The lead and copper rule: Limitations and lessons learned from Newark, New Jersey.

Flint, Michigan reignited the public discourse surrounding lead contamination in drinking water with Newark, New Jersey recently experiencing its own lead-in-water crisis. Following Flint's experience, the Environmental Protection Agency proposed changes to the Lead and Copper Rule (LCR), but these changes may not produce better detection of contamination. LCR testing requirements were evaluated for their ability to predict or identify problems from the recent (2015-2019) Newark lead exceedance data. LCR compliance and water quality data were obtained from the New Jersey Department of Environmental Protection (NJDEP) website. Between 2002 and 2015, Newark sampled on a reduced sampling plan (50 samples once every 3 years), as required, for lead and copper. These samples were divided between Newark's two water sources with uneven sampling distribution across the city, further limiting the potential to identify a risk of lead in drinking water. Results suggest a more rigorous testing requirement may have identified the problem sooner. Limitations related to the LCR that prevented Newark water suppliers from earlier detection of lead risk will continue under the revised LCR. This article is categorized under:Engineering Water > Water, Health, and SanitationScience of Water > Water Quality.

Protective role of the placental efflux transporter BCRP/ABCG2 in the relationship between prenatal cadmium exposure, placenta weight, and size at birth.

BACKGROUND AND AIM: Placental efflux transporter proteins, such as BCRP, reduce the placental and fetal toxicity of environmental contaminants but have received little attention in perinatal environmental epidemiology. Here, we evaluate the potential protective role of BCRP following prenatal exposure to cadmium, a metal that preferentially accumulates in the placenta and adversely impacts fetal growth. We hypothesized that individuals with a reduced function polymorphism in ABCG2, the gene encoding BCRP, would be most vulnerable to the adverse impacts of prenatal cadmium exposure, notably, smaller placental and fetal size. METHODS: We measured cadmium in maternal urine samples at each trimester and in term placentas from UPSIDE-ECHO study participants (NY, USA; n = 269). We fit adjusted multivariable linear regression and generalized estimating equation models to examine log-transformed urinary and placental cadmium concentrations in relation to birthweight, birth length, placental weight, and fetoplacental weight ratio (FPR) and stratified models by ABCG2 Q141K (C421A) genotype. RESULTS: Overall 17% of participants expressed the reduced-function ABCG2 C421A variant (AA or AC). Placental cadmium concentrations were inversely associated with placental weight (ß = -19.55; 95%CI: -37.06, -2.04) and trended towards higher FPR (ß = 0.25; 95%CI: -0.01, 0.52) with stronger associations in 421A variant infants. Notably, higher placental cadmium concentrations in 421A variant infants were associated with reduced placental weight (ß = -49.42; 95%CI: 98.87, 0.03), and higher FPR (ß = 0.85, 95%CI: 0.18, 1.52), while higher urinary cadmium concentration was associated with longer birth length (ß = 0.98; 95%CI: 0.37, 1.59), lower ponderal index (ß = -0.09; 95%CI: 0.15, -0.03), and higher FPR (ß = 0.42; 95%CI: 0.14, 0.71). CONCLUSIONS: Infants with reduced function ABCG2 polymorphisms may be particularly vulnerable to the developmental toxicity of cadmium as well as other xenobiotics that are BCRP substrates. Additional work examining the influence of placental transporters in environmental epidemiology cohorts is warranted.

Dose Uptake of Platinum- and Ruthenium-based Compound Exposure in Zebrafish by Inductively Coupled Plasma Mass Spectrometry with Broader Applications.

Metals and metal-based compounds comprise multifarious pharmaco-active and toxicological xenobiotics. From heavy metal toxicity to chemotherapeutics, the toxicokinetics of these compounds have both historical and modern-day relevance. Zebrafish have become an attractive model organism in elucidating pharmaco- and toxicokinetics in environmental exposure and clinical translation studies. Although zebrafish studies have the benefit of being higher-throughput than rodent models, there are several significant constraints to the model. One such limitation is inherent in the waterborne dosing regimen. Water concentrations from these studies cannot be extrapolated to provide reliable internal dosages. Direct measurements of the metal-based compounds allow for a better correlation with compound-related molecular and biological responses. To overcome this limitation for metals and metal-based compounds, a technique was developed to digest zebrafish larval tissue after exposure and quantify metal concentrations within tissue samples by inductively coupled plasma mass spectrometry (ICPMS). ICPMS methods were used to determine the metal concentrations of platinum (Pt) from cisplatin and ruthenium (Ru) from several novel Ru-based chemotherapeutics in zebrafish tissue. Additionally, this protocol distinguished concentrations of Pt that were sequestered in the chorion of the larval compared with the zebrafish tissue. These results indicate that this method can be applied to quantitate the metal dose present in larval tissues. Further, this method may be adjusted to identify specific metals or metal-based compounds in a broad range of exposure and dosing studies.

Estimating Occupational Exposure to VOCs, SVOCs, Particles and Participant Survey Reported Symptoms in Central Thailand Rice Farmers Using Multiple Sampling Techniques.

Thailand is known for its agricultural productivity and rice exportation. Most farms use small machines and manual labor, creating potential exposure to multiple health hazards. A cross-sectional study was conducted to measure pollutants liberated during preparation, pesticide application, and harvesting. Thirty rice farmers, mostly males from 41 to 50 years old, participated. The participant survey data showed that 53.3% of the respondents spent >2 h per crop on preparation, <1 h on pesticide application, and about 1-2 h harvesting; 86.7% of the respondents maintained and stored mechanical applicators at home, suggesting possible after-work exposures. Gloves, fabric masks, boots, and hats were worn during all activities, and >90% wore long sleeved shirts and pants. VOCs and SVOCs were collected using charcoal tubes and solid phase micro sample extraction (SPME). An analysis of the charcoal and SPME samplers found that 30 compounds were detected overall and that 10 were in both the charcoal tubes and SPME samplers. The chemicals most often detected were 1, 1, 1 Trichloro ethane and xylene. Additionally, farmers experienced the highest exposure to particulates during harvesting. These results demonstrated that farmers experience multiple exposures while farming and that risk communication with education or training programs may mitigate exposure.

Moving toward a Handheld "Plasma" Spectrometer for Elemental Analysis, Putting the Power of the Atom (Ion) in the Palm of Your Hand.

Many of the current innovations in instrument design have been focused on making them smaller, more rugged, and eventually field transportable. The ultimate application is obvious, carrying the instrument to the field for real time sample analysis without the need for a support laboratory. Real time data are priceless when screening either biological or environmental samples, as mitigation strategies can be initiated immediately upon the discovery that contaminant metals are present in a location they were not intended to be. Additionally, smaller "handheld" instruments generally require less sample for analysis, possibly increasing sensitivity, another advantage to instrument miniaturization. While many other instruments can be made smaller just by using available micro-technologies (e.g., eNose), shrinking an ICP-MS or AES to something someone might carry in a backpack or pocket is now closer to reality than in the past, and can be traced to its origins based on a component-by-component evaluation. While the optical and mass spectrometers continue to shrink in size, the ion/excitation source remains a challenge as a tradeoff exists between excitation capabilities and the power requirements for the plasma's generation. Other supporting elements have only recently become small enough for transport. A systematic review of both where the plasma spectrometer started and the evolution of technologies currently available may provide the roadmap necessary to miniaturize the spectrometer. We identify criteria on a component-by-component basis that need to be addressed in designing a miniaturized device and recognize components (e.g., source) that probably require further optimization. For example, the excitation/ionization source must be energetic enough to take a metal from a solid state to its ionic state. Previously, a plasma required a radio frequency generator or high-power DC source, but excitation can now be accomplished with non-thermal (cold) plasma sources. Sample introduction, for solids, liquids, and gasses, presents challenges for all sources in a field instrument. Next, the interface between source and a mass detector usually requires pressure reduction techniques to get an ion from plasma to the spectrometer. Currently, plasma mass spectrometers are field ready but not necessarily handheld. Optical emission spectrometers are already capable of getting photons to the detector but could eventually be connected to your phone. Inert plasma gas generation is close to field ready if nitrogen generators can be miniaturized. Many of these components are already commercially available or at least have been reported in the literature. Comparisons to other "handheld" elemental analysis devices that employ XRF, LIBS, and electrochemical methods (and their limitations) demonstrate that a "cold" plasma-based spectrometer can be more than competitive. Migrating the cold plasma from an emission only source to a mass spectrometer source, would allow both analyte identification and potentially source apportionment through isotopic fingerprinting, and may be the last major hurdle to overcome. Finally, we offer a possible design to aid in making the cold plasma source more applicable to a field deployment.

Translating Analytical Techniques in Geochemistry to Environmental Health.

From human health exposure related to environmental contamination to ancient deep-Earth processes related to differentiation of the Earth's geochemical reservoirs, the adaptability of inductively coupled plasma mass spectrometry (ICP-MS) has proven to be an indispensable standard technique that transcends disciplines. Continued advancements in ICP-MS, including improved auxiliary applications such as laser ablation (LA), ion/liquid chromatography (IC), automated pre-concentration systems (e.g., seaFAST), and improved desolvating nebulizer systems (e.g., Aridus and Apex) have revolutionized our ability to analyze almost any sample matrix with remarkable precision at exceedingly low elemental abundances. The versatility in ICP-MS applications allows for effective interdisciplinary crossover, opening a world of analytical possibilities. In this communication, we discuss the adaptability of geochemical techniques, including sample preparation and analysis, to environmental and biological systems, using Pb isotopes for source apportionment as a primary example.

Anticancer Activity and In Vitro to In Vivo Mechanistic Recapitulation of Novel Ruthenium-Based Metallodrugs in the Zebrafish Model.

Ruthenium is popular as a metal core for chemotherapeutics, due to versatile molecular coordination. Because new metallodrugs are synthesized at high rates, our studies included assays in zebrafish to expedite the initial evaluation as anticancer agents. Here we evaluated novel metallodrugs (PMC79 and LCR134), and cisplatin, a widely used platinum-based chemotherapeutic. We hypothesized that this model could characterize anticancer properties and recapitulate previous in vitro results in vivo. Our findings suggest anticancer properties of PMC79 and LCR134 were similar with less toxicity than cisplatin. Exposures from 24 to 72 h at or below the LOAELs of PMC79 and LCR134 (3.9 µM and 13.5 µm, respectively), impaired blood vessel development and tailfin regeneration. Blood vessel examination through live imaging of larvae revealed distinct regional antiangiogenic impacts. The significant decrease in gene expression of the VEGF-HIF pathway and beta-actin could explain the morphological effects observed in the whole organism following exposure. Tailfin amputation in larvae exposed to PMC79 or LCR134 inhibited tissue regrowth and cell division, but did not impact normal cell proliferation unlike cisplatin. This suggests Ru drugs may be more selective in targeting cancerous cells than cisplatin. Additionally, in vitro mechanisms were confirmed. PMC79 disrupted cytoskeleton formation in larvae and P-glycoprotein transporters in vivo was inhibited at low doses which could limit off-target effects of chemotherapeutics. Our results demonstrate the value for using the zebrafish in metallodrug research to evaluate mechanisms and off-target effects. In light of the findings reported in this article, future investigation of PMC79 and LCR134 are warranted in higher vertebrate models.

Cisplatin alkylating activity in zebrafish causes resistance to chorionic degradation and inhibition of osteogenesis.

Zebrafish have gained popularity as a model organism due to their rapid, external, and transparent development, high fecundity, and gene homology with higher vertebrate models and humans. Specifically, drug discovery has had high success in the implementation of zebrafish in studies for target discovery, efficacy, and toxicity. However, a major limitation of the zebrafish model is a dependence on waterborne exposure in order to maintain high throughput capabilities. Dose delivery can be impeded by a matrix of N-linked glycoproteins and other polypeptides called the chorion. This acelluar barrier is protective of the developing embryo, and thus new approaches for assessment have involved their removal. In these studies, we explored the chorionic interference of a well-characterized alkylating chemotherapeutic, cisplatin, known to accumulate in the chorion of zebrafish and cause delayed hatching. Our results indicated that increased exposure of cisplatin due to dechorionation did not alter morphological endpoints, although retained confinement reduced total body length and yolk utilization. Additionally, inhibition of osteogenesis visualized with Alizarian Red staining, was observable in dechorionated and non-dechorionated treatment groups. The chorions of cisplatin-treated embryos showed resistance to degradation unless treated with a pronase solution. This may be may be due to cisplatin covalently crosslinking which reinforces the structure. As such, the chorion may play an advantageous role in studies to determine alkylating activity of novel compounds. Furthermore, the expression of zebrafish hatching enzyme was not affected by cisplatin exposure. These studies demonstrate that not only was recapitulation of mechanistic activity supported in zebrafish, but highly relevant off-target toxicities observed in higher vertebrates were identified in zebrafish, regardless of chorionation. Experimental design in drug discovery should consider preliminary studies without dechorionation in order to determine dose impediment or off-target adducting.

Heavy metals contaminating the environment of a progressive supranuclear palsy cluster induce tau accumulation and cell death in cultured neurons.

Progressive supranuclear palsy (PSP) is a neurodegenerative disorder characterized by the presence of intracellular aggregates of tau protein and neuronal loss leading to cognitive and motor impairment. Occurrence is mostly sporadic, but rare family clusters have been described. Although the etiopathology of PSP is unknown, mutations in the MAPT/tau gene and exposure to environmental toxins can increase the risk of PSP. Here, we used cell models to investigate the potential neurotoxic effects of heavy metals enriched in a highly industrialized region in France with a cluster of sporadic PSP cases. We found that iPSC-derived iNeurons from a MAPT mutation carrier tend to be more sensitive to cell death induced by chromium (Cr) and nickel (Ni) exposure than an isogenic control line. We hypothesize that genetic variations may predispose to neurodegeneration induced by those heavy metals. Furthermore, using an SH-SY5Y neuroblastoma cell line, we showed that both heavy metals induce cell death by an apoptotic mechanism. Interestingly, Cr and Ni treatments increased total and phosphorylated tau levels in both cell types, implicating Cr and Ni exposure in tau pathology. Overall, this study suggests that chromium and nickel could contribute to the pathophysiology of tauopathies such as PSP by promoting tau accumulation and neuronal cell death.

Ruthenium-Cyclopentadienyl Bipyridine-Biotin Based Compounds: Synthesis and Biological Effect.

Prospective anticancer metallodrugs should consider target-specific components in their design in order to overcome the limitations of the current chemotherapeutics. The inclusion of vitamins, which receptors are overexpressed in many cancer cell lines, has proven to be a valid strategy. Therefore, in this paper we report the synthesis and characterization of a set of new compounds [Ru(η5-C5H5)(P(C6H4R)3)(4,4'-R'-2,2'-bpy)]+ (R = F and R' = H, 3; R = F and R' = biotin, 4; R = OCH3 and R' = H, 5; R = OCH3 and R' = biotin, 6), inspired by the exceptional good results recently obtained for the analogue bearing a triphenylphosphane ligand. The precursors for these syntheses were also described following modified literature procedures, [Ru(η5-C5H5)(P(C6H4R)3)2Cl], where R is -F (1) or -OCH3 (2). The structure of all compounds is fully supported by spectroscopic and analytical techniques and by X-ray diffraction studies for compounds 2, 3, and 5. All cationic compounds are cytotoxic in the two breast cancer cell lines tested, MCF7 and MDA-MB-231, and much better than cisplatin under the same experimental conditions. The cytotoxicity of the biotinylated compounds seems to be related with the Ru uptake by the cells expressing biotin receptors, indicating a potential mediated uptake. Indeed, a biotin-avidin study confirmed that the attachment of biotin to the organometallic fragment still allows biotin recognition by the protein. Therefore, the biotinylated compounds might be potent anticancer drugs as they show cytotoxic effect in breast cancer cells at low dose dependent on the compounds' uptake, induce cell death by apoptosis and inhibit the colony formation of cancer cells causing also less severe side effects in zebrafish.

A novel screening method for transition metal-based anticancer compounds using zebrafish embryo-larval assay and inductively coupled plasma-mass spectrometry analysis.

As novel metallodrugs continue to emerge, they are evaluated using models, including zebrafish, that offer unique sublethal endpoints. Testing metal-based anticancer compounds with high-throughput zebrafish toxicological assays requires analytical methods with the sensitivity to detect these sublethal tissue doses in very small sample masses (e.g., egg mass 100 µg). A robust bioanalytical model, zebrafish embryos coupled with inductively coupled plasma-mass spectrometry (ICPMS) for measurement of delivered dose, creates a very effective means for screening metal-based chemotherapeutic agents. In this study, we used ICPMS quantitation with the zebrafish embryo assays to detect metal equivalents at multiple response endpoints for two compounds, the chemotherapeutic agent cisplatin and ruthenium (Ru)-based prospective metallodrug, PMC79. We hypothesized that cisplatin and PMC79 have different mechanisms for inducing apoptosis and result in similar lesions but different potencies following water-borne exposure. An ICPMS method was developed to detect the metal in waterborne solution and tissue (detection limit: 5 parts per trillion for Ru or platinum [Pt]). The Ru-based compound was more potent (LC50 : 7.8 µm) than cisplatin (LC50 : 158 µm) and induced disparate lesions. Lethality from cisplatin exposure exhibited a threshold (values >15 mg/L) while no threshold was observed for delayed hatching (lowest observed adverse effect level 3.75 mg/L cisplatin; 8.7 Pt (ng)/organism). The Ru organometallic did not have a threshold for lethality. Cisplatin-induced delayed hatching was investigated further by larval-Pt distribution and preferentially distributed to the chorion. We propose that zebrafish embryo-larval assays coupled with ICPMS serve as a powerful platform to evaluate relative potency and toxic effects of metallodrug candidates.

Unprecedented inhibition of P-gp activity by a novel ruthenium-cyclopentadienyl compound bearing a bipyridine-biotin ligand.

Two new ruthenium complexes, [Ru(η5-Cp)(PPh3)(2,2'-bipy-4,4'-R)]+ with R = -CH2OH (Ru1) or dibiotin ester (Ru2) were synthesized and fully characterized. Both compounds were tested against two types of breast cancer cells (MCF7 and MDA-MB-231), showing better cytotoxicity than cisplatin in the same experimental conditions. Since multidrug resistance (MDR) is one of the main problems in cancer chemotherapy, we have assessed the potential of these compounds to overcome resistance to treatments. Ru2 showed exceptional selectivity as P-gp inhibitor, while Ru1 is possibly a substrate. In vivo studies in zebrafish showed that Ru2 is well tolerated up to 1.17 mg/L, presenting a LC50 of 5.73 mg/L at 5 days post fertilization.

Organophosphate Flame-Retardants Alter Adult Mouse Homeostasis and Gene Expression in a Sex-Dependent Manner Potentially Through Interactions With ERα.

Flame retardants (FRs) such as polybrominated diphenyl ethers and organophosphate FR (OPFR) persist in the environment and interact with multiple nuclear receptors involved in homeostasis, including estrogen receptors (ERs). However, little is known about the effects of FR, especially OPFR, on mammalian neuroendocrine functions. Therefore, we investigated if exposure to FR alters hypothalamic gene expression and whole-animal physiology in adult wild-type (WT) and ERα KO mice. Intact WT and KO males and ovariectomized WT and KO females were orally dosed daily with vehicle (oil), 17α-ethynylestradiol (2.5 µg/kg), 2,2', 4,4-tetrabromodiphenyl ether (BDE-47, 1 or 10 mg/kg), or an OPFR mixture {1 or 10 mg/kg of tris(1, 3-dichloro-2-propyl)phosphate, triphenyl phosphate, and tricresyl phosphate each} for 28 days. Body weight, food intake, body composition, glucose and insulin tolerance, plasma hormone levels, and hypothalamic and liver gene expression were measured. Expression of neuropeptides, receptors, and cation channels was differentially altered between WT males and females. OPFR suppressed body weight and energy intake in males. FR increased fasting glucose levels in males, and BDE-47 augmented glucose clearance in females. Liver gene expression indicated FXR activation by BDE-47 and PXR and CAR activation by OPFR. In males, OPFR increased ghrelin but decreased leptin and insulin independent of body weight. The loss of ERα reduced the effects of both FR on hypothalamic and liver gene expression and plasma hormone levels. The physiological implications are that males are more sensitive than ovariectomized females to OPFR exposure and that these effects are mediated, in part, by ERα.

Dysregulation of bile acid homeostasis in parenteral nutrition mouse model.

Long-term parenteral nutrition (PN) administration can lead to PN-associated liver diseases (PNALD). Although multiple risk factors have been identified for PNALD, to date, the roles of bile acids (BAs) and the pathways involved in BA homeostasis in the development and progression of PNALD are still unclear. We have established a mouse PN model with IV infusion of PN solution containing soybean oil-based lipid emulsion (SOLE). Our results showed that PN altered the expression of genes involved in a variety of liver functions at the mRNA levels. PN increased liver gene expression of Cyp7a1 and markedly decreased that of Cyp8b1, Cyp7b1, Bsep, and Shp. CYP7A1 and CYP8B1 are important for synthesizing the total amount of BAs and regulating the hydrophobicity of BAs, respectively. Consistently, both the levels and the percentages of primary BAs as well as total non-12α-OH BAs increased significantly in the serum of PN mice compared with saline controls, whereas liver BA profiles were largely similar. The expression of several key liver-X receptor-α (LXRα) target genes involved in lipid synthesis was also increased in PN mouse livers. Retinoid acid-related orphan receptor-α (RORα) has been shown to induce the expression of Cyp8b1 and Cyp7b1, as well as to suppress LXRα function. Western blot showed significantly reduced nuclear migration of RORα protein in PN mouse livers. This study shows that continuous PN infusion with SOLE in mice leads to dysregulation of BA homeostasis. Alterations of liver RORα signaling in PN mice may be one of the mechanisms implicated in the pathogenesis of PNALD.

Whole-house arsenic water treatment provided more effective arsenic exposure reduction than point-of-use water treatment at New Jersey homes with arsenic in well water.

A comparison of the effectiveness of whole house (point-of-entry) and point-of-use arsenic water treatment systems in reducing arsenic exposure from well water was conducted. The non-randomized observational study recruited 49 subjects having elevated arsenic in their residential home well water in New Jersey. The subjects obtained either point-of-entry or point-of-use arsenic water treatment. Prior ingestion exposure to arsenic in well water was calculated by measuring arsenic concentrations in the well water and obtaining water-use histories for each subject, including years of residence with the current well and amount of water consumed from the well per day. A series of urine samples was collected from the subjects, some starting before water treatment was installed and continuing for at least nine months after treatment had begun. Urine samples were analyzed and speciated for inorganic-related arsenic concentrations. A two-phase clearance of inorganic-related arsenic from urine and the likelihood of a significant body burden from chronic exposure to arsenic in drinking water were identified. After nine months of water treatment the adjusted mean of the urinary inorganic-related arsenic concentrations was significantly lower (p<0.0005) in the point-of-entry treatment group (2.5 µg/g creatinine) than in the point-of-use treatment group (7.2 µg/g creatinine). The results suggest that whole house arsenic water treatment systems provide a more effective reduction of arsenic exposure from well water than that obtained by point-of-use treatment.

Novel cystine ester mimics for the treatment of cystinuria-induced urolithiasis in a knockout mouse model.

OBJECTIVE: To assess the effectiveness of l-cystine dimethyl ester (CDME), an inhibitor of cystine crystal growth, for the treatment of cystine urolithiasis in an Slc3a1 knockout mouse model of cystinuria. MATERIALS AND METHODS: CDME (200 µg per mouse) or water was delivered by gavage daily for 4 weeks. Higher doses by gavage or in the water supply were administered to assess organ toxicity. Urinary amino acids and cystine stones were analyzed to assess drug efficacy using several analytical methods. RESULTS: Treatment with CDME led to a significant decrease in stone size compared with that of the water group (P = .0002), but the number of stones was greater (P = .005). The change in stone size distribution between the 2 groups was evident by micro computed tomography. Overall, cystine excretion in urine was the same between the 2 groups (P = .23), indicating that CDME did not interfere with cystine metabolism. Scanning electron microscopy analysis of cystine stones from the CDME group demonstrated a change in crystal habit, with numerous small crystals. l-cysteine methyl ester was detected by ultra-performance liquid chromatography-mass spectrometer in stones from the CDME group only, indicating that a CDME metabolite was incorporated into the crystal structure. No pathologic changes were observed at the doses tested. CONCLUSION: These data demonstrate that CDME promotes formation of small stones but does not prevent stone formation, consistent with the hypothesis that CDME inhibits cystine crystal growth. Combined with the lack of observed adverse effects, our findings support the use of CDME as a viable treatment for cystine urolithiasis.

Measurement of Soluble and Total Hexavalent Chromium in the Ambient Airborne Particles in New Jersey.

Hexavalent chromium (Cr(VI)) in ambient airborne particulate matter (PM) is a known pulmonary carcinogen and may have both soluble and insoluble forms. The sum of the two forms is defined as total Cr(VI). Currently, there were no methods suitable for large-scale monitoring of total Cr(VI) in ambient PM. This study developed a method to measure total Cr(VI) in ambient PM. This method includes PM collection using a Teflon filter, microwave extraction with 3% Na2CO3-2% NaOH at 95°C for 60 minutes, and Cr(VI) analysis by 1,5-diphenylcarbazide colorimetry at 540 nm. The recoveries of total Cr(VI) were 119.5 ± 10.4% and 106.3 ± 16.7% for the Cr(VI)-certified reference materials, SQC 012 and SRM 2700, respectively. Total Cr(VI) in the reference urban PM (NIST 1648a) was 26.0 ± 3.1 mg/kg (%CV = 11.9%) determined by this method. The method detection limit was 0.33 ng/m3. This method and the one previously developed to measure ambient Cr(VI), which is soluble in pH ~9.0 aqueous solution, were applied to measure Cr(VI) in ambient PM10 collected from three urban areas and one suburban area in New Jersey. The total Cr(VI) concentrations were 1.05-1.41 ng/m3 in the winter and 0.99-1.56 ng/m3 in the summer. The soluble Cr(VI) concentrations were 0.03-0.19 ng/m3 in the winter and 0.12-0.37 ng/m3 in the summer. The summer mean ratios of soluble to total Cr(VI) were 14.3-43.7%, significantly higher than 4.2-14.4% in the winter. The winter concentrations of soluble and total Cr(VI) in the suburban area were significantly lower than in the three urban areas. The results suggested that formation of Cr(VI) via atmospheric chemistry may contribute to the higher soluble Cr(VI) concentrations in the summer.

Interconversion of chromium species during air sampling: effects of O3, NO2, SO2, particle matrices, temperature, and humidity.

The interconversion between Cr(VI), a pulmonary carcinogen, and Cr(III), an essential human nutrient, poses challenges to the measurement of Cr(VI) in airborne particles. Chamber and field tests were conducted to identify the factors affecting Cr(VI)-Cr(III) interconversion in the basic filter medium under typical sampling conditions. In the chamber tests, isotopically enriched (53)Cr(VI) and (50)Cr(III) were spiked on diesel particulate matter (DPM) and secondary organic aerosol (SOA) that were precollected on a basic MCE filter. The filter samples were then exposed to clean air or the air containing SO2 (50 and 160 ppb), 100 ppb O3, or 150 ppb NO2 for 24 h at 16.7 LPM flow rate at designated temperature (20 and 31 °C) and RH (40% and 70%) conditions. Exposure to 160 ppb SO2 had the greatest effect on (53)Cr(VI) reduction, with (53)Cr(VI) recovery of 31.7 ± 15.8% (DPM) and 42.0 ± 7.9% (SOA). DPM and SOA matrix induced (53)Cr(VI) reduction when exposed to clean air while reactive oxygen species in SOA could promote (50)Cr(III) oxidation. Deliquescence when RH increased from 40% to 70% led to conversion of Cr(III) in SOA, whereas oxidized organics in DPM and SOA enhanced hygroscopicity and thus facilitated Cr(VI) reduction. Field tests showed seasonal variation of Cr(VI)-Cr(III) interconversion during sampling. Correction of the interconversion using USEPA method 6800 is recommended to improve accuracy of ambient Cr(VI) measurements.

Future challenges to protecting public health from drinking-water contaminants.

Over the past several decades, human health protection for chemical contaminants in drinking water has been accomplished by development of chemical-specific standards. This approach alone is not feasible to address current issues of the occurrence of multiple contaminants in drinking water, some of which have little health effects information, and water scarcity. In this article, we describe the current chemical-specific paradigm for regulating chemicals in drinking water and discuss some potential additional approaches currently being explored to focus more on sustaining quality water for specific purposes. Also discussed are strategies being explored by the federal government to screen more efficiently the toxicity of large numbers of chemicals to prioritize further intensive testing. Water reuse and water treatment are described as sustainable measures for managing water resources for potable uses as well as other uses such as irrigation.

Metal exposures in an inner-city neonatal population.

OBJECTIVES: We measured concentrations of lead (Pb), manganese (Mn), chromium (Cr), and copper (Cu) in umbilical cord whole blood and examined sources of environmental Pb exposures in a predominantly African-American population. METHODS: Between April and July 2006, we collected reproductive histories, questionnaires, and blood samples from 102 women, aged 16-45 years, who delivered at a Memphis, TN hospital. RESULTS: The prevalence of preeclampsia and low birth weight infancy in the study population was 11% and 10%, respectively. Twenty-eight percent of mothers reported living near a potential Pb-contaminated area, while 43% lived in a residence built before 1978. Geometric mean (GM) concentrations for umbilical cord blood in the study population were 1.3, 3.5, 9.0, and 52.0 microg/dL for Pb, Mn, Cr, and Cu, respectively. Six neonates had cord blood Pb (CBL) concentrations above 10 microg/dL, while 20 had CBL concentrations > or =2 microg/dL. GM umbilical CBL levels were higher in neonates born to women living near a potential Pb-contaminated area (2.2 vs. 1.1 microg/dL) and those with friends, family or household members exposed to lead products (1.6 vs. 1.1 microg/dL). Some evidence of an exposure-response relationship was also detected between all four metal concentrations and an increasing number of maternal lead exposures. After adjustment for confounding, proximity to a Pb-contaminated area was the strongest environmental determinant of CBL levels among neonates with CBL concentrations of > or =2 microg/dL (odds ratio=5.1; 95% CI=1.6, 16.7). CONCLUSIONS: Metal concentrations were elevated in this population, and CBL levels were associated with proximity to Pb-contaminated areas.