenic exposure. Paired t-tests, Wilcoxon signed rank tests, McNemar's chi-squared test, and linear regression were used.

RESULTS

This study included 110 matched mother-infant pairs (55 cases/55 controls). Mothers of cases and mothers of controls had similar caloric intake [median 2406 kcal/day vs. 2196 kcal/day (p = 0.071)]. Mothers in both groups consumed less than half the daily recommended 600 μg of folate. Diets were potentially deficient in vitamins A, D, E, potassium, sodium, and iron. Steamed rice was the primary food consumed for both groups, and this rice intake was not associated with toenail arsenic.

CONCLUSIONS

Dietary interventions should increase folate, vitamins A, D, E, potassium, sodium, and iron intake in Bangladeshi mothers. Folic acid fortification of grain products maybe the only viable strategy to achieve adequate folate intake for mothers. Given the central role of rice to the Bangladeshi diet, fortifying rice may be a viable option.

Mediating role of arsenic in the relationship between diet and pregnancy outcomes: prospective birth cohort in Bangladesh

BACKGROUND

Epidemiological evidence suggests that arsenic (As) exposure during pregnancy may reduce infant birth weight. One significant source of As exposure is diet; thus, As may indirectly affect infant growth by mediating the effect of maternal diet on birth weight (BW). This study evaluated the potential mediating effect of As in the relationship between maternal diet and BW, gestational age (GA), and gestational weight gain (GWG).

METHOD

The study used a prospective birth cohort in Bangladesh that captured the dietary habits of 1057 pregnant women through validated semi-quantitative food frequency questionnaires. We applied a causal mediation model with counterfactual approach and performed analyses with and without adjustment for total energy intake. Other potential confounders captured by self-report questionnaire were exposure to secondhand tobacco smoke, betel nut chewing, maternal age, education level, household income level, physical activity level during pregnancy, and daily hours spent cooking over open fire.

RESULT

No association was found between maternal toenail As and BW. Higher absolute and energy-adjusted protein, fat and fiber intakes were associated with higher toenail As and lower GA and GWG, while higher absolute and energy-adjusted carbohydrate intake was associated with lower toenail As and greater GA and GWG. Mediation analysis showed significant natural indirect effects by toenail As in the relationships between absolute fat, carbohydrate and fiber intake with GA. Specifically, 3% (95% CI: 1-6%) of the association between carbohydrate intake and GA was mediated by change in toenail As, 6% (95% CI: 1-9%) for absolute fat intake and 10% (95% CI: 4-13%) for absolute fiber intake. After adjusting for total energy, no significant mediating effect was observed, suggesting the mediating effect might be due to measurement error or that absolute amount of As exposure rather than the amount in relationship to total energy intake was a more important factor to consider when understanding the negative implication of As on fetal growth.

CONCLUSION

The mediating effect of As in the relationship between maternal diet and birth outcome was small and might be due to measurement error.

Quantification of Methadone and Main Metabolites in Nails

The quantification of drugs of abuse in keratinized matrices is becoming of special relevance for monitoring consumption and for post-mortem investigations. We aimed to implement an analytical method for the simultaneous detection of morphine (MORF), 6-monoacetylmorphine (6-MAM), methadone (MET), 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenylpyrrolidine (EMDP) in nails. After decontamination, the nail samples (30 mg) were submitted to an alkaline digestion followed by a two-step liquid-liquid and SPE extraction using mixed-mode cation exchange cartridges. The analytes were eluted with 5% NH4OH/methanol. After derivatization with N-methyl-N-(trimethylsilyl) trifluoroacetamide, the analytes were quantified by gas chromatography-mass spectrometry. The method was optimized and fully validated only for MET, EDDP and EMDP, since for MOR and 6-MAM it was not possible to obtain adequate recovery rates after extraction, although detection of MOR was still possible. The method was selective, accurate and precise. Regression analysis demonstrated linearity over a concentration range of 20.8-333.3 ng/mg for MET and 10.4-166.7 ng/mg for EDDP and EMDP. Limits of detection and quantification values ranged from 3.3 to 6.0 ng/mg and 10.4 to 20.8 ng/mg, respectively, and recovery rates ranged from 82% to 98%. The applicability of the method was demonstrated by analyzing nail and urine samples obtained from heroin consumers under substitution therapy with MET.

Chronic arsenicosis and cadmium exposure in wild snowshoe hares (Lepus americanus) breeding near Yellowknife, Northwest Territories (Canada), part 1: Evaluation of oxidative stress, antioxidant activities and hepatic damage

Previous gold mining activities and arsenopyrite ore roasting activities at the Giant mine site (1948 to 2004) resulted in the release of high amounts of arsenic and trace metals into the terrestrial and aquatic ecosystems of Yellowknife, Northwest Territories, Canada. While elevated levels of arsenic has been consistently reported in surface soils and vegetation near the vicinity of the Giant mine area and in surrounding locations, systematic studies evaluating the overall health status of terrestrial small mammals endemic to the area are lacking. The purpose of this present study was to evaluate and comparatively assess the biochemical responses and histopathological effects induced by chronic arsenic and cadmium exposure in wild snowshoe hares breeding near the city of Yellowknife, specifically around the vicinity of the abandoned Giant mine site and in reference locations. Analysis included measurement of total arsenic and cadmium concentration in nails, livers, kidneys, bones, stomach content of hares, in addition to histopathological evaluation of hepatic and ocular lesions. Biochemical responses were determined through measurement of lipid peroxidation levels and antioxidant enzymes activities (catalase, superoxide dismutase, glutathione peroxidase, and glutathione disulfide). The results revealed that arsenic concentration was 17.8 to 48.9 times higher in the stomach content, and in the range of 4 to 23 times elevated in the nails of hares from the mine area compared to the reference location. Arsenic and cadmium levels were also noted to be increased in the bones, renal and hepatic tissues of hares captured near the mine area compared to the reference site. Specifically, hares from the mine area showed nail cadmium levels that was 2.3 to 17.6 times higher than those from the reference site. Histopathological examination of the eyes revealed no specific ocular lesions, such as lens opacity (cataracts) or conjunctivitis; however, hares from both locations exhibited hepatic steatosis (fatty liver change). Lipid peroxidation levels were relatively increased and accompanied with reduced antioxidant enzyme activities in hares from the mine area compared to the hares from the reference site. The results of this preliminary study suggest that the snowshoe hares breeding near the vicinity of Yellowknife, including near the Giant mine area have been chronically exposed to elevated levels of arsenic and cadmium, which consequently led to the increased levels of oxidative stress and perturbation of antioxidant defense system in exposed animals. The results of this present study constitute the first observation of chronic arsenicosis in wild small mammal species in Canada.

Prenatal arsenic exposure, child marriage, and pregnancy weight gain: Associations with preterm birth in Bangladesh

BACKGROUND

Preterm birth is a disease of multifactorial etiologies that has environmental, social, and maternal health components. Individual studies have shown that exposure to arsenic contaminated drinking water, child marriage, and low maternal weight gain during pregnancy contribute to preterm birth. These factors are highly prevalent and often co-exist in Bangladesh, a country in South Asia with one of the world's highest prevalences of preterm birth.

OBJECTIVE

To evaluate the individual and interactive effects of prenatal arsenic exposure, child marriage, and pregnancy weight gain on preterm birth in a prospective birth cohort in Bangladesh.

METHODS

During 2008-2011, we recruited 1613 pregnant women aged ≥18years at ≤16weeks of gestation and followed them until 1-month post-partum. We measured total arsenic in drinking water (n=1184) and in maternal toenails (n=1115) collected at enrollment and ≤1-month post-partum, respectively using inductively coupled plasma mass spectrometry. Child marriage (<18years old) was defined using self-report, and 2nd and 3rd trimester pregnancy weight gain was calculated using monthly records. Gestational age was determined at enrollment by ultrasound.

RESULTS

In multivariate adjusted Poisson regression models, the risk ratios (RR) for preterm birth were 1.12 (95% CI: 1.07-1.18) for a unit change in natural log water arsenic exposure, 2.28 (95% CI: 1.76-2.95) for child marriage, and 0.64 (95% CI: 0.42-0.97) for a pound per week increase in maternal weight during the 2nd and 3rd trimesters. In stratified analysis by child marriage, pregnancy weight gain was inversely associated with preterm birth among women with a history of child marriage (RR=0.58; 95% CI: 0.37-0.92), but not among women with no history of child marriage (RR=86; 95% CI: 0.37-2.01). Mediation analysis revealed that both arsenic exposure and child marriage had small but significant associations with preterm birth via lowering pregnancy weight gain. Similar associations were observed when arsenic exposure was assessed using maternal toenail arsenic concentrations.

CONCLUSIONS

Reducing arsenic exposure and ending child marriage could reduce the risk of preterm birth in Bangladesh. Furthermore, enhancing nutritional support to ensure adequate weight gain during pregnancy may provide additional benefits especially for women with a history of child marriage.

Investigating causal relation between prenatal arsenic exposure and birthweight: Are smaller infants more susceptible?

BACKGROUND

Shortening of gestation and intrauterine growth restriction (IUGR) are the two main determinants of birthweight. Low birthweight has been linked with prenatal arsenic exposure, but the causal relation between arsenic and birthweight is not well understood.

OBJECTIVES

We applied a quantile causal mediation analysis approach to determine the association between prenatal arsenic exposure and birthweight in relation to shortening of gestation and IUGR, and whether the susceptibility of arsenic exposure varies by infant birth sizes.

METHODS

In a longitudinal birth cohort in Bangladesh, we measured arsenic in drinking water (n=1182) collected at enrollment and maternal toenails (n=1104) collected ≤1-month postpartum using inductively coupled plasma mass spectrometry. Gestational age was determined using ultrasound at ≤16weeks' gestation. Demographic information was collected using a structured questionnaire.

RESULTS

Of 1184 singleton livebirths, 16.4% (n=194) were low birthweight (<2500g), 21.9% (n=259) preterm (<37weeks' gestation), and 9.2% (n=109) both low birthweight and preterm. The median concentrations of arsenic in drinking water and maternal toenails were 2.2μg/L (range: below the level of detection [LOD]-1400) and 1.2μg/g (range: <LOD-46.6), respectively. Prenatal arsenic exposure was negatively associated with birthweight, where the magnitude of the association varied across birthweight percentiles. The effect of arsenic on birthweight mediated via shortening of gestation affected all infants irrespective of birth sizes (β range: 10th percentile=-19.7g [95% CI: -26.7, -13.3] to 90th percentile=-10.9g [95% CI: -18.5, -5.9] per natural log water arsenic increase), whereas the effect via pathways independent of gestational age affected only the smaller infants (β range: 10th percentile=-28.0g [95% CI: -43.8, -9.9] to 20th percentile=-14.9g [95% CI: -30.3, -1.7] per natural log water arsenic increase). Similar pattern was observed for maternal toenail arsenic.

CONCLUSIONS

The susceptibility of prenatal arsenic exposure varied by infant birth sizes, placing smaller infants at greater risk of lower birthweight by shortening of gestation and possibly growth restriction. It is important to mitigate prenatal arsenic exposure to improve perinatal outcomes in Bangladesh.

Maternal and Cord Blood Manganese Concentrations and Early Childhood Neurodevelopment among Residents near a Mining-Impacted Superfund Site

BACKGROUND

Environmental manganese exposure has been associated with adverse neurodevelopmental outcomes among school-aged children; yet, few studies have evaluated prenatal exposure.

OBJECTIVES

Our study examines associations between prenatal manganese concentrations and placental transfer of manganese with neurodevelopment in 224 2-y-old children residing near the Tar Creek Superfund Site.

METHODS

We collected maternal and cord blood at delivery, measured manganese using inductively coupled plasma mass spectrometry, and assessed neurodevelopment using the Bayley Scales of Infant Development-II. Associations between manganese and mental (MDI) and psychomotor (PDI) development indices were estimated in multivariable models. Placental transfer, approximated by cord/maternal manganese ratio, cord/total manganese ratio (total=maternal+cord), and by joint classification according to high or low (above or below median) maternal and cord manganese, was evaluated as a predictor of neurodevelopment.

RESULTS

Median levels [interquartile ranges (IQR)] of manganese in maternal and cord blood, respectively, were 24.0 (19.5-29.7) and 43.1 (33.5-52.1) μg/L. Adjusting for lead, arsenic, and other potential confounders, an IQR increase in maternal manganese was associated with -3.0 (95% CI: -5.3, -0.7) points on MDI and -2.3 (95% CI: -4.1, -0.4) points on PDI. Cord manganese concentrations were not associated with neurodevelopment scores. Cord/maternal and cord/total manganese ratios were positively associated with MDI [cord/maternal: β=2.6 (95% Cl: −0.04, 5.3); cord/total: β=22.0 (95% Cl: 3.2, 40.7)] and PDI (cord/maternal: β=1.7 (95% Cl: −0.5, 3.9); cord/total: β=15.6 (95% Cl: 0.3, 20.9)). Compared to mother-child pairs with low maternal and cord manganese, associations with neurodevelopment scores were negative for pairs with either high maternal, high cord, or high maternal and cord manganese.

CONCLUSIONS

Maternal blood manganese concentrations were negatively associated with early childhood neurodevelopment scores in our study. Findings highlight the importance of understanding maternal exposures during pregnancy and factors influencing placental transfer. https://doi.org/10.1289/EHP925.

Maternal/fetal metabolomes appear to mediate the impact of arsenic exposure on birth weight: A pilot study

Arsenic exposure has been associated with low birth weight. However, the underlying mechanisms are not well understood. Alterations to metabolites may act as causal mediators of the effect of arsenic exposure on low birth weight. This pilot study aimed to explore the role of metabolites in mediating the association of arsenic exposure on infant birth weight. Study samples were selected from a well-established prospectively enrolled cohort in Bangladesh comprising 35 newborns and a subset of 20 matched mothers. Metabolomics profiling was performed on 35 cord blood samples and 20 maternal peripheral blood samples collected during the second trimester of pregnancy. Inorganic arsenic (iAs) exposure was evaluated via cord blood samples and maternal toenail samples collected during the first trimester. Multiple linear regression and mediation analyses were used to explore the relationship between iAs exposure, metabolite alterations, and low birth weight. Cord blood arsenic level was correlated with elevated levels of 17-methylstearate, laurate (12:0) and 4-vinylphenol sulfate along with lower birth weight. Prenatal maternal toenail iAs level was associated with two peripheral blood metabolites (butyrylqlycine and tartarate), which likely contributed to higher cord blood iAs levels both independently and interactively. Findings of this pilot study indicate that both intrauterine and maternal peripheral blood metabolites appear to influence the toxic effect of inorganic arsenic exposure on low birth weight.

Associations between Diet and Toenail Arsenic Concentration among Pregnant Women in Bangladesh: A Prospective Study

This prospective study evaluated the relationship between long-term dietary habits and total arsenic (As) concentration in toenail clippings in a cohort of 1616 pregnant women in the Bangladeshi administrative regions of Sirajdikhan and Pabna Sadar. Diet was assessed at Gestation Week 28 and at Postpartum Month 1, using a locally-validated dish-based semi-quantitative food-frequency questionnaire. Toenail As concentration was analyzed by microwave-assisted acid digestion and inductively coupled plasma mass spectrometry. Associations between natural log-transformed consumption of individual food items and temporally matched natural log-transformed toenail As concentration were quantified using general linear models that accounted for As concentration in the primary drinking water source and other potential confounders. The analysis was stratified by As in drinking water (≤50 μg/L versus >50 μg/L) and the time of dietary assessment (Gestation Week 28 versus Postpartum Week 1). Interestingly, toenail As was not significantly associated with consumption of plain rice as hypothesized. However, toenail As was positively associated with consumption of several vegetable, fish and meat items and was negatively associated with consumption of rice, cereal, fruits, and milk based food items. Further studies in pregnant women are needed to compare As metabolism at different levels of As exposure and the interaction between dietary composition and As absorption.

Associations between post translational histone modifications, myelomeningocele risk, environmental arsenic exposure, and folate deficiency among participants in a case control study in Bangladesh

Arsenic exposure may contribute to disease risk in humans through alterations in the epigenome. Previous studies reported that arsenic exposure is associated with changes in plasma histone concentrations. Posttranslational histone modifications have been found to differ between the brain tissue of human embryos with neural tube defects and that of controls. Our objectives were to investigate the relationships between plasma histone 3 levels, history of having an infant with myelomeningocele, biomarkers of arsenic exposure, and maternal folate deficiency. These studies took place in Bangladesh, a country with high environmental arsenic exposure through contaminated drinking water. We performed ELISA assays to investigate plasma concentration of total histone 3 (H3) and the histone modification H3K27me3. The plasma samples were collected from 85 adult women as part of a case-control study of arsenic and myelomeningocele risk in Bangladesh. We found significant associations between plasma %H3K27me3 levels and risk of myelomeningocele (P<0.05). Mothers with higher %H3K27me3 in their plasma had lower risk of having an infant with myelomeningocele (odds ratio: 0.91, 95% confidence interval: 0.84, 0.98). We also found that arsenic exposure, as estimated by arsenic concentration in toenails, was associated with lower total H3 concentrations in plasma, but only among women with folate deficiency (β = -9.99, standard error = 3.91, P=0.02). Our results suggest that %H3K27me3 in maternal plasma differs between mothers of infants with myelomeningocele and mothers of infants without myelomeningocele, and may be a marker for myelomeningocele risk. Women with folate deficiency may be more susceptible to the epigenetic effects of environmental arsenic exposure.

DNA Damage, Copper and Lead Associates with Cognitive Function among Older Adults

BACKGROUND

A cross sectional study was conducted in a group of 317 subjects older than 60 in Malaysia, aimed to determine risk factors associated with cognitive impairment in older adults, focusing on trace elements and DNA damage.

METHOD

Cognitive decline was determined by Montreal Cognitive Assessment (MoCA). Oxidative stress markers (malondialdehyde-MDA and superoxide dismutase-SOD) were determined and DNA damage was assayed using Alkaline Comet Assay. Toenail samples were taken and analyzed using ICP-MS to determine trace element levels.

RESULTS

A total of 62.1 % of subjects had cognitive impairment. Subjects with cognitive impairment had significantly higher levels of MDA and DNA damage as compared to the group with normal cognitive function; MDA (2.07 ± 0.05 nmol/L vs 1.85 ± 0.06 nmol/L) (p<0.05) and DNA damage (% Tail Density, 14.52 ± 0.32 vs 10.31 ± 0.42; Tail Moment, 1.79 ± 0.06 vs 1.28 ± 0.06) (p<0.05 for all parameters). However, the level of SOD among subjects with cognitive impairment (6.67 ± 0.33 u.e/min/mg protein) was lower than the level among those with normal cognitive functions (11.36 ± 0.65 u.e/min/mg protein) (p<0.05). Multiple logistic regression revealed the predictors for cognitive impairment among the subjects were DNA damage (Adjusted odd ratio [OR], 1.37; 95% confidence interval [CI], 1.18-1.59), level of trace elements in toenails namely, lead (OR, 2.471; CI, 1.535-3.980) and copper (OR, 1.275; CI, 1.047-1.552) (p<0.05).

CONCLUSION

High levels of lead and copper can lead to increase in oxidative stress levels and are associated with DNA damage that eventually could be associated with cognitive decline.

Structural and component mining of nails using bioengineering techniques

The human nail is one of the challenging membranes for the scientists to target and to improve the clinical efficacy of ungual formulations. The understanding of nail physiology, impact of hydration on its properties and presence of trace elements in nails as biomarkers has been explored by various researchers in clinical studies. Despite the importance of biophysical techniques for the assessment of structure and physiology of nail, minimum literature analyses biophysical, biochemical and bioanalytical approaches. However, nowadays scientists in bioengineering field are keen in developing non-invasive, reliable and reproducible techniques for the assessment of different anatomical and functional parameters of nails for testing of ungual products.

Prenatal Arsenic Exposure and Birth Outcomes among a Population Residing near a Mining-Related Superfund Site

BACKGROUND

Limited epidemiologic data exist on prenatal arsenic exposure and fetal growth, particularly in the context of co-exposure to other toxic metals.

OBJECTIVE

We examined whether prenatal arsenic exposure predicts birth outcomes among a rural U.S. population, while adjusting for exposure to lead and manganese.

METHODS

We collected maternal and umbilical cord blood samples at delivery from 622 mother-infant pairs residing near a mining-related Superfund site in Northeast Oklahoma. Whole blood arsenic, lead, and manganese were measured using inductively coupled plasma mass spectrometry. We modeled associations between arsenic concentrations and birth weight, gestational age, head circumference, and birth weight for gestational age.

RESULTS

Median (25th-75th percentile) maternal and umbilical cord blood metal concentrations, respectively, were as follows: arsenic, 1.4 (1.0-2.3) and 2.4 (1.8-3.3) μg/L; lead, 0.6 (0.4-0.9) and 0.4 (0.3-0.6) μg/dL; manganese, 22.7 (18.8-29.3) and 41.7 (32.2-50.4) μg/L. We estimated negative associations between maternal blood arsenic concentrations and birth outcomes. In multivariable regression models adjusted for lead and manganese, an interquartile range increase in maternal blood arsenic was associated with -77.5 g (95% CI: -127.8, -27.3) birth weight, -0.13 weeks (95% CI: -0.27, 0.01) gestation, -0.22 cm (95% CI: -0.42, -0.03) head circumference, and -0.14 (95% CI: -0.24, -0.04) birth weight for gestational age z-score units. Interactions between arsenic concentrations and lead or manganese were not statistically significant.

CONCLUSIONS

In a population with environmental exposure levels similar to the U.S. general population, maternal blood arsenic was negatively associated with fetal growth. Given the potential for relatively common fetal and early childhood arsenic exposures, our finding that prenatal arsenic can adversely affect birth outcomes is of considerable public health importance.

CITATION

Claus Henn B, Ettinger AS, Hopkins MR, Jim R, Amarasiriwardena C, Christiani DC, Coull BA, Bellinger DC, Wright RO. 2016. Prenatal arsenic exposure and birth outcomes among a population residing near a mining-related Superfund site. Environ Health Perspect 124:1308-1315; http://dx.doi.org/10.1289/ehp.1510070.

A cross sectional study of anemia and iron deficiency as risk factors for arsenic-induced skin lesions in Bangladeshi women

BACKGROUND

In the Ganges Delta, chronic arsenic poisoning is a health concern affecting millions of people who rely on groundwater as their potable water source. The prevalence of anemia is also high in this region, particularly among women. Moreover, arsenic is known to affect heme synthesis and erythrocytes and the risk of arsenic-induced skin lesions appears to differ by sex.

METHODS

We conducted a case-control study in 147 arsenic-exposed Bangladeshi women to assess the association between anemia and arsenic-induced skin lesions.

RESULTS

We observed that the odds of arsenic-related skin lesions were approximately three times higher among women who were anemic (hemoglobin < 120 g/L) compared to women with normal hemoglobin levels [Odds Ratio (OR) = 3.32, 95% Confidence Intervals (CI): 1.29, 8.52] after adjusting for arsenic levels in drinking water and other covariates. Furthermore, 75% of the women with anemia had adequate iron stores (serum ferritin ≥ 12 μg/L), suggesting that the majority of anemia detected in this population was unrelated to iron depletion.

CONCLUSIONS

Considering the magnitude of arsenic exposure and prevalence of anemia in Bangladeshi women, additional research is warranted that identifies the causes of anemia so that effective interventions can be implemented while arsenic remediation efforts continue.

Arsenic and Other Metals' Presence in Biomarkers of Cambodians in Arsenic Contaminated Areas

Chemical analyses of metal (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Ba, and Pb) concentrations in hair, nails, and urine of Cambodians in arsenic-contaminated areas who consumed groundwater daily showed elevated levels in these biomarkers for most metals of toxicological interest. The levels of metals in biomarkers corresponded to their levels in groundwater, especially for As, whose concentrations exceeded the WHO guidelines for drinking water. About 75.6% of hair samples from the population in this study contained As levels higher than the normal level in unexposed individuals (1 mg·kg⁻¹). Most of the population (83.3%) showed As urinary levels exceeding the normal (<50 ng·mg⁻¹). These results indicate the possibility of arsenicosis symptoms in residents of the areas studied. Among the three biomarkers tested, hair has shown to be a reliable indicator of metal exposures. The levels of As (r² = 0.633), Ba (r² = 0.646), Fe (r² = 0.595), and Mo (r² = 0.555) in hair were strongly positively associated with the levels of those metals in groundwater. In addition, significant weak correlations (p < 0.01) were found between levels of exposure to As and As concentrations in both nails (r² = 0.544) and urine (r² = 0.243).

Maternal-infant biomarkers of prenatal exposure to arsenic and manganese

Because arsenic (As) and manganese (Mn) are able to pass the placenta, infants among exposed populations may be exposed to considerable levels in utero. The main objective of this paper is to evaluate infant toenails, hair, and cord blood as biomarkers of prenatal exposure to As and Mn and determine the relationship between maternal and infant As and Mn concentrations in these biomarkers. Of the 1196 pregnant women in Bangladesh who were monitored throughout pregnancy until 1 month post-partum and completed all study visits, we included 711 mother-infant pairs who had at least one maternal and one infant biomarker of exposure available for analysis. Toenail and hair samples were collected from the women during the first trimester and 1 month post-partum and from the infants at the age of 1 month. Cord blood was collected at the time of delivery. Maternal toenail concentrations were correlated with infant toenail concentrations for As and Mn (n=258, r=0.52, 95% CI: 0.43-0.60, P<0.0001 and r=0.39, 95% CI: 0.28-0.49, P<0.0001), respectively. Similarly, maternal hair concentrations were correlated with infant hair As (n=685, r=0.61, 95% CI: 0.56-0.65, P<0.0001) and infant hair Mn (n=686, r=0.21, 95% CI: 0.14-0.28, P<0.0001). Cord blood As was correlated with infant toenail and hair As, although cord blood Mn was only correlated with infant toenail. Toenails and cord blood appear to be valid biomarkers of maternal-fetal transfer of As and Mn, whereas hair may not be a suitable biomarker for in utero exposure to Mn.

Arsenic exposure to drinking water in the Mekong Delta

Arsenic (As) contamination of groundwater drinking sources was investigated in the Mekong Delta, Vietnam in order to assess the occurrence of As in the groundwater, and the magnitude of As exposure of local residents through measurements of As in toenails of residents consuming groundwater as their major drinking water source. Groundwater (n=68) and toenail (n=62) samples were collected in Dong Thap Province, adjacent to the Mekong River, in southern Vietnam. Fifty-three percent (n=36) of the wells tested had As content above the World Health Organization's (WHO) recommended limit of 10 ppb. Samples were divided into Northern (mean As=4.0 ppb) and Southern (329.0 ppb) groups; wells from the Southern group were located closer to the Mekong River. Elevated As contents were associated with depth (<200 m), salinity (low salinity), and redox state (reducing conditions) of the study groundwater. In 79% of the wells, As was primarily composed of the reduced As(III) species. Arsenic content in nails collected from local residents was significantly correlated to As in drinking water (r=0.49, p<0.001), and the relationship improved for pairs in which As in drinking water was higher than 1 ppb (r=0.56, p<0.001). Survey data show that the ratio of As in nail to As in water varied among residents, reflecting differential As bioaccumulation in specific exposed sub-populations. The data show that water filtration and diet, particularly increased consumption of animal protein and dairy, and reduced consumption of seafood, were associated with lower ratios of As in nail to As in water and thus could play important roles in mitigating As exposure in areas where As-rich groundwater is the primary drinking water source.

Associations of total arsenic in drinking water, hair and nails with serum vascular endothelial growth factor in arsenic-endemic individuals in Bangladesh

Arsenic exposure is associated with cancer and vascular diseases. Angiogenesis is an important step for the pathological development of cancer and vascular diseases. Vascular endothelial growth factor (VEGF) is a specific marker for angiogenesis. However, human study showing the association between arsenic exposure and serum VEGF levels has not yet been documented. This study was aimed to investigate the association between arsenic exposure and serum VEGF levels in the arsenic-endemic individuals in Bangladesh. A total of 260 individuals were recruited for this study. Arsenic exposure levels were measured by ICP-MS and VEGF levels were quantified using VEGF immunoassay kit. The study subjects were stratified into tertile (low, medium and high) groups based on the arsenic in water, hair and nails. Serum VEGF levels were correlated with water (rs = 0.363, p < 0.001), hair (rs = 0.205, p < 0.01) and nail (rs = 0.190, p < 0.01) arsenic. Further, VEGF levels showed dose-response relationships with water, hair and nail arsenic. Mean VEGF levels in ⩽ 10 μg L(-1), 10.1-50 μg L(-1) and > 50 μg L(-1) groups were 91.84, 129.54, and 169.86 pg mL(-1), respectively, however, significant (p < 0.01) difference in VEGF levels was only found in > 50 μg L(-1) versus ⩽ 10 μg L(-1) groups. Significant associations of arsenic exposure with VEGF levels were found even after adjusting with relevant covariates. Therefore, these results provide evidence that arsenic exposure has a pro-angiogenic effect on humans, which may be implicated in arsenic-induced tumorigenesis and vascular diseases.

Urinary arsenic speciation profile in ethnic group of the Atacama desert (Chile) exposed to variable arsenic levels in drinking water

Ethnic groups from the Atacama Desert (known as Atacameños) have been exposed to natural arsenic pollution for over 5000 years. This work presents an integral study that characterizes arsenic species in water used for human consumption. It also describes the metabolism and arsenic elimination through urine in a chronically exposed population in northern Chile. In this region, water contained total arsenic concentrations up to 1250 μg L(-1), which was almost exclusively As(V). It is also important that this water was ingested directly from natural water sources without any treatment. The ingested arsenic was extensively methylated. In urine 93% of the arsenic was found as methylated arsenic species, such as monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)]. The original ingested inorganic species [As(V)], represent less than 1% of the total urinary arsenic. Methylation activity among individuals can be assessed by measuring primary [inorganic As/methylated As] and secondary methylation [MMA/DMA] indexes. Both methylation indexes were 0.06, indicating a high biological converting capability of As(V) into MMA and then MMA into DMA, compared with the control population and other arsenic exposed populations previously reported.

Human nail usage as a Bio-indicator in contamination monitoring of heavy metals in Dizajabaad, Zanjan province-Iran

BACKGROUND

Due to pedogeochemical background and anthropogenic sources, heavy metal contamination of soil is a widespread problem in some parts of Zanjan province located in North West Iran. In this study an affected area located near National Iranian Lead and Zinc Company (NILZ) was selected for detailed study.

METHODOLOGY

Thirty soil samples and eighteen leaf samples were collected and analyzed for heavy metal contamination by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Both soil and plant samples were found to be basically polluted by Pb (72.60 and 97.11), Zn (546.47 and 166.61), and Cd (1.80 and 1.55) mg. kg(-1) respectively. High concentrations of these elements in soil and plant species signifies possible health risks to humans. The distribution maps drawn using Arc GIS (10) show high concentrations of these toxic metals around Dizajabaad village. To assess vulnerability and health risks of metal concentrations in human bodies' twenty nine fingernail samples were also collected from people living in this village.

RESULTS AND DISCUSSION

Analysis for different heavy metal contents of nail samples reveals very high levels of the same toxic elements (Pb = 15.15, Cd = 1.18, As = 15.47, Zn = 68.46 and Ni = 18.22 mg. kg(-1)) compared with samples collected from an unaffected area and available values indicated in the literature. Further, high concentration of heavy metals in the nail samples suggests long term exposure of inhabitants to these toxic metals.

A cross-sectional study of well water arsenic and child IQ in Maine schoolchildren

BACKGROUND

In recent studies in Bangladesh and elsewhere, exposure to arsenic (As) via drinking water is negatively associated with performance-related aspects of child intelligence (e.g., Perceptual Reasoning, Working Memory) after adjustment for social factors. Because findings are not easily generalizable to the US, we examine this relation in a US population.

METHODS

In 272 children in grades 3-5 from three Maine school districts, we examine associations between drinking water As (WAs) and intelligence (WISC-IV).

RESULTS

On average, children had resided in their current home for 7.3 years (approximately 75% of their lives). In unadjusted analyses, household well WAs is associated with decreased scores on most WISC-IV Indices. With adjustment for maternal IQ and education, HOME environment, school district and number of siblings, WAs remains significantly negatively associated with Full Scale IQ and Perceptual Reasoning, Working Memory and Verbal Comprehension scores. Compared to those with WAs < 5 μg/L, exposure to WAs ≥ 5 μg/L was associated with reductions of approximately 5-6 points in both Full Scale IQ (p < 0.01) and most Index scores (Perceptual Reasoning, Working Memory, Verbal Comprehension, all p's < 0.05). Both maternal IQ and education were associated with lower levels of WAs, possibly reflecting behaviors (e.g., water filters, residential choice) limiting exposure. Both WAs and maternal measures were associated with school district.

CONCLUSIONS

The magnitude of the association between WAs and child IQ raises the possibility that levels of WAs ≥ 5 μg/L, levels that are not uncommon in the United States, pose a threat to child development.

Arsenic exposure of rural populations from the Rift Valley of Ethiopia as monitored by keratin in toenails

Arsenic (As) contamination of drinking water is a worldwide phenomenon whose effect among vulnerable and rural communities in the Rift Valley of Ethiopia in eastern Africa is not well studied. This study examines As exposure and bioaccumulation from drinking water by monitoring human keratin in the form of toenails from exposed populations. Groundwater samples from drinking water wells (n=34) were collected along with toenail samples (n=58) from local communities and were analyzed for trace metals including As by inductively coupled plasma mass spectrometry (ICP-MS). Of the total number of wells tested, 53% had As level above the WHO maximum contamination level of 10 p.p.b. Arsenic in toenails was significantly correlated to corresponding drinking water (r=0.72; R(2)=0.52; P<0.001). This correlation improves for drinking water with As concentrations above 2 p.p.b. (r=0.74; R(2)=0.54; P<0.001). Male minors (<18 years old) were found to have greater nail-As concentrations compared with adults consuming equal amounts of As (P<0.05). Estimated As dose specifically from drinking water sources was also associated with nail concentrations (P<0.01). We suggest that As measurement in nails could be a reliable method for detecting As exposure in residents living in rural areas.

Assessing arsenic exposure from consumption of seafood from Vieques-Puerto Rico: a pilot biomonitoring study using different biomarkers

The various toxic effects associated with inorganic arsenic (iAs) warrants that exposure sources be identified. This pilot study evaluated if greater seafood consumption from Vieques-Puerto Rico is associated with increased exposure to iAs. Nail, hair, and urine samples were used as biomarkers of iAs exposure in adult women and men from Vieques classified as high (n = 31) and low (n = 21) seafood consumers, who reported eating fish and/or shellfish ≥1 time per week and once per month or less, respectively. The sum of urinary iAs (As III + As V), monomethylarsonic acid (MA[V]), and dimethylarsinic acid (DMA[V]), denoted as SumAs, fluctuated from 3.3 µg/g Cr (1.2 μg/L) to 42.7 μg/g Cr (42 μg/L) (n = 52). Levels of As in nail samples (n = 49) varied from 0.04 to 0.82 μg/g dry weight (dw), whereas in hair (n = 49) As was only detected in 49 % of the samples with a maximum value of 0.95 μg/g dw. None of the biomarkers of exposure to As exceeded exposure reference values for urine (50 μg/g Cr or 50 μg/L), nails (1 μg/g), or hair (1 μg/g). However, median (10.0 μg/g Cr; 10.6 μg/L) and 95th percentile (31.9 μg/g Cr; 40.4 μg/L) of urinary SumAs were higher in Vieques samples than in the those from the general population of other countries. Among the three biomarkers of exposure, nail samples reflected better the exposure to iAs from seafood consumption with significantly higher average As concentrations in high (0.24 μg/g) than low (0.12 μg/g) seafood consumers. Multivariate results for As in nail samples (R(2) = 0.55, p < 0.0001) showed a positive association with fish consumption, particularly for men, with levels increasing with years of residency in Vieques.

Association of low to moderate levels of arsenic exposure with risk of type 2 diabetes in Bangladesh

Chronic exposure to high levels of arsenic in drinking water is associated with increased risk of type 2 diabetes mellitus (T2DM), but the association between lower levels of arsenic and T2DM is more controversial. Therefore, this study evaluated the association between low to moderate arsenic exposure and T2DM. In 2009-2011, we conducted a study of 957 Bangladeshi adults who participated in a case-control study of skin lesions in 2001-2003. The odds ratio of T2DM was evaluated in relationship to arsenic exposure measured in drinking water and in subjects' toenails (in 2001-2003) prior to the diagnosis of T2DM (in 2009-2011). Compared with those exposed to the lowest quartile of arsenic in water (≤ 1.7 µg/L), the adjusted odds ratio for T2DM was 1.92 (95% confidence interval (CI): 0.82, 4.35) for those in the second quartile, 3.07 (95% CI: 1.38, 6.85) for those in the third quartile, and 4.51 (95% CI: 2.01, 10.09) for those in the fourth quartile. The relative excess risk of T2DM was 4.78 for individuals who smoked and 8.93 for people who had a body mass index (weight (kg)/height (m)(2)) greater than 25. These findings suggest that exposure to modest levels of arsenic in drinking water was associated with increased risk of T2DM in Bangladesh. Being overweight or smoking was also associated with increased risk of T2DM.

Levels of metallic elements and their potential relationships to cognitive function among elderly from Federal Land Development Authority (FELDA) settlement in Selangor Malaysia

Exposure to toxic metals and excessive amount of trace elements is a risk factor of cognitive decline. Continuous monitoring of these elements by the use of metabolically inactive tissues such as fingernails may help in taking preventive measures to delay the cognitive decline process. In this study, the cognitive function of 54 elderlies (60-72 years old) from FELDA Sungai Tengi, Selangor, was evaluated using the Malay version of Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). The levels of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), lead (Pb), and zinc (Zn) in fingernail were detected using Inductively Coupled Plasma-Mass Spectrometry. Results showed that (92.6 %) our population was cognitively impaired based on the MoCA with mean score of 18.07 ± 5.11. The mean level of elements in fingernails for As, Cd, Cu, Mn, Pb, and Zn were 16.68 ± 3.52, 4.26 ± 0.91, 4.81 ± 1.16, 1.00 ± 0.23, 1.83 ± 0.47, and 40.86 ± 10.81 μg/g, respectively. Significant inverse correlations were observed between MoCA with age (r = -0.543, p < 0.01), Cu level (r = -0.330, p < 0.05), and Mn level (r = -0.496, p < 0.01). MMSE was correlated to age (r = -0.346, p < 0.05) only. In conclusion, besides aging, the progression of cognitive decline among the elderly FELDA population was associated with increased levels of copper and manganese.

Arsenic exposure and motor function among children in Bangladesh

BACKGROUND

Several reports indicate that drinking water arsenic (WAs) and manganese (WMn) are associated with children's intellectual function. Very little is known, however, about possible associations with other neurologic outcomes such as motor function.

METHODS

We investigated the associations of WAs and WMn with motor function in 304 children in Bangladesh, 8-11 years of age. We measured As and Mn concentrations in drinking water, blood, urine, and toenails. We assessed motor function with the Bruininks-Oseretsky test, version 2, in four subscales-fine manual control (FMC), manual coordination (MC), body coordination (BC), and strength and agility-which can be summarized with a total motor composite score (TMC).

RESULTS

Log-transformed blood As was associated with decreases in TMC [β = -3.63; 95% confidence interval (CI): -6.72, -0.54; p < 0.01], FMC (β = -1.68; 95% CI: -3.19, -0.18; p < 0.05), and BC (β = -1.61; 95% CI: -2.72, -0.51; p < 0.01), with adjustment for sex, school attendance, head circumference, mother's intelligence, plasma ferritin, and blood Mn, lead, and selenium. Other measures of As exposure (WAs, urinary As, and toenail As) also were inversely associated with motor function scores, particularly TMC and BC. Square-transformed blood selenium was positively associated with TMC (β = 3.54; 95% CI: 1.10, 6.0; p < 0.01), FMC (β = 1.55; 95% CI: 0.40, 2.70; p < 0.005), and MC (β = 1.57; 95% CI: 0.60, 2.75; p < 0.005) in the unadjusted models. Mn exposure was not significantly associated with motor function.

CONCLUSION

Our research demonstrates an adverse association of As exposure and a protective association of Se on motor function in children.

Human nails analysis as biomarker of exposure to perfluoroalkyl compounds

Extensive human exposure to perfluoroalkyl compounds (PFAA) together with their persistence and various toxicities have arisen increasing concern. A noninvasive method would improve exposure assessment for large population, especially the children susceptible to contaminants. The aim of the study was to assess the use of PFAA measurements in human nails as a biomarker of exposure to PFAAs. Fingernail, toenail, and blood samples were collected from 28 volunteers. The PFAA concentrations were determined by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Six PFAA were detected in nails, with perfluorooctane sulfonate (PFOS) being the compound with the highest median concentration (33.5 and 26.1 ng/g in fingernail and toenail, respectively). Followed was perfluorononanoate (PFNA), with the median concentrations of 20.4 and 16.8 ng/g, respectively, in fingernail and toenail. Other PFAA detected were perfluorooctanoate (PFOA), perfluorodecanoate (PFDA), perfluorododecanoate (PFDoA), and perfluorotetradecanoate (PFTA), with median levels ranging between 0.19 and 8.94 ng/g. PFOS and PFNA concentrations in fingernail significantly correlated with those in serum. Fingernail PFOS and PFNA levels were 2.8 and 24.4 times, respectively, higher than the serum levels. The accumulation of PFAA in nails, together with its advantages in noninvasive sampling and ability of reflecting long-term exposure, made nails PFAA an attractive biomarker of exposure.

Dose-response relationship between arsenic exposure and the serum enzymes for liver function tests in the individuals exposed to arsenic: a cross sectional study in Bangladesh

BACKGROUND

Chronic arsenic exposure has been shown to cause liver damage. However, serum hepatic enzyme activity as recognized on liver function tests (LFTs) showing a dose-response relationship with arsenic exposure has not yet been clearly documented. The aim of our study was to investigate the dose-response relationship between arsenic exposure and major serum enzyme marker activity associated with LFTs in the population living in arsenic-endemic areas in Bangladesh.

METHODS

A total of 200 residents living in arsenic-endemic areas in Bangladesh were selected as study subjects. Arsenic concentrations in the drinking water, hair and nails were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The study subjects were stratified into quartile groups as follows, based on concentrations of arsenic in the drinking water, as well as in subjects' hair and nails: lowest, low, medium and high. The serum hepatic enzyme activities of alkaline phosphatase (ALP), aspartate transaminase (AST) and alanine transaminase (ALT) were then assayed.

RESULTS

Arsenic concentrations in the subjects' hair and nails were positively correlated with arsenic levels in the drinking water. As regards the exposure-response relationship with arsenic in the drinking water, the respective activities of ALP, AST and ALT were found to be significantly increased in the high-exposure groups compared to the lowest-exposure groups before and after adjustments were made for different covariates. With internal exposure markers (arsenic in hair and nails), the ALP, AST and ALT activity profiles assumed a similar shape of dose-response relationship, with very few differences seen in the higher groups compared to the lowest group, most likely due to the temporalities of exposure metrics.

CONCLUSIONS

The present study demonstrated that arsenic concentrations in the drinking water were strongly correlated with arsenic concentrations in the subjects' hair and nails. Further, this study revealed a novel exposure- and dose- response relationship between arsenic exposure metrics and serum hepatic enzyme activity. Elevated serum hepatic enzyme activities in the higher exposure gradients provided new insights into arsenic-induced liver toxicity that might be helpful for the early prognosis of arsenic-induced liver diseases.

Trace elements in nails as biomarkers in clinical research

BACKGROUND

The importance of trace elements in relation to human health has been increasingly recognized. Accurate and adequate quantification of trace elements are crucial in clinical research.

DESIGN

This review was to discuss the rationale of using nail trace elements as biomarkers in clinical studies.

RESULTS

For most trace elements, dietary instruments cannot appropriately capture the intakes because of the minimal amounts and wide variations in the same foods grown in different area as well as the nondietary exposures. Therefore, biomarkers may be essential in studying trace elements. Although there are notable differences among trace elements in the availability of biomarkers, increasing evidence supports that nails, particularly toenail concentrations of most trace elements, are useful biomarkers of exposure in which a single sample is assumed to represent long-term exposure.

CONCLUSIONS

Compared with other potential biomarkers of trace elements, nail measurement has certain advantages in clinical research.

Collection of biological samples in forensic toxicology

Forensic toxicology is the study and practice of the application of toxicology to the purposes of the law. The relevance of any finding is determined, in the first instance, by the nature and integrity of the specimen(s) submitted for analysis. This means that there are several specific challenges to select and collect specimens for ante-mortem and post-mortem toxicology investigation. Post-mortem specimens may be numerous and can endow some special difficulties compared to clinical specimens, namely those resulting from autolytic and putrefactive changes. Storage stability is also an important issue to be considered during the pre-analytic phase, since its consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample. The knowledge on degradation mechanisms and methods to increase storage stability may enable the forensic toxicologist to circumvent possible difficulties. Therefore, advantages and limitations of specimen preservation procedures are thoroughfully discussed in this review. Presently, harmonized protocols for sampling in suspected intoxications would have obvious utility. In the present article an overview is given on sampling procedures for routinely collected specimens as well as on alternative specimens that may provide additional information on the route and timing of exposure to a specific xenobiotic. Last, but not least, a discussion on possible bias that can influence the interpretation of toxicological results is provided. This comprehensive review article is intented as a significant help for forensic toxicologists to accomplish their frequently overwhelming mission.

Monitoring exposure to heavy metals among children in Lake Victoria, Kenya: environmental and fish matrix

This study used hair and nails to biomonitor heavy metals (Pb, Cd, Cr and Cu) from geological source and exposure through regular fish consumption among children in Lake Victoria, Kenya. Concentration of Pb and Cu in water reflected anthropogenic pathways, while Cd and Cr reflected accumulation from the catchment basin. Higher concentration of heavy metals in the nails samples than the hair samples suggested longer term exposure. The estimated intake of Cd and Cr from fish in one site associated with high concentration of the metals from geological source was appreciably above the respective recommended daily allowance, signifying possible health risks to humans. Significant correlations between Pb, Cd and Cu in hair, nails and heavy metals from fish consumed suggested fish consumption as possible pathway of heavy metals in humans. Possible health risks from heavy metals were likely due to consumption of higher quantities of fish and from geological basins.

Association between arsenic exposure and plasma cholinesterase activity: a population based study in Bangladesh

BACKGROUND

Arsenic is a potent pollutant that has caused an environmental catastrophe in certain parts of the world including Bangladesh where millions of people are presently at risk due to drinking water contaminated by arsenic. Chronic arsenic exposure has been scientifically shown as a cause for liver damage, cancers, neurological disorders and several other ailments. The relationship between plasma cholinesterase (PChE) activity and arsenic exposure has not yet been clearly documented. However, decreased PChE activity has been found in patients suffering liver dysfunction, heart attack, cancer metastasis and neurotoxicity. Therefore, in this study, we evaluated the PChE activity in individuals exposed to arsenic via drinking water in Bangladesh.

METHODS

A total of 141 Bangladeshi residents living in arsenic endemic areas with the mean arsenic exposure of 14.10 +/- 3.27 years were selected as study subjects and split into tertile groups based on three water arsenic concentrations: low (< 129 microg/L), medium (130-264 microg/L) and high (> 265 microg/L). Study subjects were further sub-divided into two groups ( 50 microg/L) based on the recommended upper limit of water arsenic concentration (50 microg/L) in Bangladesh. Blood samples were collected from the study subjects by venipuncture and arsenic concentrations in drinking water, hair and nail samples were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PChE activity was assayed by spectrophotometer.

RESULTS

Arsenic concentrations in hair and nails were positively correlated with the arsenic levels in drinking water. Significant decreases in PChE activity were observed with increasing concentrations of arsenic in water, hair and nails. The average levels of PChE activity in low, medium and high arsenic exposure groups were also significantly different between each group. Lower levels of PChE activity were also observed in the > 50 microg/L group compared to the

CONCLUSIONS

We found a significant inverse relationship between arsenic exposure and PChE activity in a human population in Bangladesh. This research demonstrates a novel exposure-response relationship between arsenic and PChE activity which may explain one of the biological mechanisms through which arsenic exerts its neuro-and hepatotoxicity in humans.

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MESH Headings

• Adult
• Age Factors
• Arsenic/adverse effects
• Arsenic/analysis
• Arsenic/blood
• Arsenic Poisoning/diagnosis
• Bangladesh/epidemiology
• Cholinesterases/blood
• Cholinesterases/drug effects
• Environmental Exposure/adverse effects
• Female
• Hair/chemistry
• Humans
• Male
• Nails/chemistry
• Sex Factors
• Water Pollutants, Chemical/adverse effects
• Water Pollutants, Chemical/analysis
• Water Supply/analysis

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Affiliation(s)

Nurshad Ali Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Md Ashraful Hoque Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Abedul Haque Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Kazi Abdus Salam Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Md Rezaul Karim Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Aminur Rahman Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Khairul Islam Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Zahangir Alam Saud Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh
Md Abdul Khalek Department of Statistics, Rajshahi University, Rajshahi-6205, Bangladesh
Anwarul Azim Akhand Department of Genetic Engineering and Biotechnology, Dhaka University, Dhaka-1000, Bangladesh
Mostaque Hossain Department of Medicine, Rajshahi Medical College Hospital, Rajshahi-6000, Bangladesh
Abul Mandal School of Life Sciences, University of Skövde, PO Box 408, SE-541 28 Skövde, Sweden
Md Rezaul Karim Department of Applied Nutrition and Food Technology, Islamic University, Kushtia-7003, Bangladesh
Hideki Miyataka Laboratory of Molecular Nutrition and Toxicology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan
Seiichiro Himeno Laboratory of Molecular Nutrition and Toxicology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan
Khaled Hossain Department of Biochemistry and Molecular Biology, Rajshahi University, Rajshahi-6205, Bangladesh

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Maternal arsenic exposure and impaired glucose tolerance during pregnancy

BACKGROUND

Accumulating evidence has shown an increased risk of type 2 diabetes in general populations exposed to arsenic, but little is known about exposures during pregnancy and the association with gestational diabetes (GD).

OBJECTIVES

We studied 532 women living proximate to the Tar Creek Superfund Site to investigate whether arsenic exposure is associated with impaired glucose tolerance during pregnancy.

METHODS

Blood glucose was measured between 24 and 28 weeks gestation after a 1-hr oral glucose tolerance test (GTT) as part of routine prenatal care. Blood and hair were collected at delivery and analyzed for arsenic using inductively coupled plasma mass spectrometry with dynamic reaction cell.

RESULTS

Arsenic concentrations ranged from 0.2 to 24.1 microg/L (ppb) (mean +/- SD, 1.7 +/-1.5) and 1.1 to 724.4 ng/g (ppb) (mean +/- SD, 27.4 +/- 61.6) in blood and hair, respectively. One-hour glucose levels ranged from 40 to 284 mg/dL (mean +/- SD, 108.7 +/- 29.5); impaired glucose tolerance was observed in 11.9% of women when using standard screening criterion (> 140 mg/dL). Adjusting for age, Native-American race, prepregnancy body mass index, Medicaid use, and marital status, women in the highest quartile of blood arsenic exposure had 2.8 higher odds of impaired GTT than women in the lowest quartile of exposure (95% confidence interval, 1.1-6.9) (p-trend = 0.008).

CONCLUSIONS

Among this population of pregnant women, arsenic exposure was associated with increased risk of impaired GTT at 24-28 weeks gestation and therefore may be associated with increased risk of GD.

Arsenic in hair and nails of individuals exposed to arsenic-rich groundwaters in Kandal province, Cambodia

The health implications of the consumption of high arsenic groundwater in Bangladesh and West Bengal are well-documented, however, little is known about the level of arsenic exposure elsewhere in Southeast Asia, where widespread exploitation of groundwater resources is less well established. We measured the arsenic concentrations of nail and hair samples collected from residents of Kandal province, Cambodia, an area recently identified to host arsenic-rich groundwaters, in order to evaluate the extent of arsenic exposure. Nail and hair arsenic concentrations ranged from 0.20 to 6.50 microg g(-1) (n=70) and 0.10 to 7.95 microg g(-1) (n=40), respectively, in many cases exceeding typical baseline levels. The arsenic content of the groundwater used for drinking water purposes (0.21-943 microg L(-1) (n=31)) was positively correlated with both nail (r=0.74, p<0.0001) and hair (r=0.86, p<0.0001) arsenic concentrations. In addition, the nail and hair samples collected from inhabitants using groundwater that exceeded the Cambodian drinking water legal limit of 50 microg L(-1) arsenic contained significantly more arsenic than those of individuals using groundwater containing <50 microg L(-1) arsenic. X-ray absorption near edge structure (XANES) spectroscopy suggested that sulfur-coordinated arsenic was the dominant species in the bulk of the samples analysed, with additional varying degrees of As(III)-O character. Tentative linear least squares fitting of the XANES data pointed towards differences in the pattern of arsenic speciation between the nail and hair samples analysed, however, mismatches in sample and standard absorption peak intensity prevented us from unambiguously determining the arsenic species distribution. The good correlation with the groundwater arsenic concentration, allied with the relative ease of sampling such tissues, indicate that the arsenic content of hair and nail samples may be used as an effective biomarker of arsenic intake in this relatively recently exposed population.