Rice consumption and urinary arsenic concentrations in U.S. children

Arsenic Bioaccessibility in Rice and Its Application to Derive Health-Based Limits in China

Arsenic (As) contamination in rice is a global public health concern, particularly in Asian countries where rice is the staple food. Current health-based limits for As in rice are typically derived from total As concentrations, resulting in overly stringent values. This study aimed to determine As bioaccessibility in rice, estimate dietary intakes of inorganic As (iAs) at different consumption rates, evaluate the cancer and non-cancer risks associated with iAs exposure through rice consumption, and assess the feasibility of deriving more accurate health-based limits for As in rice after incorporating rice As bioaccessibility. Bioaccessibility of As ranged from 60.7% to 104.5% in rice samples. Estimated iAs intake varied from 0.04 to 1.40 μg/kg BW/day at rice consumption rates of 100-300 g/day. Incorporating rice As bioaccessibility resulted in lower iAs intake estimates of 0.03-1.18 μg/kg BW/day. The non-cancer and cancer risks associated with iAs exposure are concerning for populations with higher rice consumption rates and elevated rice iAs concentrations. Health-based limits for iAs in rice for different regions across China are discussed after incorporating rice As bioaccessibility. This study contributes to the development of regional or national safety limits for As in rice, based on As bioaccessibility in rice.

Augmenting the National Nutrition Data System to Promote Diet Sustainability Analyses

Research on sustainable diets has become an important and growing area of the nutrition field, but recent studies have pointed to a lack of sustainability metrics and methods that are hindering research and policy progress. To fill this gap, the White House National Strategy on Hunger, Nutrition, and Health calls for increased funding to improve metrics, data collection, and research to address all domains of sustainability, which include nutrition/health, economic, environmental, and social domains. Commodity recipe databases, such as the Food Commodity Intake Database (FCID), are important tools for conducting diet sustainability analyses because they translate mixed dishes from dietary surveys, such as the National Health and Nutrition Examination Survey (NHANES), into commodity ingredients. These ingredients have been linked to data on environmental impacts and economic costs from other databases, thus facilitating collaboration between nutrition researchers, environmental scientists, economists, and others. These linkages cannot be made with other components of the national nutrition data system, such as the Food Patterns Equivalents Database (FPED), because the disaggregated food groups from them are not relevant for examining environmental impacts. Although the NHANES is conducted on an ongoing basis, and FPED is continually updated, the FCID has not been officially updated since 2010. This severely limits advancements in sustainability research and related policy analyses. In this commentary, we argue that the federal government should promote this diet sustainability work by integrating a commodity recipe database into the national nutrition data system, and updating it on a regular basis, as it does with other component databases.

A State-of-the-Science Review on Metal Biomarkers

PURPOSE OF REVIEW

Biomarkers are commonly used in epidemiological studies to assess metals and metalloid exposure and estimate internal dose, as they integrate multiple sources and routes of exposure. Researchers are increasingly using multi-metal panels and innovative statistical methods to understand how exposure to real-world metal mixtures affects human health. Metals have both common and unique sources and routes of exposure, as well as biotransformation and elimination pathways. The development of multi-element analytical technology allows researchers to examine a broad spectrum of metals in their studies; however, their interpretation is complex as they can reflect different windows of exposure and several biomarkers have critical limitations. This review elaborates on more than 500 scientific publications to discuss major sources of exposure, biotransformation and elimination, and biomarkers of exposure and internal dose for 12 metals/metalloids, including 8 non-essential elements (arsenic, barium, cadmium, lead, mercury, nickel, tin, uranium) and 4 essential elements (manganese, molybdenum, selenium, and zinc) commonly used in multi-element analyses.

RECENT FINDINGS

We conclude that not all metal biomarkers are adequate measures of exposure and that understanding the metabolic biotransformation and elimination of metals is key to metal biomarker interpretation. For example, whole blood is a good biomarker of exposure to arsenic, cadmium, lead, mercury, and tin, but it is not a good indicator for barium, nickel, and uranium. For some essential metals, the interpretation of whole blood biomarkers is unclear. Urine is the most commonly used biomarker of exposure across metals but it should not be used to assess lead exposure. Essential metals such as zinc and manganese are tightly regulated by homeostatic processes; thus, elevated levels in urine may reflect body loss and metabolic processes rather than excess exposure. Total urinary arsenic may reflect exposure to both organic and inorganic arsenic, thus, arsenic speciation and adjustment for arsebonetaine are needed in populations with dietary seafood consumption. Hair and nails primarily reflect exposure to organic mercury, except in populations exposed to high levels of inorganic mercury such as in occupational and environmental settings. When selecting biomarkers, it is also critical to consider the exposure window of interest. Most populations are chronically exposed to metals in the low-to-moderate range, yet many biomarkers reflect recent exposures. Toenails are emerging biomarkers in this regard. They are reliable biomarkers of long-term exposure for arsenic, mercury, manganese, and selenium. However, more research is needed to understand the role of nails as a biomarker of exposure to other metals. Similarly, teeth are increasingly used to assess lifelong exposures to several essential and non-essential metals such as lead, including during the prenatal window. As metals epidemiology moves towards embracing a multi-metal/mixtures approach and expanding metal panels to include less commonly studied metals, it is important for researchers to have a strong knowledge base about the metal biomarkers included in their research. This review aims to aid metals researchers in their analysis planning, facilitate sound analytical decision-making, as well as appropriate understanding and interpretation of results.

Associations of arsenic exposure with liver injury in US adults: NHANES 2003-2018

Arsenic is a natural element with complex toxicity. Long-term exposure to arsenic can cause a variety of health damage. In recent years, there are some studies on arsenic exposure and liver injury. But few of them tried to measure the quantitative relationship between arsenic exposure and indicators of liver injury in adult. Therefore, this study aimed to elucidate the relationship between them. This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) in 2003-2018. Arsenic exposure was assessed using total urinary arsenic and dimethylarsenate acid (DMA). We selected alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), total protein (TP), ALT/AST, total bilirubin (TBIL), and albumin (ALB) as markers of liver injury. Multiple linear regression was used to explore the relationship between urinary arsenic concentrations and these markers of liver function injury. In addition, six covariables (age, sex, smoker, alcohol user, BMI, diabetes) were further analyzed in subgroups. A total of 13,420 adults were included in the analysis. The multivariate linear regression analyses showed that urinary DMA was positively correlated with ALT (β 0.135, 95%CI 0.090, 0.180, p < 0.001), AST (β 0.053, 95%CI 0.014, 0.092, p < 0.01), ALT/AST (β 0.052, 95%CI 0.030, 0.074, p < 0.001), TBIL (β 0.061, 95%CI 0.034, 0.089, p < 0.001), and GGT (β 0.178, 95%CI 0.110, 0.246, p < 0.001). Similar results were observed for total urinary arsenic, suggesting a positive association with AST (β 0.048, 95%CI 0.016, 0.081, p < 0.01), ALT (β 0.090, 95%CI 0.049, 0.132, p < 0.001), and TBIL (β 0.062, 95%CI 0.037, 0.088, p < 0.001). In subgroup analysis, sex and smoker showed significant differences between subgroups. Our results demonstrate a positive association between urinary arsenic exposure and liver injury in adults. Sex and smokers may be related to arsenic pathogenicity.

Urinary polycyclic aromatic hydrocarbon, arsenic, and metal exposure and correlation with emphysema in smokers

PURPOSE

Environmental exposure to metals and chemicals can increase the risk of acute and chronic pulmonary diseases in the human population. This study aimed to analyze seven forms of polycyclic aromatic hydrocarbons (PAHs), seven types of arsenic species, fourteen types of urinary metals including antimony, barium, cadmium, cesium, cobalt, lead, manganese, mercury, molybdenum, strontium, thallium, tin, tungsten, uranium, and the link with emphysema in the US adult cigarette smoking population.

METHODS

A specialized weighted complex survey design analysis using 2011-2016 National Health and Nutrition Examination Survey (NHANES) datasets was conducted. Multivariate logistic regression models were used to assess the association between urinary metals, arsenic, PAHs, and emphysema in adult smokers. R software was used to conduct the statistical analysis.

RESULTS

All 4th quantile concentrations of PAHs, including 1-hydroxynaphthalene, 2-hydroxynaphthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxypyrene, 1-hydroxyphenanthrene, and 2 & 3-hydroxyphenanthrene, were significantly associated with emphysema in smokers. The 3rd quantile of 1-hydroxypyrene were also associated with increased odds of emphysema in smokers. Among arsenic and metals, the 4th quantile of cadmium was associated with an increased odds of emphysema in smokers. The 3rd quantile of dimethylarsinic acid (DMA) and 4th quantile of mercury were found to have inverse relationships with emphysema in smokers. Several demographic factors had significant associations with emphysema in smokers.

CONCLUSION

Urinary PAHs and cadmium were associated with increased odds of emphysema in smokers. DMA and mercury had an inverse association with emphysema in smokers.

Exposure to arsenolipids and inorganic arsenic from marine-sourced dietary supplements

Dietary supplements sourced from marine environments, such as fish oils and seaweed-based supplements, are widely consumed to boost nutrient intakes, including by vulnerable populations such as pregnant women. Like other marine foods, these supplements are also a potential source of exposure to arsenic, including the known toxic species, inorganic arsenic, and the cytotoxic, lipid-soluble arsenic compounds, arsenic hydrocarbons. A study of 32 marine-sourced supplements found higher total arsenic concentrations (>1000 ng g^-1) in supplements made from seaweed, krill and calanus oil, and in fish and fish liver products marketed as "unprocessed". Inorganic arsenic was only detectable in the seaweed samples, and was elevated (8900 ng g^-1) in one product. Arsenic hydrocarbons were not detected in krill oil samples but were present at concentrations from 169 to 2048 ng g^-1 in "unprocessed" fish and fish liver oil, and calanus oil. Survey data from the New Hampshire Birth Cohort Study (NHBCS) found 13.5% of pregnant women (n = 1997) reported taking fish oil supplements; and of those, most did so daily (75.6%, 6 or more times per week). Only a small percentage (9%) of those who reported consuming fish oil used products associated with higher arsenic levels. Higher urinary arsenic concentrations were found among women who consumed fish oil compared with those who did not, and specifically higher arsenobetaine and dimethyl arsenic concentrations. Dietary supplements are becoming common components of modern diets, and some marine-sourced dietary supplements are a source of inorganic arsenic and arsenic hydrocarbons.

Association of As, Pb, Cr, and Zn urinary heavy metals levels with predictive indicators of cardiovascular disease and obesity in children and adolescents

BACKGROUND

Although the basic causes of obesity and cardiovascular illness have been extensively researched, little is known about the influence of environmental variables such as heavy metals on obesity development and cardiovascular disease in children and adolescents. The assumption that arsenic (As), lead (Pb), chromium (Cr), and zinc (Zn) exposure impact obesity and predictors of cardiovascular disease was explored in this study.

METHOD

A questionnaire was used to gather demographic information as well as certain determinants of exposure to As, Pb, Cr, and Zn from 106 children and adolescents aged 6 to 18. Physical tests (height, weight, waist circumference (WC), BMI, BMI Z-score, Systolic blood pressure (SBP), Diastolic blood pressure (DBP)), blood samples for clinical trials (Fasting Blood Sugar (FBS), Total Cholesterol (TC), Triglyceride (TG), Low-Density Lipoprotein (LDL), High-Density Lipoprotein (HDL) (, and urine samples for urinary creatinine measurement and measures of As, Pb, Cr, and Zn in urine were obtained using the Inductively coupled plasma mass spectrometry (ICP/MS).

RESULTS

The average age of the participants in the research was 11.42 ± 3.68. The majority of the participants in the research were boys (56 people). As, Pb, and Zn mean concentrations (μg/L) were greater in obese adults (42.60 ± 22.59, 20.63 ± 14.64, 326 ± 164.82), respectively. After adjusting for possible confounding factors, the data revealed that adolescents aged 12-18 years had higher levels of As and Pb (8.69 and 5.02 μg/L) than children aged 6 to 11. As and Zn metals had significant association with FBS and lipid profile (TC, TG, LDL, HDL), lead had significant correlations with lipid profile, while Cr had significant correlations with WC, SBP, FBS, LDL, TC.

CONCLUSION

Childhood and adolescent exposure to As, Pb, Cr, and Zn can impact obesity and cardiovascular disease markers. The current research was a cross-sectional study, which necessitates group studies and case studies to evaluate causal relationships.

Joint effect of urinary arsenic species and serum one-carbon metabolism nutrients on gestational diabetes mellitus: A cross-sectional study of Chinese pregnant women

BACKGROUND

Growing evidence indicates that arsenic (As) exposure can increase the risk of gestational diabetes mellitus (GDM). However, little is known about As species and GDM and the combined effect of As and one-carbon metabolism (OCM) on GDM.

OBJECTIVES

We aimed to examine the associations between As species and GDM and evaluate the potential interactions of folate, vitamin B₁₂, and homocysteine (Hcy) with As species on GDM prevalence.

METHOD

We measured levels of arsenite (As³⁺), arsenate (As⁵⁺), dimethylarsinic acid (DMA), and arsenobetaine (AsB) species in urine and folate, vitamin B₁₂, and Hcy in serum from 396 pregnant women in Tianjin, China. The diagnosis of GDM was based on an oral glucose tolerance test. Associations of As species in urine with GDM were evaluated using generalized linear models (GLMs) and Bayesian kernel machine regression (BKMR). Additive interactions of As and OCM with GDM were estimated by determining the relative excess risk due to interaction (RERI).

RESULTS

Of the 396 pregnant women, 89 were diagnosed with GDM. Continuous increases in urinary inorganic As were associated with GDM in the GLMs, with adjusted odds ratios of 2.12 (95% CI: 0.96, 4.71) for As³⁺, and 0.27 (95% CI: 0.07, 0.98) for As⁵⁺. The BKMR in estimating the exposure-response functions showed that As³⁺ and AsB were positively associated with GDM. However, As⁵⁺ showed a negative relationship with GDM. Although the additive interactions between As exposure and OCM indicators were not significant, we found that pregnant women with higher urinary As³⁺ and total As accompanied by lower serum vitamin B₁₂ were more likely to have higher odds of GDM (3.12, 95% CI: 1.32, 7.38 and 3.10, 95% CI: 1.30, 7.38, respectively).

CONCLUSIONS

Our data suggest a positive relation between As³⁺ and GDM but a negative relation between As⁵⁺ and GDM. Potential additive interaction of As and OCM with GDM requires further investigation.

Provision of folic acid for reducing arsenic toxicity in arsenic-exposed children and adults

BACKGROUND

Arsenic is a common environmental toxin. Exposure to arsenic (particularly its inorganic form) through contaminated food and drinking water is an important public health burden worldwide, and is associated with increased risk of neurotoxicity, congenital anomalies, cancer, and adverse neurodevelopment in children. Arsenic is excreted following methylation reactions, which are mediated by folate. Provision of folate through folic acid supplements could facilitate arsenic methylation and excretion, thereby reducing arsenic toxicity.

OBJECTIVES

To assess the effects of provision of folic acid (through fortified foods or supplements), alone or in combination with other nutrients, in lessening the burden of arsenic-related health outcomes and reducing arsenic toxicity in arsenic-exposed populations.

SEARCH METHODS

In September 2020, we searched CENTRAL, MEDLINE, Embase, 10 other international databases, nine regional databases, and two trials registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing the provision of folic acid (at any dose or duration), alone or in combination with other nutrients or nutrient supplements, with no intervention, placebo, unfortified food, or the same nutrient or supplements without folic acid, in arsenic-exposed populations of all ages and genders.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included two RCTs with 822 adults exposed to arsenic-contaminated drinking water in Bangladesh. The RCTs compared 400 µg/d (FA400) or 800 µg/d (FA800) folic acid supplements, given for 12 or 24 weeks, with placebo. One RCT, a multi-armed trial, compared FA400 plus creatine (3 g/d) to creatine alone. We judged both RCTs at low risk of bias in all domains. Due to differences in co-intervention, arsenic exposure, and participants' nutritional status, we could not conduct meta-analyses, and therefore, provide a narrative description of the data. Neither RCT reported on cancer, all-cause mortality, neurocognitive function, or congenital anomalies. Folic acid supplements alone versus placebo Blood arsenic. In arsenic-exposed individuals, FA likely reduces blood arsenic concentrations compared to placebo (2 studies, 536 participants; moderate-certainty evidence). For folate-deficient and folate-replete participants who received arsenic-removal water filters as a co-intervention, FA800 reduced blood arsenic levels more than placebo (percentage change (%change) in geometric mean (GM) FA800 -17.8%, 95% confidence intervals (CI) -25.0 to -9.8; placebo GM -9.5%, 95% CI -16.5 to -1.8; 1 study, 406 participants). In one study with 130 participants with low baseline plasma folate, FA400 reduced total blood arsenic (%change FA400 mean (M) -13.62%, standard error (SE) ± 2.87; placebo M -2.49%, SE ± 3.25), and monomethylarsonic acid (MMA) concentrations (%change FA400 M -22.24%, SE ± 2.86; placebo M -1.24%, SE ± 3.59) more than placebo. Inorganic arsenic (InAs) concentrations reduced in both groups (%change FA400 M -18.54%, SE ± 3.60; placebo M -10.61%, SE ± 3.38). There was little to no change in dimethylarsinic acid (DMA) in either group. Urinary arsenic. In arsenic-exposed individuals, FA likely reduces the proportion of total urinary arsenic excreted as InAs (%InAs) and MMA (%MMA) and increases the proportion excreted as DMA (%DMA) to a greater extent than placebo (2 studies, 546 participants; moderate-certainty evidence), suggesting that FA enhances arsenic methylation. In a mixed folate-deficient and folate-replete population (1 study, 352 participants) receiving arsenic-removal water filters as a co-intervention, groups receiving FA had a greater decrease in %InAs (within-person change FA400 M -0.09%, 95% CI -0.17 to -0.01; FA800 M -0.14%, 95% CI -0.21 to -0.06; placebo M 0.05%, 95% CI 0.00 to 0.10), a greater decrease in %MMA (within-person change FA400 M -1.80%, 95% CI -2.53 to -1.07; FA800 M -2.60%, 95% CI -3.35 to -1.85; placebo M 0.15%, 95% CI -0.37 to 0.68), and a greater increase in %DMA (within-person change FA400 M 3.25%, 95% CI 1.81 to 4.68; FA800 M 4.57%, 95% CI 3.20 to 5.95; placebo M -1.17%, 95% CI -2.18 to -0.17), compared to placebo. In 194 participants with low baseline plasma folate, FA reduced %InAs (%change FA400 M -0.31%, SE ± 0.04; placebo M -0.13%, SE ± 0.04) and %MMA (%change FA400 M -2.6%, SE ± 0.37; placebo M -0.71%, SE ± 0.43), and increased %DMA (%change FA400 M 5.9%, SE ± 0.82; placebo M 2.14%, SE ± 0.71), more than placebo. Plasma homocysteine: In arsenic-exposed individuals, FA400 likely reduces homocysteine concentrations to a greater extent than placebo (2 studies, 448 participants; moderate-certainty evidence), in the mixed folate-deficient and folate-replete population receiving arsenic-removal water filters as a co-intervention (%change in GM FA400 -23.4%, 95% CI -27.1 to -19.5; placebo -1.3%, 95% CI -5.3 to 3.1; 1 study, 254 participants), and participants with low baseline plasma folate (within-person change FA400 M -3.06 µmol/L, SE ± 3.51; placebo M -0.05 µmol/L, SE ± 4.31; 1 study, 194 participants). FA supplements plus other nutrient supplements versus nutrient supplements alone In arsenic-exposed individuals who received arsenic-removal water filters as a co-intervention, FA400 plus creatine may reduce blood arsenic concentrations more than creatine alone (%change in GM FA400 + creatine -14%, 95% CI -22.2 to -5.0; creatine -7.0%, 95% CI -14.8 to 1.5; 1 study, 204 participants; low-certainty evidence); may not change urinary arsenic methylation indices (FA400 + creatine: %InAs M 13.2%, SE ± 7.0; %MMA M 10.8, SE ± 4.1; %DMA M 76, SE ± 7.8; creatine: %InAs M 14.8, SE ± 5.5; %MMA M 12.8, SE ± 4.0; %DMA M 72.4, SE ±7.6; 1 study, 190 participants; low-certainty evidence); and may reduce homocysteine concentrations to a greater extent (%change in GM FA400 + creatinine -21%, 95% CI -25.2 to -16.4; creatine -4.3%, 95% CI -9.0 to 0.7; 1 study, 204 participants; low-certainty evidence) than creatine alone.

AUTHORS' CONCLUSIONS

There is moderate-certainty evidence that FA supplements may benefit blood arsenic concentration, urinary arsenic methylation profiles, and plasma homocysteine concentration versus placebo. There is low-certainty evidence that FA supplements plus other nutrients may benefit blood arsenic and plasma homocysteine concentrations versus nutrients alone. No studies reported on cancer, all-cause mortality, neurocognitive function, or congenital anomalies. Given the limited number of RCTs, more studies conducted in diverse settings are needed to assess the effects of FA on arsenic-related health outcomes and arsenic toxicity in arsenic-exposed adults and children.

Urinary arsenic and heart disease mortality in NHANES 2003-2014

BACKGROUND

Evidence evaluating the prospective association between low-to moderate-inorganic arsenic (iAs) exposure and cardiovascular disease in the general US population is limited. We evaluated the association between urinary arsenic concentrations in National Health and Nutrition Examination Survey (NHANES) 2003-2014 and heart disease mortality linked from the National Death Index through 2015.

METHODS

We modeled iAs exposure as urinary total arsenic and dimethylarsinate among participants with low seafood intake, based on low arsenobetaine levels (N = 4990). We estimated multivariable adjusted hazard ratios (HRs) for heart disease mortality per interquartile range (IQR) increase in urinary arsenic levels using survey-weighted, Cox proportional hazards models, and evaluated flexible dose-response analyses using restricted quadratic spline models. We updated a previously published relative risk of coronary heart disease mortality from a dose-response meta-analysis per a doubling of water iAs (e.g., from 10 to 20 μg/L) with our results from NHANES 2003-2014, assuming all iAs exposure came from drinking water.

RESULTS

A total of 77 fatal heart disease events occurred (median follow-up time 75 months). The adjusted HRs (95% CI) of heart disease mortality for an increase in urinary total arsenic and DMA corresponding to the interquartile range were 1.20 (0.83, 1.74) and 1.18 (0.68, 2.05), respectively. Restricted quadratic splines indicate a significant association between increasing urinary total arsenic and the HR of fatal heart disease for all participants at the lowest exposure levels <4.5 μg/L. The updated pooled relative risk of coronary heart disease mortality per doubling of water iAs (μg/L) was 1.16 (95% CI 1.07, 1.25).

CONCLUSIONS

Despite a small number of events, relatively short follow-up time, and high analytical limits of detection for urinary arsenic species, iAs exposure at low-to moderate-levels is consistent with increased heart disease mortality in NHANES 2003-2014 although the associations were only significant in flexible dose-response models.

Associations between rice consumption, arsenic metabolism, and insulin resistance in adults without diabetes

Rice consumption is an important source of arsenic exposure. Little has known about the impact of rice consumption on arsenic metabolism, which is related to insulin resistance. In this study, we examined the associations between rice consumption and arsenic metabolism, and between arsenic metabolism and insulin resistance in non-diabetic U.S adults who participated in the National Health and Nutrition Examination Survey (NHANES) 2003-2016. Rice consumer was defined as ≥0.25 cups of cooked rice/day. HOMA2-IR was calculated using HOMA2 Calculator software based on participant's fasting glucose and insulin values. Urinary arsenic concentrations below limits of detection were imputed first, and then arsenic metabolism (the proportions of inorganic arsenic (iAs), monomethylarsonate (MMA), and dimethylarsinate (DMA) to their sum) were calculated (expressed as iAs%, MMA%, and DMA%). Using the leave-one-out approach, rice consumers compared with non-consumers had a 1.71% (95% CI: 1.12%, 2.29%) higher DMA% and lower MMA% when iAs% fixed; a 1.55% (95% CI: 0.45%, 2.66%) higher DMA% and lower iAs% when MMA% fixed; and a 1.62% (95% CI: 0.95%, 2.28%) higher iAs% and lower MMA% when DMA% fixed, in multivariable adjustment models. With every 10% decrease in MMA%, the geometric mean ratio of HOMA2-IR was 1.06 (95% CI: 1.03,1.08) and 1.05 (95% CI: 1.02, 1.09) when DMA% and iAs% was fixed, respectively; however, the associations were attenuated after adjusting for body mass index. In stratified analysis, we found that lower MMA% was associated with higher HOMA2-IR in participants with obesity: a 10% increase in iAs% with a 10% decrease in MMA% was associated with higher HOMA2-IR with the geometric mean ratio of 1.05 (95% CI: 1.01, 1.09). Our findings suggest that rice consumption may contribute to lower MMA% that was further associated with higher insulin resistance, especially in individuals with obesity. Future prospective studies are needed to confirm our results in different populations.

The effects of the exposure to neurotoxic elements on Italian schoolchildren behavior

Neurodevelopmental disorders are constantly increasing on a global scale. Some elements like heavy metals are known to be neurotoxic. In this cross-sectional study we assessed the neurobehavioral effect of the exposure to trace elements including lead, mercury, cadmium, manganese, arsenic and selenium and their interactions among 299 schoolchildren residing in the heavily polluted Taranto area in Italy. Whole blood, urine and hair were collected for metal analyses, while the Child Behavior Checklist and the Social Responsiveness Scale, administered to the main teacher and the mothers were considered to identify behavioral problems in children. Blood lead mainly influenced social problems, aggressive behavior, externalizing and total problems. Urinary arsenic showed an impact on anxiety and depression, somatic problems, attention problems and rule breaking behavior. A significant interaction between lead and arsenic was observed, with a synergistic effect of the two metals increasing the risk of attention problems, aggressive behavior, externalizing problems and total problems. Overall, we were able to test that higher blood lead, urinary arsenic concentrations and their interaction increase the risk of neurobehavioral problems. This is in line with the U.S. Environmental Protection Agency’s priority list of hazardous substances where arsenic and lead are ranked as first and second respectively.

Demographic predictors of urinary arsenic in a low-income predominantly Hispanic pregnancy cohort in Los Angeles

BACKGROUND

Arsenic (As) is a contaminant of top public health concern, due to its range of detrimental health effects. Arsenic exposure has not been well-characterized among the US Hispanic populations and has been particularly understudied in this population during pregnancy.

METHODS

As part of the MADRES ongoing pregnancy cohort of predominantly lower-income, Hispanic women in Los Angeles, CA, we examined levels of maternal first trimester urinary As, including total As and As metabolites (inorganic (iAs), monomethylated (MMA) and dimethylated As (DMA)), in relation to participant demographics, lifestyle characteristics, and rice/seafood consumption, to identify factors that may influence As exposure and its metabolites during pregnancy (N = 241).

RESULTS

Total As concentrations ranged from low to high (0.8-506.2 μg/L, mean: 9.0 μg/L, SD: 32.9) in our study population. Foreign-born Hispanic women had 8.6% higher %DMA (95% CI: 3.3%, 13.9%) and -7.7% lower %iAs (95% CI: -12.6%, -2.9%) than non-Hispanic women. A similar trend was observed for US-born Hispanic women. In addition, maternal age was associated with 0.4% higher %iAs (95% CI: 0.1%, 0.6%) and 0.4% lower %DMA (95% CI: -0.7%, -0.1%) per year, which may indicate poor As methylation capacity.

CONCLUSION

Individual factors may predict As exposure and metabolism in pregnancy, and in turn, greater risk of adverse health effects.

Association between rice consumption and risk of cancer incidence in the California Teachers Study

PURPOSE

We evaluated the contribution of rice intake, a source of dietary arsenic, to cancer risk in a population of women with likely low arsenic exposure from drinking water and variable rice intake who participated in the California Teachers Study.

METHODS

Rice consumption was categorized into quartiles (< 9.6, 9.7-15.6, 15.7-42.7, and ≥ 42.8 g/day). Multivariable-adjusted hazard ratios and 95% confidence intervals (95% CI) for incident cancer were estimated comparing rice consumption categories with bladder, breast, kidney, lung, and pancreatic cancer, with progressive adjustment for age, total calories, BMI, race, smoking status, physical activity, and cancer-specific covariates.

RESULTS

The number of breast, lung, pancreatic, bladder, and kidney cancer cases was 7,351; 1,100; 411; 344; and 238, respectively. The adjusted hazard ratios (95% CI) comparing the highest versus lowest rice intake quartiles were 1.07 (1.00-1.15); 0.87 (0.72-1.04); 0.95 (0.66-1.37); 1.11 (0.81-1.52) and 1.07 (0.72-1.59) for breast, lung, pancreatic, bladder, and kidney cancers, respectively. Results were consistent when rice was modeled as a continuous variable and in analyses stratified by smoking status.

CONCLUSION

Rice consumption was not associated with risk of kidney, lung or pancreatic cancer, except maybe a small excess risk for breast cancer and a small non-significant excess risk for bladder cancer, comparing the highest versus lowest quartile of rice intake. Due to lower consumption patterns in this cohort, future studies should involve populations for which rice is a staple food and use of an arsenic biomarker.

Long-term arsenic exposure impairs differentiation in mouse embryonal stem cells

Arsenic is a contaminant found in many foods and drinking water. Exposure to arsenic during development can cause improper neuronal progenitor cell development, differentiation, and function, while in vitro studies have determined that acute arsenic exposure to stem and progenitor cells reduced their ability to differentiate. In the current study, P19 mouse embryonal stem cells were exposed continuously to 0.1-μM (7.5 ppb) arsenic for 32 weeks. A cell lineage array examining messenger RNA (mRNA) changes after 8 and 32 weeks of exposure showed that genes involved in pluripotency were increased, whereas those involved in differentiation were reduced. Therefore, temporal changes of select pluripotency and neuronal differentiation markers throughout the 32-week chronic arsenic exposure were investigated. Sox2 and Oct4 mRNA expression were increased by 1.9- to 2.5-fold in the arsenic-exposed cells, beginning at Week 12. Sox2 protein expression was similarly increased starting at Week 16 and remained elevated by 1.5-fold to sixfold. One target of Sox2 is N-cadherin, whose expression is a hallmark of epithelial-mesenchymal transitions (EMTs). Exposure to arsenic significantly increased N-cadherin protein levels beginning at Week 20, concurrent with increased grouping of N-cadherin positive cells at the perimeter of the embryoid body. Expression of Zeb1, which helps increase the expression of Sox2, was also increased started at Week 16. In contrast, Gdf3 mRNA expression was reduced by 3.4- to 7.2-fold beginning at Week 16, and expression of its target protein, phospho-Smad2/3, was also reduced. These results suggest that chronic, low-level arsenic exposure may delay neuronal differentiation and maintain pluripotency.

Children exposure to inorganic and organic arsenic metabolites: A cohort study in Northeast Italy

The aim of this study was to provide urinary levels of total arsenic (TAs) and As species as arsenobetaine (AsB), arsenocholine (AsC), inorganic As (i.e., [As(III)+As(V)]), methylarsonic acid (MMA) and dimethylarsinic acid (DMA) in 7 year-old-children (n = 200) enrolled in the Northern Adriatic Cohort II (NACII), a prospective cohort in a coastal area of Northeast Italy. TAs was determined by sector field-inductively coupled plasma mass spectrometry (SF-ICP-MS) and AsB, AsC, As(III), As(V), MMA and DMA by ion chromatography coupled to ICP-MS (IC-ICP-MS). The geometric mean (GM) for TAs was 12.9 μg/L and for [iAs + MMA + DMA] was 4.26 μg/L. The species AsB (GM of 5.09 μg/L) and DMA (GM of 3.20 μg/L) had the greatest percentage contribution to TAs levels; a greater percentage contribution from AsB is seen at TAs >10 μg/L and from DMA at TAs <10 μg/L. Urinary [iAs + MMA] levels were positively associated with [iAs + MMA + DMA] and DMA with AsB levels. Fish, shellfish and crustaceans consumption increased the AsB and TAs levels, while rice intake, mothers' education level and selenium (Se) concentration influenced the DMA concentration. Children have a high capacity to metabolize and detoxify the iAs because of the higher secondary methylation index (ratio DMA/MMA) with respect to primary methylation index (ratio MMA/iAs). In addition, the median level of [iAs + MMA + DMA] in the whole population of children was lower than the Biomonitoring Equivalent (BE) value for non-cancer endpoints. Also the Margin of Safety (MOS) value based on the population median was greater than 1, thus the exposure to the toxicologically relevant As species was not likely to be of concern.

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

AIM

Irrigating rice with groundwater can lead to As accumulation in soil and rice grains. Matched sets of irrigation water, paddy soil, and rice grains were collected to assess the scale of the problem in the Punjab plains of Pakistan.

METHODS

From a total of 60 sites, irrigation water and rice grains as well as 103 soil samples were collected and analyzed in the laboratory. Irrigation water and 660 soil samples were also analyzed in the field using a field kit.

RESULTS

Concentrations of As in irrigation water (65±32 μg/L) are higher in the floodplain of the Ravi River compared to the Chenab (13±9 μg/L) and Jhelum (4±5 μg/L) rivers, as well as the intervening Rechna (6±6 μg/L) and Chaj doabs (0.8±0.2 μg/L). Area-weighted mean soil As concentrations are 12±3 mg/kg along the Ravi, 8.9±2 and 8.1±2 mg/kg along the Chenab and Jhelum, respectively, and 6.2±0.2 mg/kg within the Rachna and 6.1±0.1 mg/kg in Chaj doabs. The As content of polished grains export-quality basmati rice of 0.09±0.05 mg/kg, however, is low across the entire area.

CONCLUSIONS

Groundwater irrigation leads to elevated As concentrations in paddy soil of some rice-growing regions of Punjab but does not result in increased uptake of As in basmati rice grains.

Positive Association of Cardiovascular Disease (CVD) with Chronic Exposure to Drinking Water Arsenic (As) at Concentrations below the WHO Provisional Guideline Value: A Systematic Review and Meta-Analysis

To the best of our knowledge, a dose-response meta-analysis of the relationship between cardiovascular disease (CVD) and arsenic (As) exposure at drinking water As concentrations lower than the WHO provisional guideline value (10 µg/L) has not been published yet. We conducted a systematic review and meta-analyses to estimate the pooled association between the relative risk of each CVD endpoint and low-level As concentration in drinking water both linearly and non-linearly using a random effects dose-response model. In this study, a significant positive association was found between the risks of most CVD outcomes and drinking water As concentration for both linear and non-linear models (p-value for trend < 0.05). Using the preferred linear model, we found significant increased risks of coronary heart disease (CHD) mortality and CVD mortality as well as combined fatal and non-fatal CHD, CVD, carotid atherosclerosis disease and hypertension in those exposed to drinking water with an As concentration of 10 µg/L compared to the referent (drinking water As concentration of 1 µg/L) population. Notwithstanding limitations included, the observed significant increased risks of CVD endpoints arising from As concentrations in drinking water between 1 µg/L and the 10 µg/L suggests further lowering of this guideline value should be considered.

Rice Intake, Arsenic Exposure, and Subclinical Cardiovascular Disease Among US Adults in MESA

Background Arsenic-related cardiovascular effects at exposure levels below the US Environmental Protection Agency's standard of 10 μg/L are unclear. For these populations, food, especially rice, is a major source of exposure. We investigated associations of rice intake, a marker of arsenic exposure, with subclinical cardiovascular disease (CVD) markers in a multiethnic population. Methods and Results Between 2000 and 2002, MESA (Multi-Ethnic Study of Atherosclerosis) enrolled 6814 adults without clinical CVD. We included 5050 participants with baseline data on rice intake and markers of 3 CVD domains: inflammation (hsCRP [high-sensitivity C-reactive protein], interleukin-6, and fibrinogen), vascular function (aortic distensibility, carotid distensibility, and brachial flow-mediated dilation), and subclinical atherosclerosis at 3 vascular sites (carotid intima-media thickness, coronary artery calcification, and ankle-brachial index). We also evaluated endothelial-related biomarkers previously associated with arsenic. Rice intake was assessed by food frequency questionnaire. Urinary arsenic was measured in 310 participants. A total of 13% of participants consumed ≥1 serving of rice/day. Compared with individuals consuming <1 serving of rice/week, ≥1 serving of rice/day was not associated with subclinical markers after demographic, lifestyle, and CVD risk factor adjustment (eg, geometric mean ratio [95% CI] for hsCRP, 0.98 [0.86-1.11]; aortic distensibility, 0.99 [0.91-1.07]; and carotid intima-media thickness, 0.98 [0.91-1.06]). Associations with urinary arsenic were similar to those for rice intake. Conclusions Rice intake was not associated with subclinical CVD markers in a multiethnic US population. Research using urinary arsenic is needed to assess potential CVD effects of low-level arsenic exposure. Understanding the role of low-level arsenic as it relates to subclinical CVD may contribute to CVD prevention and control.

Rice Intake and Emerging Concerns on Arsenic in Rice: a Review of the Human Evidence and Methodologic Challenges

PURPOSE OF REVIEW

Rice is a major staple food worldwide and a dietary source of arsenic. We therefore summarized the state of the epidemiologic evidence on whether rice consumption relates to health outcomes associated with arsenic exposure.

RECENT FINDINGS

While epidemiologic studies have reported that higher rice consumption may increase the risk of certain chronic conditions, i.e., type 2 diabetes, most did not consider specific constituents of rice or other sources of arsenic exposure. Studies that examined rice intake stratified by water concentrations of arsenic found evidence of increasing trends in cardiovascular disease risk, skin lesions, and squamous cell skin cancers and bladder cancer associated with higher rice consumption. Further studies are needed to understand the health impacts of arsenic exposure from rice consumption taking into account all sources of rice intake and potential confounding by other dietary constituents or contaminants and arsenic exposure from sources such as water.

Low level arsenic exposure, B-vitamins, and achievement among Uruguayan school children

OBJECTIVES

Millions of children globally, including the U.S., are exposed to low levels of arsenic from water and food. Arsenic is a known neurotoxicant at high levels but its effects at lower exposure levels are understudied. Arsenic methylation capacity, influenced by B-vitamin intake and status, potentially influences arsenic toxicity. In a cross-secitonal study of 5-8 year-old children from Montevideo, we assessed the relationship between urinary arsenic (U-As) and academic achievement, and tested for effect modification by B-vitamin intake, status, and arsenic methylation capacity.

METHODS

Broad math and reading scores were calculated based on six subtests (calculation, math facts fluency, applied problems, sentence reading fluency, letter word identification, passage comprehension) from the Woodcock-Muñoz Achievement Battery. B-vitamin intake was assessed from two non-consecutive 24-h dietary recalls, serum folate and vitamin B-12 levels were measured in a subset of participants. Arsenic methylation capacity was measured as the proportion of urinary monomethylarsonic acid (%MMA). Multiple imputation using chained equations was conducted to account for missing covariate and exposure data. Ordinal regressions assessed associations between U-As and achievement score tertiles in the complete case and imputed samples. A "B-vitamin index" was calculated using principal component analysis. Interactions by urinary %MMA and the B-vitamin index were assessed.

RESULTS

Median specific gravity adjusted U-As was 11.7 μg/L (range: 2.6, 50.1). We found no association between U-As and broad math and reading scores, nor effect modification by %MMA or B-vitamins.

CONCLUSION

At low-levels of exposure, U-As does not appear to affect children's academic achievement.

Dietary determinants of inorganic arsenic exposure in the Strong Heart Family Study

BACKGROUND

Chronic exposure to inorganic arsenic (iAs) in the US occurs mainly through drinking water and diet. Although American Indian (AI) populations have elevated urinary arsenic concentrations compared to the general US population, dietary sources of arsenic exposure in AI populations are not well characterized.

METHODS

We evaluated food frequency questionnaires to determine the major dietary sources of urinary arsenic concentrations (measured as the sum of arsenite, arsenate, monomethylarsonate, and dimethylarsinate, ΣAs) for 1727 AI participants in the Strong Heart Family Study (SHFS). We compared geometric mean ratios (GMRs) of urinary ΣAs for an interquartile range (IQR) increase in reported food group consumption. Exploratory analyses were stratified by gender and study center.

RESULTS

In fully adjusted generalized estimating equation models, the percent increase (95% confidence interval) of urinary ΣAs per increase in reported food consumption corresponding to the IQR was 13% (5%, 21%) for organ meat, 8% (4%, 13%) for rice, 7% (2%, 13%) for processed meat, and 4% (1%, 7%) for non-alcoholic drinks. In analyses stratified by study center, the association with organ meat was only observed in North/South Dakota. Consumption of red meat [percent increase -7% (-11%, -3%)] and fries and chips [-6% (-10%, -2%)] was inversely associated with urinary ΣAs.

CONCLUSIONS

Organ meat, processed meat, rice, and non-alcoholic drinks contribute to ΣAs exposure in the SHFS population. Organ meat is a unique source of ΣAs exposure for North and South Dakota participants and may reflect local food consumption. Further studies should comprehensively evaluate drinking water arsenic in SHFS communities and determine the relative contribution of diet and drinking water to total arsenic exposure.

Neurocognitive impact of metal exposure and social stressors among schoolchildren in Taranto, Italy

BACKGROUND

Metal exposure is a public health hazard due to neurocognitive effects starting in early life. Poor socio-economic status, adverse home and family environment can enhance the neurodevelopmental toxicity due to chemical exposure. Disadvantaged socio-economic conditions are generally higher in environmentally impacted areas although the combined effect of these two factors has not been sufficiently studied.

METHODS

The effect of co-exposure to neurotoxic metals including arsenic, cadmium, manganese, mercury, lead, selenium, and to socio-economic stressors was assessed in a group of 299 children aged 6-12 years, residing at incremental distance from industrial emissions in Taranto, Italy. Exposure was assessed with biological monitoring and the distance between the home address and the exposure point source. Children's cognitive functions were examined using the Wechsler Intelligence Scale for Children (WISC) and the Cambridge Neuropsychological Test Automated Battery (CANTAB). Linear mixed models were chosen to assess the association between metal exposure, socio-economic status and neurocognitive outcomes.

RESULTS

Urinary arsenic, cadmium and hair manganese resulted inversely related to the distance from the industrial emission source (β - 0.04; 95% CI -0.06, - 0.01; β - 0.02; 95% CI -0.05, - 0.001; β - 0.02 95% CI -0.05, - 0.003) while the WISC intellectual quotient and its sub-scores (except processing speed index) showed a positive association with distance. Blood lead and urinary cadmium were negatively associated with the IQ total score and all sub-scores, although not reaching the significance level. Hair manganese and blood lead was positively associated with the CANTAB between errors of spatial working memory (β 2.2; 95% CI 0.3, 3.9) and the reaction time of stop signal task (β 0.05; 95% CI 0.02, 0.1) respectively. All the other CANTAB neurocognitive tests did not show to be significantly influenced by metal exposure. The highest socio-economic status showed about five points intellectual quotient more than the lowest level on average (β 4.8; 95% CI 0.3, 9.6); the interaction term between blood lead and the socio-economic status showed a significant negative impact of lead on working memory at the lowest socio-economic status level (β - 4.0; 95% CI -6.9, - 1.1).

CONCLUSIONS

Metal exposure and the distance from industrial emission was associated with negative cognitive impacts in these children. Lead exposure had neurocognitive effect even at very low levels of blood lead concentration when socio-economic status is low, and this should further address the importance and prioritize preventive and regulatory interventions.

Mendelian randomization of inorganic arsenic metabolism as a risk factor for hypertension- and diabetes-related traits among adults in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) cohort

BACKGROUND

Hypertension and diabetes have been associated with inefficient arsenic metabolism, primarily through studies undertaken in populations exposed through drinking water. Recently, rice has been recognized as a source of arsenic exposure, but it remains unclear whether populations with high rice consumption but no known water exposure are at risk for the health problems associated with inefficient arsenic metabolism.

METHODS

The relationships between arsenic metabolism efficiency (% inorganic arsenic, % monomethylarsenate and % dimethylarsinate in urine) and three hypertension- and seven diabetes-related traits were estimated among 12 609 participants of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). A two-sample Mendelian randomization approach incorporated genotype-arsenic metabolism relationships from literature, and genotype-trait relationships from HCHS/SOL, with a mixed-effect linear model. Analyses were stratified by rice consumption and smoking.

RESULTS

Among never smokers with high rice consumption, each percentage point increase in was associated with increases of 1.96 mmHg systolic blood pressure (P = 0.034) and 1.85 mmHg inorganic arsenic diastolic blood pressure (P = 0.003). Monomethylarsenate was associated with increased systolic (1.64 mmHg/percentage point increase; P = 0.021) and diastolic (1.33 mmHg/percentage point increase; P = 0.005) blood pressure. Dimethylarsinate, a marker of efficient metabolism, was associated with lower systolic (-0.92 mmHg/percentage point increase; P = 0.025) and diastolic (-0.79 mmHg/percentage point increase; P = 0.004) blood pressure. Among low rice consumers and ever smokers, the results were consistent with no association. Evidence for a relationship with diabetes was equivocal.

CONCLUSIONS

Less efficient arsenic metabolism was associated with increased blood pressure among never smokers with high rice consumption, suggesting that arsenic exposure through rice may contribute to high blood pressure in the Hispanic/Latino community.

Urinary metals and metal mixtures in midlife women: The Study of Women's Health Across the Nation (SWAN)

BACKGROUND

Little is known about the extent of exposure to metals and metal mixtures among midlife women.

OBJECTIVES

We assessed exposure to multiple metals in the Study of Women's Health Across the Nation (SWAN), a multi-site, multi-racial/ethnic cohort of women at midlife.

METHODS

We measured urinary concentrations of 21 metals (arsenic, barium, beryllium, cadmium, cobalt, chromium, cesium, copper, mercury, manganese, molybdenum, nickel, lead, platinum, antimony, tin, thallium, uranium, vanadium, tungsten and zinc) using high-resolution inductively coupled plasma-mass spectrometry among 1335 white, black, Chinese and Japanese women aged 45-56 years at the third SWAN annual visit (1999-2000). Least squared geometric mean concentrations were compared across race/ethnicity, education, financial hardship, smoking, secondhand smoking, seafood intake and rice intake groups. Overall exposure patterns of multiple metals were derived using k-means clustering method.

RESULTS

The percentage of women with detectable concentrations of metals ranged from 100% for arsenic, cesium, molybdenum and zinc, to less than 5% for platinum; 15 metals had detection rates of 70% or more. Asian women, both Chinese and Japanese, had higher urinary concentrations of arsenic, cadmium, copper, mercury, molybdenum, lead and thallium, compared with other race/ethnic groups, independent of sociodemographic, lifestyle, dietary, and geographic characteristics. Seafood and rice intake were important determinants of urinary arsenic, cesium, mercury, molybdenum and lead levels. Two distinct overall exposure patterns- "high" vs. "low" -- were identified. Women in the "high" overall exposure pattern were more likely to be Asians, current smokers, and to report high consumption of seafood and rice. Black women were less likely to have the high exposure pattern.

CONCLUSIONS

Metal exposure of midlife women differs by racial/ethnic, sociodemographic, lifestyle, dietary, and geographic characteristics. Asian women may be experiencing the highest exposures to multiple metals compared with other racial/ethnic groups in the United States.

Arsenic in cooked rice foods: Assessing health risks and mitigation options

Human exposure to arsenic (As) through the consumption of rice (Oryza sativa L.) is a worldwide health concern. In this paper, we evaluated the major causes for high inorganic As levels in cooked rice foods, and the potential of post-harvesting and cooking options for decreasing inorganic As content in cooked rice, focusing particularly on As endemic areas. The key factors for high As concentration in cooked rice in As endemic areas are: (1) rice cultivation on As-contaminated paddy soils; (2) use of raw rice grains which exceed 200 μg kg^-1 of inorganic As to cook rice; and (3) use of As-contaminated water for cooking rice. In vitro and in vivo methods can provide useful information regarding the bioaccessibility of As in the gastrointestinal tract. Urinary levels of As can also be used as a valid measure of As exposure in humans. Polishing of raw rice grains has been found to be a method to decrease total As content in cooked rice. Sequential washing of raw rice grains and use of an excess volume of water for cooking also decrease As content in cooked rice. The major concern with those methods (i.e. polishing of raw rice, sequential washing of raw rice, and use of excess volume of water for cooking rice) is the decreased nutrient content in the cooked rice. Cooking rice in percolating water has recently gained significant attention as a way to decrease As content in cooked rice. Introducing and promoting rainwater harvesting systems in As endemic areas may be a sustainable way of reducing the use of As-contaminated water for cooking purposes. In conclusion, post-harvesting methods and changes in cooking practices could reduce As content in cooked rice to a greater extent. Research gaps and directions for future studies in relation to different post-harvesting and cooking practices, and rainwater harvesting systems are also discussed in this review.

Long-Term Combinatorial Exposure to Trichloroethylene and Inorganic Arsenic in Genetically Heterogeneous Mice Results in Renal Tubular Damage and Cancer-Associated Molecular Changes

Trichloroethylene (TCE) and inorganic arsenic (iAs) are environmental contaminants that can target the kidney. Chronic exposure to TCE is associated with increased incidence of renal cell carcinoma, while co-exposure to TCE and iAs likely occurs in exposed human populations, such as those near Superfund sites. In order to better understand the kidney health consequences of TCE and/or iAs exposure, a genetically heterogeneous mouse population derived from FVB/NJ and CAST/EiJ mouse strains and deficient for multidrug resistance genes (Abcb1atm1Bor , Abcb1btm1Bor ) was chronically exposed for 52-weeks to varying concentrations of TCE and iAs. Although no exposure group resulted in primary renal cell tumors, kidneys from exposed mice did have significant increases in histologic and biochemical evidence of renal tubular disease with each toxicant alone and with combined exposure, with males having significantly higher levels of damage. Although no added increase in tubular disease was observed with combination exposure compared to single toxicants, molecular changes in kidneys from mice that had the combined exposure were similar to those previous observed in an embryonic stem cell assay for the P81S TCE-induced renal cell carcinoma mutation in the Von Hippel-Lindau syndrome (VHL) gene. While this model more accurately reflects human exposure conditions, development of primary renal tumors observed in humans following chronic TCE exposure was not reproduced even after inclusion of genetic heterogeneity and co-carcinogenic iAs.

Global burden of cancer and coronary heart disease resulting from dietary exposure to arsenic, 2015

Arsenic is a ubiquitous, naturally occurring metalloid that poses a significant risk for human cancer and non-cancer diseases. It is now evident that arsenic contamination in food, especially rice and grains, presents a significant exposure to hundreds of millions of individuals worldwide. However, the disease risk from chronic exposure to the low amounts of arsenic found in food remains to be established. Thus, this research estimates the global burdens of disease expressed as Disability-Adjusted Life Years (DALYs) for lung, skin and bladder cancers, as well as coronary heart disease (CHD) attributable to inorganic arsenic in food. To determine foodborne inorganic arsenic exposures worldwide, we used the World Health Organization (WHO) estimates of food consumption in 17 country clusters, in conjunction with the reported measurements of total and inorganic arsenic in different foods. We estimated cancer potency factors for arsenic related bladder and lung cancers, and from US Environmental Protection Agency risk estimates for skin cancer to calculate the cancer incidence in males and females within each of the WHO member states. Summary relative risk estimates and population attributable fractions were developed to estimate the YLD, YLL, and DALYs for arsenic-induced CHD. The findings indicate that, globally, each year the combined DALYs for all cancers attributable to inorganic arsenic in food are approximately 1.4 million with variation in global distribution based on population and food consumption patterns. The global burden of CHD attributable to foodborne inorganic arsenic also varied with WHO region and may contribute as much as 49 million DALYs. However, in contrast to cancer burden, there is a threshold effect for arsenic-associated CHD with no increased risk of heart disease at the expected lower bound of arsenic consumption in food. These estimates indicate that foodborne arsenic exposure causes a significant yet avoidable global burden of human disease.

Ethnic, geographic and dietary differences in arsenic exposure in the multi-ethnic study of atherosclerosis (MESA)

Differences in residential location as well as race/ethnicity and dietary habits may result in differences in inorganic arsenic (iAs) exposure. We investigated the association of exposure to iAs with race/ethnicity, geography, and dietary intake in a random sample of 310 White, Black, Hispanic, and Chinese adults in the Multi-Ethnic Study of Atherosclerosis from 6 US cities with inorganic and methylated arsenic (ΣAs) measured in urine. Dietary intake was assessed by food-frequency questionnaire. Chinese and Hispanic race/ethnicity was associated with 82% (95% CI: 46%, 126%) and 37% (95% CI: 10%, 70%) higher urine arsenic concentrations, respectively, compared to White participants. No differences were observed for Black participants compared to Whites. Urine arsenic concentrations were higher for participants in Los Angeles, Chicago, and New York compared to other sites. Participants that ate rice ≥2 times/week had 31% higher urine arsenic compared to those that rarely/never consumed rice. Participants that drank wine ≥2 times/week had 23% higher urine arsenic compared to rare/never wine drinkers. Intake of poultry or non-rice grains was not associated with urinary arsenic concentrations. At the low-moderate levels typical of the US population, exposure to iAs differed by race/ethnicity, geographic location, and frequency of rice and wine intake.

Long-Term Health Effects and Underlying Biological Mechanisms of Developmental Exposure to Arsenic

PURPOSE OF REVIEW

Exposure to inorganic arsenic (iAs) via drinking water represents a significant global public health threat with chronic exposure associated with cancer, skin lesions, neurological impairment, and cardiovascular diseases. Particularly susceptible populations include the developing fetus and young children. This review summarizes some of the critical studies of the long-term health effects and underlying biological mechanisms related to developmental exposure to arsenic. It also highlights the complex factors, such as the sex of the exposed individual, that contribute to susceptibility to the later life health effects of iAs.

RECENT FINDINGS

Studies in animal models, as well as human population-based studies, have established that prenatal and early life iAs exposures are associated with long-term effects, and many of these effects display sexually dimorphic responses. As an underlying molecular basis, recent epidemiologic and toxicologic studies have demonstrated that changes to the epigenome may play a key mechanistic role underlying many of the iAs-associated health outcomes. Developmental exposure to iAs results in early and later life health effects. Mechanisms underlying these outcomes are likely complex, and include disrupted key biological pathways with ties to the epigenome. This highlights the importance of continued research, particularly in animal models, to elucidate the important underpinnings (e.g., timing of exposure, metabolism, dose) of these complex health outcomes and to identify the biological mechanisms underlying sexual dimorphism in iAs-associated diseases. Future research should investigate preventative strategies for the protection from the detrimental health endpoints associated with early life exposure to iAs. Such strategies could include potential interventions focused on dietary supplementation for example the adoption of a folate-rich diet.

Ameliorative role of antioxidant supplementation on sodium-arsenite induced adverse effects on the developing rat cerebellum

Background

Arsenic is an environmental contaminant of global concern. Consumption of ground water contaminated with inorganic arsenic (iAs) continues to be the major source of its exposure. The developing nervous system is especially vulnerable to environmental insults due to its higher rate of oxygen consumption and provision of weaker antioxidant (AOX) machinery.

Objective

Since oxidative stress has been reported as one of the major factors underlying iAs induced toxicity, the aim of the present study is to study the effect of two AOXs i.e., Alpha Lipoic Acid (ALA) and Curcumin (Cur) in developing cerebellum of rats exposed to arsenic during postnatal period.

Materials and Methods

The study was carried out on mother reared neonatal rat pups grouped as normal (Ia) and sham (vehicle) controls (Ib,c,d), while the experimental groups IIa/ IIb received sodium arsenite (NaAsO2) [(1.5/2.5 mg/kg body weight (bw)] alone or along with ALA (70 mg/kg bw)- IIIa/ IIIb or along with Cur (150 mg/kg bw)- IVa/ IVb. Behavioural, biochemical and immunohistochemical procedures were carried out to understand the underlying mechanisms.

Results

The observations indicated deficits in locomotor function, accumulation of iAs, increased levels of oxidative stress markers along with downregulation of the expression of proteins closely associated with synaptic functioning (Synaptophysin and Postsynaptic density protein95) in the cerebellum of iAs treated animals. Substantial recovery in all these parameters was observed in AOX co-treated groups.

Conclusion

Our results support the potential of ALA and Cur in amelioration of iAs induced developmental neurotoxicity. ALA and Cur can be proposed as dietary adjuvants amongst populations inhabiting areas with high iAs contamination as a safe and cost effective antidotes.

Lead, Cadmium, and Arsenic Bioaccessibility of 24 h Duplicate Diet Ingested by Preschool Children Attending Day Care Centers in Brazil

Lead, known as a metal with high neurotoxicity to children, cadmium, which is a carcinogenic and bioaccumulative contaminant, and arsenic, a class 1 carcinogenic according to the International Agency for Research on Cancer, are toxic elements (TEs) whose relevant route of exposure may be diet. We determined the bio-accessible fraction of lead, cadmium, and arsenic from the diet of preschool children from two day care centers (DCC). A cross-sectional study was conducted with 64 one–four-year-old children from two DCCs where the 24-h duplicate diet samples were collected. The diet samples were analyzed by ICP-MS for lead, cadmium, and arsenic total concentrations (n = 64) and their bio-accessibility were analyzed for a subsample (n = 10). The dietary intake (DI) mean for lead, cadmium, and arsenic were 0.18 ± 0.11 µg kg⁻¹ bw, 0.08 ± 0.04 µg kg⁻¹ bw, and 0.61 ± 0.41 µg kg⁻¹ bw, respectively. All DI calculated for TEs, considering total intake, were found lower than the tolerable limits (TL) (European Union, or World Health Organization, WHO, when applicable) except for one child’s Pb intake. Bio-accessibilities ranged between 0% to 93%, 0% to 103%, and 0% to 69%, for lead, cadmium, and arsenic, respectively. Although DI for TEs has been found lower than TL, these reference values have been recently decreased or withdrawn since it was for lead and arsenic whose TL were withdrawn by WHO.

Potential Co-exposure to Arsenic and Fluoride and Biomonitoring Equivalents for Mexican Children

BACKGROUND

Mexico is included in the list of countries with concurrent arsenic and fluoride contamination in drinking water. Most of the studies have been carried out in the adult population and very few in the child population. Urinary arsenic and urinary fluoride levels have been accepted as good biomarkers of exposure dose. The Biomonitoring Equivalents (BE) values are useful tools for health assessment using human biomonitoring data in relation to the exposure guidance values, but BE information for children is limited.

METHODS

We conducted a systematic review of the reported levels of arsenic and fluoride in drinking water, urinary quantification of speciated arsenic (inorganic arsenic and its methylated metabolites), and urinary fluoride levels in child populations. For BE values, urinary arsenic and fluoride concentrations reported in Mexican child populations were revised discussing the influence of factors such as diet, use of dental products, sex, and metabolism.

RESULTS

Approximately 0.5 and 6 million Mexican children up to 14 years of age drink water with arsenic levels over 10 μg/L and fluoride over 1.5 mg/L, respectively. Moreover, 40% of localities with arsenic levels higher than 10 μg/L also present concurrent fluoride exposure higher than 1.5 mgF/L. BE values based in urinary arsenic of 15 μg/L and urinary fluoride of 1.2 mg/L for the environmentally exposed child population are suggested.

CONCLUSIONS

An actual risk map of Mexican children exposed to high levels of arsenic, fluoride, and both arsenic and fluoride in drinking water was generated. Mexican normativity for maximum contaminant level for arsenic and fluoride in drinking water should be adjusted and enforced to preserve health. BE should be used in child populations to investigate exposure.

Serum folate and cobalamin levels and urinary dimethylarsinic acid in US children and adults

Nutritional status could affect arsenic metabolism and toxicity in the general population chronically exposed to low levels of inorganic arsenic. In this study, we examined the association of serum folate and cobalamin with urinary concentrations of dimethylarsinic acid (DMA), the most abundant metabolite of inorganic arsenic measured in urine, in children and adults who participated in the 2003-2006 US National Health and Nutrition Examination Surveys. A total of 1161 children (aged 6-19 years) and 1938 adults (aged 20-85 years) were analyzed for the association using multivariate general linear models, adjusting for potential confounders. We observed a positive association between serum levels of folate and cobalamin and creatinine-corrected urinary concentrations of DMA in both children and adults. Furthermore, serum levels of folate and cobalamin were inversely associated with homocysteine (Hcy). These results suggest that dietary intake of folate and cobalamin may exhibit protective functions against arsenic toxicity by increasing arsenic metabolism to the less toxic metabolite DMA and decreasing serum levels of Hcy.

Metals in urine in relation to the prevalence of pre-diabetes, diabetes and atherosclerosis in rural India

OBJECTIVE

Diabetes and cardiovascular diseases are growing burdens in rural communities worldwide. We have observed a high prevalence of diabetes among rural farming communities in India and sought to evaluate the association of non-traditional risk factors, such as metals, with diabetes and other cardiometabolic risk factors in this community.

METHODS

Anthropometric measurements, chemistries and carotid intima-media thickness were determined in 865 participants of the Kovai Medical Center and Hospital-Nallampatti Non-Communicable Disease Study-I (KMCH-NNCD-I, 2015), a cross-sectional study conducted in a farming village in South India. Urinary metal levels were determined by inductively couped plasma-mass spectrometry analysis and corrected to urinary creatinine level. Statistical analyses were performed to study the association between urinary metal levels and clinical parameters.

RESULTS

82.5% of the study population were involved in farming and high levels of toxic metals were detected in the synthetic fertilisers used in the study village. The prevalence of pre-diabetes, diabetes and atherosclerosis was 43.4%, 16.2% and 10.3%, respectively. On logistic regression analysis, no association of traditional risk factors such as body mass index, blood pressure and total cholesterol with disease conditions was observed, but urinary levels of metals such as arsenic, chromium, aluminium and zinc showed an association with diabetes, while arsenic and zinc showed an association with pre-diabetes and atherosclerosis.

CONCLUSIONS

Our data suggest a probable role of metals in the aetiology of diabetes and cardiovascular diseases in rural communities. Identifying and eliminating the causes of increased levels of these environmental chemicals could have a beneficial impact on the burden of non-communicable diseases in rural population.

HPLC-ICP-MS speciation analysis and risk assessment of arsenic in Cordyceps sinensis

BACKGROUND

Cordyceps sinensis, one of the most valued traditional herbal medicines in China, contains high amount of arsenic. Considering the adverse health effects of arsenic, this is of particular concern. The aim of this study was to determine and analyze arsenic speciation in C. sinensis, and to measure the associated human health risks.

METHODS

We used microwave extraction and high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry to determine and analyze the arsenic content in C. sinensis, and measured the associated human health risks according to the hazard index (HI), lifetime cancer risk (CR), and target hazard quotient (THQ).

RESULTS

The main arsenic speciation in C. sinensis were not the four organic arsenic compounds, including dimethyl arsenic, monomethyl arsenic, arsenobetaine, and arsenocholine, but comprised inorganic arsenic and other unknown risk arsenic compounds. HI scores indicated that the risk of C. sinensis was acceptable. CR results suggested that the cancer risk was greater than the acceptable lifetime risk of 10-5, even at low exposure levels. THQ results indicated that at the exposure level < 2.0 months/year, the arsenic was not likely to harm human health during a lifetime; however, if the exposure rate was > 3.0 months/year, the systemic effects of the arsenic in C. sinensis was of great concern.

CONCLUSION

The arsenic in C. sinensis might not be free of risks. The suggested C. sinensis consumption rate of 2.0 months/year provided important insights into the ways by which to minimize potential health risks. Our study not only played the role of "cast a brick to attract jade" by which to analyze arsenic speciation in C. sinensis but also offered a promising strategy of risk assessment for harmful residues in traditional herbal medicines.

Trends in urinary arsenic among the U.S. population by drinking water source: Results from the National Health and Nutritional Examinations Survey 2003-2014

BACKGROUND

In 2001, the United States revised the arsenic maximum contaminant level for public drinking water systems from 50µg/L to 10µg/L. This study aimed to examine temporal trends in urinary arsenic concentrations in the U.S. population from 2003 to 2014 by drinking water source among individuals aged 12 years and older who had no detectable arsenobetaine - a biomarker of arsenic exposure from seafood intake.

METHODS

We examined data from 6 consecutive cycles of the National Health and Nutrition Examination Survey (2003-2014; N=5848). Total urinary arsenic (TUA) was calculated by subtracting arsenobetaine's limit of detection and detectable arsenocholine from total arsenic. Additional sensitivity analyses were conducted using a second total urinary arsenic index (TUA2, calculated by adding arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid). We classified drinking water source using 24-h dietary questionnaire data as community supply (n=3427), well or rain cistern (n=506), and did not drink tap water (n=1060).

RESULTS

Geometric means (GM) of survey cycles were calculated from multivariate regression models adjusting for age, gender, race/ethnicity, BMI, income, creatinine, water source, type of water consumed, recent smoking, and consumption of seafood, rice, poultry, and juice. Compared to 2003-2004, adjusted TUA was 35.5% lower in 2013-2014 among the general U.S.

POPULATION

Stratified analysis by smoking status indicated that the trend in lower TUA was only consistent among non-smokers. Compared to 2003-2004, lower adjusted TUA was observed in 2013-2014 among non-smoking participants who used community water supplies (1.98 vs 1.16µg/L, p<0.001), well or rain cistern users (1.54 vs 1.28µg/L, p<0.001) and who did not drink tap water (2.24 vs 1.53µg/L, p<0.001). Sensitivity analyses showed consistent results for participants who used a community water supplier and to a lesser extent those who did not drink tap water. However, the sensitivity analysis showed overall exposure stayed the same or was higher among well or rain cistern users. Finally, the greatest decrease in TUA was among participants within the highest exposure percentiles (e.g. 95th percentile had 34% lower TUA in 2013/2014 vs 2003/2004, p<0.001).

CONCLUSIONS

Overall, urinary arsenic levels in the U.S. population declined over a 12-year period that encompassed the adoption of the revised Arsenic Rule. The most consistent trends in declining exposure were observed among non-smoking individuals using public community water systems. These results suggest regulation and prevention strategies to reduce arsenic exposures in the U.S. may be succeeding.

Accumulation of Heavy Metals in People on a Gluten-Free Diet

BACKGROUND & AIMS

Specific foods such as fish and rice have high concentrations of metals such as arsenic, mercury, lead, cadmium, and cobalt. Many gluten-free diets (GFDs) include these foods, so we evaluated whether a GFD was associated with increased metal bioaccumulation.

METHODS

We performed a population-based, cross-sectional study using data collected from the National Health and Nutrition Examination Survey (NHANES), from 2009 through 2012, collecting information on the diagnosis of celiac disease and adherence to a GFD. We tested NHANES blood samples to identify individuals with undiagnosed celiac disease, using assays for immunoglobulin A tissue transglutaminase followed by a confirmatory test for endomysial antibody. Among a total of 11,354 NHANES participants, celiac disease was diagnosed in 55 participants, based on test results or a reported clinical diagnosis. We collected NHANES survey data on blood levels of lead, mercury, and cadmium from subjects who were on a GFD (n = 115) and participants who were not on a GFD (n = 11,239). Levels of total arsenic in urine samples were available from 3901 subjects not following a GFD and 32 individuals following a GFD. NHANES participants were asked questions about fish and shellfish consumption. We performed multivariate logistic regression analyses to associate gluten-related conditions with blood concentrations of mercury, cadmium, and lead and urine concentration of total arsenic, adjusting for demographic characteristics, as well as for rice consumption or seafood intake. Geometric means were reported for urinary concentrations of total arsenic and blood concentrations of mercury, cadmium, and lead for demographic groups and subjects with gluten-related conditions (subjects without celiac disease who avoid gluten).

RESULTS

Persons following a GFD had significantly increased total blood mercury levels (1.37 mcg/L) compared with persons not on a GFD (0.93 mcg/L) (P = .008), as well as increased blood levels of lead (1.42 vs 1.13 mcg/L; P = .007) and cadmium (0.42 vs 0.34 mcg/L; P = .03). Urine samples from subjects on a GFD had higher concentrations of total arsenic (15.15 mcg/L) than urine samples from subjects not on a GFD (8.38 mcg/L) (P = .002). After controlling for demographic characteristics, levels of all heavy metals remained significantly higher in persons following a GFD, compared with those not following a GFD. After exclusion of persons with celiac disease, people without celiac disease on a GFD (n = 101) had significantly increased blood concentrations of total mercury (1.40 mcg/L) than persons without celiac disease and not on a GFD (n = 10,890) (0.93 mcg/L; P = .02) and higher blood concentrations of lead (1.44 vs 1.13 mcg/L; P = .01) and higher urine concentrations of total arsenic (14.69 mcg/L [n = 3632] vs 8.32 mcg/L [n = 28]; P = .01). Blood samples from persons without celiac disease avoiding gluten had higher levels of cadmium (0.42 mcg/L) than persons without celiac disease and not following a GFD (0.34 mcg/L), but this difference was not significant (P = .06).

CONCLUSIONS

In an analysis of data collected from NHANES, persons on a GFD had significantly higher urine levels of total arsenic and blood levels of mercury, lead, and cadmium than persons not avoiding gluten. Studies are needed to determine the long-term effects of accumulation of these elements in persons on a GFD.

Arsenic exposure and risk of nonalcoholic fatty liver disease (NAFLD) among U.S. adolescents and adults: an association modified by race/ethnicity, NHANES 2005-2014

BACKGROUND

While associated with obesity, the cause of the rapid rise in prevalence of nonalcoholic fatty liver disease (NAFLD) in children, which is highest among Hispanics, is not well understood. Animal experiments have demonstrated that arsenic exposure contributes to liver injury. Our objective was to examine the association between arsenic exposure and NAFLD in humans and to determine if race/ethnicity modifies the association.

METHODS

Urinary inorganic arsenic concentrations among those ≥12 years in the National Health and Nutrition Examination Survey, 2005-2014 were used to assess the cross-sectional association with serum alanine aminotransferase (ALT) levels, a marker of liver dysfunction. We excluded high alcohol consumers (>4-5 drinks/day; n = 939), positive hepatitis B or C (n = 2330), those missing body mass index (n = 100) and pregnant women (n = 629) for a final sample of 8518. Arsenic was measured using liquid chromatography coupled with mass spectrometry and ALT was measured using standard methods. Sampling weights were used to obtain national estimates. Due to lack of normality, estimates were log transformed and are presented as geometric means. Logistic regression models controlling for age, sex, income, and weight category estimate adjusted odd ratios (aOR) of elevated ALT by quartile of arsenic and tested for effect modification by race/ethnicity and weight. Elevated ALT was defined as >25 IU/L and >22 IU/L for boys and girls ≤17 years, respectively and >30 IU/L and >19 IU/L for men and women, respectively.

RESULTS

Among all, aOR of elevated ALT were higher among those in the highest vs. lowest arsenic quartile (referent), 1.4 (95% confidence interval [CI]: 1.1, 1.7) with a borderline significant interaction (p = 0.07) by race/ethnicity but not weight (p = 0.4). In analysis stratified by race/ethnicity, aOR of elevated ALT among those in the 4th quartile were higher among Mexican Americans, 2.0 (CI: 1.3, 3.1) and non-Hispanic whites only, aOR 1.4 (CI: 1.1, 1.8) despite the fact that obesity prevalence was highest among non-Hispanic blacks.

CONCLUSIONS

Our findings demonstrate a positive association between urinary arsenic exposure and risk of NAFLD among U.S. adolescents and adults that is highest among Mexican Americans and among those obese, regardless of race/ethnicity.

A dose-response meta-analysis of chronic arsenic exposure and incident cardiovascular disease

Background

Consistent evidence at high levels of water arsenic (≥100 µg/l), and growing evidence at low-moderate levels (<100 µg/l), support a link with cardiovascular disease (CVD). The shape of the dose-response across low-moderate and high levels of arsenic in drinking water is uncertain and critical for risk assessment.

Methods

We conducted a systematic review of general population epidemiological studies of arsenic and incident clinical CVD (all CVD, coronary heart disease (CHD) and stroke) with three or more exposure categories. In a dose-response meta-analysis, we estimated the pooled association between log-transformed water arsenic (log-linear) and restricted cubic splines of log-transformed water arsenic (non-linear) and the relative risk of each CVD endpoint.

Results

Twelve studies (pooled N = 408 945) conducted at high (N = 7) and low-moderate (N = 5) levels of water arsenic met inclusion criteria, and 11 studies were included in the meta-analysis. Compared with 10 µg/l, the estimated pooled relative risks [95% confidence interval (CI)] for 20 µg/l water arsenic, based on a log-linear model, were 1.09 (1.03, 1.14) (N = 2) for CVD incidence, 1.07 (1.01, 1.14) (N = 6) for CVD mortality, 1.11 (1.05, 1.17) (N = 4) for CHD incidence, 1.16 (1.07, 1.26) (N = 6) for CHD mortality, 1.08 (0.99, 1.17) (N = 2) for stroke incidence and 1.06 (0.93, 1.20) (N = 6) for stroke mortality. We found no evidence of non-linearity, although these tests had low statistical power.

Conclusions

Although limited by the small number of studies, this analysis supports quantitatively including CVD in inorganic arsenic risk assessment, and strengthens the evidence for an association between arsenic and CVD across low-moderate to high levels.

Cyclin D1 promoter -56 and -54bp CpG un-methylation predicts invasive progression in arsenic-induced Bowen's disease

BACKGROUND

Patients with arsenic-induced Bowen's disease (As-BD) are at risk of developing invasive cancers in the skin, lung, and urinary bladder. However, a longitudinal follow-up study on the association between As-BD and invasive cancers is still lacking.

OBJECTIVES

This study aims to investigate the underlying molecular mechanisms of this malignant progression in the skin and internal organs.

METHODS

This is a biopsy-based follow-up study. We tested the DNA histograms, Cyclin D1 (CCND1) protein expression and CCND1 promoter DNA methylation in 40 pathologically confirmed specimens from As-BD patients to correlate with individual's invasive cancer occurrence in the 5-year follow-up.

RESULTS

Flow cytometric DNA histogram analysis of skin specimens showed aneuploid (n=15), G2/M arrest (n=22), and normal (n=3) DNA histograms. No patients with normal DNA histograms developed invasive cancers, whereas 13 developed invasive cancers in the aneuploid group and 2 developed invasive cancers in the G2/M arrest group. The aneuploid group showed a high risk of invasive cancer development. In all assessed aneuploid specimens, the CCND1 promoter hypomethylation was observed. Statistically, percentage of un-methylation more than 55.85% among 17 detected CpG sites showed extremely high predictive power in the occurrence of invasive arsenical cancers. Furthermore, the un-methylation at -56 and -54bp CpG sites was statistically significantly associated with invasive arsenical cancer development (p=1.29×10^-5).

CONCLUSIONS

As-BD lesions showing an aneuploid DNA histogram had a high risk of invasive cancer development. Un-methyaltion at -56 and -54bp CpG in the CCND1 promoter serves as a predictor for invasive progression in As-BD patients.

Rice Consumption and Squamous Cell Carcinoma of the Skin in a United States Population

BACKGROUND

Rice contains arsenic, a known skin carcinogen. Rice intake has been associated with arsenic-related skin lesions in South Asia, but its association with skin cancers is as yet unknown.

OBJECTIVES

We aimed to investigate whether rice intake contributes to urinary arsenic concentration and risk of squamous cell carcinoma (SCC) of the skin in a U.S. population.

METHODS

Rice consumption was assessed using a food frequency questionnaire administered as part of a population-based case-control study of 487 SCC cases and 462 age- and gender-matched controls. Arsenic concentration in household tap water and urine samples were measured using inductively coupled mass spectrometry (ICP-MS) and high-resolution ICP-MS, respectively. Odds ratios (OR) for SCC associated with the frequency of rice consumption were estimated using logistic regression, with adjustment for age, gender, and caloric intake.

RESULTS

Those who reported any rice consumption had higher urinary arsenic concentrations than those who did not consume rice, and the association was most pronounced among those with <1μg/L arsenic in their household water (19.2% increase in total urinary arsenic, 95% CI: 5.0, 35.3%). Any rice consumption was associated with a 1.5-fold (95% CI: 1.1, 2.0) higher odds of SCC compared with those who reported no rice consumption, and the relation appeared to be largely among those with <1μg/L water arsenic.

CONCLUSION

Rice consumption may be related to the occurrence of SCC in the United States, especially among those with relatively low drinking water arsenic exposure. https://doi.org/10.1289/EHP1065.

Arsenic and Obesity: A Comparison of Urine Dilution Adjustment Methods

INTRODUCTION

A commonly used approach to adjust for urine dilution in analyses of biomarkers is to adjust for urinary creatinine. However, creatinine is a product of muscle mass and is therefore associated with body mass. In studies of urinary analytes and obesity or obesity-related outcomes, controlling for creatinine could induce collider stratification bias. We illustrate this phenomenon with an analysis of urinary arsenic.

OBJECTIVE

We aimed to evaluate various approaches of adjustment for urinary dilution on the associations between urinary arsenic concentration and measures of obesity.

METHODS

Using data from the National Health and Nutrition Examination Survey, we regressed body mass index (BMI) and waist-to-height ratios on urinary arsenic concentrations. We compared eight approaches to account for urine dilution, including standardization by urinary creatinine, osmolality, and flow rates, and inclusion of these metrics as independent covariates. We also used a recently proposed method known as covariate-adjusted standardization.

RESULTS

Inverse associations between urinary arsenic concentration with BMI and waist-to-height ratio were observed when either creatinine or osmolality were used to standardize or as covariates. Not adjusting for dilution, standardizing or adjusting for urinary flow rate, and using covariate-adjusted standardization resulted in null associations observed between arsenic concentration in relation to BMI and waist-to-height ratio.

CONCLUSIONS

Our findings suggest that arsenic exposure is not associated with obesity, and that urinary creatinine and osmolality may be colliders on the causal pathway from arsenic exposure to obesity, as common descendants of hydration and body composition. In studies of urinary biomarkers and obesity or obesity-related outcomes, alternative metrics such as urinary flow rate or analytic strategies such as covariate-adjusted standardization should be considered. https://doi.org/10.1289/EHP1202.