Arsenic concentration variability, health risk assessment, and source identification using multivariate analysis in selected villages of public water system, Lahore, Pakistan

This paper reports high levels and variability in arsenic (As) levels at locations identified as one of the highest As-contaminated locations in Pakistan. Groundwater pollution related to arsenic has been reported since many years in the areas lying in outskirts of District Lahore, Pakistan. A comparative study is done to determine temporal variations of As from three villages, i.e., Kalalanwala (KLW), Manga Mandi (MM), and Shamki Bhattian (SKB). Seventy-three percent of the 30 investigated samples ranging in depth from 20 to 200 m, show an increasing trend in variations of As concentration over a time span of 4 years and 87 % of samples exceeded the WHO standard of 10 mu g/L for As while 77 % of samples have As concentration > 50 mu g/L (national standard). Further results indicate that high levels of As is accompanied with increase pH (r = 0.8) favoring desorption of As from minerals at higher pH under oxidizing conditions. For health risk assessment of arsenic, the average daily dose, hazard quotient (HQ), and cancer risk were calculated. The residents of the studied areas had toxic risk index in the order of SKB > KLW > MM, with 87 % of samples exceeding the typical toxic risk index 1.00 (ranging from 2.3-48.6) which was 83 % (ranging from 0.3-41) 4 years before. The results of the present study therefore indicate that arsenic concentrations are increasing in the area, which needs an immediate attention to provide alternate sources of water to save people at risk.