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: 7.03). 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.

  • Source
    [Show abstract] [Hide abstract]
    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; · 7.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    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). · 2.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The monitoring and assessment of water has become an environmental concern due to contamination caused by man-kind. The main aim of this study is to evaluate the levels of As and some other heavy metals in the pre and post treated water of the projects in Duhok province and to assess the efficiency of these water projects for filtration and purification of drinking water in terms of potentially toxic metals. This study coveres the water purification projects of the entire Duhok governorate areas (Semel, Chambarkat, Zakho, Akre, Shekhan and Amedy). Water samples were collected monthly from August 2008 to July 2009. The results indicated that the As concentration in pretreated water from the Duhok and zakho water project was higher than the WHO guide lines for drinking water (10µg.L-1), whereas in the treated water from the Duhok project its concentration remains above guideline levels. Other metals such as Cd, Pb and Ni at all of the studied projects were higher than the permissible limits in both pre and post treated water, according to the WHO guideline values (3,10 and 20 µg.L-1) respectively, while Cr and Zn were lower than the permissible limit. The values of combined HQ were >1 for all PTEs in drinking water of Duhok, Chamberkat, Zakho and Amedy samples indicating health hazards for the local population. To conclude, the consumption of drinking water may pose high risk to the local population.
    Journal of Environment Pollution and Human Health. 06/2014; 2(2):44-51.

Full-text (2 Sources)

Available from
Jul 28, 2014