Assessment of combined effects of chemical toxicity of potable water in Bangladesh

Abstract

Nowadays, majority of the people of Bangladesh are completely depending on groundwater for household potable water use because surface water usage has previously led to some detrimental health effects causing diarrhea, cholera etc. But, recently this groundwater source has also become a dubious resource for the whole country as Arsenic and many other harmful metals were discovered in it from national surveys. As a result of drinking this water, people are severely suffering from skin and internal cancers as well as other non-cancer effects at many places throughout the whole country. But it is unclear whether these effects are due to any antagonistic or synergistic effect of toxic elements present in water. This study addresses mixtures of chemicals in drinking water and potential interactions that might affect the joint noncancer toxicity (Cardiovascular, Neurological, Hematological and Renal effects) of chemicals present in potable drinking water in Bangladesh. Secondary data of Arsenic, Cadmium and Manganese were garnered from potable drinking water sources of Bangladesh to evaluate the individual as well as combined mixture toxicity of different chemicals. The present study has utilized empirical methods with environmental data to analyze the additive hazard index and interactive hazard index for illustrating different health effects. Results might help in scaling up risk assessment studies for complex mixtures of different types of chemicals throughout the entire country on a regional basis. The spatial variation of toxicity indices have also been presented using Arc-GIS with three hazard index scores (additive, synergistic, and antagonistic) for each mixture at upazila scale. Present analysis shows that, for cardiovascular, hematological and neurological health effects, the individual effects of binary and ternary mixture of chemicals are strongly interactive (synergistic or antagonistic) whereas for renal health effects binary mixtures are mostly additive. More specifically, for neurological effects in almost every upazilas of Bangladesh there is strong synergistic interaction of chemicals whereas for cardiovascular effects in few places especially the northeastern zone and Meghna delta’s of Bangladesh, there is strong likelihood of potential toxicity.