Analysis of benzene, toluene, and xylene contaminants in the groundwater of Tripoli, Lebanon

Special Issue on Drinking Water Safety, Security, and Sustainability

The National Water-Quality Assessment Program of the United States (US) Geological Survey conducted surveys of the occurrence of methyl tert-butyl ether (MTBE) and other fuel oxygenates in ground water used as a source of drinking water and in drinking water in the United States (USA) from 1993 to 2001. MTBE was detected in about 4% of samples of source water collected from private and public supply wells located throughout the USA and in about 9% of samples of drinking water from 12 Northeastern states. Other fuel oxygenates were detected very infrequently. Few samples of source water or drinking water had concentrations of MTBE greater than the US Environmental Protection Agency drinking-water advisory or state-level benchmarks.As many as five million people in the USA may potentially be exposed to MTBE through source water derived from ground water. Public wells appear to be more vulnerable to contamination by MTBE than private wells, and more people in the USA rely on drinking water from public wells than private wells. Because of the uncertainty in the long-term health effects of MTBE in drinking water, it is important to monitor for MTBE in ground water used as a source of drinking water, especially ground water from public wells. Better understanding of the sources of MTBE to ground water, the intrinsic susceptibility of aquifers to contamination, and the behavior and fate of MTBE in ground water would aid in adequately protecting ground-water resources from contamination by MTBE.KeywordsMTBESource WaterDrinking WaterOccurrenceFuel Oxygenates

Associations between private well water and community water supply arsenic concentrations in the conterminous United States

Ambient concentrations of C2-C12 volatile organic compounds (VOCs) were measured at Bursa, which is the fourth largest city of Turkey. Two measurement campaigns were carried out between September 14 to November 6, 2005 and March 17 to May 10, 2006. Fifty one VOCs were regularly determined in each chromatogram. However, only BTX compounds are discussed in this study. Concentrations of BTX compounds showed well-defined diurnal cycles. Concentrations increased starting at 06:00 am in the morning, reaching to a maximum somewhere between 9:00 to 11:00 am. Then concentration decreased, until the evening rush hour, owing to increasing mixing height during day time. Then concentrations of BTX increased in the afternoon rush hour which extended to 08:00 pm. BTX concentrations remained low throughout the night. High binary correlations between BTX compounds suggest a common source, which are traffic emissions. However, other non-traffic sources were also found to be effective, for benzene in the November to March campaign.

Editor's perspective – Per‐ and polyfluorinated substances pose substantial challenges to remediation practitioners

Whereas a large number of empirical studies have been devoted to analyzing determinants of environmental compliance (EC) by firms, less attention has been paid to EC by public water systems (PWS). To address this gap in the literature, this article uses data on compliance with maximum contaminant levels (MCL) under the Safe Drinking Water Act for 971 PWS in Arizona and identifies the characteristics of PWS that are associated with violation of MCL standards. Three main findings emerge from the analysis. First, larger PWS are more likely to violate MCL standards than smaller PWS. Second, publicly owned PWS have slightly higher probability of violating MCL standards than privately owned systems. Finally, PWS serving residential areas are more likely to violate MCL standards, as opposed to PWS serving school districts or office buildings. The results suggest that for ensuring safe water for people, effectiveness of monitoring policy, and an efficient utilization of resources, the environmental agencies may focus their monitoring and enforcement efforts on these water systems.(JEL K32, Q53)

Effects of time and point-of-use devices on arsenic levels in Southeastern Michigan drinking water, USA

Occurrence of male-specific and somatic coliphages and relationship with rainfall in privately-owned wells from peri‑urban and rural households

BACKGROUND AND AIM: Important inequalities exist in arsenic (As) in drinking water across US populations. A critical research gap is how water As corresponds to internal dose, measured by urinary biomarkers. We evaluated the association between assigned private well and regulated community water system (CWS) As and urinary As concentrations in the National Health and Nutrition Examination Survey (NHANES). METHODS: We assigned 13,163 NHANES 2003-2014 participants county-level population- weighted CWS concentrations (µg/L) and private well estimates (probability >10 µg/L) using published nationwide estimates from US Environmental Protection Agency and US Geological Survey datasets, respectively. The internal dose of inorganic As related to drinking water was estimated by recalibrating urine dimethylarsinate (DMA) concentrations to adjust for arsenobetaine, seafood, smoking status, and past 24-hour intake of rice and other dietary sources. We evaluated geometric mean ratios (GMRs) of DMA across tertiles of water As, the lowest tertile as reference, for all participants and stratified by census region and quartile of geologic risk of elevated water As. RESULTS: Among CWS users, participants in the highest tertile of CWS As had significantly higher DMA overall (GMR= 1.17, 95% CI 1.09, 1.26) and in the South (GMR =1.23, 95% CI 1.09, 1.38), compared to participants in the lowest tertile. Among private well users, participants in the highest tertile of private well As had significantly higher DMA overall (GMR = 1.23, 95% CI 1.01, 1.50) and in the West (GMR = 1.34, 95% CI 1.18, 1.53). CONCLUSIONS: Arsenic in private wells and CWSs contributes to As exposure, measured in urine, in general US populations. Water As and urine DMA were more strongly associated among private-well users compared to CWS users nationwide, with differences by region. Positive associations were also observed among CWS users in the highest two quartiles of geologic risk. KEYWORDS: arsenic, exposure, water quality

To evaluate the performance of domestic water purification units with respect to contaminating enteric viruses. Eight domestic water purification systems widely used in India were evaluated using hepatitis E virus (HEV) as a model virus. For HEV concentration and detection, membrane filtration and real-time PCR were used respectively. Viral log reduction value (LRV) was calculated for each unit. Viral log reduction value was 0.21 for unit 6 (polyester + carbon), 1.45 for unit 4 (filter + UV), 1.52 for unit 3 (filter + chlorine), 1.70 for a carbon + exhaust indication contact disinfection unit, 2.20 for an iodine resin unit, 2.51 for a dual filter unit and 6.53 for a hollow fibre membrane unit and a gravity-fed filter unit. Thus, only the technologies employed by the latter two were efficient in complete removal of HEV. The majority of the water purifiers under use are inadequate. Virological standards in evaluating such devices need to be established urgently, in order to help manufacturers to improve the performance of such products and most importantly, to help consumers.

Revealing the sources of arsenic in private well water using Random Forest Classification and Regression.

Review objective The review objective is to synthesise the best available evidence on exposure to chlorinated water and risk of cancer. Risks associated with colorectal or bladder cancers have already been established and therefore will not be considered in this systematic review. Inclusion criteria Types of participants This review will consider studies that include males and females of all ages. Types of intervention(s)/phenomena of interest This review will consider studies that evaluate exposure to chlorine disinfection by-products by drinking (ingesting), bathing, showering, swimming, cooking, cleaning and dishwashing (dermal and inhalation) and identify incidence and mortality outcomes of cancer (excluding colorectal and bladder) compared with exposure without chemical disinfection (chlorine) or alternative disinfection processes. Types of outcomes This review will consider studies that include the following outcome measures. Incidence, mortality and specifically measures of risk between exposure and outcome of cancers with the exception of bowel and bladder. For example the following cancers have been associated with chlorine disinfection by products, kidney/adrenal, liver, thyroid, pituitary, lymphoma and leukaemia, pancreatic, gastrointestinal (other than colorectal), testicular, breast and lung cancer. These and any other cancers identified as relevant eg. skin cancers will be included.

Hydraulic and water quality models have become widely used to understand both the hydraulic behaviour, and the fate and transport of contaminants in drinking water distribution systems. Research conducted by the United States (US) Environmental Protection Agency (EPA) played a major role in the development and application of hydraulic/water quality modelling in the United States and throughout the world. Eventually this research led to the development of EPANET, an integrated hydraulic/water quality model, and had a major influence on the implementation of the United States Safe Drinking Water Act (SDWA). The modelling research conducted by the US EPA has helped many drinking water utilities throughout the world alleviate public health threats due to the deterioration of water quality in drinking water networks. The US EPA has provided over 100 000 downloads of the EPANET software over the last 2 years.

Potential threats to drinking water and water quality continue to be a major concern in many regions of the United States. New Jersey, in particular, has been at the forefront of assessing and managing potential contamination of its drinking water supplies from hazardous substances. The purpose of the current analysis is to provide an up-to-date evaluation of the occurrence and detected concentrations of methyl tertiary butyl ether (MTBE) and several other volatile organic compounds (VOCs) in public water systems, private wells, and ambient groundwater wells in New Jersey based on the best available data, and to put these results into context with federal and state regulatory and human-health benchmarks. Analyses are based on the following three databases that contain water quality monitoring data for New Jersey: Safe Drinking Water Information System (SDWIS), Private Well Testing Act (PWTA), and National Water Information System (NWIS). For public water systems served by groundwater in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 30 (2%), 21 (1.4%), and five (0.3%) of sampled systems from 1997 to 2011, respectively. For private wells in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 385 (0.5%), 183 (0.2%), and 46 (0.05%) of sampled wells from 2001 to 2011, respectively. For ambient groundwater wells in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 14 (2.1%), 9 (1.3%), and 4 (0.6%) of sampled wells from 1993 to 2012, respectively. Average detected concentrations of MTBE, as well as detected concentrations at upper-end percentiles, were less than corresponding benchmarks for all three datasets. The available data show that MTBE is rarely detected in various source waters in New Jersey at a concentration that exceeds the State's health-based drinking water standard or other published benchmarks, and there is no evidence of an increasing trend in the detection frequency of MTBE. Other VOCs, such as tetrachloroethylene (PCE), trichloroethylene (TCE), and benzene, are detected more often above corresponding regulatory or human-health benchmarks due to their higher detected concentrations in water and/or greater toxicity values. The current analysis provides useful data for evaluating the nature and extent of historical and current contamination of water supplies in New Jersey and potential opportunities for public exposures and health risks due to MTBE and other VOCs on a statewide basis. Additional forensic or forecasting analyses are required to identify the sources or timing of releases of individual contaminants at specific locations or to predict potential future water contamination in New Jersey.

Hydrocarbons such as benzene, toluene, and xylene (BTX) have been widely used in life and especially, they are the major components in many petroleum products. BTX have been considered as the environmental contaminants as they pose hamful effects on living organisms as well as on human health. The aims of this study were isolation and screening for indigenous bacteria capable of effectively degrading BTX compounds. Twenty-one bacterial isolates isolated from five sediment samples in a wastewater tank of a petroleum refining plant grew in minimal salt medium supplemented with BTX compounds as the only carbon source. Among these, two bacterial isolates BTX-S21 and BTX-S22 were capable of producing higher biomass as compared to others on minimal salt medium supplemented with different concentrations of BTX including 0.01; 0.025; 0.05; 0.1; 0.25; 0.5 and 1% (v/v) for each compound. In the liquid media containing four different concentrations of BTX compounds such as 0.01; 0.05; 0.1 and 0.25% (v/v), BTX-S21 degraded 100% benzene, 100% toluene and more than 92% xylene after 24 hours of inoculation.