Geogenic fluoride and arsenic in groundwater of Sri Lanka and its implications to community health

Abstract

Fluoride and arsenic in groundwater are two of the most discussed elements in the emerging science “Medical Geology”. This paper reviews the studies conducted during the last 30 years in Sri Lanka on fluoride and arsenic in groundwater. These studies have clearly indicated that several regions of the dry zone of Sri Lanka are affected by excessive quantities of fluoride in the groundwater. Apart from the well-known dental fluorosis, skeletal fluorosis was also reported up to a certain extent in the high fluoride regions. The recent increase in the incidence of chronic kidney disease of unknown etiology (CKDu) has also highlighted the importance of the geochemistry of fluoride in groundwater of the dry zone. Although geologically, the dry zone of Sri Lanka does not differ markedly from the wet zone, the climate and the hydrological conditions play a significant role in the geochemistry of fluoride and its impact on human health. Over 50% of wells in the dry zone regions of Sri Lanka have fluoride levels higher than 1.0 mg/L while the fluoride content is also higher in deep wells compared to the shallow wells. Arsenic in groundwater is not yet considered as a serious issue in Sri Lanka, particularly in aquifers in the metamorphic terrain, but higher arsenic levels were recorded in sedimentary terrains. The toxicity effects of high arsenic in such terrains still remain a neglected health concern that needs greater attention. Since high fluoride is a major problem in the dry zone regions with severe health concerns, suitable defluoridation methods need to be introduced at the household level.