36 research outputs found
Secondary stress responses of zebrafish to different pH: Evaluation in a seasonal manner
AbstractStress is one of the most critical factors in fish health. The response to stress in fish is characterized by the stimulation of the hypothalamus, which results in the activation of the neuroendocrine system and a subsequent cascade of metabolic and physiological changes. The present paper deals with the stress responses of water pH on certain biochemical indices and hematological parameters of zebrafish in a seasonal basis. Zebrafish were exposed to different pH e.g., 7.2, 5.0 and 10.0 and the secondary stress responses were observed. The result showed that exposure to pH 5.0 and 10.0 on zebrafish exerted stresses with reference to seasons. Higher values of blood glucose content observed in the month of summer than the month of winter and females showed higher values than males. Chronic effects of pH on the hematological parameters were also significant between these seasons. In conclusion, exposure to pH at sub-lethal concentrations induced biochemical and hematological alterations in zebrafish and offers a simple tool to evaluate the potential risk of polluted water (acid and base) to fish
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One Solution to the Arsenic Problem: A Return to Surface (Improved Dug) Wells
Arsenic contamination in drinking-water in Bangladesh is a major catastrophe, the consequences of which exceed most other man-made disasters. The national policy encourages the use of surface water as much as possible without encountering the problems of sanitation that led to the use of groundwater in the first place. This paper describes the success of the Dhaka Community Hospital (DCH) team and the procedure in implementing sanitary, arsenic-free, dugwells. The capital cost for running water is US$ 5-6 per person. Sixty-six sanitary dugwells were installed in phases between 2000 and 2004 in Pabna district of Bangladesh where there was a great need of safe water because, in some villages, 90% of tubewells were highly contaminated with arsenic. In total, 1,549 families now have access to safe arsenic-free dugwell water. Some of them have a water-pipe up to their kitchen. All of these were implemented with active participation of community members. They also pay for water-use and are themselves responsible for the maintenance and water quality. The DCH helped the community with installation and maintenance protocol and also with monitoring water quality. The bacteria levels are low but not always zero, and studies are in progress to reduce bacteria by chlorination.Physic
One Solution to the Arsenic Problem: A Return to Surface (Improved Dug) Wells
Arsenic contamination in drinking-water in Bangladesh is a major catastrophe, the consequences of which exceed most other man-made disasters. The national policy encourages the use of surface water as much as possible without encountering the problems of sanitation that led to the use of groundwater in the first place. This paper describes the success of the Dhaka Community Hospital (DCH) team and the procedure in implementing sanitary, arsenic-free, dugwells. The capital cost for running water is US$ 5–6 per person. Sixty-six sanitary dugwells were installed in phases between 2000 and 2004 in Pabna district of Bangladesh where there was a great need of safe water because, in some villages, 90% of tubewells were highly contaminated with arsenic. In total, 1,549 families now have access to safe arsenic-free dugwell water. Some of them have a water-pipe up to their kitchen. All of these were implemented with active participation of community members. They also pay for water-use and are themselves responsible for the maintenance and water quality. The DCH helped the community with installation and maintenance protocol and also with monitoring water quality. The bacteria levels are low but not always zero, and studies are in progress to reduce bacteria by chlorination
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Prenatal Arsenic Exposure and DNA Methylation in Maternal and Umbilical Cord Blood Leukocytes
Background: Arsenic is an epigenetic toxicant and could influence fetal developmental programming. Objectives: We evaluated the association between arsenic exposure and DNA methylation in maternal and umbilical cord leukocytes. Methods: Drinking-water and urine samples were collected when women were at ≤ 28 weeks gestation; the samples were analyzed for arsenic using inductively coupled plasma mass spectrometry. DNA methylation at CpG sites in p16 (n = 7) and p53 (n = 4), and in LINE-1 and Alu repetitive elements (3 CpG sites in each), was quantified using pyrosequencing in 113 pairs of maternal and umbilical blood samples. We used general linear models to evaluate the relationship between DNA methylation and tertiles of arsenic exposure. Results: Mean (± SD) drinking-water arsenic concentration was 14.8 ± 36.2 μg/L (range: < 1–230 μg/L). Methylation in LINE-1 increased by 1.36% [95% confidence interval (CI): 0.52, 2.21%] and 1.08% (95% CI: 0.07, 2.10%) in umbilical cord and maternal leukocytes, respectively, in association with the highest versus lowest tertile of total urinary arsenic per gram creatinine. Arsenic exposure was also associated with higher methylation of some of the tested CpG sites in the promoter region of p16 in umbilical cord and maternal leukocytes. No associations were observed for Alu or p53 methylation. Conclusions: Exposure to higher levels of arsenic was positively associated with DNA methylation in LINE-1 repeated elements, and to a lesser degree at CpG sites within the promoter region of the tumor suppressor gene :p16. Associations were observed in both maternal and fetal leukocytes. Future research is needed to confirm these results and determine if these small increases in methylation are associated with any health effects
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Genetic Susceptible Locus in NOTCH2 Interacts with Arsenic in Drinking Water on Risk of Type 2 Diabetes
Abstract: Background: Chronic exposure to arsenic in drinking water is associated with increased risk of type 2 diabetes mellitus (T2DM) but the underlying molecular mechanism remains unclear.
Objectives: This study evaluated the interaction between single nucleotide polymorphisms (SNPs) in genes associated with diabetes and arsenic exposure in drinking water on the risk of developing T2DM.
Methods: In 2009-2011, we conducted a follow up study of 957 Bangladeshi adults who participated in a case-control study of arsenic-induced skin lesions in 2001-2003. Logistic regression models were used to evaluate the association between 38 SNPs in 18 genes and risk of T2DM measured at follow up. T2DM was defined as having a blood hemoglobin A1C level greater than or equal to 6.5% at follow-up. Arsenic exposure was characterized by drinking water samples collected from participants' tubewells. False discovery rates were applied in the analysis to control for multiple comparisons.
Results: Median arsenic levels in 2001-2003 were higher among diabetic participants compared with non-diabetic ones (71.6 mu g/L vs. 12.5 mu g/L, p-value <0.001). Three SNPs in ADAMTS9 were nominally associated with increased risk of T2DM (rs17070905, Odds Ratio (OR) = 2.30, 95% confidence interval (CI) 1.17-4.50; rs17070967, OR = 2.02, 95% CI 1.00-4.06; rs6766801, OR = 2.33, 95% CI 1.18-4.60), but these associations did not reach the statistical significance after adjusting for multiple comparisons. A significant interaction between arsenic and NOTCH2 (rs699780) was observed which significantly increased the risk of T2DM (p for interaction = 0.003; q-value = 0.021). Further restricted analysis among participants exposed to water arsenic of less than 148 mu g/L showed consistent results for interaction between the NOTCH2 variant and arsenic exposure on T2DM (p for interaction = 0.048; q-value = 0.004)
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Arsenic Reduction in Drinking Water and Improvement in Skin Lesions: A Follow-Up Study in Bangladesh
BACKGROUND: Chronic exposure to arsenic is associated with skin lesions. However, it is not known whether reducing arsenic exposure will improve skin lesions.
OBJECTIVE: We evaluated the association between reduced arsenic exposures and skin lesion recovery over time.
METHODS: A follow-up study of 550 individuals was conducted in 2009-2011 on a baseline population of skin lesion cases (n = 900) previously enrolled in Bangladesh in 2001-2003. Arsenic in drinking water and toenails, and skin lesion status and severity were ascertained at baseline and follow-up. We used logistic regression and generalized estimating equation (GEE) models to evaluate the association between log(10)-transformed arsenic exposure and skin lesion persistence and severity.
RESULTS: During the study period, water arsenic concentrations decreased in this population by 41% overall, and 65 individuals who had skin lesions at baseline had no identifiable lesions at follow-up. In the adjusted models, every log(10) decrease in water arsenic and toenail arsenic was associated with 22% [odds ratio (OR) = 1.22; 95% CI: 0.85, 1.78] and 4.5 times (OR = 4.49; 95% CI: 1.94, 11.1) relative increase in skin lesion recovery, respectively. In addition, lower baseline arsenic levels were significantly associated with increased odds of recovery. A log(10) decrease in toenail arsenic from baseline to follow-up was also significantly associated with reduced skin lesion severity in cases over time (mean score change of -5.22 units; 95% CI: -8.61, -1.82).
CONCLUSIONS: Reducing arsenic exposure increased the odds that an individual with skin lesions would recover or show less severe lesions within 10 years. Reducing arsenic exposure must remain a public health priority in Bangladesh and in other regions affected by arsenic-contaminated water.This is the publisher’s final pdf. The published article is copyrighted by National Institute of Environmental Health Sciences and can be found at: http://ehp.niehs.nih.gov/. Reproduced with permission from Environmental Health Perspectives.Keywords: Arsenic, Change, Skin lesion, Bangladesh, RecoveryKeywords: Arsenic, Change, Skin lesion, Bangladesh, Recover
Variability in Biomarkers of Arsenic Exposure and Metabolism in Adults over Time
Background: Urinary arsenic metabolites (UAs) are used as biomarkers of exposure and metabolism. Ojectives: To characterize inter- and intraindividual variability in UAs in healthy individuals. Methods: In a longitudinal study conducted in Bangladesh, we collected water and spot urine samples from 196 participants every 3 months for 2 years. Water arsenic (As) was measured by inductively coupled plasma-mass spectrometry and urinary As [arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)] were detected using high-performance liquid chromatography-hydride-generated atomic absorption spectrometry. We used linear mixed-effects models to compute variance components and evaluate the association between UAs and selected factors. Results: The concentrations of UAs were fairly reproducible within individuals, with intraclass correlation coefficients (ICCs) of 0.41, 0.35, 0.47, and 0.49 for inorganic As (InAs), MMA, DMA, and total urinary As (TUA). However, when expressed as a ratio, the percent InAs (%InAs), %MMA, and %DMA were poorly reproducible within individuals, with ICCs of 0.16, 0.16, and 0.17, respectively. Arsenic metabolism was significantly associated with sex, exposure, age, smoking, chewing betel nut, urinary creatinine, and season. Specificity and sensitivity analyses showed that a single urine sample adequately classified a participant's urinary As profile as high or low, but TUA had only moderate specificity for correctly classifying drinking water exposures. Conclusions: Epidemiologic studies should use both urinary As concentrations and the relative proportion of UAs to minimize measurement error and to facilitate interpretation of factors that influence As metabolism
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Prenatal Arsenic Exposure and DNA Methylation in Maternal and Umbilical Cord Blood Leukocytes
BACKGROUND: Arsenic is an epigenetic toxicant and could influence fetal developmental programming.
OBJECTIVES: We evaluated the association between arsenic exposure and DNA methylation in maternal and umbilical cord leukocytes.
METHODS: Drinking-water and urine samples were collected when women were at <= 28 weeks gestation; the samples were analyzed for arsenic using inductively coupled plasma mass spectrometry. DNA methylation at CpG sites in p16 (n = 7) and p53 (n = 4), and in LINE-1 and Alu repetitive elements (3 CpG sites in each), was quantified using pyrosequencing in 113 pairs of maternal and umbilical blood samples. We used general linear models to evaluate the relationship between DNA methylation and tertiles of arsenic exposure.
RESULTS: Mean (+/- SD) drinking-water arsenic concentration was 14.8 +/- 36.2 mu g/L (range: < 1-230 mu g/L). Methylation in LINE-1 increased by 1.36% [95% confidence interval (CI): 0.52, 2.21%] and 1.08% (95% CI: 0.07, 2.10%) in umbilical cord and maternal leukocytes, respectively, in association with the highest versus lowest tertile of total urinary arsenic per gram creatinine. Arsenic exposure was also associated with higher methylation of some of the tested CpG sites in the promoter region of p16 in umbilical cord and maternal leukocytes. No associations were observed for Alu or p53 methylation.
CONCLUSIONS: Exposure to higher levels of arsenic was positively associated with DNA methylation in LINE-1 repeated elements, and to a lesser degree at CpG sites within the promoter region of the tumor suppressor gene p16. Associations were observed in both maternal and fetal leukocytes. Future research is needed to confirm these results and determine if these small increases in methylation are associated with any health effects.Keywords:
Arsenic,
Alu,
Epitenetics,
DNA methylation,
Environmental exposures,
Developmental programming,
in utero exposur