Longitudinal Investigation of Exposure to Arsenic, Cadmium, and Lead in Drinking Water

Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
Environmental Health Perspectives (Impact Factor: 7.98). 08/2000; 108(8):731-5. DOI: 10.1289/ehp.00108731
Source: PubMed

ABSTRACT Arsenic, cadmium, and lead have been associated with various forms of cancer, nephrotoxicity, central nervous system effects, and cardiovascular disease in humans. Drinking water is a well-recognized pathway of exposure to these metals. To improve understanding of the temporal dimension of exposure to As, Cd, and Pb in drinking water, we obtained 381 samples of tap and/or tap/filtered water and self-reported rates of drinking water consumption from 73 members of a stratified random sample in Maryland. Data were collected at approximately 2-month intervals from September 1995 through September 1996. Concentrations of As (range < 0.2-13.8 microg/L) and Pb (< 0.1-13.4 microg/L) were within the ranges reported for the United States, as were the rates of drinking water consumption (median < 0.1-4.1 L/day). Cd was present at a detectable level in only 8.1% of the water samples. Mean log-transformed concentrations and exposures for As and Pb varied significantly among sampling cycles and among respondents, as did rates of drinking water consumption, according to a generalized linear model that accounted for potential correlation among repeated measures from the same respondent. We used the intraclass correlation coefficient of reliability to attribute the total variance observed for each exposure metric to between-person and within-person variability. Between-person variability was estimated to account for 67, 81, and 55% of the total variance in drinking water consumption, As exposure (micrograms per day), and Pb exposure (micrograms per day), respectively. We discuss these results with respect to their implications for future exposure assessment research, quantitative risk assessment, and environmental epidemiology.

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Available from: David Macintosh, Jul 28, 2014
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    • "To evaluate the hypothesis that metals are prospectively related to DNA methylation and hydroxymethylation levels, we examined the association of baseline metal exposure biomarkers with visit 3 global DNA methylation and global DNA hydroxymethylation. For arsenic, under constant conditions of exposure over time, urinary concentrations and metabolism biomarkers have been fairly constant, as previously shown in our study population (Navas-Acien et al. 2009) and in previous studies measuring arsenic in private and public drinking water systems over long periods of time (Karagas et al. 2001; Ryan et al. 2000; Steinmaus et al. 2005). Given this background, evaluating the association of arsenic exposure and metabolism with epigenetic measures in visits 1 and 3 allowed us to evaluate the consistency of the associations assuming constant arsenic exposure and metabolic processes. "
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    ABSTRACT: The association between human blood DNA global methylation and global hydroxymethylation has not been evaluated in population-based studies. No studies have evaluated environmental determinants of global DNA hydroxymethylation, including exposure to metals. We evaluated the association between global DNA methylation and global DNA hydroxymethylation in 48 Strong Heart Study participants who had selected metals measured in urine at baseline and DNA available in 1989-1991 and 1998-1999. % 5-methylcytosine (5-mC) and % 5-hydroxymethyl-cytosine (5-hmC) levels were measured by capture and detection antibodies followed by colorimetric quantification. We explored the association of participant characteristics (i.e. age, adiposity, smoking, and metal exposure) with both global DNA methylation and global DNA hydroxymethylation. The Spearman's correlation coefficient for 5-mC and 5-hmC levels was 0.32 (p -value = 0.03) at visit 1 and 0.54 (p - value < 0.001) at visit 3. Trends for both epigenetic modifications were consistent across potential determinants. In cross-sectional analyses the odds ratios of methylated and hydroxymethylated DNA were 1.56 (95% CI: 0.95, 2.57) and 1.76 (95% CI: 1.07, 2.88), respectively, comparing participants above and below the median of % dimethylarsinate. The corresponding odds ratios were 1.64 (95% CI: 1.02, 2.65) and 1.16 (95% CI: 0.70, 1.94), respectively, comparing participants above and below median cadmium. Arsenic exposure and metabolism were consistently associated with both epigenetic markers in cross-sectional and prospective analyses. The positive correlation of 5-mC and 5-hmC levels was confirmed in an independent study population. Our findings support that both epigenetic measures are related at the population level. The consistent trends in the associations between these two epigenetic modifications and the characteristics evaluated, specially arsenic exposure and metabolism, suggest the need for understanding which of the two measures is a better biomarker for environmental epigenetic effects in future large-scale epidemiologic studies.
    Environmental Health Perspectives 04/2014; 122(9). DOI:10.1289/ehp.1306674 · 7.98 Impact Factor
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    • "We also confirmed that individual well concentrations of inorganic arsenic do not vary over long periods of time. These results concur with past studies that analyzed datasets within the USA with at least 25 wells with at least five measurements per well (Focazio et al. 2000; Ryan et al. 2000; Karagas et al. 1998; Meliker et al. 2008; Steinmaus et al. 2005; Seiler 2004). Steinmaus et al. (2005) assessed 759 wells in Nevada over 20 years and found a strong correlation (r = 0.85; 95 % CI 0.81–0.88) "
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    ABSTRACT: Consumption of inorganic arsenic in drinking water at high levels has been associated with chronic diseases. Risk is less clear at lower levels of arsenic, in part due to difficulties in estimating exposure. Herein we characterize spatial and temporal variability of arsenic concentrations and develop models for predicting aquifer arsenic concentrations in the San Luis Valley, Colorado, an area of moderately elevated arsenic in groundwater. This study included historical water samples with total arsenic concentrations from 595 unique well locations. A longitudinal analysis established temporal stability in arsenic levels in individual wells. The mean arsenic levels for a random sample of 535 wells were incorporated into five kriging models to predict groundwater arsenic concentrations at any point in time. A separate validation dataset (n = 60 wells) was used to identify the model with strongest predictability. Findings indicate that arsenic concentrations are temporally stable (r = 0.88; 95 % CI 0.83-0.92 for samples collected from the same well 15-25 years apart) and the spatial model created using ordinary kriging best predicted arsenic concentrations (ρ = 0.72 between predicted and observed validation data). These findings illustrate the value of geostatistical modeling of arsenic and suggest the San Luis Valley is a good region for conducting epidemiologic studies of groundwater metals because of the ability to accurately predict variation in groundwater arsenic concentrations.
    Environmental Geochemistry and Health 01/2014; 36(4). DOI:10.1007/s10653-014-9595-6 · 2.57 Impact Factor
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    • "This approach usually requires an assumption that arsenic concentrations in drinking water are stable over time and that study subjects do not consume water from other sources. Support for these assumptions has been found in several study populations (Navas-Acien et al. 2009b; Ryan et al. 2000). "
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    ABSTRACT: Background: Diabetes affects an estimated 346 million persons globally, and total deaths from diabetes are projected to increase > 50% in the next decade. Understanding the role of environmental chemicals in the development or progression of diabetes is an emerging issue in environmental health. In 2011, the National Toxicology Program (NTP) organized a workshop to assess the literature for evidence of associations between certain chemicals, including inorganic arsenic, and diabetes and/or obesity to help develop a focused research agenda. This review is derived from discussions at that workshop. Objectives: Our objectives were to assess the consistency, strength/weaknesses, and biological plausibility of findings in the scientific literature regarding arsenic and diabetes and to identify data gaps and areas for future evaluation or research. The extent of the existing literature was insufficient to consider obesity as an outcome. Data Sources, Extraction, and Synthesis: Studies related to arsenic and diabetes or obesity were identified through PubMed and supplemented with relevant studies identified by reviewing the reference lists in the primary literature or review articles. Conclusions: Existing human data provide limited to sufficient support for an association between arsenic and diabetes in populations with relatively high exposure levels (≥ 150 µg arsenic/L in drinking water). The evidence is insufficient to conclude that arsenic is associated with diabetes in lower exposure (< 150 µg arsenic/L drinking water), although recent studies with better measures of outcome and exposure support an association. The animal literature as a whole was inconclusive; however, studies using better measures of diabetes-relevant end points support a link between arsenic and diabetes.
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