Drinking Water from Hand-Pumps in Mali, Niger, and Ghana, West Africa: Review of Health Effects ()
1. Introduction
This paper presents data on concentrations of 22 parameters in 3337 groundwater samples from hand pumps in Ghana, Mali, and Niger in West Africa. Samples were grouped by three-country “region” or by individual country. All samples were analyzed for concentrations of Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sr, Tl, U, V, Zn, and F with respect to World Health Organization (WHO) drinking water guidelines. The purpose of this study was to evaluate drinking water quality from hand-pumps, assess risk as percent of population exposed, provide overview of human health effects from hand-pump water, and evaluate evidence of these health effects in the population, if available.
Collection and analyses of samples was done in collaboration by World Vision International (WVI) and the Desert Research Institute (DRI) and is part of an ongoing effort to provide rural populations with potable water. Samples reported in this study were collected and analyzed between 2002 and 2012. The distribution of sampling points was driven by hand-pump location, which, in turn, was dictated by local need for potable water. Thus, there existed a compromise in sampling for the specific purpose of hypothesis testing, such as analysis of elevated concentrations and geographic trends, or elevated concentrations and specific population. Approximate sampling areas are shown in Figure 1.
To-date, several thousand hand-pumps have been commissioned, providing approximately one million rural community members with potable water via this particular project. Across sub-Saharan Africa, however, approximately 880 million people still lack access to safe
drinking water [1]. Groundwater is increasingly relied on as a source of safe drinking water for rural communities in the countries of Ghana, Mali, and Niger in West Africa and elsewhere. Reasons for developing groundwater include ease of developing hand-pumps in remote locations, availability during drought, relative low price compared with methods of treating surface water, and superior chemical and biological quality as compared with surface water sources [2,3].
Though generally considered to be a safer source of drinking water than surface water, groundwater may contain parameters that have either adverse or beneficial effects on human health. Some parameters have typically low concentrations and, in the case of Co, Cr, Cu, Fe, I, Mn, Mo, Se, V and Zn, are essential to human life, but at higher concentrations, there may be potential health risks for humans including diseases, disorders, cancers, reduced growth, and increased mortality and mutagenic effects [4]. The effects depend on concentration and a different range of acceptable concentrations exist for each parameter.
To evaluate risk and avoid adverse health effects, WHO drinking water guidelines may be used. These guidelines are derived on the basis of health and internationally agreed procedures for risk assessment [5]. These guidelines are neither regulations nor standards, though they may be used to develop local guidelines or standards on water quality. On the one hand there are guidelines for those considered toxic and for which a relative amount of research has been conducted (As, Fl), while there are no guidelines for those whose effects on human health are not know or unclear (Ag, Be, Co, Sr, and V).
In each country, the water projects seek to supply potable water in rural areas. These areas are characterized by small holder subsistence agriculture, and are generally devoid of industrial activity. While some hot spots may be associated with highly localized cottage industries, parameters in excess of WHO guidelines are largely geologic in origin, naturally occurring, and not likely to be from anthropogenic sources. The distribution of parameters found in the samples, thus, reflects the diverse geological terrains from the three countries.
2. Methods
Samples were collected at hand-pumps during borehole development or after drilling but before hand-pump placement. In some cases, samples were collected at actively-used hand-pumps. Samples were collected by staff at Ghana Rural Water Project (GRWP), Mali Rural Water Project (MRWP), and Niger Rural Water Project (NRWP). All water projects are overseen by WVI. After collection, samples were shipped to DRI for analysis. As much as possible, standard methods were applied, however, samples were not field-filtered. Timing was random as sample collection was hampered by monsoonal rains and extreme heat.
Each sample was analyzed for concentrations of 22 parameters. Fluoride was analyzed according to EPA standard methods 4500F [6]. The parameters Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sr, Tl, U, V, and Zn were analyzed on an inductively coupled plasma-mass spectrometry (ICPMS) according to EPA methods standard methods for drinking water 200.8 [7].
Between 2002 and 2011, detection limits of several parameters analyzed on the ICPMS changed, ultimately becoming lower. Thus, on some figures, previous detection limits will appear as solid lines of data, rather than points. In this study, all data were reported in their originnal format and no efforts were made to adjust, infill, or perform additional measures for values below the detection limit. The results provided are thus reproducible.
3. Results
Table 1 shows WHO guidelines for each parameter and percentage of samples exceeding the guidelines. Table 2