Quantifying Potential Benefits of Monitoring and Surveillance of Rural Water Supplies in Bangladesh
Approximately 20 million people are drinking arsenic contaminated water, and there are at least 37,000 arsenicosis patients in Bangladesh. Although arsenic occurs in groundwater naturally in a large part of the country, millions of domestic hand tube wells have been installed since the 1980s, and 90% of population are currently relying on tube wells as their drinking water sources. A vast number of small-scale water sources make systematic monitoring and surveillance difficult; thus only 55% of water sources have ever tested for arsenic to date.
The present study aims to quantify potential benefits of monitoring and surveillance of rural water supplies in Bangladesh with a purpose of proposing effective strategies for water supply and arsenic mitigation. A quantitative risk assessment model using a concept of Disability Adjusted Life Years (DALYs) was applied to evaluate public health benefits of monitoring and surveillance as reduced burden of associated diseases. In order to reflect uncertainty and variation of existing data on the calculation, a method of Monte Carlo Simulation was also adopted.
The present study showed that the country could gain DALYs (median: 1,289, 5th%ile: 388 and 95th%ile: 11,891 DALYs person-years) through a nationwide water quality screening for arsenic as 4.7 – 5.7 million people were likely to switch their wells at their own initiatives. The estimated cost per DALY gained showed that arsenic screening was 3.8 times more cost-efficient than installation of community-based alternative water supplies.
Meanwhile, previous data from a pilot of Water Safety Plan (WSP) evidenced significant reduction of microbial contamination of community-based alternative water sources by monitoring and surveillance. The associated disease burden in this programme was estimated to be reduced by 32 – 61 %. The estimation also showed that risks from microbial contamination of alternative water sources overweigh risks from arsenic, unless chlorination disinfection was applied to the water sources.
Effective information provision about their drinking-water status, surveillance of a supportive nature, more arsenic testing in less contaminated areas, more alternative water supplies in highly contaminated areas, a wise use of deep aquifers, and ensuring chlorination disinfection for alternative community water supplies were suggested as recommendations made in the present study.