Influence of folic acid and vitamin B12 supplementation on arsenic methylation: A double-blinded, placebo-controlled trial in Bangladeshi children.

BACKGROUND: Inorganic arsenic is metabolized to monomethyl- (MMAs) and dimethyl- (DMAs) species via one-carbon metabolism (OCM); this facilitates urinary arsenic elimination. OCM is influenced by folate and vitamin B12 and previous randomized control trials (RCTs) showed that folic acid (FA) supplementation increases arsenic methylation in adults. This RCT investigated the effects of FA + B12 supplementation on arsenic methylation in children, a key developmental stage where OCM supports growth. METHODS: A total of 240 participants (8-11 years, 53 % female) drinking from wells with arsenic concentrations > 50 µg/L, were encouraged to switch to low arsenic wells and were randomized to receive 400 µg FA + 5 µg B12 or placebo daily for 12-weeks. Urine and blood samples were collected at baseline, week 1 (only urine) and week 12. Generalized estimated equation (GEE) models were used to assess treatment effects on arsenic species in blood and urine. RESULTS: At baseline, the mean ± SD total blood and urinary arsenic were 5.3 ± 2.9 µg/L and 91.2 ± 89.5 µg/L. Overall, total blood and urine arsenic decreased by 11.7% and 17.6%, respectively, at the end of follow up. Compared to placebo, the supplementation group experienced a significant increase in the concentration of blood DMAs by 14.0% (95% CI 5.0, 25.0) and blood secondary methylation index (DMAs/MMAs) by 0.19 (95% CI: 0.09, 0.35) at 12 weeks. Similarly, there was a 1.62% (95% CI: 0.43, 20.83) significantly higher urinary %DMAs and -1.10% (95% CI: -1.73, -0.48) significantly lower urinary %MMAs in the supplementatio group compared to the placebo group after 1 week. The direction of the changes in the urinary %iAs, %MMAs, and %DMAs at week 12 were consistent with those at week 1, though estimates were not significant. Treatment effects were stronger among participants with higher baseline blood arsenic concentrations. Results were consistent across males and females, and participants with higher and lower folate and B12 status at baseline. CONCLUSION: This RCT confirms that FA + B12 supplementation increases arsenic methylation in children as reflected by decreased MMAs and increased DMAs in blood and urine. Nutritional interventions may improve arsenic methylation and elimination in children, potentially reducing arsenic toxicity while also improving nutritional status.

Elevated arsenic concentrations in groundwater of the Upper Indus Plain of Pakistan across a range of redox conditions.

Groundwater of the Ravi River floodplain is particularly elevated in arsenic (As) on both sides of the Pakistan-India border. To understand this pattern, 14 sites were drilled to 12-30 m depth across floodplains and doabs of Pakistan after testing over 20,000 wells. Drill cuttings were collected at 1.5 m intervals, 132 of which were sand overlain by 77 intervals of clay and/or silt. Radiocarbon dating of clay indicates deposition of the aquifer sands tapped by wells 20-30 kyr ago. Most (85 %) of the sand samples were gray in color, indicating partial reduction to Fe(II) oxides, whereas most (92 %) of the clay and/or silt samples were orange. Associations between groundwater electrical conductivity, dissolved Fe, sulfate, and nitrate suggest that wells can be elevated (>10 µg/L) in As in the region due to either reductive dissolution of Fe oxides, evaporative concentration, or alkali desorption. In the Ravi floodplain, 47 % of 6445 wells tested contain >10 µg/L As compared to only 9 % of 14,165 tested wells in other floodplains and doabs. The As content of aquifer sands in the Ravi floodplain of Pakistan averages 4 ± 4 mg/kg (n = 66) and is higher than the average of 2 ± 2 mg/kg (n = 51) for aquifer sands outside the Ravi. Synchrotron spectroscopy and column-based speciation indicate predominance of As(V) over As(III) in both aquifer sands and groundwater. Whereas multiple processes may be responsible for elevated levels of As in groundwater across the region, spatial heterogeneity in groundwater As concentrations in the Ravi floodplain seems linked to variations in As concentrations in aquifer sands. Regulation by the solid phase may limit variations in groundwater As over time in response to natural and human-induced changes in hydrology. This means spatial heterogeneity could be taken advantage of to lower the exposure across the region with more testing and targeted drilling.

Transient use of hemolymph for hydraulic wing expansion in cicadas.

Insect wings must be flexible, light, and strong to allow dynamic behaviors such as flying, mating, and feeding. When winged insects eclose into adults, their wings unfold, actuated hydraulically by hemolymph. Flowing hemolymph in the wing is necessary for functioning and healthy wings, both as the wing forms and as an adult. Because this process recruits the circulatory system, we asked, how much hemolymph is pumped into wings, and what happens to the hemolymph afterwards? Using Brood X cicadas (Magicicada septendecim), we collected 200 cicada nymphs, observing wing transformation over 2 h. Using dissection, weighing, and imaging of wings at set time intervals, we found that within 40 min after emergence, wing pads morphed into adult wings and total wing mass increased to ~ 16% of body mass. Thus, a significant amount of hemolymph is diverted from body to wings to effectuate expansion. After full expansion, in the ~ 80 min after, the mass of the wings decreased precipitously. In fact, the final adult wing is lighter than the initial folded wing pad, a surprising result. These results demonstrate that cicadas not only pump hemolymph into the wings, they then pump it out, producing a strong yet lightweight wing.

Groundwater fluoride across the Punjab plains of Pakistan and India: Distribution and underlying mechanisms.

Chronic exposure from drinking well-water with naturally high concentrations of fluoride (F-) has serious health consequences in several regions across the world including South Asia, where the rural population is particularly dependent on untreated groundwater pumped from private wells. An extensive campaign to test 28,648 wells was conducted across the Punjab plains of Pakistan and India by relying primarily on field kits to document the scale of the problem and shed light on the underlying mechanisms. Groundwater samples were collected from a subset of 712 wells for laboratory analysis of F- and other constituents. A handful of sites showing contrasting levels of F- in groundwater were also drilled to determine if the composition of aquifer sediment differed between these sites. The laboratory data show that the field kits correctly classified 91% of the samples relative to the World Health Organization guideline for drinking water of 1.5 mg/L F-. The kit data indicate that 9% of wells across a region extending from the Indus to the Sutlej rivers were elevated in F- relative to this guideline. Field data indicate an association between the proportion of well-water samples with F- > 1.5 mg/L and electric conductivity (EC) > 1.5 mS/cm across six floodplains and six intervening doabs. Low Ca2+ concentrations and elevated bicarbonate (HCO3- > 500 mg/L) and sodium (Na+ > 200 mg/L) in high F- groundwater suggest regulation by fluorite. This could be through either the lack of precipitation or the dissolution of fluorite regulated by the loss of Ca2+ from groundwater due to precipitation of calcite and/or ion exchange with clay minerals. Widespread salinization of Punjab aquifers attributed to irrigation may have contributed to higher F- levels in groundwater of the region. Historical conductivity data suggest salinization has yet to be reversed in spite of changes in water resources management.

Testing Homes for Potential Sources of Lead Exposure as a High-School Science Project.

High-school students tested soil, paint, and water for lead (Pb) in a total of 80 houses in their town of Pelham, New York, where blood-Pb data indicate relatively high levels of child exposure. All the samples were tested in the laboratory using established procedures but this was preceded by testing of soil and paint in the field with a kit by the students. The total Pb concentration in 32 of the 159 soil samples that were collected exceeded 400 ppm, the EPA standard for bare soil in residential areas where children play. Only 4 of the 118 tap water samples that were collected contained over 15 ppb Pb, with the data showing that flushing for 2 min clearly lowered Pb concentration further across the board. The highest risk of child exposure may be posed by old Pb-based paint, however, which was detected in 9 of the 48 samples that were tested. Residents were also the least willing to let the students test or sample their paint. High-school students could help reduce exposure in the many towns where child blood-Pb levels remain high today by identifying sources and, while doing so, learn about environmental science and measurement from this hands-on experience.

Recommended Sampling Intervals for Arsenic in Private Wells.

Geogenic arsenic in drinking water is a worldwide problem. For private well owners, testing (e.g., private or government laboratory) is the main method to determine arsenic concentration. However, the temporal variability of arsenic concentrations is not well characterized and it is not clear how often private wells should be tested. To answer this question, three datasets, two new and one publicly available, with temporal arsenic data were utilized: 6370 private wells from New Jersey tested at least twice since 2002, 2174 wells from the USGS NAWQA database, and 391 private wells sampled 14 years apart from Bangladesh. Two arsenic drinking water standards are used for the analysis: 10 µg/L, the WHO guideline and EPA standard or maximum contaminant level (MCL) and 5 µg/L, the New Jersey MCL. A rate of change was determined for each well and these rates were used to predict the temporal change in arsenic for a range of initial arsenic concentrations below an MCL. For each MCL and initial concentration, the probability of exceeding an MCL over time was predicted. Results show that to limit a person to below a 5% chance of drinking water above an MCL, wells that are ½ an MCL and above should be tested every year and wells below ½ an MCL should be tested every 5 years. These results indicate that one test result below an MCL is inadequate to ensure long-term compliance. Future recommendations should account for temporal variability when creating drinking water standards and guidance for private well owners.

Reduction of iron (hydr)oxide-bound arsenate: Evidence from high depth resolution sampling of a reducing aquifer in Yinchuan Plain, China.

Sediment in fluvial-deltaic plains with high-As groundwater is heterogenous but its characterization of As and Fe oxidation states lacks resolution, and is rarely attempted for aqueous and solid phases simultaneously. Here, we pair high-resolution (> 1 sample/meter) Fe extended fine-structure spectroscopy (EXAFS, n = 40) and As X-ray absorption near-edge spectroscopy (XANES, n = 49) with groundwater composition and metagenomics measurements for two sediment cores and their associated wells (n = 8) from the Yinchuan Plain in northwest China. At shallower depths, nitrate and Mn/Fe reducing sediment zones are fine textured, contain 9.6 ± 5.6 mg kg-1 of As(V) and 2.3 ± 2.7 mg kg-1 of As(III) with 9.1 ± 8.1 g kg-1 of Fe(III) (hydr)oxides, with bacterial genera capable of As and Fe reduction identified. In four deeper 10-m sections, sulfate-reducing sediments are coarser and contain 2.6 ± 1.3 mg kg-1 of As(V) and 1.1 ± 1.0 mg kg-1 of As(III) with 3.2 ± 2.6 g kg-1 of Fe(III) (hydr)oxides, even though groundwater As concentrations can exceed 200 µg/L, mostly as As(III). Super-enrichment of sediment As (42-133 mg kg-1, n = 7) at shallower depth is due to redox trapping during past groundwater discharge. Active As and Fe reduction is supported by the contrast between the As(III)-dominated groundwater and the As(V)-dominated sediment, and by the decreasing sediment As(V) and Fe(III) (hydr)oxides concentrations with depth.

Similar retardation of arsenic in gray Holocene and orange Pleistocene sediments: Evidence from field-based column experiments in Bangladesh.

Groundwater flow has the potential to introduce arsenic (As) in previously uncontaminated aquifers. The extent to which As transport is retarded by adsorption is particularly relevant in Bangladesh where low-As wells offer the best chance of reducing chronic exposure to As of a large rural population dependent on groundwater. In this study, column experiments were conducted with intact cores in the field to measure As retardation. Freshly collected cores of reduced iron (Fe-II) dominated gray sediment of Holocene age as well as oxidized Fe (III)-coated orange sediment of Pleistocene age were eluted at pore-water velocities of 40-230 cm/day with anoxic groundwater pumped directly from a well and containing 320 µg/L As. Up to 100 µg/L As was immediately released from gray sand but the main As breakthrough for both gray and orange sand occurred between 30 and 70 pore volumes, depending on flow rate. The early release of As from gray sand is attributed to the presence of a weakly bound pool of As. The sorption of As was kinetically limited in both gray and orange sand columns. We used a reversible multi-reaction transport model to simulate As breakthrough curves while keeping the model parameters as constant as possible. Contrary to the notion that dissolved As is sorbed more strongly to orange sands, we show that As was similarly retarded in both gray and orange sands in the field.

Soil arsenic but not rice arsenic increasing with arsenic in irrigation water in the Punjab plains of Pakistan.

AIM: Irrigating rice with groundwater can lead to As accumulation in soil and rice grains. Matched sets of irrigation water, paddy soil, and rice grains were collected to assess the scale of the problem in the Punjab plains of Pakistan. METHODS: From a total of 60 sites, irrigation water and rice grains as well as 103 soil samples were collected and analyzed in the laboratory. Irrigation water and 660 soil samples were also analyzed in the field using a field kit. RESULTS: Concentrations of As in irrigation water (65±32 µg/L) are higher in the floodplain of the Ravi River compared to the Chenab (13±9 µg/L) and Jhelum (4±5 µg/L) rivers, as well as the intervening Rechna (6±6 µg/L) and Chaj doabs (0.8±0.2 µg/L). Area-weighted mean soil As concentrations are 12±3 mg/kg along the Ravi, 8.9±2 and 8.1±2 mg/kg along the Chenab and Jhelum, respectively, and 6.2±0.2 mg/kg within the Rachna and 6.1±0.1 mg/kg in Chaj doabs. The As content of polished grains export-quality basmati rice of 0.09±0.05 mg/kg, however, is low across the entire area. CONCLUSIONS: Groundwater irrigation leads to elevated As concentrations in paddy soil of some rice-growing regions of Punjab but does not result in increased uptake of As in basmati rice grains.

Fallout of Lead Over Paris From the 2019 Notre-Dame Cathedral Fire.

The roof and spire of Notre-Dame cathedral in Paris that caught fire and collapsed on 15 April 2019 were covered with 460 t of lead (Pb). Government reports documented Pb deposition immediately downwind of the cathedral and a twentyfold increase in airborne Pb concentrations at a distance of 50 km in the aftermath. For this study, we collected 100 samples of surface soil from tree pits, parks, and other sites in all directions within 1 km of the cathedral. Concentrations of Pb measured by X-ray fluorescence range from 30 to 9,000 mg/kg across the area, with a higher proportion of elevated concentrations to the northwest of the cathedral, in the direction of the wind prevailing during the fire. By integrating these observations with a Gaussian process regression model, we estimate that the average concentration of Pb in surface soil downwind of the cathedral is 430 (95% interval, 300-590) mg/kg, nearly double the average Pb concentration in the other directions of 240 (95% interval, 170-320) mg/kg. The difference corresponds to an integrated excess Pb inventory within a 1 km radius of 1.0 (95% interval, 0.5-1.5) t, about 0.2% of all the Pb covering the roof and spire. This is over 6 times the estimated amount of Pb deposited downwind 1-50 km from the cathedral. To what extent the concentrated fallout within 1 km documented here temporarily exposed the downwind population to Pb is difficult to confirm independently because too few soil, dust, and blood samples were collected immediately after the fire.

Early life and adolescent arsenic exposure from drinking water and blood pressure in adolescence.

OBJECTIVES: Evidence of the association between inorganic arsenic (As) exposure, especially early-life exposure, and blood pressure (BP) in adolescence is limited. We examined the association of As exposure during early childhood, childhood, and adolescence with BP in adolescence. METHODS: We conducted a cross-sectional study of 726 adolescents aged 14-17 (mean 14.75) years whose mothers were participants in the Bangladesh Health Effects of Arsenic Longitudinal Study (HEALS). Adolescents' BP was measured at the time of their recruitment between December 2012 and December 2016. We considered maternal urinary As (UAs), repeatedly measured during childhood, as proxy measures of early childhood (<5 years old, A1) and childhood (5-12 years old, A2) exposure. Adolescents' current UAs was collected at the time of recruitment (14-17 years of age, A3). RESULTS: Every doubling of UAs at A3 and maternal UAs at A1 was positively associated with a difference of 0.7-mmHg (95% confidence interval [CI]: 0.1, 1.3) and a 0.7-mmHg (95% CI: 0.05, 1.4) in SBP, respectively. These associations were stronger in adolescents with a BMI above the median (17.7 kg/m2) than those with a BMI below the median (P for interaction = 0.03 and 0.03, respectively). There was no significant association between any of the exposure measures and DBP. The Weighted Quantile Sum (WQS) regression confirmed that adolescents' UAs at A3 and maternal UAs at A1 contributed the most to the overall effect of As exposure at three life stages on SBP. Mixture analyses using Bayesian Kernel Machine Regression identified UAs at A3 as a significant contributor to SBP and DBP independent of other concurrent blood levels of cadmium, lead, manganese, and selenium. CONCLUSION: Our findings suggest an association of current exposure and early childhood exposure to As with higher BP in adolescents, which may be exacerbated by higher BMI at adolescence.

A Field Procedure To Screen Soil for Hazardous Lead.

Soils retain lead contamination from possible sources such as mining, smelting, battery recycling, waste incineration, leaded gasoline, and crumbling paint. Such contamination is often concentrated in toxic hot spots that need to be identified locally. To address this need, a simple field procedure was designed to screen soil for hazardous Pb for use by the general public. The procedure is a modification of the in vitro soil Pb extraction described by Drexler and Brattin ( Hum. Ecol. Risk Assess. 2007, 13, 383 ) and EPA Method 1340, and uses a 0.4 M glycine solution at pH 1.5. A higher soil-to-solution ratio of 1:10 allows for classifying soil samples based on extractable Pb concentrations of <200 mg/kg (low), 200-400 mg/kg (medium), and >400 mg/kg (high) using sodium rhodizonate as a color indicator. The 1:10 soil-to-solution ratio also makes it possible to measure Pb concentrations in the glycine extract solutions on a continuous scale using a portable X-ray fluorescence analyzer. The procedure rather consistently extracts about one-third of the Pb extracted by the standard method across a wide range of Pb concentrations. Manufacturing the kit in larger quantities could reduce the cost of the materials well below the current $5/test.

Field testing of over 30,000 wells for arsenic across 400 villages of the Punjab plains of Pakistan and India: Implications for prioritizing mitigation.

Most of the rural population of 90 million in Punjab province in Pakistan and Punjab state in India drinks, and cooks with, untreated water drawn from shallow wells. Limited laboratory testing has shown that groundwater in the region can contain toxic levels of arsenic. To refine this assessment, a total of 30,567 wells from 383 villages were tested with a field kit in northern Punjab province of Pakistan and western Punjab state of India. A subset of 431 samples also tested in the laboratory show that 85% of wells were correctly classified by the kit relative to the World Health Organization guideline of 10 µg/L for arsenic in drinking water. The kit data show that 23% of the tested wells did not meet the WHO guideline for arsenic but also that 87% of households with a well high in arsenic live within 100 m of a well that meets the WHO guideline. The implication is that many households could rapidly lower their exposure if the subset of safe wells could be shared. In a follow-up conducted one year later in five villages where 59% of wells were elevated in arsenic, two-thirds of households indicated that they had switched to a neighboring well in response to the testing. The blanket testing of millions of wells for arsenic in the region should therefore be prioritized over much costlier water treatment and piped water supply projects that will take much longer to have a comparable impact.

Inversion of High-Arsenic Soil for Improved Rice Yield in Bangladesh.

Rice is the primary crop in Bangladesh, and rice yield is diminished due to the buildup of arsenic (As) in soil from irrigation with high-As groundwater. Implementing a soil inversion, where deeper low-As soil is exchanged with the surface high-As soil in contact with rice roots, may mitigate the negative impacts of As on yield. We compared soil As, soil nutrients, and rice yield in control plots with those in adjacent soil inversion plots. We also estimated the quantity of soil As deposited on a yearly basis via irrigation water, to explore the longevity of a soil inversion to reduce surface As. Soil As, organic carbon, nitrogen, and phosphorus concentrations decreased by about 40% in response to the inversion and remained lowered over four seasons of monitoring. Inversion plot yields increased above control plot yields by 15-30% after a one-season lag despite the recovering but still reduced nutrient levels. Farmers have started conducting soil inversions of their own volition, typically close to where irrigation water enters the field. However, the yield gain will be limited to a few decades at most due to deposition of As via well water, unless the field is irrigated with low-As river or pond water.

How Do You Deal With Uncertainty? Cochlear Implant Users Differ in the Dynamics of Lexical Processing of Noncanonical Inputs.

OBJECTIVES: Work in normal-hearing (NH) adults suggests that spoken language processing involves coping with ambiguity. Even a clearly spoken word contains brief periods of ambiguity as it unfolds over time, and early portions will not be sufficient to uniquely identify the word. However, beyond this temporary ambiguity, NH listeners must also cope with the loss of information due to reduced forms, dialect, and other factors. A recent study suggests that NH listeners may adapt to increased ambiguity by changing the dynamics of how they commit to candidates at a lexical level. Cochlear implant (CI) users must also frequently deal with highly degraded input, in which there is less information available in the input to recover a target word. The authors asked here whether their frequent experience with this leads to lexical dynamics that are better suited for coping with uncertainty. DESIGN: Listeners heard words either correctly pronounced (dog) or mispronounced at onset (gog) or offset (dob). Listeners selected the corresponding picture from a screen containing pictures of the target and three unrelated items. While they did this, fixations to each object were tracked as a measure of the time course of identifying the target. The authors tested 44 postlingually deafened adult CI users in 2 groups (23 used standard electric only configurations, and 21 supplemented the CI with a hearing aid), along with 28 age-matched age-typical hearing (ATH) controls. RESULTS: All three groups recognized the target word accurately, though each showed a small decrement for mispronounced forms (larger in both types of CI users). Analysis of fixations showed a close time locking to the timing of the mispronunciation. Onset mispronunciations delayed initial fixations to the target, but fixations to the target showed partial recovery by the end of the trial. Offset mispronunciations showed no effect early, but suppressed looking later. This pattern was attested in all three groups, though both types of CI users were slower and did not commit fully to the target. When the authors quantified the degree of disruption (by the mispronounced forms), they found that both groups of CI users showed less disruption than ATH listeners during the first 900 msec of processing. Finally, an individual differences analysis showed that within the CI users, the dynamics of fixations predicted speech perception outcomes over and above accuracy in this task and that CI users with the more rapid fixation patterns of ATH listeners showed better outcomes. CONCLUSIONS: Postlingually deafened CI users process speech incrementally (as do ATH listeners), though they commit more slowly and less strongly to a single item than do ATH listeners. This may allow them to cope more flexible with mispronunciations.

Does Involving Parents in Soil Sampling Identify Causes of Child Exposure to Lead? A Case Study of Community Engagement in Mining-Impacted Towns in Peru.

Over a million people in Peru may be exposed to lead (Pb) due to past or present mining-related activities; however, neither soil Pb nor blood Pb are routinely monitored throughout the country. Because little is known about Pb contamination in smaller mining-impacted towns, soil Pb was mapped in four such towns with a portable X-ray fluorescence analyzer in 2015. The roadside mapping delineated hotspots of highly contaminated soil (1,000-6,000 mg/kg Pb) in two of the towns. The local health department, provided with a LeadCare II analyzer, then measured blood-Pb levels >5 in 65% and >10 µg/dL in 15% of children (n = 200) up to 6 years of age in these same four communities. There were no clear relations between child blood-Pb levels and Pb levels in soil samples collected inside (n = 50) or outside the home (n = 50). Increased child blood Pb was associated with decreased level of cleanliness of parent clothing (n = 136) and shoes (n = 138), linking a possible behavioral factor for transferring contaminated soil and dust to children. In order to explore individual exposure and variations in soil Pb, 10 parents of children with blood Pb >10 µg/dL and 10 parents of children with blood Pb <5 µg/dL were invited to collect soil samples in areas where their children play and screen it for Pb using a color-based field procedure. Importantly, parents identified a new hotspot of Pb contamination that had been missed by the previous portable X-ray fluorescence soil mapping. The findings highlight the feasibility and value of involving families impacted by environmental contamination to identify and reduce environmental health risk.

Urinary metals and metal mixtures in Bangladesh: Exploring environmental sources in the Health Effects of Arsenic Longitudinal Study (HEALS).

INTRODUCTION: Environmental exposure to toxic metals and metalloids is pervasive and occurs from multiple sources. The Health Effects of Arsenic Longitudinal Study (HEALS) is an ongoing prospective study predominantly focused on understanding health effects associated with arsenic exposure from drinking water. The goal of this project was to measure a suite of elements in urine to better understand potential exposure patterns and to identify common environmental sources of exposure among this semi-rural Bangladeshi population. METHODS: In a random sample of 199 adult HEALS participants (50% female), the concentrations of 15 urinary elements (As, Ba, Cd, Co, Cs, Cu, Mn, Mo, Ni, Pb, Se, Sr, Tl, W, Zn) were assessed by Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) to assess commonalities with sociodemographic characteristics and potential sources of exposure. We used principal component analysis (PCA) with varimax normalized rotations, and hierarchical cluster analysis (CA), using Ward's method with Euclidean distances, to evaluate these relationships. RESULTS: PCA and CA showed similar patterns, suggesting 6 principal components (PC) and 5 clusters: 1)PC: Sr-Ni-Cs/ CA: Sr-Ni-Co; 2) Pb-Tl/Pb-Tl-Se-Cs; 3) As-Mo-W/As-Mo-W; 4) Ba-Mn/Ba-Mn; 5) Cu-Zn/Cu-Zn-Cd; and 6) Cd. There was a strong significant association between the As-Mo-W PC/cluster and water arsenic levels (p < 0.001) and between the Cd PC and betel nut use (p = 0.003). The Sr-Ni-Cs PC was not related to any of the socio-demographic characteristics investigated, including smoking status and occupation. The first PC, Sr-Ni-Cs, explained 21% of the variability; the third PC, As-Mo-W, explained 12.5% of the variability; and the sixth PC, Cd, explained 10% of the variability. Day laborers appeared to have the highest exposure. CONCLUSIONS: Groundwater and betel nut use are likely important sources of metal and metalloid exposure in this population. These findings will guide future exposure assessment research in Bangladesh and future epidemiologic research investigating the degree to which metal mixtures play a role in disease development.

A cross-sectional study of water arsenic exposure and intellectual function in adolescence in Araihazar, Bangladesh.

BACKGROUND: Exposure to inorganic arsenic (As) from drinking water is associated with modest deficits in intellectual function in young children; it is unclear whether deficits occur during adolescence, when key brain functions are more fully developed. OBJECTIVES: We sought to determine the degree to which As exposure is associated with adolescent intelligence, and the contributory roles of lead, cadmium, manganese and selenium. METHODS: We recruited a cross-section of 726 14-16 year olds (mean age = 14.8 years) whose mothers are participants in the Bangladesh Health Effects of Arsenic Longitudinal Study (HEALS), and whose household well water As levels, which varied widely, were well characterized. Using a culturally modified version of the WISC-IV, we examined raw Full Scale scores, and Verbal Comprehension, Perceptual Reasoning, Working Memory and Processing Speed Indices. Blood levels of As (BAs), Mn, Pb, Cd and Se were assessed at the time of the visit, as was creatinine-adjusted urinary As (UAs/Cr). RESULTS: Linear regression analyses revealed that BAs was significantly negatively associated with all WISC-IV scores except for Perceptual Reasoning. With UAs/Cr as the exposure variable, we observed significantly negative associations for all WISC-IV scores. Except for Se, blood levels of other metals, were also associated with lower WISC-IV scores. Controlling for covariates, doubling BAs, or UAs/Cr, was associated with a mean decrement (95% CI) of 3.3 (1.1, 5.5), or 3.0 (1.2, 4.5) points, respectively, in raw Full scale scores with a sample mean of 177.6 (SD = 36.8). Confirmatory analyses using Bayesian Kernel Machine Regression, which identifies important mixture members, supported these findings; the primary contributor of the mixture was BAs, followed by BCd. CONCLUSIONS: Our data indicate that the adverse consequences of As exposure on neurodevelopment observed in other cross-sectional studies of younger children are also apparent during adolescence. They also implicate Cd as a neurotoxic element that deserves more attention.

A giant planet undergoing extreme-ultraviolet irradiation by its hot massive-star host.

The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extrasolar planets now known, only six have been found that transit hot, A-type stars (with temperatures of 7,300-10,000 kelvin), and no planets are known to transit the even hotter B-type stars. For example, WASP-33 is an A-type star with a temperature of about 7,430 kelvin, which hosts the hottest known transiting planet, WASP-33b (ref. 1); the planet is itself as hot as a red dwarf star of type M (ref. 2). WASP-33b displays a large heat differential between its dayside and nightside, and is highly inflated-traits that have been linked to high insolation. However, even at the temperature of its dayside, its atmosphere probably resembles the molecule-dominated atmospheres of other planets and, given the level of ultraviolet irradiation it experiences, its atmosphere is unlikely to be substantially ablated over the lifetime of its star. Here we report observations of the bright star HD 195689 (also known as KELT-9), which reveal a close-in (orbital period of about 1.48 days) transiting giant planet, KELT-9b. At approximately 10,170 kelvin, the host star is at the dividing line between stars of type A and B, and we measure the dayside temperature of KELT-9b to be about 4,600 kelvin. This is as hot as stars of stellar type K4 (ref. 5). The molecules in K stars are entirely dissociated, and so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. Furthermore, KELT-9b receives 700 times more extreme-ultraviolet radiation (that is, with wavelengths shorter than 91.2 nanometres) than WASP-33b, leading to a predicted range of mass-loss rates that could leave the planet largely stripped of its envelope during the main-sequence lifetime of the host star.