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Ā© 2017 The Author(s) This is an Open Access book chapter distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-SA 4.0), which permits copying and redistribution for non-commercial purposes, provided the original work is properly cited and that any new works are made available on the same conditions (http://creativecommons.org/licenses/by-nc-sa/4.0/). This does not affect the rights licensed or assigned from any third party in this book. The chapter is from the book Best Practice Guide on the Control of Arsenic in Drinking Water, Prosun Bhattacharya, David A. Polya and Dragana Jovanovic (Eds.).
DOI: 10.2166/9781780404929_001
Chapter 1
Arsenic in drinking water: sources & human exposure
David A. Polya and Daniel R. S. Middleton
School of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
1.1 INTRODUCTION
Although the detrimental health impacts of chronic arsenic exposure from drinking water or beverages has been suspected for over 200 years (Martin, 1759; Neubauer, 1947; citing Egger, 1932; citing Lambe, 1809) and has been well documented for well over 100 years (Geyer, 1898; The Royal Commission on Arsenical Poisoning, 1903), it is only in the last 50 years (1964ā2014) that there has been the extensive discovery of high arsenic drinking water supplies in many regions of the world. In the English language literature, reports of these include for: Taiwan (Chen & Chen, 1964), Chile (ZaldĆvar, 1974), northern India (Datta & Paul, 1976), Mexico (Cebrian et al. 1983), eastern India (Garai et al. 1984; Das et al. 1994; Chakraborti et al. 2009), UK (Farmer et al. 1989), Hungary (Varsanyi et al. 1991), USA (Frost et al. 1993), Bangladesh (Dhar et al. 1997), China (Sun et al. 1999), Vietnam (Berg et al. 2001), Cambodia (Polya et al. 2003a) and Nepal (Thanduker, 2000; Shrestha et al. 2003; Bhattacharya et al. 2003).
Notwithstanding these discoveries, particularly in Germany, Taiwan, Chile, Hungary and India, there has been an apparent widespread tardiness to recognise the importance of groundwater arsenic hazards. As late as 1999, the European Environmental Agency published an extensive report on groundwater quality and quantity in Europe (Scheidleder et al. 1999) that does not mention āarsenicā, presumably reflecting the paucity of relevant long-term monitoring data. Extensive drilling of what turned out subsequently to be arsenic contaminated wells in India and Bangladesh took place many years after high arsenic groundwaters and their ill-effects had been documented in Europe, South America and elsewhere in Asia. The lack of recognition of this hazard reflects in part a lack of effective distribution of local, regional and international scientific and technical knowledge. In part this may be because much of the early literature was not written in English ā for example reports of groundwater arsenic in Argentina by Fernandez (1925) and in Germany by Geyer (1898, 1940) ā however other reasons for the apparent lack of institutional awareness of the seriousness of arsenic hazard in drinking water systems must exist (at least in the English speaking world) given notable relevant English-language articles including the Royal Commission on Arsenical Poisoning (1903), Neubauerās (1947) review of arsenical cancer and numerous epidemiological papers from C.-J. Chen and his group in Taiwan. Even Rachel Carsonās (1962) widely read totem of the early environmental movement, āSilent Springā, notes briefly the health risks associated with the chronic consumption of high arsenic drinking water.
Within both many regulatory institutions and the scientific community, this situation has now substantially changed. The EEAās 2013 report (KodeÅ” et al. 2013) on groundwater quality and quantity in Europe, superseding the EEAās 1999 report, highlights non-compliance of groundwater supplies with European Union drinking water standards (10 Āµg As/L) in 13 European countries, (albeit not Hungary, Romania and Serbia, all countries where substantial arsenic groundwater arsenic hazard has been identified). At the time of writing (mid, 2014), there were around 5000 publications matching the topic keywords of āarsenicā and ādrinking waterā and these have been collectively cited over 100,000 times in other publications. The 2002 review of arsenic in natural waters by Smedley and Kinniburgh (2002) is one of the most highly cited papers in the Earth Sciences literature, whilst the highly cited reviews of Mandal and Suzuki (2002), Mohan and Pittman (2007) and Smith et al. (2000) now provide readily available information of arsenic distribution in natural waters, arsenic removal technologies and health impacts respectively.
This chapter aims to summarise some of the now extensive literature on arsenic occurrences in drinking water supplies and, together with reviewed data on water consumption rates, provide a perspective on the absolute and relative importance of drinking water as an arsenic exposure route across the globe. For the most part, these water supplies have derived from groundwaters (Section 1.2) contaminated with geogenic arsenic (i.e. arsenic of natural origin) but there are also examples of groundwaters with high anthropogenic arsenic and of high arsenic surface water supplies (Section 1.3), with arsenic of either geogenic or anthropogenic origin. For a more detailed account than is presented in this brief chapter of the distribution of arsenic in groundwater and surface waters, the reader is referred to Matschullat (2000), Welch (2000), Mandal and Suzuki (2002), Smedley and Kinniburgh (2002), Henke (2009), Ravenscroft et al. (2009), Barringer and Reilly (2013) and Polya and Lawson (2015).
1.2 ARSENIC IN GROUNDWATER SOURCES
Although many groundwaters do not contain arsenic at concentrations higher than the WHO provisional guideline value of 10 Āµg/L, many groundwaters do ā high arsenic groundwaters are not unusual and any competent or prudent operator supplying groundwater as a drinking water supply, even perhaps in medium-term emergency circumstances, should be compelled to determine and report to the potential users whether or not the arsenic concentrations in the water supply are lower than at least local regulations require.
There is an abundant literature on the main causes of high arsenic hazard in various types of groundwater and this can be used to indicate regions of the world where high arsenic hazard may be more likely ā see for example compilations and reviews by, amongst others, Smedley and Kinniburgh (2002) and Ravenscroft et al. (2009). Recently, geostatistical models incorporating consideration of environmental parameters that may influence the genesis of high arsenic groundwaters have been developed on both a global (Amini et al. 2008; Winkel et al. 2008) and a more local/national scale (Lado et al. 2008; Rodriguez-Lado et al. 2013; Sovann & Polya, 2014).
Many groundwater systems, particularly shallow systems hosted in complex sedimentary aquifers, are highly hetereogeneous. This means that high arsenic and low arsenic groundwaters may often be found in close proximity, giving rise to opportunities for well switching (van Geen et al. 2002). This heterogeneity also means that prediction of arsenic concentrations in yet-to-be-drilled wells may be a precarious business. Notwithstanding this, a consideration of plausible regional and local controls of groundwater arsenic concentrati...
