Human Health Risk Assessment Through Consumption of Organophosphate Pesticide-Contaminated Water of Peshawar Basin, Pakistan

In this study, the concentrations of organophosphate pesticides (OPPs) were determined in drinking water samples collected from Peshawar Basin (Charsadda, Nowshera, Peshawar, Mardan, and Swabi districts), Khyber Pakhtunkhwa, Pakistan. The selected OPPs such as methamidophos, dichlorvos, and chlorpyrifos were extracted through liquid-liquid extraction procedure and quantified using gas chromatography-mass spectrometry. The results revealed that among OPPs, the highest contamination was observed for methamidophos, while the lowest for dichlorvos. The OPP concentrations were compared with their respective permissible limits set by European Union (EU in Council Directive 98/83/EC on the quality of water intended for human consumption. European Union, 1998), Australia (NHMRC in Australian drinking water guidelines. Agricultural and Resource Management Council of Australia and New Zealand Commonwealth of Australia, Canberra, 1996), and World Health Organization (WHO in Guidelines for drinking water quality, 2nd edn, WHO, Geneva 1998). In majority samples (94.4%), methamidophos concentrations exceeded its respective permissible limit set by EU. The concentrations of dichlorvos exceeded the limit set by Australia and EU in 17.2 and 69% samples, respectively. However, the concentrations of chlorpyrifos exceeded the EU limit in only 2.3% samples, while found within the safe limits set by WHO. The concentrations of studied OPPs were also used to assess the health risk including chronic risk such as average daily dose (ADD), hazard quotient (HQ), and carcinogenic risk or cancer risk (CR). The ADD values for OPPs showed a great variation in the study area. The values of HQ were>1 for methamidophos in drinking water samples of Peshawar Basin. Moreover, the CR values through consumption of dichlorvos in drinking water exceeded US-EPA safe limit. Among all drinking water sources, the shallow water sources along agriculture productive zones revealed higher contamination and serious health risk. Therefore, this study recommends to stop the use of shallow drinking water and use the deep groundwater at depths>98m that showed comparatively less contamination.