1 Scientific RepoRts | 7:42516 | DOI: 10.1038/srep42516 www.nature.com/scientificreports WHo water quality standards Vs Synergic efect(s) of fuoride, heavy metals and hardness in drinking water on kidney tissues Hewa M. s. Wasana 1 , Gamage D. R. K. perera 2 , Panduka De S. Gunawardena 3 , Palika S. Fernando 4 & Jayasundera Bandara 1 Despite WHO standards, waterborne diseases among the human being are rising alarmingly. It is known that the prolong exposure to contaminated water has major impact on public health. The efect of chemical contaminations in drinking water on human being is found to be chronic rather than acute and hence can be defned “consumption of contaminated drinking water could be a silent killer”. As the WHO recommended water quality standards are only for individual element and synergic efects of trace metals and anions have not been considered, investigation of synergic efects of trace metals and anions and their efect on human being is of prime important research. By an animal trial, we investigated the synergic efect(s) of heavy metals, aluminium, arsenic, fuoride and hardness in drinking water on kidney tissues of mice. Our investigation strongly suggests existing of a synergic efect especially among Cd, F and hardness of water which could lead to severe kidney damage in mice, even at WHO maximum recommended levels. Hence, the synergic efect(s) of trace metals, fuoride and hardness present in drinking water should be investigated meticulously when stipulating the water quality at WHO maximum recommended levels. Contamination of freshwater resources by naturally occurring phenomena or chemical wastes due to rapid indus- trial growth and urbanization is one of the major ecological concerns of the contemporary world. Te biggest water pollutants are heavy metals, nitrate, arsenic, fuoride and synthetic chemical emissions especially due to industrialization 1–3 . Quality of drinking water has a major infuence on public health and prolong exposure to contaminated water has been known to increase the risks of cancer and disorders in kidney, liver and repro- ductive organs, etc 1,4,5 . Te efect of chemical contaminations in drinking water on human being is found to be chronic rather than acute. Terefore, understanding of water quality on public health is vital because waterborne diseases are still a major cause of death in many parts of the world 6,7 . Tough the quality of drinking water is regu- lated by the WHO stipulated standards, water-related disease is complex and diverse in nature. Te recommended WHO water quality standards are only a guideline and cannot be considered as the safe level of contaminants especially for the tropical countries due to consumption of excess water due to hot-dry conditions. On the other hand, the WHO recommended water quality standards are only for individual element and chronic synergic efects of trace metals and anions have not been considered. Tough, the acute synergic efects of trace metals have been reported, those studies do not mimic the natural environmental conditions. i.e. when Sprague–Dawley male rats were given cadmium (50 mg/L) and fuoride (100 mg/L) alone or in combination via drinking water for twelve weeks, an increased liver and kidney damages has been noted in cadmium and fuoride co-exposed rats compared with that exposed to cadmium or fuoride alone 8 . As such, synergic efects of trace heavy metals and common anions present in water could be a major critical factor on public health and the investigation of interaction among trace metals and anions and their efect(s) on human being is of prime important research. Our earlier fnding revealed a clear correlation between incidence 1 National Institute of Fundamental Studies, Hantana Road, CP 20000, Kandy, Sri Lanka. 2 Ministry of Social empowerment and Welfare,Department of Divineguma Development, Peradeniya, Sri Lanka. 3 Department of Veterinary Pathobiology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya, Sri Lanka. 4 Division of Pathobiology, Veterinary Research Institute, Gannoruwa, Sri Lanka. Correspondence and requests for materials should be addressed to J.B. (email: bandaraj@ifs.ac.lk or jayasundera@yahoo.com) received: 16 September 2016 Accepted: 10 January 2017 Published: 14 February 2017 opeN