Disinfection research in developing countries has strongly prioritized pathogen removal, and rightly so. However, as disinfection becomes widely practiced in some developing countries, minimizing the risk of waterborne illness, exposure to disinfection byproducts (DBPs) increases. The four major trihalomethane species (THM4) are typically regarded as a sufficient indicator of overall DBP formation in this context, despite research demonstrating that THM4 is not predictive of other DBP species, most of which are far more toxic than the constituents of THM4. Little is known about the occurence of other DBP species in developing countries, as observations are largely limited to THM4. South Asia is of particular interest due to documented prevalence of wastewater contamination of drinking water resources. Wastewater-associated precursors tend to promote the formation of more toxic DBPs. We investigated the occurrence of 25 DBPs in Dhaka, Bangladesh and several large urban areas in western India, where disinfection is practiced in full-scale distribution systems and community collection points. Wastewater indicators revealed ubiquitous contamination by municipal wastewater. Although THM4 concentrations rarely exceeded international guidelines, high concentrations of DBPs of greater toxicological concern were observed. When DBP concentrations were weighted by toxicity values as a tool for comparison, haloacetonitriles contributed the majority of the calculated toxicity in most cases, while THM4 contributed a negligible fraction. THM4 and calculated toxicity were found to be poorly correlated. Several factors particular to under-resourced settings that may promote DBP formation were investigated, and solutions for reducing DBP-associated toxicity were explored. Overall, the results indicate THM4 may be an inadequate indicator of the DBP-associated chronic health risk, particularly in degraded water sources utilized by many under-resourced communities. Developing countries typically base new DBP regulations on World Health Organization guidelines, which only refer to DBP data from high-income countries. More robust and locally relevant DBP research is needed to ensure disinfection practices and policy are optimized to protect health in developing countries where disinfection is now common.

Is it time to move beyond the trihalomethane paradigm in developing countries? Lessons learned from wastewater-impacted drinking waters in South Asia

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.