Health Organization Provisional Guideline Research Articles

Membrane-Assisted Electrochlorination for Zero-Chemical-Input Point-of-Use Drinking Water Disinfection.

Due to the challenges of providing centralized drinking water infrastructure in low-income and rural settings, point-of-use (POU) disinfection systems are an attractive option for enhancing access to safe drinking water. Electrochlorinators offer an easily scalable and adaptable alternative to POU disinfection systems that require frequent replenishment and accurate dosing of chlorine, but they also require addition of salts on a regular basis. To address this need, we developed an electrochemical disinfection system that efficiently produces chlorine without any chemical inputs. To convert the low concentration of chloride in source waters (i.e., 10-200 mg L-1) to free chlorine (i.e., HOCl/OCl-), an anion exchange membrane was positioned between two electrodes, creating two separate chambers. By providing continuous water flow through the catholyte while operating the anolyte in the batch mode, chloride was concentrated into the anolyte, where it was more efficiently converted into chlorine. This approach allowed us to produce chlorine at rates that were about 50% faster than that of an undivided cell operating under similar conditions. Chlorate production was approximately 20% slower in the separated cell compared to an undivided cell; concentrations in finished water never exceeded the World Health Organization's provisional guideline value of 0.7 mg L-1. The performance of the system was further improved by retaining some of the anolyte between operating cycles. This helped avoid periods of high cell potential before salts were concentrated in the anolyte chamber. Use of an anion exchange membrane and a recycled anolyte mode of operation reduced energy consumption by 30%-70% relative to an undivided cell. The energy required to disinfect water ranged from approximately 0.05 to 1 kWh m-3, depending on the chloride content and conductivity of the source water.

Mobilization and health risk assessment of fertilizer induced uranium in coastal groundwater

Uranium (U) in groundwater is hazardous to human health, especially if it is present in drinking water. The semiarid regions of southern India chiefly depend on groundwater for drinking purposes. In this regard, a comprehensive sampling strategy was adopted to collect groundwater representing different lithologies of the region. The samples were collected in two different seasons and analysed for major and minor ions along with total U in the groundwater. Two samples during pre monsoon (PRM) and seven samples during post monsoon (POM) had U > 30 μgL−1, which is above the World Health Organization's provisional guideline value. The high concentration of U (188 μgL−1) was observed in the alluvial formation though a few samples showed the release of U near the pink granite (39 μgL−1) and the concentration was low in the lateritic formation (10 μgL−1). The uranyl carbonato complexes UO2(CO3)22− and UO2(CO3)34− were associated with high pH which facilitated the transport of U into groundwater especially during POM. U3O8 is the major form observed in groundwater compared to either UO2 or UO3 in the both seasons. The uranium oxides were observed to be more prevalent at the neutral pH. Though U concentration increases with pH, it is mainly governed by the redox conditions. The principal component analysis (PCA) analysis also suggested redox conditions in groundwater to be the major process facilitating the U release mechanism regardless of the season. The POM season has an additional source of U in groundwater due to the application of nitrogenous fertilizers in the alluvium region. Furthermore, redox mobilization factor was predominantly observed near the coastal region and in the agricultural regions. The process of infiltration of the fertilizer-induced U was enhanced by the agricultural runoff into the surface water bodies in the region. Health risk assessment was also carried out by determining annual effective dose rate, cancer mortality risk, lifetime average daily dose and hazard quotient to assess the portability of groundwater in the study area. Artificial recharge technique and reducing the usage of chemical based fertilizers for irrigation are suggested as sustainable plans to safeguard the vulnerable water resource in this region.

Spatio-temporal variations of Uranium in groundwater: Implication to the environment and human health

Groundwater overexploitation has resulted in huge scarcity and increase in the demand for water and food security in India. Groundwater in India has been observed to have experienced various water quality issues like arsenic, fluoride, and Uranium (U) contamination, leading to risk in human health. Markedly, the health risk of higher U in drinking water, as well as its chemical toxicity in groundwater have adverse effects on human. This study has reported occurrence of U as an emerging and widespread phenomenon in South Indian groundwater. Data on U in groundwater were generated from 284 samples along the Cretaceous Tertiary boundary within 4 seasons viz. pre-monsoon (PRM), southwest monsoon (SWM), northeast monsoon (NEM), and post-monsoon (POM). High U concentrations (74 μgL−1) showed to be above the World Health Organization's provisional guideline value of 30 μgL−1. The geochemical, stable isotope and geophysical studies suggested that U in groundwater could vary with respect to season and was noted to be highest during NEM. The bicarbonate (HCO3) released by weathering process during monsoon could affect the saturation index (SI)Calcite and carbonate species of U. However, the primary source of U was found to be due to geogenic factors, like weathering, dissolution, and groundwater level fluctuation, and that, U mobilization could be enhanced due to anthropogenic activities. The findings further indicated that groundwater in the study area has reached the alarming stage of chemical toxicity. Hence, it is urgent and imperative that workable management strategies for sustainable drinking water source be developed and preventive measures be undertaken, relative to these water quality concerns to mitigate their disconcerting effect on human health.

Lead (Pb) contamination of self-supply groundwater systems in coastal Madagascar and predictions of blood lead levels in exposed children.

Thousands of households in coastal Madagascar rely on locally manufactured pitcher-pump systems to provide water for drinking, cooking, and household use. These pumps typically include components made from lead (Pb). In this study, concentrations of Pb in water were monitored at 18 household pitcher pumps in the city of Tamatave over three sampling campaigns. Concentrations of Pb frequently exceeded the World Health Organization's provisional guideline for drinking water of 10 μg/L. Under first-draw conditions (i.e., after a pump had been inactive for 1 h), 67% of samples analyzed were in excess of 10 μg/L Pb, with a median concentration of 13 μg/L. However, flushing the pump systems before collecting water resulted in a statistically significant (p < 0.0001) decrease in Pb concentrations: 35% of samples collected after flushing exceeded 10 μg/L, with a median concentration of 9 μg/L. Based on measured Pb concentrations, a biokinetic model estimates that anywhere from 15% to 70% of children living in households with pitcher pumps may be at risk for elevated blood lead levels (>5 μg/dL). Measured Pb concentrations in water were not correlated at statistically significant levels with pump-system age, well depth, system manufacturer, or season of sample collection; only the contact time (i.e., flushed or first-draw condition) was observed to correlate significantly with Pb concentrations. In two of the 18 systems, Pb valve weights were replaced with iron, which decreased the observed Pb concentrations in the water by 57-89% in one pump and by 89-96% in the other. Both systems produced samples exclusively below 10 μg/L after substitution. Therefore, relatively straightforward operational changes on the part of the pump-system manufacturers and pump users might reduce Pb exposure, thereby helping to ensure the continued sustainability of pitcher pumps in Madagascar.

A preliminary exposure assessment of microcystins from consumption of drinking water in the United States

This preliminary human exposure assessment of cyanotoxins from consumption of treated drinking water in the United States is based on reported concentrations of microcystin-LR equivalents, (herein referred to as MC-LR), a cyanotoxin measured in a study of North American drinking waters conducted by the American Water Works Association from June 1996 to January 1998. The sampling protocol resulted in a distribution of MC-LR concentrations in waters that likely overestimates the actual distribution encountered by the exposed population, yielding conservatively biased estimates of exposure. Over a 75-year lifetime, the estimated lifetime average daily dose of MC-LR from the consumption of drinking water was estimated to be 1.7 × 10−3 μg/kg-day with a standard deviation of 0.02. The 90 and 95 percentile exposure estimates were 1.5 × 10−3 and 3.9 × 10−3, respectively. Our results suggest that most individuals are exposed to cyanotoxin levels in finished North American drinking waters that are approximately an order of magnitude lower than the World Health Organization's provisional guideline level of 1 μg/L, which corresponds to approximately 0.04 μg/kg-day.

First evidence of arsenic phytoremediation

Since the mid-1990s, bioremediation of contaminated soils, groundwater and surface water has been addressed by a new technology – phytoremediation – involving plants and plant–microbe systems. The mechanisms responsible for plant tolerance to a broad spectrum of metals have been studied intensively to determine those characteristics that are essential for application to phytoremediation. However, there is not, as yet, an effective solution for the phytoremediation of arsenic, one of the most noxious metals to humans. Both soil and water arsenic toxicity continues to be reported in many countries. The most dramatic case was reported in Bangladesh, where groundwater concentrations of arsenic reach 2 mg l−1 1 Ullah, S.M. (1998) Arsenic contamination of groundwater and irrigated soils of Bangladesh. Abstract: International Conference on Arsenic Pollution of Groundwater in Bangladesh: Causes, Effects and Remedies, 8–12 February 1998, p. 133, Dhaka Community Hospital, Dhaka, Bangladesh 1Ullah, S.M. (1998) Arsenic contamination of groundwater and irrigated soils of Bangladesh. Abstract: International Conference on Arsenic Pollution of Groundwater in Bangladesh: Causes, Effects and Remedies, 8–12 February 1998, p. 133, Dhaka Community Hospital, Dhaka, Bangladesh; the World Health Organization's provisional guideline value for drinking water is only 0.01 mg l−1 (http://www.who.int/inf-fs/en/fact210.html). It is estimated that the high levels of arsenic in the drinking water will lead to 200 000–270 000 cancer-caused deaths in Bangladesh. Moreover, the use of contaminated irrigation water has led to soil levels of arsenic of ∼80 mg kg−1, which is tenfold higher than levels in soils considered non-contaminated. The consumption of produce from these regions could also be detrimental to living organisms. Agricultural zones facing this type of contamination need to act quickly to achieve safe levels of soil and water arsenic.