Importance of Arsenic Speciation in Populations Exposed to Arsenic in Drinking Water

Total arsenic in urine is often the principal means for assessing chronic exposure to arsenic-contaminated drinking water. This approach ignores many components of the human diet, especially fish and seafood that contain arsenic at significant concentrations. The toxicity differences between the inorganic forms and the dietary forms suggest both should be evaluated when attempting to assess risk from arsenic exposure. Urine biomonitoring for 53 participants was used to confirm reduction in arsenic exposure resulting from well water remediation removing inorganic arsenic from drinking water. Initially, only total arsenic urine assays were performed, but spikes in total arsenic urine concentrations were determined to be diet related and demonstrated the need for analytical methods that differentiate the arsenic species. A secondary analysis was added that quantified inorganic-related arsenic in urine and the dietary forms related to fish and seafood by subtraction from total arsenic. Significant differences were found between the inorganic arsenic component and the total arsenic measured in their urine. On average, approximately 76% of total arsenic in urine was attributed to fish and other organo-arsenic dietary sources, implying a potential significant overestimate of exposure, and demonstrating the need for differentiation of the inorganic-related arsenic from dietary arsenic.     

Sensitivity Analysis of U.S. EPA's Estimates of Skin Cancer Risk from Inorganic Arsenic in Drinking Water

The current U.S. Environmental Protection Agency's (USEPA's) risk analysis on the Integrated Risk Information System (IRIS) for arsenic in drinking water is based on an epidemiological study of skin cancer in Taiwan. Assumptions used in the USEPA application of the multistage-Weibull model for risk estimation were varied to assess the effect on predicted risk of skin cancer to the U.S. population at arsenic concentrations of 1 to 50?µg/L in drinking water. Among the assumptions tested, the only notable change in risk estimates was a reduction when the arsenic concentration used as representative for Taiwan villages in the low range (<300?µg/L) was increased to the 75th percentile (245?µg/L) in place of the mean used in the USEPA analysis (170?µg/L), but the representative value for Taiwan villages in the high range (≥600?µg/L) was not increased simultaneously to the 75th percentile. Additionally, a simulation study was conducted using records of arsenic measurements in wells from the same period and region of Taiwan as the original study. The exposure-response curve estimated from 60 villages (60 data points) differed only marginally from the outcome when data were summarized into four data points (as in the USEPA skin cancer analysis). Briefly discussed are differences between the study area of Taiwan and the U.S. in nutritional status and consumption of inorganic arsenic in food that might bias predicted U.S. skin cancer risks.     

Intake of Inorganic Arsenic in the North American Diet

Dietary intake of inorganic arsenic, previously assumed to be an insignificant source of arsenic exposure in humans, was estimated for Canadian and United States populations. Input data included arsenic contents of various food groups, a limited historical database from the Ontario Ministry of the Environment measuring the percent inorganic arsenic in food groups, and food consumption data. Estimated daily dietary intake of inorganic arsenic ranges from 8.3 to 14?µg/day in the United States and from 4.8 to 12.7?µg/day in Canada for various age groups. These data suggest that between 21% to 40% of total dietary arsenic occurs in inorganic forms. Uncertainties regarding total arsenic in dairy products in the data set applied here may account for observed differences between United States and Canadian estimates. While estimates provided here are preliminary because of limitations in data on the proportion of inorganic arsenic in foods, this analysis suggests that dietary intake of inorganic arsenic is higher than is currently assumed. Additional research is needed to more fully characterize inorganic arsenic concentrations in foods. Future study is also needed on the variability of total and inorganic arsenic in foods and the bioavailability of dietary inorganic arsenic.     

Arsenic Removal Technologies for Drinking Water Treatment

Arsenic contamination as a consequence of human activities such as mining and pesticide use is affecting the water resource quality worldwide. Because of the high risk of arsenic exposure, specific water treatment processes are required to meet the anticipated more severe water quality standards. Better understanding of presently available processes is necessary to develop economic, efficient and effective methods for arsenic removal. Arsenic could either be coagulated, adsorbed using a wide range of materials both mineral and organic or could be directly rejected by membrane processes such as reverse osmosis and nanofiltration. The recent development of submerged hybrid membrane systems, such as membrane bioreactor in wastewater treatment, offers alternative technologies for arsenic treatment. The membrane in hybrid systems allows a better phase separation between the particles binding the arsenic and the treated water. The effect of pH and contact time, and the existence of other ionic compounds must be taken into account when designing the system for optimum arsenic rejection. Further research on both hydraulic and removal performances of hybrid adsorption/membrane technology is still required to assess the full potential of this technology for arsenic removal.     

Estimation of Dietary Intake of Inorganic Arsenic in U.S. Children

Arsenic is a natural component of the environment and is ubiquitous in soils, water, and the diet. Because dietary intake can be a significant source of background exposure to inorganic arsenic (the most toxicologically significant form), accurate intake estimates are needed to provide a context for risk management of arsenic exposure. Intake of inorganic arsenic by adults is fairly well characterized, but previous estimates of childhood intake were based on inorganic arsenic analyses in a limited number of foods (13 food types). This article estimates dietary intake for U.S. children (1 to 6 years of age) based on reported inorganic arsenic concentrations in 38 foods and in water used in cooking those foods (inorganic arsenic concentration of 0.8 μg/L), and U.S. Department of Agriculture food consumption data. This information is combined using a probabilistic software model to extract food consumption patterns and compute exposure distributions. The mean childhood dietary intake estimate for inorganic arsenic was 3.2 μg/day with a range of 1.6 to 6.2 μg/day for the 10th and 95th percentiles, respectively. For both the mean and 95th percentile inorganic arsenic intake rates, intake was predominantly contributed by grain and grain products, fruits and fruit juices, rice and rice products, and milk.     

Assessing Risk of Inorganic Arsenic in Drinking Water in the United States

Limitations of the current EPA risk assessment for inorganic arsenic in drinking water in the U.S. are discussed. An empirical approach is suggested that would sample survey the populations in regions with the highest arsenic levels in drinking water for signs of arsenicism, which has been much more prevalent and appeared much earlier in exposed populations than cancer (e.g., of the skin). Biomarkers of exposure, such as arsenic content in urine, nails, hair, and skin scales, may provide even earlier indications of subpopulations with excessive arsenic exposure and identify individuals at risk. Further study is needed to evaluate fully the potential for use of biomarkers, focusing on the accuracy and reliability of analytical methods, the utility of biomarkers as indicators of short-term and long-term exposure and as precursors to clinical signs of arsenicism, and the use of “normal” ranges of biomarkers for interpretation of field observations.     

Determination of Arsenic Scalp Hair of Pakistani Children and Drinking Water for Environmental Risk Assessment

This cross-sectional study measured the arsenic level in scalp hair samples of children from two age groups exposed to contaminated underground water in Pakistan. The As concentrations in water and scalp hair samples were analyzed by electrothermal atomic absorption spectrometry. The studied areas were divided into three regions based on concentration of As in water and scalp hair of children who had been exposed to different levels of As through drinking water. The average As concentrations in underground water samples of sub-districts Faiz Ganj, Thari Mirwah, and Gambat were observed to be 15.2, 28.5, and 98.3 μg/L, respectively, which were marked as less, medium, and highly contaminated areas, respectively. The proportion of the children with lower body mass index significantly increased with increasing As exposure level; the dose–response relationship was consistently observed among the subgroups. The range of As concentrations in scalp hair samples of children of age 1–5 and 6–10 years was 0.21–3.88 and 0.32–3.63 μg/g, respectively. Thus, it is likely that children in our study areas are chronically exposed to As through drinking groundwater, suggesting that there is an urgent need to take immediate solution, especially in the Gambat sub-district.     

Arsenic in Seafood: Speciation Issues for Human Health Risk Assessment

Major sources of arsenic exposure for humans are foods, particularly aquatic organisms, which are called seafood in this report. Although seafood contains a variety of arsenicals, including inorganic arsenic, which is toxic and carcinogenic, and arsenobetaine, which is considered nontoxic, the arsenic content of seafood commonly is reported only as total arsenic. A goal of this literature survey is to determine if generalizable values can be derived for the percentage of total arsenic in seafood that is inorganic arsenic. Generalizable values for percent inorganic arsenic are needed for use as default values in U.S. human health risk assessments of seafood from arsenic-contaminated sites. Data from the worldwide literature indicate the percent of inorganic arsenic in marine/estuarine finfish does not exceed 7.3% and in shellfish can reach 25% in organisms from presumably uncontaminated areas, with few data available for freshwater organisms. However, percentages can be much higher in organisms from contaminated areas and in seaweed. U.S. site-specific data for marine/estuarine finfish and shellfish are similar to the worldwide data, and for freshwater finfish indicate that the average percent inorganic arsenic is generally < 10%, but ranges up to nearly 30%. Derivation of nationwide defaults for percent inorganic arsenic in fish, shellfish, and seaweed collected from arsenic-contaminated areas in the United States is not supported by the surveyed literature.     

The Association of Body Weight,Dietary Intake,and Energy Expenditure with Dietary Restraint and Disinhibition

LAWSON, OLGA J, DONALD A WILLIAMSON, CATHERINE M CHAMPAGNE, JAMES P DELANY, ELLEN R BROOKS, PAULA M HOWAT, PATRICIA J WOZNIAK, GEORGE A BRAY AND DONNA H RYAN. The association of body weight, dietary intake, and energy expenditure with dietary restraint and disinhibition. Obes Res. 1995;3:153–161. The hypotheses that dieting and/or overeating are associated with adiposity, eating disturbances, and lowered energy expenditure were tested in this study. A sample of 44 premenopausal women scoring high and low on measures of dietary restraint and disinhibition of dietary control, as measured by the Three Factor Eating Questionnaire, was studied. A 2 × 2 factorial design was employed (High/Low Restraint x High/Low Disinhibition). Dependent variables were: body composition, dietary intake, activity, resting metabolic rate, and thermic effect of food. Unrestrained overeaters (Low Restraint/High Disinhibition group) were very obese. High Dietary Restraint was associated with intent to diet and controlled eating. High scores on the Disinhibition Scale were associated with episodic overeating. Groups did not differ in resting metabolic rate (controlled for fat-free mass). Lower thermic effect of food was found to be associated with the obesity found in High Disinhibition subjects. Thus, Dietary Restraint was not associated with significant adverse effects upon physical or psychological health. High Disinhibition, however, was associated with adiposity and significant disturbances of eating.     

How Creditable are Cancer Risk Estimates from the S.W. Taiwan Database for Arsenic in Drinking Water?

A database of cancer mortality and arsenic concentrations in village wells in an arseniasis-endemic area of southwestern Taiwan has been the predominant source of information for risk assessments of U.S. Environmental Protection Agency and two National Research Council reports on arsenic and drinking water. A limitation of the data, however, is that exposure is ecological, that is, cancer mortality cannot be matched with arsenic exposure on an individual basis, just grouped by village. The resultant potential for bias is examined by comparing dose-response analyses of villages divided into two groups, those with well concentrations in a narrow range and the remainder. The narrow range group suggests a flat or downward change in risk in the low dose range, whereas the other group indicates increasing risk. More disturbingly, however, the dose-response data are highly dispersed for both groups and the dose-response curve predicts background bladder/lung cancer levels much higher than a southwestern Taiwan comparison population. This may be due to a large variability between villages of the study area in bladder/lung cancer not directly attributable to arsenic. Including the comparison population in the dose-response analysis artificially anchors the dose-response curve at a background level inconsistent with the study population and likely just biases the slope factor upward.     

Use of Tape‐Recorded Food Records in Assessing Children's Dietary Intake

Background: Dietary assessment among children is particularly problematic when techniques are dependent on memory skills or advanced cognitive development. Objective: The current study explored the use of self‐report by tape recorders to document children's dietary intake immediately upon consumption, and compared this method with the traditional, interviewer‐guided recall technique. In addition, the influence of body fatness and sociodemographic characteristics on the accuracy of recall and tape‐recorded food records was determined. Research Methods and Procedures: The sample included 30 black and white children aged 6.5 to 11.6 years (x¯ = 9.5). Energy intake (EI), measured by six 24‐hour food records (three for each method), was compared with total energy expenditure calculated by the doubly labeled water technique. Paired t tests, correlation analyses, and multiple re‐gression analyses were performed. Results: The analyses revealed poor validity of the tape recorder method (x¯ misreporting score = ?1.13 ± 2.62 MJ/day, r for total energy expenditure and EI = ?0.06, p = 0.74). Estimates of EI differed significantly between the tape recorder and recall methods (p < 0.01). The traditional recall method was confirmed as a valid estimate of energy intake (x¯ misreporting score = 0.04 ± 2.38 MJ/day), although demonstrating a modest correlation with TEE (r = 0.32, p = 0.08). Although no significant predictors of misreporting using the recall method were identified in the multivariate analyses, older children and children with higher adiposity were more likely to misreport using the tape recorder method. Discussion: The results suggest that the use of the tape recorder for estimating EI does not result in accurate assessments among children, although this techniquemay be useful for specific subgroups (i.e., younger and leaner children).     

Dietary Fat Intake and Insulin Resistance in Black and White Children

Objective: The purpose of this study was to determine whether dietary fat intake above current Acceptable Macronutrient Distribution Range (AMDR) guidelines was associated with greater insulin resistance in black and white children. Research Methods and Procedures: We studied 142 healthy children (n = 81 whites, n = 61 blacks), 6.5 to 14 years old. Dietary composition was determined by repeated 24‐hour dietary recall, body composition by DXA, visceral fat by computed tomography, and insulin sensitivity (SI) and acute insulin response to glucose (AIRg) by frequently sampled intravenous glucose tolerance test. Subjects were categorized by ethnicity (white/black) and dietary fat intake (above‐AMDR/within‐AMDR guidelines), and differences were analyzed by 2 × 2 analysis of covariance, adjusting for covariates. Results: After adjusting for total body fat, gender, and Tanner stage, subjects consuming dietary fat above AMDR intake guidelines had lower SI and higher AIRg. This effect was specific to black children (32% lower SI and 62% higher AIRg in above‐AMDR compared with within‐AMDR blacks) and was not seen in whites. Discussion: In black, but not white, children, those with dietary fat intake above current AMDR guidelines had lower SI and higher AIRg than those who met AMDR guidelines. These findings support current AMDR guidelines for dietary fat in black children and adolescents. The mechanism(s) underlying the ethnic differences in the relationship between dietary fat intake and SI in children require further investigation.     

Estimation of Multimedia Inorganic Arsenic Intake in the U.S. Population

Arsenic is widely distributed in the environment by natural and human means. The potential for adverse health effects from inorganic arsenic depends on the level and route of exposure. To estimate potential health risks of inorganic arsenic, the apportionment of exposure among sources of inorganic arsenic is critical. In this study, daily inorganic arsenic intake of U.S. adults from food, water, and soil ingestion and from airborne particle inhalation was estimated. To account for variations in exposure across the U.S., a Monte Carlo approach was taken using simulations for 100,000 individuals representing the age, gender, and county of residence of the U.S. population based on census data. Our analysis found that food is the greatest source of inorganic arsenic intake and that drinking water is the next highest contributor. Inhalation of airborne arsenic-containing particles and ingestion of arsenic-containing soils were negligible contributors. The exposure is best represented by the ranges of inorganic arsenic intake (at the 10^th and 90^th percentiles), which were 1.8 to 11.4 µg/day for males and 1.3 to 9.4 µg/day for females. Regional differences in inorganic arsenic exposure were due mostly to consumption of drinking water containing differing inorganic arsenic content rather than to food preferences.     

Arsenic Concentrations in the Surface,Well, and Drinking Waters of the Hisarcik,Turkey, Area

Arsenic is one of the most important water pollutants because of its carcinogenicity. The association between arsenical poisoning and the development of internal malignancies and skin cancer is well known. The U.S. Environmental Protection Agency (USEPA) sets maximum contaminant level goals at zero for carcinogens. In this study are presented groundwater arsenic concentrations in the area of naturally rich boron sources of Turkey. Water samples were collected from the Hisarcik, Turkey, area, which has a large boron mine. An inductively coupled plasma/mass spectrometry method was used to analyze arsenic concentrations in water samples. The arsenic levels in water ranged from no detectable amounts to 3.00 mg As/L (mean: 0.46 ± 0.07SD). This mean As level exceeds by a factor of 10 the USEPA's current Maximum Contaminant Level of 0.05 mgAs/L. Some possible health problems associated with consumption of arsenic-contaminated water are discussed and public health interventions proposed.     

Arsenic speciation in marine interstitial water. The occurrence of organoarsenicals

Arsenic speciation data are presented for pore waters squeezed from some native and anthropogenically influenced sediments.Ten stations were sampled with a box corer (to 20 cm) at two British Columbia coastal sites that are influenced by mine-tailings discharges. These are Rupert Inlet and Alice Arm as well as their associated systems of Quatsino Sound/Holberg Inlet and Hastings Arm respectively.Total dissolved arsenic concentrations (As _D) usually exhibited subsurface maxima at 5–10 cm and were generally related to solid phase arsenic (As _p) levels, but there was also a dependence on the nature of the substrate. Tailings exhibited both the lowest (Rupert Inlet) and the highest (Alice Arm) As _D values. Inorganic arsenicals, arsenate (AsV) and arsenite (AsIII) constituted the majority (>90%) of the dissolved species butevery sample contained organoarsenicals. This is the first report of mono-, di- and tri-methylated arsenic species in marine interstitial water.A strong positive correlation between the sum of the methylarsenic compounds (MeAs) and the total dissolved arsenic (As _D) was found, indicating in situ microbial methylation similar to that observed in non-aquatic systems. Flux values for arsenic at the sediment-water interface suggest that, at present, there is no significant mobilization of arsenic from these mine-derived sediments into the water column.     

Mechanisms Preserving Insulin Action during High Dietary Fat Intake

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