Urinary Arsenic Species Research Articles

Low-moderate urine arsenic and biomarkers of thrombosis and inflammation in the Strong Heart Study.

The underlying pathology of arsenic-related cardiovascular disease (CVD) is unknown. Few studies have evaluated pathways through thrombosis and inflammation for arsenic-related CVD, especially at low-moderate arsenic exposure levels (<100 μg/L in drinking water). We evaluated the association of chronic low-moderate arsenic exposure, measured as the sum of inorganic and methylated arsenic species in urine (ΣAs), with plasma biomarkers of thrombosis and inflammation in American Indian adults (45–74 years) in the Strong Heart Study. We evaluated the cross-sectional and longitudinal associations between baseline ΣAs with fibrinogen at three visits (baseline, 1989–91; Visit 2, 1993–95, Visit 3, 1998–99) using mixed models and the associations between baseline ΣAs and Visit 2 plasminogen activator inhibitor-1 (PAI-1) and high sensitivity C-reactive protein (hsCRP) using linear regression. Median (interquartile range) concentrations of baseline ΣAs and fibrinogen, and Visit 2 hsCRP and PAI-1 were 8.4 (5.1, 14.3) μg/g creatinine, 346 (304, 393) mg/dL, 44 (30, 67) mg/L, and 3.8 (2.0, 7.0) ng/mL, respectively. Comparing the difference between the 75th and the 25th percentile of ΣAs (14.3 vs. 5.1 μg/g creatinine), ΣAs was positively associated with baseline fibrinogen among those with diabetes (adjusted geometric mean ratio (GMR): 1.05, 95% CI: 1.02, 1.07) not associated among those without diabetes (GMR: 1.01, 95% CI: 0.99, 1.02) (p-interaction for diabetes = 0.014), inversely associated with PAI-1 (GMR: 0.94, 95% CI: 0.90, 0.99), and not associated with hsCRP (GMR: 1.00, 95% CI: 0.93, 1.08). We found no evidence for an association between baseline ΣAs and annual change in fibrinogen over follow-up (p-interaction = 0.28 and 0.12 for diabetes and non-diabetes, respectively). Low-moderate arsenic exposure was positively associated with baseline fibrinogen in participants with diabetes and unexpectedly inversely associated with PAI-1. Further research should evaluate the role of prothrombotic factors in arsenic-related cardiovascular disease.

Concentrations of urinary arsenic species in relation to rice and seafood consumption among children living in Spain

Inorganic arsenic (i-As) has been related to wide-ranging health effects in children, leading to lifelong concerns. Proportionally, dietary i-As exposure dominates in regions with low arsenic drinking water. This study aims to investigate the relation between rice and seafood consumption and urinary arsenic species during childhood and to assess the proportion of urinary i-As metabolites. Urinary arsenic species concentration in 400 4-year-old children living in four geographical areas of Spain, in addition to repeated measures from 100 children at 7 years of age are included in this study. Rice and seafood products intake was collected from children's parents using a validated food frequency questionnaire (FFQ). At 4 years of age, children's urine i-As and monomethylarsonic acid (MMA) concentrations increased with rice product consumption (p-value = 0.010 and 0.018, respectively), and urinary arsenobetaine (AsB) with seafood consumption (p = 0.002). Four-year-old children had a higher consumption of both rice and seafood per body weight and a higher urinary %MMA (p-value = 0.001) and lower % dimethylarsinic acid (DMA) (p-value = 0.017). This study suggests increased dietary i-As exposure related to rice product consumption among children living in Spain, and the younger ones may be especially vulnerable to the health impacts of this exposure also considering that they might have a lower i-As methylation capacity than older children. In contrast, seafood consumption did not appear to influence the presence of potentially toxic arsenic species in this population of children.

The polymorphism XRCC1 Arg194Trp and 8-hydroxydeoxyguanosine increased susceptibility to arsenic-related renal cell carcinoma

This study was designed to explore the relationship between X-ray repair cross-complementing group 1 (XRCC1) gene polymorphisms and renal cell carcinoma (RCC) and to investigate whether individuals with an XRCC1 risk genotype, a high level of 8-OHdG or a high urinary total arsenic concentration have a modified odds ratio (OR) of RCC. We recruited 180 RCC patients and 360 age- and sex-matched controls from a hospital-based pool. Image-guided biopsy or surgical resection of renal tumors was performed on RCC patients for pathological verification. Genomic DNA was used to examine the genotype of XRCC1(Arg399Gln), XRCC1(Arg194Trp), XRCC3(Thr241Met) and XPD(Lys751Gln) by PCR-RFLP. Liquid chromatography with tandem mass spectrometry was used to determine urinary 8-OHdG levels. A HPLC-HG-AAS was used to determine the concentrations of urinary arsenic species. Participants with the genotype XRCC1(Arg194Trp) Arg/Trp+Trp/Trp had a significantly higher OR of RCC than those with the Arg/Arg genotype; the OR and 95% confidence interval was 0.66 (0.45–0.97) after multivariate adjustment. The OR of RCC for the combined effect of high urinary 8-OHdG levels and high urinary total arsenic concentration in individuals with a XRCC1(Arg194Trp) Arg/Trp+Trp/Trp genotype was higher than in patients with an Arg/Arg genotype, which was evident in a dose response manner. In conclusion, this is the first study to show that the XRCC1 Arg194 allele is a predicting factor for RCC. The more risk factors (high urinary 8-OHdG levels, high urinary total arsenic concentrations, and XRCC1 Arg194 allele) that were present, the higher the OR of RCC.

Abstract LB-159: A missense variant in FTCD is associated with arsenic metabolism efficiency and arsenic toxicity in Bangladesh

Abstract Exposure to drinking water contaminated with inorganic arsenic (iAs), a known human carcinogen, affects over 100 million people worldwide. Arsenic-induced skin lesions are an early sign of arsenic toxicity and a risk factor for subsequent cancer. Once absorbed into the blood, iAs can be converted to mono-methylated (MMA) and then di-methylated (DMA) forms of arsenic, with methylation facilitating the excretion of arsenic in urine. The relative abundance of these arsenic species in urine (iAs%, MMA%, DMA%) represents the efficiency with which an individual metabolizes arsenic. The AS3MT region is the only locus known to harbor variants that influence arsenic metabolism efficiency in humans. In order to identify additional variants that impact arsenic metabolism, we measured protein-coding variants across the human exome using Illumina’s Exome Chip for 1,660 Bangladeshi individuals participating in the Health Effects of Arsenic Longitudinal Study. Among 20,265 exonic variants with a minor allele frequency greater than 1%, only rs61735836 showed associations of experiment-wide significance for all three arsenic metabolite percentages (P=8x10-22, P=7x10-16, and P=2x10-12 for DMA%, MMA%, and iAs%, respectively). The minor allele (A) has a frequency of ~7% in our study (consistent with 1,000 Genomes data) and is associated with decreased DMA% and increased MMA% and iAs%. In subsequent analyses of 2,401 skin lesions cases and 2,472 controls, the low-efficiency allele (A) was associated with increased skin lesion risk (OR=1.25; P=5x10-4), suggesting this variant impacts arsenic toxicity through its impact on metabolism and internal dose of arsenic. rs61735836 is a missense variant (p.Val101Met) in exon 3 of FTCD, which codes for forminidoyltransferase cyclodeaminase. This enzyme is involved in one-carbon metabolism and is critical for production of methenyltetrahydrofolate, a donor of one-carbon groups to the methionine cycle. Methionine provides methyl groups for arsenic metabolism, and variation in folate status and one-carbon metabolism have long been hypothesized to influence arsenic metabolism, with folate supplementation resulting in increased arsenic metabolism efficiency in a randomized trial. FTCD expression in liver (the primary site of arsenic metabolism) is higher than in any other human tissue, but rs614735826 is not associated with gene expression in any tissue (based on GTEx). Furthermore, rs61735836 is not in LD (r2&amp;lt;0.1) with any nearby variant in South Asian populations, suggesting its effect on arsenic metabolism is likely through an amino acid substitution that alters FTCD function. This work implicates FTCD as a novel locus influencing arsenic metabolism efficiency, with potential implications for arsenic-induced cancer risk, and establishes an additional link between one-carbon metabolism and the methylation/metabolism of inorganic arsenic. Citation Format: Brandon L. Pierce, Lin Tong, Maria Argos, Farzana Jasmine, Mary V. Gamble, Joseph Graziano, Muhammad G. Kibriya, Habibul Ahsan. A missense variant in FTCD is associated with arsenic metabolism efficiency and arsenic toxicity in Bangladesh [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-159. doi:10.1158/1538-7445.AM2017-LB-159

The Methylation Capacity of Arsenic and Insulin Resistance are Associated with Psychological Characteristics in Children and Adolescents

The goal of the present study was to compare the influence of the methylation capacity of arsenic, as well as insulin resistance on psychological characteristics of school students from elementary and junior high school. 296 elementary and 318 junior high school students participated in health examinations, completed questionnaires and determined their concentrations of urinary arsenic species and psychological characteristics. Insulin resistance was determined by means of the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). We found that HOMA-IR values were significantly related to increased score of the depression and anger after adjusted for age, gender, schools, father’s educational levels, mother’s educational levels, BMI, body fat, and urinary creatinine in all students. Anxiety scores and depression scores of junior high school children were significantly higher compared to elementary school children, but lower in disruptive behavior scores. HOMA-IR levels were significantly inversely related to self-concept scores in junior high school students. A greater urinary inorganic arsenic percentage (iAs%) was marginally significantly related to a higher depression score in junior high school students. This is the first study to show a relationship between HOMA-IR levels or urinary arsenic profiles and psychological distress in school students from elementary and junior high school.

Low-level inorganic arsenic exposure and neuropsychological functioning in American Indian elders

BackgroundInorganic arsenic at high and prolonged doses is highly neurotoxic. Few studies have evaluated whether long-term, low-level arsenic exposure is associated with neuropsychological functioning in adults. ObjectivesTo investigate the association between long-term, low-level inorganic arsenic exposure and neuropsychological functioning among American Indians aged 64–95. MethodsWe assessed 928 participants in the Strong Heart Study by using data on arsenic species in urine samples collected at baseline (1989–1991) and results of standardized tests of global cognition, executive functioning, verbal learning and memory, fine motor functioning, and speed of mental processing administered during comprehensive follow-up evaluations in 2009–2013. We calculated the difference in neuropsychological functioning for a 10% increase in urinary arsenic with adjustment for sex, age, education, and study site. ResultsThe sum of inorganic and methylated arsenic species (∑As) in urine was associated with limited fine motor functioning and processing speed. A 10% increase in ∑As was associated with a .10 (95% CI −.20, −.01) decrease on the Finger Tapping Test for the dominant hand and a .13 decrease (95% CI −.21, −.04) for the non-dominant hand. Similarly, a 10% increase in ∑As was associated with a .15 (95% CI −.29, .00) decrease on the Wechsler Adult Intelligence Scale–Fourth Edition Coding Subtest. ∑As was not associated with other neuropsychological functions. ConclusionsFindings indicate an adverse association between increased urinary arsenic fine motor functioning and processing speed, but not with other neuropsychological functioning, among elderly American Indians.

Total arsenic and speciation analysis of saliva and urine samples from individuals living in a chronic arsenicosis area in China

BackgroundIt is generally acknowledged that the determination of harmful chemical compounds excreted into saliva is useful for assessing their exposure levels. The aim of the present study was to compare the total arsenic and its species in saliva and urine samples collected from the people residing in an arsenic-contaminated area of China and to further verify the feasibility of using salivary arsenic as a new biomarker of arsenic exposure.MethodsTotal arsenic and speciation analyses in urine and saliva samples among 70 residents exposed to arsenic from drinking water in Shanxi, China were carried out by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP/MS).ResultsThe result showed that, total arsenic concentration in saliva was relatively lower than in urine samples, but it existed a strong positive correlation with total urinary arsenic, drinking water arsenic and different skin lesions. For arsenic metabolism analyses, AsIII, AsV, MMA, and DMA were detected in all of the urine samples with the dominating species of DMA (73.2%). Different with urinary arsenic species, most arsenic species in saliva were not methylated. The major species in saliva was iAs (AsIII + AsV, 76.18%), followed by DMA (13.08%) and MMA (9.13%). And the primary methylation index (PMI), second methylation index (SMI) and proportion of the four different species (AsIII, AsV, MMA, and DMA) in saliva showed no significant positive relationship with that of in urine.ConclusionsThese findings indicated saliva may be used as a useful tool for biological monitoring of total arsenic exposure in the crowd rather than an efficient tool for assessing arsenic metabolism in human body after exposed to arsenic.

Relation of polymorphism of arsenic metabolism genes to arsenic methylation capacity and developmental delay in preschool children in Taiwan

Inefficient arsenic methylation capacity has been associated with developmental delay in children. The present study was designed to explore whether polymorphisms and haplotypes of arsenic methyltransferase (AS3MT), glutathione-S-transferase omegas (GSTOs), and purine nucleoside phosphorylase (PNP) affect arsenic methylation capacity and developmental delay. A case-control study was conducted from August 2010 to March 2014. All participants were recruited from the Shin Kong Wu Ho-Su Memorial Teaching Hospital. In total, 179 children with developmental delay and 88 children without delay were recruited. Urinary arsenic species, including arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) were measured using a high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. The polymorphisms of AS3MT, GSTO, and PNP were performed using the Sequenom MassARRAY platform with iPLEX Gold chemistry. Polymorphisms of AS3MT genes were found to affect susceptibility to developmental delay in children, but GSTO and PNP polymorphisms were not. Participants with AS3MT rs3740392 A/G+G/G genotype, compared with AS3MT rs3740392 A/A genotype, had a significantly lower secondary methylation index. This may result in an increased OR for developmental delay. Participants with the AS3MT high-risk haplotype had a significantly higher OR than those with AS3MT low-risk haplotypes [OR and 95% CI, 1.59 (1.08–2.34)]. This is the first study to show a joint dose-response effect of this AS3MT high-risk haplotype and inefficient arsenic methylation capacity on developmental delay. Our data provide evidence that AS3MT genes are related to developmental delay and may partially influence arsenic methylation capacity.

Urinary arsenic species concentration in residents living near abandoned metal mines in South Korea.

BackgroundArsenic is a carcinogenic heavy metal that has a species-dependent health effects and abandoned metal mines are a source of significant arsenic exposure. Therefore, the aims of this study were to analyze urinary arsenic species and their concentration in residents living near abandoned metal mines and to monitor the environmental health effects of abandoned metal mines in Korea.MethodsThis study was performed in 2014 to assess urinary arsenic excretion patterns of residents living near abandoned metal mines in South Korea. Demographic data such as gender, age, mine working history, period of residency, dietary patterns, smoking and alcohol use, and type of potable water consumed were obtaining using a questionnaire. Informed consent was also obtained from all study subjects (n = 119). Urinary arsenic species were quantified using high performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP/MS).ResultsThe geometric mean of urinary arsenic (sum of dimethylarsinic acid, monomethylarsonic acid, As3+, and As5+) concentration was determined to be 131.98 μg/L (geometric mean; 95% CI, 116.72–149.23) while urinary inorganic arsenic (As3+ and As5+) concentration was 0.81 μg/L (95% CI, 0.53–1.23). 66.3% (n = 79) and 21.8% (n = 26) of these samples exceeded ATSDR reference values for urinary arsenic (>100 μg/L) and inorganic arsenic (>10 μg/L), respectively. Mean urinary arsenic concentrations (geometric mean, GM) were higher in women then in men, and increased with age. Of the five regions evaluated, while four regions had inorganic arsenic concentrations less than 0.40 μg/L, one region showed a significantly higher concentration (GM 15.48 μg/L; 95% CI, 7.51–31.91) which investigates further studies to identify etiological factors.ConclusionWe propose that the observed elevation in urinary arsenic concentration in residents living near abandoned metal mines may be due to environmental contamination from the abandoned metal mine.Trial registrationNot Applicable (We do not have health care intervention on human participants).

Peripheral Arterial Disease and Its Association With Arsenic Exposure and Metabolism in the Strong Heart Study.

At high levels, inorganic arsenic exposure is linked to peripheral arterial disease (PAD) and cardiovascular disease. To our knowledge, no prior study has evaluated the association between low-to-moderate arsenic exposure and incident PAD by ankle brachial index (ABI). We evaluated this relationship in the Strong Heart Study, a large population-based cohort study of American Indian communities. A total of 2,977 and 2,966 PAD-free participants who were aged 45-74 years in 1989-1991 were reexamined in 1993-1995 and 1997-1999, respectively, for incident PAD defined as either ABI <0.9 or ABI >1.4. A total of 286 and 206 incident PAD cases were identified for ABI <0.9 and ABI >1.4, respectively. The sum of inorganic and methylated urinary arsenic species (∑As) at baseline was used as a biomarker of long-term exposure. Comparing the highest tertile of ∑As with the lowest, the adjusted hazard ratios were 0.57 (95% confidence interval (CI): 0.32, 1.01) for ABI <0.9 and 2.24 (95% CI: 1.01, 4.32) for ABI >1.4. Increased arsenic methylation (as percent dimethylarsinate) was associated with a 2-fold increased risk of ABI >1.4 (hazard ratio=2.04, 95% CI: 1.02, 3.41). Long-term low-to-moderate ∑As and increased arsenic methylation were associated with ABI >1.4 but not with ABI <0.9. Further studies are needed to clarify whether diabetes and enhanced arsenic metabolism increase susceptibility to the vasculotoxic effects of arsenic exposure.

Arsenic, diabetes-related genes and diabetes prevalence in a general population from Spain: The Hortega Study

Background Several studies suggest that inorganic arsenic exposure may be associated with diabetes, but the evidence is not sufficient, especially in populations exposed at low-moderate levels. Polymorphisms (SNPs) in diabetes-related genes have been clearly involved in diabetes risk. We evaluated the interaction of 256 polymorphisms in diabetes-related genes with inorganic arsenic exposure on diabetes risk in the Hortega Study, a representative sample of a general population from Valladolid, Spain. Methods Total urine arsenic was measured in 1451 men and women from Valladolid, Spain. Urine arsenic species (inorganic and methylated arsenic species and arsenobetaine (Asb)) were available in 295 randomly selected participants. To account for the confounding introduced by seafood arsenic (mostly Asb) in total arsenic, we designed a multiple imputation model to predict the missing Asb levels. Prevalent type 2 diabetes (T2D) was defined as fasting glucose levels ≥ 126 mg/dL, non-fasting glucose levels ≥ 200 mg/dL, by physician diagnosis or by diabetes treatment use. Results 108 (7.4%) participants had prevalent T2D. The overall geometric mean of total arsenic was 65.9 μg/g (99.1 and 64.4 μg/g in participants with and without T2D, respectively). The adjusted odds ratios (95% confidence intervals) for T2D comparing the highest with the lowest tertile of total arsenic were 1.71 (0.94 3.13) and 2.52 (1.68 3.80) before and after adjusting for Asb, respectively. Several genotypes were marginally associated with higher risk of diabetes. Top 3 SNPs were rs4135168 (p-value=0.003), rs4135225 (p-value=0.007) in gene TXN and rs9435739 (p-value=0.008) in gene SDHB. Conclusions The findings support the role of arsenic as a diabetogenic factor and the importance of controlling for seafood arsenic in populations with high seafood intake. These preliminary arsenic-gene interaction results require confirmation but provide support to evaluate gene-environment interactions in larger studies.

Urinary Arsenic Speciation in Children and Pregnant Women from Spain

Inorganic arsenic (i-As) is a non-threshold human carcinogen that has been associated with several adverse health outcomes. Exposure to i-As is of particular concern among pregnant women, infants and children, as they are specifically vulnerable to the adverse health effects of i-As, and in utero and early-life exposure, even low to moderate levels of i-As, may have a marked effect throughout the lifespan. Ion chromatography-mass spectrometry detection (IC-ICP-MS) was used to analyse urinary arsenic speciation, as an exposure biomarker, in samples of 4-year-old children with relatively low-level arsenic exposure living in different regions in Spain including Asturias, Gipuzkoa, Sabadell and Valencia. The profile of arsenic metabolites in urine was also determined in samples taken during pregnancy (1st trimester) and in the children from Valencia of 7 years old. The median of the main arsenic species found in the 4-year-old children was 9.71 μg/l (arsenobetaine—AsB), 3.97 μg/l (dimethylarsinic acid—DMA), 0.44 μg/l (monomethylarsonic acid—MMA) and 0.35 μg/l (i-As). Statistically significant differences were found in urinary AsB, MMA and i-As according to the study regions in the 4-year-old, and also in DMA among pregnant women and their children. Spearman’s correlation coefficient among urinary arsenic metabolites was calculated, and, in general, a strong methylation capacity to methylate i-As to MMA was observed.

Low-level environmental arsenic exposure correlates with unexplained male infertility risk

Humans are exposed to arsenic via drinking water, dietary intake and inhaled particulates. Endemic chronic arsenic exposure related reproductive toxicity is well documented, but the effect of low-level general environmental arsenic exposure on unexplained male infertility (UMI) remains unclear.In this case-control study, we aimed to investigate the relationship between non-geogenic environmental arsenic exposure and UMI risk. One hundred and one infertile men with normal semen as cases and sixty one fertile men as controls were recruited. Five urinary arsenic species: pentavalent arsenate (AsiV), trivalent arsenite (AsiIII), methylated to monomethylarsonic acid (MMAV), dimethylarsinic acid (DMAV), arsenobetaine (AsB) were quantitatively measured by liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS). To assess the semen quality, semen volume, sperm concentration, total motility, and progressive motility were measured.The nonparametric Mann-Whitney U test was used to compare the differences of arsenic species and index between the case and the control group; we observed that concentrations of AsiV, AsB, MMAV, DMAV, total inorganic As and total As were significantly higher in the cases than the controls. The urine AsiV level increased more than twenty folds in case group. Moreover, higher redox index (AsiV/AsiIII) and lower primary arsenic methylation index (PMI=MMAV/Asi) were observed for case group. Furthermore, through the logistic regression analysis, we observed that the urine AsiV level and PMI were most significantly associated with UMI risk among the observations. Specifically, in comparison to the first quartile, the subjects with higher AsiV levels were more likely to exhibit UMI with increasing adjusted odds ratios (AORs) (adjusted by age, body mass index, drinking status and smoking status) of 8.39 [95% confidence interval (CI), 2.59–27.17], 13.12 (95% CI, 3.44–50.12) and 36.51 (95% CI, 8.25–161.66) at the second, third and fourth quartiles, respectively. Also a concentration-dependent decrease of AOR was also observed for PMI in comparison to the fourth quartile: 15.43 [95% CI, 4.28–55.69], 9.69 (95% CI, 2.78–33.78) and 6.93 (95% CI, 2.21–21.76) at the first, second and third quartiles, respectively. These findings provide evidences that low-level environmental arsenic exposure was positively associated with UMI risk.

Total and speciated urinary arsenic levels in the Spanish population

BackgroundVery few studies exist on urinary arsenic exposure in Spain. ObjectiveTo evaluate total and speciated urinary arsenic (As) levels in a Spanish population sample. MethodsDemographic, lifestyle and dietary data was collected for 124 volunteers (aged 20–76years; 88 women and 36 men), who were tested for total arsenic and five arsenic species using high-performance liquid chromatography-inductively coupled plasma mass spectrometry. ResultsArsenobetaine (AB) and dimethylarsinic acid (DMA) were detected in 96.8% of the study participants (limit of detection (LOD) 1.0μg/L for AB and 1.9μg/L for DMA). Monomethylarsonic acid (MMA) and arsenous acid (As(III)) were detected in 5.6% (LOD 1.8μg/L) and 1.6% (LOD 1.4μg/L) of the participants, respectively; arsenic acid (As(V)) was not detected (LOD 1.4μg/L). AB and DMA (geometric mean (GM) 29.1μg/L and 7.5μg/L, respectively) were the main contributors to total urinary arsenic levels. Urinary DMA was positively associated with AB. ConclusionTotal arsenic levels observed in the Spanish population sample were higher than those reported by other European studies. The most recurrent urinary arsenic species was AB, followed by DMA, probably attributable to the high Spanish consumption of seafood. We recommend using inorganic As+MMA as the two main urinary biomarkers for inorganic As exposure. Our results provide reference data for analysing arsenic speciation results and assessing human exposure.

Association of Cardiometabolic Genes with Arsenic Metabolism Biomarkers in American Indian Communities: The Strong Heart Family Study (SHFS).

Background:Metabolism of inorganic arsenic (iAs) is subject to inter-individual variability, which is explained partly by genetic determinants.Objectives:We investigated the association of genetic variants with arsenic species and principal components of arsenic species in the Strong Heart Family Study (SHFS).Methods:We examined variants previously associated with cardiometabolic traits (~ 200,000 from Illumina Cardio MetaboChip) or arsenic metabolism and toxicity (670) among 2,428 American Indian participants in the SHFS. Urine arsenic species were measured by high performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC-ICP-MS), and percent arsenic species [iAs, monomethylarsonate (MMA), and dimethylarsinate (DMA), divided by their sum × 100] were logit transformed. We created two orthogonal principal components that summarized iAs, MMA, and DMA and were also phenotypes for genetic analyses. Linear regression was performed for each phenotype, dependent on allele dosage of the variant. Models accounted for familial relatedness and were adjusted for age, sex, total arsenic levels, and population stratification. Single nucleotide polymorphism (SNP) associations were stratified by study site and were meta-analyzed. Bonferroni correction was used to account for multiple testing.Results:Variants at 10q24 were statistically significant for all percent arsenic species and principal components of arsenic species. The index SNP for iAs%, MMA%, and DMA% (rs12768205) and for the principal components (rs3740394, rs3740393) were located near AS3MT, whose gene product catalyzes methylation of iAs to MMA and DMA. Among the candidate arsenic variant associations, functional SNPs in AS3MT and 10q24 were most significant (p < 9.33 × 10–5).Conclusions:This hypothesis-driven association study supports the role of common variants in arsenic metabolism, particularly AS3MT and 10q24.Citation:Balakrishnan P, Vaidya D, Franceschini N, Voruganti VS, Gribble MO, Haack K, Laston S, Umans JG, Francesconi KA, Goessler W, North KE, Lee E, Yracheta J, Best LG, MacCluer JW, Kent J Jr., Cole SA, Navas-Acien A. 2017. Association of cardiometabolic genes with arsenic metabolism biomarkers in American Indian communities: the Strong Heart Family Study (SHFS). Environ Health Perspect 125:15–22; http://dx.doi.org/10.1289/EHP251

Combined effects of DNA methyltransferase 1 and 3A polymorphisms and urinary total arsenic levels on the risk for clear cell renal cell carcinoma

Our previous study showed that high urinary total arsenic levels were associated with higher odds ratio (OR) for renal cell carcinoma (RCC). Single nucleotide polymorphisms (SNPs) of DNA methyltransferases (DNMTs) might influence DNMT enzyme activity associated with tumorigenesis. In this study, we investigated the association of five SNPs from DNMT1 (rs8101626 and rs2228611), DNMT3A (rs34048824 and rs1550117), and DNMT3B (rs1569686) with the risk of clear cell renal cell carcinoma (ccRCC). We also examined the combined effects of DNMT genotypes and urinary arsenic levels on ccRCC risk. We conducted a hospital-based case-control study, which included 293 subjects with ccRCC and 293 age- and gender-matched controls. The urinary arsenic species were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Genotypes were investigated using polymerase chain reaction and restriction fragment length polymorphism analyses. We observed that the DNMT1 rs8101626 G/G genotype was significantly associated with reduced odds ratio (OR) of ccRCC [OR=0.38, 95% confidence interval (CI) 0.14–0.99]. Subjects with concurrent DNMT1 rs8101626 A/A+A/G and DNMT3A rs34048824 T/T+T/C genotypes had significantly higher OR for ccRCC [OR=2.88, 95% CI 1.44–5.77]. Participants with the high-risk genotype of DNMT1 rs8101626 and DNMT3A rs34048824 with concurrently high urinary total arsenic levels had even higher OR of ccRCC in a dose-response manner. This is the first study to evaluate variant DNMT1 rs8101626 and DNMT3A rs34048824 genotypes that modify the arsenic-related ccRCC risk in a geographic area without significant arsenic exposure in Taiwan.

Genetic polymorphisms of PPAR gamma, arsenic methylation capacity and breast cancer risk in Mexican women.

To evaluate whether the presence of polymorphisms of peroxisome proliferator-activated receptor gamma PPARγ (Pro 1 2Ala) and PPARGC1B (Ala203Pro) modifies the association between the inorganic arsenic (iAs) methylation capacity and breast cancer (BC). Mexican women were interviewed, and blood and urine samples were collected from them (cases/controls= 197/220). The concentration of urinary arsenic species and the polymorphisms of interest were determined by high-performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and polymerase chain reaction (PCR), respectively. In women with a high %MMA (urinary monomethyl arsenic) and high primary methylation ratio (PM = MMA/iAs), the risk of BC was increased (odds ratio [OR]%MMA T3 vs.T1= 3.60: 95% confidence interval [CI] 2.02-6.41, ORPMI T3 vs.T1= 3.47: 95%CI 1.95-6.17), which was maintained after adjusting for polymorphisms. No significant interactions were observed between the polymorphisms and the arsenic variables on the risk of BC. Pro 12Ala and Ala203Pro polymorphisms did not modify the association between the iAs methylation capacity and BC.

Determination of Arsenic Species in Urine Samples of Subjects Not Exposed to Dietary Arsenic by High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

Arsenic (As) speciation in human urine was performed by anion exchange chromatography (AEC), followed by inductively coupled plasma mass spectrometry detection (ICP-MS). Separation of arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)L dimethylarsinic acid [DMA(V], arsenobetaine (AsB), and arsenocholine (AsC) in urine samples was accomplished in 9 minutes, resulting in quantification limits within the 0.3-0.9 ug L-1 range. The gradient elution program comprises two different mobile phases consisting of ultrapure water (phase A) and aqueous 20 mM nitric acid (phase B), both modified with 2% (v/v) methanol. Sample pre-treatment is based on human urine centrifugation (5000 rpm, 10 min), followed by filtration (0.45 μm) and dilution (1:4) with ultrapure water. Relative standard deviations (N=l 1) of the overall procedure were 8% for AsB and DMA(V), 11% for As(III), and 9% for MMA(V), As(V), and AsC. Arsenics quantification was performed using the standard addition method covering arsenic concentration ranges of 0-100 μ L-1 (expressed as arsenic) for all species. Germanium (5 μg L-1) was used as an internal standard. Analytical recoveries from the anion exchange column varied from 94 to 101% (urine sample spiked with low target concentrations), from 99-103% (urine sample spiked with intermediate target concentrations), and from 97-103% (urine sample spiked with high target concentrations). The developed procedure has been tested by analyzing the certified reference material NIST CRM 2669 Arsenic Species in Frozen Human Urine which offers certified contents for all arsenic species. After AEC and mass spectrometry detection, MMA(V), DMA(V), AsB, AsC, and also tetramethylarsonium ion (TETRA) were identified in several urine samples. The method has been applied to assess arsenic speciation in several human urine samples collected from volunteers not chronically exposed to arsenic via water and food.

Joint Effect of Urinary Total Arsenic Level and VEGF-A Genetic Polymorphisms on the Recurrence of Renal Cell Carcinoma.

The results of our previous study suggested that high urinary total arsenic levels were associated with an increased risk of renal cell carcinoma (RCC). Germline genetic polymorphisms might also affect cancer risk and clinical outcomes. Vascular endothelial growth factor (VEGF) plays an important role in vasculogenesis and angiogenesis, but the combined effect of these factors on RCC remains unclear. In this study, we explored the association between the VEGF-A -2578C>A, -1498T>C, -1154G>A, -634G>C, and +936C>T gene polymorphisms and RCC. We also evaluated the combined effects of the VEGF-A haplotypes and urinary total arsenic levels on the prognosis of RCC. This case-control study was conducted with 191 RCC patients who were diagnosed with renal tumors on the basis of image-guided biopsy or surgical resections. An additional 376 age- and gender-matched controls were recruited. Concentrations of urinary arsenic species were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Genotyping was investigated using fluorescent-based TaqMan allelic discrimination. We observed no significant associations between VEGF-A haplotypes and RCC risk. However, the VEGF-A ACGG haplotype from VEGF-A -2578, -1498, -1154, and -634 was significantly associated with an increased recurrence of RCC (OR = 3.34, 95% CI = 1.03–10.91). Urinary total arsenic level was significantly associated with the risk of RCC in a dose-response manner, but it was not related to the recurrence of RCC. The combination of high urinary total arsenic level and VEGF-A risk haplotypes affected the OR of RCC recurrence in a dose-response manner. This is the first study to show that joint effect of high urinary total arsenic and VEGF-A risk haplotypes may influence the risk of RCC recurrence in humans who live in an area without obvious arsenic exposure.

Polymorphisms of human 8-oxoguanine DNA glycosylase 1 and 8-hydroxydeoxyguanosine increase susceptibility to arsenic methylation capacity-related urothelial carcinoma.

Arsenic causes oxidative stress in cultured animal and human cells, and it is a well-documented human carcinogen. We conducted a hospital-based case-control study including 167 cases of urothelial carcinoma (UC) and 334 age- and gender-matched healthy controls to evaluate the relationships between urinary arsenic profiles, urinary 8-hydroxydeoxyguanosine (8-OHdG) levels, and human 8-oxoguanine DNA glycosylase (hOGG1) genotypes and UC. The urinary arsenic species were analyzed by high-performance liquid chromatography and hydride generator-atomic absorption spectrometry. Genotyping for hOGG1 (Ser326Cys) and hOGG1 (-15C>G) was performed using the Sequenom MassARRAY platform with iPLEX Gold chemistry. Urinary 8-OHdG was measured with high-sensitivity enzyme-linked immunosorbent assay kits. The results indicated that the hOGG1 326 Cys/Cys genotype and the hOGG1 -15C>G G/G genotype were associated with an increased risk of UC (OR [95% CI] 1.57 [1.04-2.35] and 1.57 [1.04-2.35], respectively). Participants with high urinary total arsenic, regardless of the haplotype of hOGG1 Ser326Cys and the -15C>G polymorphism, had significantly higher urinary 8-OHdG compared to participants with low urinary total arsenic. This is the first study to investigate the joint effects of high urinary total arsenic or inefficient arsenic methylation capacity indices, and the high-risk G-G haplotype of hOGG1 on the risk of UC. The findings are especially meaningful for participants with risk factors such as high urinary total arsenic, inefficient arsenic methylation indices, high urinary 8-OHdG, and the high-risk G-G haplotype of hOGG1 which are all associated with an increased UC risk.