Lead, Soils, and Children: An Ecological Analysis of Lead Contamination in Parks and Elevated Blood Lead Levels in Brooklyn, New York.

Although the prevalence of elevated childhood blood lead levels (BLLs) has been declining, there are still an estimated 500,000 children (1 to 5 years) with BLLs above the CDC's reference value (≥ 5 µg/dL). The objective of this study was to evaluate the ecological association between soil lead (Pb) concentrations in greenspaces in Brooklyn, NY and elevated BLLs of children aged 1 to 5 years old. Soil samples (n = 1504) were collected from a wide variety of parks within 43 neighborhood tabulation areas (NTAs) located in Brooklyn, NY, analyzed with a portable XRF with a subset (n = 350), and also analyzed by ICP-MS. Lead concentrations were right skewed with a mean of 160.4 ppm and a median of 113.1 ppm. The Pb concentration range spanned three orders of magnitude with most samples (66.7%) ≥ 80 ppm and 6.7% of samples ≥ 400 ppm. Elevated BLL (≥ 5ug/dL) data on children 1 to 5 years were obtained from the New York City Department of Health and Mental Hygiene (2011-2015). Weighted median soil Pb concentrations were calculated for each NTA and stratified into quartiles. The overall median rate of children from 1 to 5 years old with BLLs ≥ 5 µg/dL was 28.6 per 1000; the median rate was highest (p = 0.070) in the fourth quartile (Pb concentrations ≥ 150 ppm) compared to the first quartile (Pb concentrations < 88 ppm), 37.2 vs. 28.3 per 1000, respectively. We then used multivariable linear regression to determine the ecological association between BLL rates and soil Pb concentrations. In the final stepwise multivariable regression model, controlling for known risk factors, there was a significant positive association between soil Pb concentrations and increased childhood BLL rates (beta = 0.0008; p = 0.004). Our findings suggest that there is an ecological association between high soil Pb levels and increased rates of elevated childhood BLLs.

Soil lead (Pb) and urban grown lettuce: Sources, processes, and implications for gardener best management practices.

Urban community gardeners employ a range of best practices that limit crop contamination by toxicants like lead (Pb). While Pb root uptake is generally low, the relative significance of various Pb deposition processes and the effectiveness of best practices in reducing these processes have not been sufficiently characterized. This study compared leafy lettuce (Lactuca sativa) grown in high Pb (1150 mg/kg) and low Pb (90 mg/kg) soils, under three different soil cover conditions: 1) bare soil, 2) mulch cover to limit splash, and 3) mulch cover under hoophouses to limit splash and air deposition, in a New York City (NYC) community garden and a rural site in Ithaca, New York (NY). The lettuces were further compared to greenhouse (Ithaca) and supermarket (NYC) samples. Atmospheric deposition was monitored by passive trap collection through funnel samplers. Results show that in low Pb soils, splash and atmospheric deposition accounted for 84 and 78% of lettuce Pb in NYC and Ithaca, respectively. In high Pb soils, splash and atmospheric deposition accounted for 88 and 93% of Pb on lettuces, with splash being the dominant mechanism. Soil covers were shown to be effective at significantly (p < 0.05) reducing lettuce Pb contamination, and mulching is strongly recommended as a best practice.

The limits of lead (Pb) phytoextraction and possibilities of phytostabilization in contaminated soil: a critical review.

This review article focuses on lead (Pb), one of the most ubiquitous and harmful toxicants found in soil. Our objective is to address misconceptions regarding the ability of plants to uptake Pb through their roots and translocate it to above-ground tissues, and their ability to act as hyperaccumulators and thereby phytoextract Pb. In accordance with a number of cited definitions, we suggest that species capable of Pb phytoextraction can be rated with the following three criteria: (1) root uptake above a nominal threshold of 1,000 mg Pb/kg, (2) bioconcentration factor (BCF or shoot/soil concentration) >1, and (3) translocation factor (TF or shoot/root concentration) > 1. We review the literature in the updated USDA Phytoremediation Database and conclude that without amendments: no plant has met all three criteria; no plant has been confirmed as a Pb hyperaccumulator. Our analysis suggests that Pb phytoextraction is not a viable remediation option. Pb phytostabilization, however, may be an effective remediation tool in a variety of settings. Planting some of the many species capable of tolerating soil Pb exposure and sequestering it in or around the root zone will limit Pb movement into other ecosystems, prevent resuspended dusts, and mitigate Pb exposure.

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.

Sediment exchange to mitigate pollutant exposure in urban soil.

Urban soil is an ongoing source for lead (Pb) and other pollutant exposure. Sources of clean soil that are locally-available, abundant and inexpensive are needed to place a protective cover layer over degraded urban soil to eliminate direct and indirect pollutant exposures. This study evaluates a novel sediment exchange program recently established in New York City (NYC Clean Soil Bank, CSB) and found that direct exchange of surplus sediment extracted from urban construction projects satisfies these criteria. The CSB has high total yield with 4.2 × 105 t of sediment exchanged in five years. Average annual yield (8.5 × 104 t yr-1) would be sufficient to place a 15-cm (6-in.) sediment cover layer over 3.2 × 105 m2 (80 acres) of impacted urban soil or 1380 community gardens. In a case study of sediment exchange to mitigate community garden soil contamination, Pb content in sediment ranged from 2 to 5 mg kg-1. This sediment would reduce surface Pb concentrations more than 98% if it was used to encapsulate soil with Pb content exceeding USEPA residential soil standards (400 mg kg-1). The maximum observed sediment Pb content is a factor of 42 and 71 lower than median surface soil and garden soil in NYC, respectively. All costs (transportation, chemical testing, etc.) in the CSB are paid by the donor indicating that urban sediment exchange could be an ultra-low-cost source for urban soil mitigation. Urban-scale sediment exchange has advantages over existing national- or provincial-scale sediment exchanges because it can retain and upcycle local sediment resources to attain their highest and best use (e.g. lowering pollutant exposure), achieve circular urban materials metabolism, improve livability and maximize urban sustainability.

Bioavailability-Based In Situ Remediation To Meet Future Lead (Pb) Standards in Urban Soils and Gardens.

Recently the Centers for Disease Control and Prevention lowered the blood Pb reference value to 5 µg/dL. The lower reference value combined with increased repurposing of postindustrial lands are heightening concerns and driving interest in reducing soil Pb exposures. As a result, regulatory decision makers may lower residential soil screening levels (SSLs), used in setting Pb cleanup levels, to levels that may be difficult to achieve, especially in urban areas. This paper discusses challenges in remediation and bioavailability assessments of Pb in urban soils in the context of lower SSLs and identifies research needs to better address those challenges. Although in situ remediation with phosphate amendments is a viable option, the scope of the problem and conditions in urban settings may necessitate that SSLs be based on bioavailable rather than total Pb concentrations. However, variability in soil composition can influence bioavailability testing and soil amendment effectiveness. More data are urgently needed to better understand this variability and increase confidence in using these approaches in risk-based decision making, particularly in urban areas.

Comparison of ATR-FTIR and NIR spectroscopy for identification of microplastics in biosolids.

Biosolids are considered a potentially major input of microplastics (MPs) to agricultural soils. Our study aims to identify the polymeric origin of MPs extracted from biosolid samples by comparing their Attenuated Total Reflection (ATR) - Fourier-transform infrared (FTIR) spectra with the corresponding near-infrared (NIR) spectra. The reflectance spectra were preprocessed by Savitzky-Golay (SG), first derivative (FD) and compared with analogous spectra acquired on a set of fifty-two selected commercial plastic (SCP) materials collected from readily available products. According to the results portrayed in radar chart and built from both ATR-FTIR and NIR spectral datasets, the MPs showed high correlations with polymers such as polyethylene (LDPE, HDPE), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP) and polyamide (PA), determined in SCP samples. Each unknown MP sample had on average three or more links to several types of SCP, according to the correlation coefficients for each polymer ranging from 0.7 up to 1. The comparison analysis classified the majority of MPs as composed mainly by LDPE/HDPE, according to the top correlation coefficients (r > 0.90). PP and PET were better identified with NIR than ATR-FTIR. In contrast to ATR-FTIR analysis, NIR was unable to identify PS. Based on these results, the primary sources of MPs in the biosolids could be identified as discarded consumer packaging (containers, bags, bottles) and fibers from laundry, disposable glove, and cleaning cloth. SYNOPSIS: Microplastics (MPs) are considered contaminants of emerging concern. This study compares two simple and fast spectroscopy techniques to identify microplastics in the biosolid matrix.

Bioaccessibility of arsenic in various types of rice in an in vitro gastrointestinal fluid system.

Rice can be a major contributor to dietary arsenic exposure because of the relatively high total arsenic concentration compared to other grains, especially for people whose main staple is rice. This study employed in vitro gastrointestinal fluid digestion to determine bioaccessible or gastrointestinal fluid extractable arsenic concentration in rice. Thirty-one rice samples, of which 60 % were grown in the United States, were purchased from food stores in New York City. Total arsenic concentrations in these samples ranged from 0.090 ± 0.004 to 0.85 ± 0.03 mg/kg with a mean value of 0.275 ± 0.161 mg/kg (n = 31). Rice samples with relatively high total arsenic (>0.20 mg/kg, n = 18) were treated by in vitro artificial gastrointestinal fluid digestion, and the extractable arsenic ranged from 53 % to 102 %. The bioaccessibility of arsenic in rice decreases in the general order of extra long grain, long grain, long grain parboiled, to brown rices.

Prediction of bioaccessible lead in urban and suburban soils with Vis-NIR diffuse reflectance spectroscopy.

The successful use of visible and near-infrared (Vis-NIR) reflectance spectroscopy analysis requires selecting an optimal procedure of data acquisition and an accurate modeling approach. In this study, Vis-NIR with 350-2500 nm wavelengths were applied to detect different forms of lead (Pb) through the spectrally active soil constituents combining principal component regression (PCR) and Partial least-square regression (PLSR) for the Vis-NIR model calibration. Three clouds with different soil spectral properties were divided by the Linear discriminant analysis (LDA) in categories of Pb contamination risks: "low," "health," "ecological," ranging from 200 to 750 mg kg-1. Farm soils were used for calibration (n = 26), and more polluted garden soils (n = 36) from New York City were used for validation. Total and bioaccessible Pb concentrations were examined with PLSR models and compared with Support Vector Machine (SVM) Regression and Boosting Regression Tree (BRT) models. Performances of all models' predictions were qualitatively evaluated by the Root Mean Square Error (RMSE), Residual Prediction Deviation (RPD), and coefficient of determination (R2). For total Pb, the best predictive models were obtained with BRT (R2 = 0.82 and RMSE 341.80 mg kg-1) followed by SVM (validation, R2 = 0.77 and RMSE 337.96 mg kg-1), and lastly by PLSR (validation, R2 = 0.74 and RMSE 499.04 mg kg-1). The PLSR technique is the most accurate calibration model for bioaccessible Pb with an R2 value of 0.91 and RMSE of 68.27 mg kg-1. The regression analysis indicated that bioaccessible Pb is strongly influenced by organic content, and to a lesser extent, by Fe concentrations. Although PLSR obtained lower accuracy, the model selected many characteristic bands and, thus, provided accurate approach for Pb pollution monitoring.

Effectiveness of washing in reducing lead concentrations of lettuce grown in urban garden soils.

Urban gardeners contribute to sustainable cities and often take great care to limit exposure to soil contaminants like lead (Pb). Although best management practices (BMPs) like mulching to reduce soil splash can limit crop contamination, they may not eliminate all contamination for leafy greens, which trap soil particles. How effective is washing at removing Pb contamination from leafy greens when using BMPs? Are certain washing techniques more effective than others? We present results from two experiments addressing these questions. We grew lettuce (Lactuca sativa L.) in homogenized high-Pb (∼1,150 mg kg-1 ) and low-Pb (∼90 mg kg-1 ) soils in Brooklyn, NY, and Ithaca, NY. Our results show that washing can remove 75-94% of Pb from lettuce, including that remaining after the use of contamination-reducing BMPs. It was estimated that washing removed 97% of Pb deposited by splash, which is the dominant source of Pb, and removed 91% deposited by downward deposition. All washing techniques were effective at reducing Pb levels, with differences in effectiveness ranked as: commercial soak > vinegar soak > water soak (and water rinse not significantly different from vinegar or water soak). Washing crops grown in low-Pb soils is also important. Without washing, lettuce grown in low-Pb soil may still have Pb levels above the European Commission comparison value. We offer these empirical findings and recommendations in support of urban growers.

Urban soils research: SUITMA 10.

Research on Soils in Urban, Industrial, Traffic, Mining and Military Areas (SUITMA) has been presented at biennial SUITMA conferences held in cities around the world. Soils from these areas often present environmental, ecological, and health risks and can limit ecological functions and ecosystem services. However, as with all soils, they are an integral part of the local ecosystem. In urban areas in particular, soil is a critical resource and can play a key role in the long-term sustainability and resiliency of cities. This special section contains five papers from the SUITMA 10 conference held in Seoul, South Korea, in 2019. They cover diverse topics that include urban soil properties, risk from contaminated soils, biological indicators for ecological functions, air deposition in urban gardens, and international summer field school opportunities. This section highlights research on anthropogenic soils conducted by the SUITMA community to promote better understanding and management of these soils.

Lead in New York City's soils: Population growth, land use, and contamination.

Soil is an important exposure pathway for lead (Pb) and predictor of blood lead levels (BLL) among children. Over the past two decades, many areas within New York City (NYC) have undergone a transition from industrial and manufacturing land use to residential housing. This can bring new residents to areas which contain the legacy of historic Pb contamination. The objective of this study was to evaluate the difference in soil Pb concentrations between community parks and greenspaces in areas undergoing rapid redevelopment and land use changes and stable areas without redevelopment. Three high- and three low-risk Pb contaminated areas within NYC were identified based on an additive index that included population growth, industrial land use, and new construction. Soil samples (n=358) were collected across 34 parks and analyzed with an XRF with a subset also analyzed by ICP-MS. Areas within NYC, evaluated in this study, with a high-risk index had significantly (p<0.0001) larger mean concentrations of Pb in soil (374 mg/kg vs. 150 mg/kg, respectively) and double the rate of children under the age of six years with BLL > 5ug/dL (37.94 vs. 18.72 per 1000, respectively) compared to low-risk areas. There was a statistically significant (p <0.05) positive correlation between street density, manufacturing/industrial land density and population density change within 0.40 km of a park and soil Pb concentrations. However, we were unable to estimate the source-specific contribution of Pb concentrations in soil, since many of the variables assessed were correlated with one another. Regardless of the source, large population increases are occurring in areas with elevated soil Pb levels. In the three high-risk areas investigated in this study, the population has increased by over 35,000 residents between 2010 to 2017 compared to just 8,500 in the low-risk areas.

Remediation of an urban garden with elevated levels of soil contamination.

Urban gardening is popular in many cities. However, many urban soils are contaminated and pose risks to human health. This study was conducted in a highly publicized urban garden in Brooklyn, NY with elevated Pb and As levels. Our objectives were to: (1) assess the nature and extent of Pb and As contamination at this site; (2) evaluate the effectiveness of amendments on reducing the bioaccessibility and phytoavailability of Pb and As in soil; and (3) assess the potential exposure of children to Pb and As through direct and indirect exposure pathways. Field surveys of the site revealed that contamination was highly concentrated in one area of the garden associated with fruit tree production. Field plots were established in this area, with three different treatments (bone meal, compost, sulfur) and an unamended control. Bioaccessibility of Pb was significantly reduced by all three treatments compared to the control (33%): bone meal (24%), compost (23%), sulfur (24%). In this study, As bioaccessibility remained high (80-93%) with or without treatments. We found that the effectiveness of soil remediation with amendments is variable and often limited, and contaminated sites can still pose a significant risk to urban gardeners. The results of a simple assessment model suggested that Pb and As exposure was mostly from soil and dust ingestion, rather than vegetable consumption. This work is unique in that it evaluates actual elevated levels of contamination, in actively gardened urban soils, in a highly visible public context. It fills important gaps between basic research and analysis of human exposure to toxic trace metals that can be a constraint on a highly beneficial activity.

Green Infrastructure Design Influences Communities of Urban Soil Bacteria.

The importance of natural ecosystem processes is often overlooked in urban areas. Green Infrastructure (GI) features have been constructed in urban areas as elements to capture and treat excess urban runoff while providing a range of ancillary benefits, e.g., ecosystem processes mediated by microorganisms that improve air and water quality, in addition to the associations with plant and tree rhizospheres. The objective of this study was to characterize the bacterial community and diversity in engineered soils (Technosols) of five types of GI in New York City; vegetated swales, right of way bioswales (ROWB; including street-side infiltration systems and enhanced tree pits), and an urban forest. The design of ROWB GI features directly connects with the road to manage street runoff, which can increase the Technosol saturation and exposure to urban contaminants washed from the street and carried into the GI feature. This GI design specifically accommodates dramatic pulses of water that influence the bacterial community composition and diversity through the selective pressure of contaminants or by disturbance. The ROWB had the highest biodiversity, but no significant correlation with levels of soil organic matter and microbially-mediated biogeochemical functions. Another important biogeochemical parameter for soil bacterial communities is pH, which influenced the bacterial community composition, consistent with studies in non-urban soils. Bacterial community composition in GI features showed signs of anthropogenic disturbance, including exposure to animal feces and chemical contaminants, such as petroleum products. Results suggest the overall design and management of GI features with a channeled connection with street runoff, such as ROWB, have a comprehensive effect on soil parameters (particularly organic matter) and the bacterial community. One key consideration for future assessments of GI microbial community would be to determine the source of organic matter and elucidate the relationship between vegetation, Technosol, and bacteria in the designed GI features.

Comparison of dissolved and particulate arsenic distributions in shallow aquifers of Chakdaha, India, and Araihazar, Bangladesh.

BACKGROUND: The origin of the spatial variability of dissolved As concentrations in shallow aquifers of the Bengal Basin remains poorly understood. To address this, we compare here transects of simultaneously-collected groundwater and aquifer solids perpendicular to the banks of the Hooghly River in Chakdaha, India, and the Old Brahmaputra River in Araihazar, Bangladesh. RESULTS: Variations in surface geomorphology mapped by electromagnetic conductivity indicate that permeable sandy soils are associated with underlying aquifers that are moderately reducing to a depth of 10-30 m, as indicated by acid-leachable Fe(II)/Fe ratios <0.6 in the solid phase and concentrations of dissolved sulfate >5 mg L(-1). More reducing aquifers are typically capped with finer-grained soils. The patterns suggest that vertical recharge through permeable soils is associated with a flux of oxidants on the banks of the Hooghly River and, further inland, in both Chakdaha and Araihazar. Moderately reducing conditions maintained by local recharge are generally associated with low As concentrations in Araihazar, but not systematically so in Chakdaha. Unlike Araihazar, there is also little correspondence in Chakdaha between dissolved As concentrations in groundwater and the P-extractable As content of aquifer particles, averaging 191 +/- 122 microg As/L, 1.1 +/- 1.5 mg As kg(-1) (n = 43) and 108 +/- 31 microg As/L, 3.1 +/- 6.5 mg As kg(-1) (n = 60), respectively. We tentatively attribute these differences to a combination of younger floodplain sediments, and therefore possibly more than one mechanism of As release, as well as less reducing conditions in Chakdaha compared to Araihazar. CONCLUSION: Systematic dating of groundwater and sediment, combined with detailed mapping of the composition of aquifer solids and groundwater, will be needed to identify the various mechanisms underlying the complex distribution of As in aquifers of the Bengal Basin.

Accumulation of arsenic and lead in garden-grown vegetables: Factors and mitigation strategies.

Pesticides containing lead and arsenic were widely used in the US through the 20th century. Legacy contamination from this use poses a health risk as interest in cultivation of abandoned agricultural lands has grown in recent years. We addressed these risks by quantifying Pb and As in soils and produce from a suburban farm in New Jersey, USA and examining the ability of phosphate-bearing amendments (bone meal, triple super phosphate, manure compost and raised bed soil) in combination with Fe and/or Mn amendments to stabilize these metals and prevent their movement into vegetables. Common produce (tomato, carrot, lettuce, and radish) was grown in soils with 133-307 mg Pb kg-1 and 19-73 mg As kg-1. Our results suggest that vegetables produced on these soils can have Pb and As at levels above health and safety standards, especially root and leafy green vegetables. Phosphate-bearing amendments can reduce extractable Pb but can increase extractable As in soils, and can have similar effects on vegetables. Iron amendment increased both extractable Pb and As, likely due to the presence of elemental sulfur in the Fe amendment, which lowered soil pH, while Mn amendment had the opposite effect. Most of the Pb and As in vegetables appear to be associated with soil particles adhered to the vegetables, and the contribution from uptake was relatively small except for plots treated with Fe-amendments and for carrots. Thus, proper crop selection, rigorous cleaning, and dust and dirt control are critical to reduce the risk of contaminant exposure through the consumption of garden produce.

Association between manganese exposure through drinking water and infant mortality in Bangladesh.

BACKGROUND: Manganese is a common natural contaminant of groundwater in Bangladesh. In this cross-sectional study we assessed the association between water manganese and all-cause infant mortality in the offspring of female participants in the Health Effects of Arsenic Longitudinal Study Cohort. METHODS: In 2001, drinking water samples were collected, a history of well use was obtained, and a history of birth outcomes was ascertained. To avoid misclassification of exposure, women were included only if they had been drinking from the same well for most of their childbearing years (marriage years - well years

Water arsenic exposure and intellectual function in 6-year-old children in Araihazar, Bangladesh.

BACKGROUND: We recently reported results of a cross-sectional investigation of intellectual function in 10-year-olds in Bangladesh, who had been exposed to arsenic from drinking water in their home wells. OBJECTIVES: We present results of a similar investigation of 301 randomly selected 6-year-olds whose parents participated in our ongoing prospective study of the health effects of As exposure in 12,000 residents of Araihazar, Bangladesh. METHODS: Water As and manganese concentrations of tube wells at each home were obtained by surveying all study region wells. Children and mothers were first visited at home, where the quality of home stimulation was measured, and then seen in our field clinic, where children received a medical examination wherein weight, height, and head circumference were assessed. We assessed children's intellectual function using subtests drawn from the Wechsler Preschool and Primary Scale of Intelligence, version III, by summing weighted items across domains to create Verbal, Performance, Processing Speed, and Full-Scale raw scores. Children provided urine specimens for measuring urinary As and were asked to provide blood samples for blood lead measurements. RESULTS: Exposure to As from drinking water was associated with reduced intellectual function before and after adjusting for water Mn, for blood lead levels, and for sociodemographic features known to contribute to intellectual function. With covariate adjustment, water As remained significantly negatively associated with both Performance and Processing Speed raw scores; associations were less strong than in our previously studied 10-year-olds. CONCLUSION: This second cross-sectional study of As exposure expands our concerns about As neurotoxicity to a younger age group.

Determinants of arsenic metabolism: blood arsenic metabolites, plasma folate, cobalamin, and homocysteine concentrations in maternal-newborn pairs.

BACKGROUND: In Bangladesh, tens of millions of people have been consuming waterborne arsenic for decades. The extent to which As is transported to the fetus during pregnancy has not been well characterized. OBJECTIVES: We therefore conducted a study of 101 pregnant women who gave birth in Matlab, Bangladesh. METHODS: Maternal and cord blood pairs were collected and concentrations of total As were analyzed for 101 pairs, and As metabolites for 30 pairs. Maternal urinary As metabolites and plasma folate, cobalamin, and homocysteine levels in maternal cord pairs were also measured. Household tube well-water As concentrations exceeded the World Health Organization guideline of 10 microg/L in 38% of the cases. RESULTS: We observed strong associations between maternal and cord blood concentrations of total As (r = 0.93, p < 0.0001). Maternal and cord blood arsenic metabolites (n = 30) were also strongly correlated: in dimethylarsinate (DMA) (r = 0.94, p < 0.0001), monomethylarsonate (r = 0.80, p < 0.0001), arsenite (As(+3)) (r = 0.80, p < 0.0001), and arsenate (As(+5)) (r = 0.89, p < 0.0001). Maternal homocysteine was a strong predictor of %DMA in maternal urine, maternal blood, and cord blood (beta = -6.2, p < 0.02; beta = -10.9, p < 0.04; and beta = -13.7, p < 0.04, respectively). Maternal folate was inversely associated with maternal blood As(5+) (beta = 0.56, p < 0.05), and maternal cobalamin was inversely associated with cord blood As(5+) (beta = -1.2, p < 0.01). CONCLUSIONS: We conclude that exposure to all metabolites of inorganic As occurs in the prenatal period.

Arsenic in tree rings at a highly contaminated site.

Arsenic concentrations were measured in annual rings, pith, bark, and leaves of five tree species (four genera) from a site highly contaminated with As in Vineland, New Jersey, and two nearby uncontaminated areas. The highest As concentrations were found in bark (0.68+/-0.89 mg/kg, n=16) and leaves (1.9+/-1.8 mg/kg, n=4) from the contaminated area. Tree-ring As levels from the contaminated area (0.28+/-0.15 mg/kg, n=32) were low but still considerably higher than those from the control areas (0.06+/-0.06 mg/kg, n=30). There is a generally positive relationship between soil and tree-ring As levels. The overall low uptake of As by trees contrasts with that of P, a chemical analog for As(V) in aerated soils. Much higher P concentration in sapwood than in heartwood indicates that P is exported into more recently formed wood during the conversion from sapwood to heartwood; this again is drastically different than the behavior of As which is present in sapwood and heartwood at comparable levels. Variable sapwood As concentrations observed in detailed radial profiles of tree-ring chemistry of a pine and an oak from the contaminated site suggest that As is most likely transported among multiple rings within the sapwood. Therefore, tree species for which sapwood is thin (e.g., oak as in this study) should be preferred for reconstructing the history of contamination of a site. Due to the possibility of lateral translocation between growth rings, further studies are necessary to understand within-tree As transport and storage before dendrochemistry can be confidently accepted for such applications.