Influence of Household Water Filters on Bacteria Growth and Trace Metals in Tap Water of Doha, Qatar

Deteriorating water quality from aging infrastructure, growing threat of pollution from industrialization and urbanization, and increasing awareness about waterborne diseases are among the factors driving the surge in worldwide use of point-of-entry (POE) and point-of-use (POU) filters. Any adverse influence of such consumer point-of-use systems on quality of water at the tap remains poorly understood, however. We determined the chemical and microbiological changes in municipal water from the point of entry into the household plumbing system until it leaves from the tap in houses equipped with filters. We show that POE/POU devices can induce significant deterioration of the quality of tap water by functioning as traps and reservoirs for sludge, scale, rust, algae or slime deposits which promote microbial growth and biofilm formation in the household water distribution system. With changes in water pressure and physical or chemical disturbance of the plumbing system, the microorganisms and contaminants may be flushed into the tap water. Such changes in quality of household water carry a potential health risk which calls for some introspection in widespread deployment of POE/POU filters in water distribution systems.Other Information Published in: Scientific Reports License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1038/s41598-018-26529-8</p

Speciation of Arsenic in Saliva Samples from a Population of West Bengal, India

Saliva, an easily accessible biofluid, is validated as biomarker of arsenic (As) exposure in several villages of West Bengal, India. Pentavalent arsenic [As­(V)] was found to be the predominant species in saliva, with the amount of inorganic As [As­(V) and trivalent form, As­(III)] being more than half of the total As in the samples. Significant association was found between total daily ingestion of As and As­(V) (<i>r</i> = 0.59; <i>p</i> = 0.000), As­(III) (<i>r</i> = 0.60; <i>p</i> = 0.000), dimethylarsinous acid (DMA^V) (<i>r</i> = 0.40; <i>p</i> = 0.000), and monomethylarsonous acid (MMA^V) (<i>r</i> = 0.44; <i>p</i> = 0.000), implying that these species have mainly been derived from the methylation of the inorganic As in the water that study participants drank and the food they ate. Analysis of confounding effects of age, sex, smoking, body mass index and the prevalence of skin lesion suggests that women and controls with no skin lesion had a higher capacity to methylate the ingested As compared to the rest of the population. Thus, our study demonstrates that As species in saliva can be an useful tool to predict the individual susceptibility where higher As exposure and a lower methylation capacity are implicated in the development of As-induced health effects

Consumption of Brown Rice: A Potential Pathway for Arsenic Exposure in Rural Bengal

This study assesses the arsenic (As) accumulation in different varieties of rice grain, that people in rural Bengal mostly prefer for daily consumption, to estimate the potential risk of dietary As exposure through rice intake. The rice samples have been classified according to their average length (<i>L</i>) and <i>L</i> to breadth (<i>B</i>) ratio into four categories, such as short-bold (SB), medium-slender (MS), long-slender (LS), and extra-long slender (ELS). The brown colored rice samples fall into the SB, MS, or LS categories; while all Indian Basmati (white colored) are classified as ELS. The study indicates that the average accumulation of As in rice grain increases with a decrease of grain size (ELS: 0.04; LS: 0.10; MS: 0.16; and SB: 0.33 mg kg^–1), however people living in the rural villages mostly prefer brown colored SB type of rice because of its lower cost. For the participants consuming SB type of brown rice, the total daily intake of inorganic As (TDI-iAs) in 29% of the cases exceeds the previous WHO recommended provisional tolerable daily intake value (2.1 μg day^–1 kg^–1 BW), and in more than 90% of cases, the As content in the drinking water equivalent to the inorganic As intake from rice consumption (<i>C</i>_W,eqv) exceeds the WHO drinking water guideline of 10 μg L^–1. This study further demonstrates that participants in age groups 18–30 and 51–65 yrs are the most vulnerable to the potential health threat of dietary As exposure compared to participants of age group 31–50 yrs, because of higher amounts of brown rice consumption patterns and lower BMI

Risk of Arsenic Exposure from Drinking Water and Dietary Components: Implications for Risk Management in Rural Bengal

This study investigates the risk of arsenic (As) exposure to the communities in rural Bengal, even when they have been supplied with As safe drinking water. The estimates of exposure via dietary and drinking water routes show that, when people are consuming water with an As concentration of less than 10 μg L^–1, the total daily intake of inorganic As (TDI-iAs) exceeds the previous provisional tolerable daily intake (PTDI) value of 2.1 μg day^–1 kg^–1 BW, recommended by the World Health Organization (WHO) in 35% of the cases due to consumption of rice. When the level of As concentration in drinking water is above 10 μg L^–1, the TDI-iAs exceeds the previous PTDI for all the participants. These results imply that, when rice consumption is a significant contributor to the TDI-iAs, supplying water with an As concentration at the current national drinking water standard for India and Bangladesh would place many people above the safety threshold of PTDI. We also found that the consumption of vegetables in rural Bengal does not pose a significant health threat to the population independently. This study suggests that any effort to mitigate the As exposure of the villagers in Bengal must consider the risk of As exposure from rice consumption together with drinking water

Is Saliva a Potential Biomarker of Arsenic Exposure? A Case-Control Study in West Bengal, India

Saliva is a biological fluid that has not been used extensively as a biomonitoring tool in epidemiological studies. This study presents the arsenic (As) concentrations in saliva and urine samples collected from populations of West Bengal, India who had been previously exposed to high As levels in their drinking water. We found a significant (<i>p</i> < 0.05) association between the Log transformed Daily Ingestion of As (μg day^–1) and the As concentration in saliva (<i>r</i> = 0.68). Additionally, As concentration of saliva and urine also had a significant positive correlation (<i>r</i> = 0.60, <i>p</i> < 0.05). Male participants, smokers, and cases of skin lesion were independently and significantly associated with an increase in salivary As. Thus our findings show that saliva is a useful biomarker of As exposure in the study population. The study also advocates that measurement of the forms of As in saliva may additionally provide insight into the internal dose and any individual differences in susceptibility to As exposure