Unsafe concentrations of As have been discovered in tubewell water throughout much of Bangladesh (BGS/DPHE 2001; Frisbie et al. 1999; USAID 1997). Residents who drink water contaminated with As are at risk of developing dermatological diseases, skin cancers, internal cancers, adverse pregnancy outcomes, and increased mortality (Ashraf et al. 2004; Frisbie et al. 2005). The Bangladeshi government, nongovernmental organizations, and the scientific community have responded by instituting widespread drinking water testing for As, as well as education programs designed to inform the populace about the dangers of drinking As-contaminated water. As a result, approximately 5,000,000 of the country’s 10,000,000 tubewells have been tested for As (UNICEF 2007), and increasing numbers of villagers are becoming aware of the health risks associated with drinking As-contaminated water (Parvez et al. 2006).
Routine testing of drinking water for As is crucial for promoting public health in Bangladesh. However, 2 national-scale surveys of tubewell water for other toxic elements revealed that As, Mn, U, B, Ba, Cr, Mo, Ni, and Pb are found at concentrations that exceed WHO health-based drinking water guidelines (BGS/DPHE 2001; Frisbie et al. 2002). It should be noted that our 2002 study was prompted, in part, by clinical observations that certain As patients had more severe symptoms than would be expected given the levels of As in their drinking water, suggesting possible synergistic effects from other toxins, such as Sb, as well as deficient quantities of beneficial elements such as Se and Zn.
While there is much ongoing research about the distribution of As in the geologic materials of the region (Bhattacharya et al. 2002), the distribution of the other toxic elements commonly found in the region’s drinking water has received much less attention. An essential question for those charged with ensuring public health is whether drinking water with As concentrations that meet national or WHO criteria can be designated as safe without further testing for other toxic elements. It is crucial for public health policy to determine whether the concentrations of other commonly occurring toxic elements are correlated with the concentration of As. If the concentrations of these other toxins are positively correlated with the concentration of As, then the current practice of testing every tubewell for just As might be sufficient to identify safe drinking water supplies. If the concentrations of these other toxins are not positively correlated with the concentration of As, then testing every tubewell for just As will not identify safe drinking water supplies. Drinking water must be safe with respect to As and all other toxic elements.