Arsenic in rice: II. Arsenic speciation in USA grain and implications for human health

Rice is a potentially important route of human exposure to arsenic, especially in populations with rice-based diets. However, arsenic toxicity varies greatly with species. The initial purpose of the present study was to evaluate arsenic speciation in U.S. rice. Twenty-four samples containing high levels of arsenic and produced in different regions of the U.S were selected from a previous market-basket survey. Arsenite and dimethyl arsinic acid (DMA) were the major species detected. DMA increased linearly with increasing total As but arsenite remained fairly constant at approximately 0.1 mg kg(-1), showing that rice high in As was dominated by DMA. A similar result was obtained when our data was combined with other published speciation studies for U.S. rice. However, when all published speciation data for rice was analyzed a second population dominated by inorganic As and lower levels of DMA was found. We thus categorized rice into DMA and Inorganic As types. Rice from the U.S. was predominantly the DMA type, as were single samples from Australia and China, whereas rice from Asia and Europe was the Inorganic As type. We suggest that methylation of As occurs within rice and that genetic differences lead to the two rice types. Insufficient understanding of DMA toxicity precludes a firm assessment of the relative health risks associated with the two rice types but, based on current knowledge, we suggest that the DMA rice type is likely to be less of a health risk than the Inorganic As rice type and, on this basis, rice from the U.S. may be safer than rice from Asia and Europe.     

Human adenoviruses in water: occurrence and health implications: a critical review

Adenoviruses are important human pathogens that are responsible for both enteric illnesses and respiratory and eye infections. Recently, these viruses have been found to be prevalent in rivers, coastal waters, swimming pool waters, and drinking water supplies worldwide. United Sates Environmental Protection Agency (USEPA) listed adenovirus as one of nine microorganisms on the Contamination Candidate List for drinking water because their survival characteristic during water treatment is not yet fully understood. Adenoviruses have been found to be significantly more stable than fecal indicator bacteria and other enteric viruses during UV treatment. Adenovirus infection may be caused by consumption of contaminated water or inhalation of aerosolized droplets during water recreation. The goal of this review is to summarize the state of technology for adenovirus detection in natural and drinking waters and the human health risk imposed by this emerging pathogen. The occurrence of these viruses in natural and treated waters is summarized from worldwide reports.     

Arsenic removal from groundwater by household sand filters: comparative field study, model calculations, and health benefits

Arsenic removal efficiencies of 43 household sand filters were studied in rural areas of the Red River Delta in Vietnam. Simultaneously, raw groundwater from the same households and additional 31 tubewells was sampled to investigate arsenic coprecipitation with hydrous ferric iron from solution, i.e., without contact to sand surfaces. From the groundwaters containing 10-382 microg/L As, < 0.1-48 mg/L Fe, < 0.01-3.7 mg/L P, and 0.05-3.3 mg/L Mn, similar average removal rates of 80% and 76% were found for the sand filter and coprecipitation experiments, respectively. The filtering process requires only a few minutes. Removal efficiencies of Fe, phosphate, and Mn were > 99%, 90%, and 71%, respectively. The concentration of dissolved iron in groundwater was the decisive factor for the removal of arsenic. Residual arsenic levels below 50 microg/L were achieved by 90% of the studied sand filters, and 40% were even below 10 microg/L. Fe/As ratios of > or = 50 or > or = 250 were required to ensure arsenic removal to levels below 50 or 10 microg/L, respectively. Phosphate concentrations > 2.5 mg P/L slightly hampered the sand filter and coprecipitation efficiencies. Interestingly, the overall arsenic elimination was higher than predicted from model calculations based on sorption constants determined from coprecipitation experiments with artificial groundwater. This observation is assumed to result from As(lll) oxidation involving Mn, microorganisms, and possibly dissolved organic matter present in the natural groundwaters. Clear evidence of lowered arsenic burden for people consuming sand-filtered water is demonstrated from hair analyses. The investigated sand filters proved to operate fast and robust for a broad range of groundwater composition and are thus also a viable option for mitigation in other arsenic affected regions. An estimation conducted for Bangladesh indicates that a median residual level of 25 microg/L arsenic could be reached in 84% of the polluted groundwater. The easily observable removal of iron from the pumped water makes the effect of a sand filter immediately recognizable even to people who are not aware of the arsenic problem.     

Arsenic in cereals,their relation with human health risk,and possible mitigation strategies

Arsenic (As) contamination of edible plants is now well recognized mainly in Bangladesh, India, and some other countries of South and Southeast Asia and Latin America. It is well known that long-term use of As-contaminated irrigation water adds As to soils and edible plants to adversely affect food production and quality. Consolidated evidence shows that As uptake in edible plants and crops is proportionally associated with the presence of high As in soils and irrigation waters. However, factors such as cultivation method, As speciation, soil composition, origin, and type of plant have major impact on the amount of As uptake. When As is absorbed by crops and edible plants, this may add substantially to the dietary As intake, thus posing human health risks to local inhabitants and to places where the As-contaminated food is exported. To date, limited attention has been paid to the risk of consumption of As-contaminated foods. In this context, our aim was to review As uptake in some of the common and popular cereals that have been a cause of human health risk. We also reviewed possible mitigation options and what needs to be done in the future.     

Co‐occurrence of citrinin and ochratoxin A in rice in Asia and its implications for human health

Citrinin (CIT) and ochratoxin A (OTA) are nephrotoxic mycotoxins, produced by several Aspergillus and Penicillium species and their co‐occurrence in rice may cause health effects in humans. Rice is an important food crop worldwide and is a major staple food in Asia which may be invaded by CIT and OTA producing fungal spores in the field, during harvest and storage. Humans are exposed to these mycotoxins through ingestion of contaminated rice and other food commodities. Yet, data on the combined presence to these food contaminants are still insufficient to estimate human exposure in Asia. This review describes the prevalence of CIT and OTA in rice in Asia and its implications on human health, which may help in establishing and carrying out proper management strategies against mould development on rice. From the health point of view, combined exposition of CIT and OTA should be a public concern as both are nephrotoxic and long‐term exposure can pose detrimental health effects. Thus, it is necessary for local farmers and food factories to implement strict measures and to improve methods for rice preservation during the distribution to consumers, particularly in the markets. Moreover, regular surveys for CIT and OTA occurrence in rice and human biomonitoring are recommended to reduce the health effects in Asian population. © 2017 Society of Chemical Industry     

Nanomaterials in sunscreens: Potential human and ecological health implications

Inorganic nanomaterials such as TiO₂ and ZnO provide significant benefits in terms of UV protection, and their use generally has increased in commercial sunscreens. However, more recently there have been concerns about their potential human and ecological health implications, mostly driven by perception rather than by formal assessments. The large and increasing body of literature on these nanomaterials indicates that in most circumstances their risk are minimal. Penetration of the human epidermis is minimal for these nanomaterials, significantly reducing the potential effects that these nanomaterials may pose to internal organs. The excess Zn ion dose is very small compared to normal dietary consumption of Zn, which is a necessary element. The levels of residual nanomaterials or released ions in public swimming pools is also low, with minimal effect in case this water is ingested during swimming or bathing. In natural environments with significant water flow due to wind and water currents, the concentrations of nanomaterials and released ions are generally well below levels that would cause effects in aquatic organisms. However, sensitive habitats with slow currents, such as coral reefs, may accumulate these nanomaterials. The number of studies of the levels and effects of nanomaterials in these sensitive habitats is very small; more research is needed to determine if there is an elevated risk to these ecosystems from the use of sunscreens with these nanomaterials.     

Arsenic and lead in foods: a potential threat to human health in Bangladesh

The non-carcinogenic and carcinogenic risk of arsenic and lead to adults and children via daily dietary intake of food composites in Bangladesh was estimated. The target hazard quotients (THQs), hazard index (HI) and target carcinogenic risk (TR) were calculated to evaluate the non-carcinogenic and carcinogenic health risk from arsenic and lead. Most of the individual food composites contain a considerable amount of arsenic and lead. The highest mean concentrations of arsenic were found in cereals (0.254 mg kg^–1 fw) and vegetables (0.250 mg kg^–1 fw), and lead in vegetables (0.714 mg kg^–1 fw) and fish (0.326 mg kg^–1 fw). The results showed the highest THQs of arsenic in cereals and lead in vegetables for both adults and children which exceeded the safe limit (> 1) indicating that cereals and vegetables are the main food items contributing to the potential health risk. The estimated TR from ingesting dietary arsenic and lead from most of the foods exceeded 10^?6, indicating carcinogenic risks for all adult people of the study area.     

Methyl tert-butyl ether (MTBE) in public and private wells in New Hampshire: occurrence, factors, and possible implications

Methyl tert-butyl ether (MTBE) concentrations > or = 0.2 /microg/L were found in samples of untreated water in 18% of public-supply wells (n = 284) and 9.1% of private domestic wells (n = 264) sampled in 2005 and 2006 in New Hampshire. In counties that used reformulated gasoline (RFG), MTBE occurred at or above 0.2 microg/L in 30% of public- and 17% of private-supply wells. Additionally, 52% of public-supply wells collocated with fuel storage and 71% of mobile home park wells had MTBE. MTBE occurrence in public-supply wells was predicted by factors such as proximity to sources of fuel, land use, and population density, as well as low pH and distance from mapped lineaments. RFG use, land-use variables, and pH were important predictors of private-well MTBE occurrence. Variables representing sources of MTBE, such as the distance to known fuel sources, were not significant predictors of MTBE occurrence in private-supply wells. It is hypothesized that private wells may become contaminated from the collective effects of sources in high population areas and from undocumented incidental releases from onsite or proximal gasoline use. From 2003 to 2005, MTBE occurrence decreased in 63 public-supply wells and increased in 60 private-supply wells, but neither trend was statistically significant.     

Widespread occurrence of bisphenol A in paper and paper products: implications for human exposure

Bisphenol A (BPA) is used in a variety of consumer products, including some paper products, particularly thermal receipt papers, for which it is used as a color developer. Nevertheless, little is known about the magnitude of BPA contamination or human exposure to BPA as a result of contact with paper and paper products. In this study, concentrations of BPA were determined in 15 types of paper products (n = 202), including thermal receipts, flyers, magazines, tickets, mailing envelopes, newspapers, food contact papers, food cartons, airplane boarding passes, luggage tags, printing papers, business cards, napkins, paper towels, and toilet paper, collected from several cities in the USA. Thermal receipt papers also were collected from Japan, Korea, and Vietnam. BPA was found in 94% of thermal receipt papers (n = 103) at concentrations ranging from below the limit of quantitation (LOQ, 1 ng/g) to 13.9 mg/g (geometric mean: 0.211 mg/g). The majority (81%) of other paper products (n = 99) contained BPA at concentrations ranging from below the LOQ to 14.4 μg/g (geometric mean: 0.016 μg/g). Whereas thermal receipt papers contained the highest concentrations of BPA (milligram-per-gram), some paper products, including napkins and toilet paper, made from recycled papers contained microgram-per-gram concentrations of BPA. Contamination during the paper recycling process is a source of BPA in paper products. Daily intake (DI) of BPA through dermal absorption was estimated based on the measured BPA concentrations and handling frequency of paper products. The daily intake of BPA (calculated from median concentrations) through dermal absorption from handling of papers was 17.5 and 1300 ng/day for the general population and occupationally exposed individuals, respectively; these values are minor compared with exposure through diet. Among paper products, thermal receipt papers contributed to the majority (>98%) of the exposures.     

Arsenic occurrence and species in near-shore macroalgae-feeding marine animals

This study was undertaken to improve the understanding of arsenic species and their pathways of formation in marine animals: fish (Odax cyanomelas), abalone (Haliotis rubra), and sea urchins (Heliocidaris erythrogramma and Centrostephanus rodgersii) that are directly exposed through their diets to dimethyl arsenoriboses in macroalgae (Phyllospora comosa and Halopteris platycena). The identification of dimethyl arsenoriboses (phosphate, sulfonate, and glycerol) in both dominant macroalgae species, and especially digestive tissues of marine animals that consume them, suggests these arsenic species, are to some degree accumulated directly from their diets without degradation or conversion. An unknown arsenic species in H. rubra intestinal tissue was identified using tandem mass spectrometry as 2',3'-dihydroxypropyl 5-deoxy-5-trimethyl arsonioriboside (trimethyl glycerol arsenoribose). The concentration of trimethyl glycerol arsenoribose in H. rubra intestinal tissue was estimated to account for 28% (5.0 microg g(-1) dry mass) of the methanol-water-soluble arsenic fraction. The presence of a trimethyl glycerol arsenoribose in marine animal tissues may be due to microbial-mediated processes that promote the reduction and methylation of dimethyl arsenoriboses released during the breakdown of macroalgae in their diets. Arsenobetaine formation may then occur in the lumen of the digestive tract (i.e., mediated by microorganisms) or in the liver catalyzed by enzymes. The identification of a large amount of trimethyl glycerol arsenoribose in H. rubra intestinal tissue suggests this species is a main constituent in the pathway for arsenic in this marine animal.     

Coal-tar-based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management

Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20-35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments-including stormwater runoff, lake sediment, soil, house dust, and most recently, air-contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them.     

Arsenic and other trace elements in wines of eastern Croatia

Levels of arsenic and other trace elements (Al, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, Ti, Tl, U, V and Zn) in nine brands of wine from Slavonia (eastern Croatia) were investigated. Wines from two other viticulture areas, Istria (western Croatia) and Vojvodina (northern Serbia), were used for comparison. Elemental concentrations were determined by high resolution ICP-MS. Statistical methods were applied for the interpretation of obtained data. Regional differences were identified based on a set of geogenic elements (Al, Li, Be, Ti). Elements As and Pb were found to be of predominantly natural origin. Significant differences between the obtained values for As in wines from Slavonia and Vojvodina, compared to wines from Istria indicate that the geochemical arsenic anomalies present in these regions contribute to some extent to higher As content in analysed wines. The Cd, Ni, Zn, Fe and Cr in wine were found to be primarily of anthropogenic origin.     

The food matrix: implications in processing,nutrition and health

Abstract

The concept of food matrix has received much attention lately in reference to its effects on food processing, nutrition and health. However, the term matrix is used vaguely by food and nutrition scientists, often as synonymous of the food itself or its microstructure. This review analyses the concept of food matrix and proposes a classification for the major types of matrices found in foods. The food matrix may be viewed as a physical domain that contains and/or interacts with specific constituents of a food (e.g., a nutrient) providing functionalities and behaviors which are different from those exhibited by the components in isolation or a free state. The effect of the food matrix (FM-effect) is discussed in reference to food processing, oral processing and flavor perception, satiation and satiety, and digestion in the gastrointestinal tract. The FM-effect has also implications in nutrition, food allergies and food intolerances, and in the quality and relevance of results of analytical techniques. The role of the food matrix in the design of healthy foods is also discussed.     

Modeling the probability of arsenic in groundwater in New England as a tool for exposure assessment

We developed a process-based model to predict the probability of arsenic exceeding 5 microg/L in drinking water wells in New England bedrock aquifers. The model is being used for exposure assessment in an epidemiologic study of bladder cancer. One important study hypothesis that may explain increased bladder cancer risk is elevated concentrations of inorganic arsenic in drinking water. In eastern New England, 20-30% of private wells exceed the arsenic drinking water standard of 10 micrograms per liter. Our predictive model significantly improves the understanding of factors associated with arsenic contamination in New England. Specific rock types, high arsenic concentrations in stream sediments, geochemical factors related to areas of Pleistocene marine inundation and proximity to intrusive granitic plutons, and hydrologic and landscape variables relating to groundwater residence time increase the probability of arsenic occurrence in groundwater. Previous studies suggest that arsenic in bedrock groundwater may be partly from past arsenical pesticide use. Variables representing historic agricultural inputs do not improve the model, indicating that this source does not significantly contribute to current arsenic concentrations. Due to the complexity of the fractured bedrock aquifers in the region, well depth and related variables also are not significant predictors.     

Arsenic occurrence, mobility, and retardation in sandstone and dolomite formations of the Fox River Valley, Eastern Wisconsin

Elevated levels of groundwater arsenic (approximately 100 microg L(-1) = 1.3 x 10(-6) M) are found in the Fox River Valley, eastern Wisconsin. The goals of this study were to identifythe sources of As contamination and to determine the reactions responsible for As mobilization and retardation in areas lacking a discrete zone of As-enriched sulfides, shown previouslyto cause elevated arsenic in groundwater. Detailed mineralogical and chemical analyses were conducted on samples from the Sinnipee Group dolomite and St. Peter sandstone in eastern Wisconsin. Solution chemistry was monitored in batch reactions of dolomite, quartz, and sulfide mineral fractions with a 0.01 M CsCl solution at pH 7 for 3 weeks in air. Results indicate that arsenic is present in isomorphous substitution with pyrite/marcasite (FeS2), which occurs as disseminated veins, grains, and nodules in the dolomite and sandstone. The released As subsequently sorbs on the ferric oxyhydroxides formed or coprecipitates in a scorodite-like phase. Significantly, oxidative dissolution of the disseminated As-rich FeS2 grains and nodules is sufficient to explain the elevated As levels observed in eastern Wisconsin groundwater. Although complete uptake of As is observed in the batch experiments, persistent elevated As levels with spatial and temporal variations in regional groundwaters are attributed to differences in the type of sulfide occurrence (discrete horizon vs dispersed grains, veins, and nodules), variations in the dissolved oxygen content of the groundwater, and variable (limited) buildup of reacted surface layers on sulfide grains in the natural flow-through system. Discrete nanoparticulate As phases, As surface precipitates on sulfides, and sorbed As on dolomite and quartz are eliminated as major sources, and sorption of arsenic on dolomite and quartz is deemed less important than association with ferric oxyhydroxides for retardation in the regional system.     

Bromate in chlorinated drinking waters: occurrence and implications for future regulation

Bromate is a contaminant of commercially produced solutions of sodium hypochlorite used for disinfection of drinking water. However, no methodical approach has been carried out in U.S. drinking waters to determine the impact of such contamination on drinking water quality. This study utilized a recently developed method for quantitation of bromate down to 0.05 microg/L to determine the concentration of bromate present in finished waters that had been chlorinated using hypochlorite. Forty treatment plants throughout the United States using hypochlorite in the disinfection step were selected and the levels of bromate in the water both prior to and following the addition of hypochlorite were measured. The levels of bromate in the hypochlorite feedstock were also measured and together with the dosage information provided by the plants and the amount of free chlorine in the feedstock, it was possible to calculate the theoretical level of bromate that would be imparted to the water. A mass balance was performed to compare the level of bromate in finished drinking water samples to that found in the corresponding hypochlorite solution used for treatment. Additional confirmation of the source of elevated bromate levels was provided by monitoring for an increase in the level of chlorate, a co-contaminant of hypochlorite, atthe same point in the treatment plant where bromate was elevated. This study showed that bromate in hypochlorite-treated finished waters varies across the United States based on the source of the chemical feedstock, which can add as much as 3 microg/L bromate into drinking water. Although this is within the current negotiated industry standard that allows up to 50% of the maximum contaminant level (MCL) for bromate in drinking water to be contributed by hypochlorite, it would be a challenge to meet a tighter standard. Given that distribution costs encourage utilities to purchase chemical feedstocks from local suppliers, utilities in certain regions of the United States may be put at a distinct disadvantage if future lower regulations on bromate levels in finished drinking water are put into place. Moreover, with these contaminant levels it would be almost impossible to lower the maximum permissible contribution to bromate in finished water from hypochlorite to 10% of the MCL, which is the norm for other treatment chemicals. Until this issue is resolved, it will be difficult to justify a lowering of the bromate MCL from its current level of 10 to 5 microg/L or lower.     

Hydroxylated metabolites of beta- and delta-hexachlorocyclohexane: bacterial formation, stereochemical configuration, and occurrence in groundwater at a former production site

Although the use of hexachlorocyclohexane (HCH), one of the most popular insecticides after the Second World War, has been discontinued in many countries, problems remain from former production and waste sites. Despite the widespread occurrence of HCHs, the environmental fate of these compounds is not fully understood. In particular, environmental metabolites of the more persistent beta-HCH and delta-HCH have not been fully identified. Such knowledge, however, is important to follow degradation and environmental fate of the HCHs. In the present study, several hydroxy metabolites that formed during incubation of beta- and delta-HCH with the common soil microorganism Sphingobium indicum B90A were isolated, characterized, and stereochemically identified by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR). The metabolites were identified as isomeric pentachlorocyclohexanols (B1, D1) and tetrachlorocyclohexane-1,4-diols (B2, D2); delta-HCH additionally formed a tetrachloro-2-cyclohexen-1-ol (D3) and a trichloro-2-cyclohexene-1,4-diol (D4), most likely by hydroxylation of delta-pentachlorocyclohexene (delta-PCCH), initially formed by dehydrochlorination. The dehydrochlorinase LinA was responsible for conversion of delta-HCH into delta-PCCH, and the haloalkane dehalogenase LinB was responsible for the transformation of beta-HCH and delta-HCH into B1 and D1, respectively, and subsequently into B2 and D2, respectively. LinB was also responsible for transforming delta-PCCH into D3 and subsequently into D4. These hydroxylations proceeded in accordance with SN2 type reactions with initial substitution of equatorial Cls and formation of axially hydroxylated stereoisomers. The apparently high reactivity of equatorial Cls in beta- and delta-HCH toward initial hydroxylation by LinB of Sphingobium indicum B90A is remarkable when considering the otherwise usually higher reactivity of axial Cls. Several of these metabolites were detected in groundwater from a former HCH production site in Switzerland. Their presence indicates that these reactions proceed under natural environmental conditions and that the metabolites are of environmental relevance.