Risk assessment of arsenic mitigation options in Bangladesh

Abstract

The provision of alternative water sources is the principal arsenic mitigation strategy in Bangladesh, but can lead to risk substitution. A study of arsenic mitigation options was undertaken to assess water quality and sanitary condition and to estimate the burden of disease associated with each technology in disability-adjusted life years (DALYs). Dugwells and pond-sand filters showed heavy microbial contamination in both dry and monsoon seasons, and the estimated burden of disease was high. Rainwater was of good quality in the monsoon but deteriorated in the dry season. Deep tubewells showed microbial contamination in the monsoon but not in the dry season and was the only technology to approach the World Health Organization's reference level of risk of 10-6 DALYs. A few dugwells and one pond-sand filter showed arsenic in excess of 50 microg/L. The findings suggest that deep tubewells and rainwater harvesting provide safer water than dugwells and pond-sand filters and should be the preferred options.

Fig. 1.

Quality of water in relation to the Bangladesh standard for TTCs and arsenic

Fig. 2.

Combined risk assessment for microbial contamination

Fig. 3.

Burden of disease by technology and season