Spatial distribution and accumulation of arsenic in biological samples and associated health risks by drinking groundwater in Bahawalnagar, Pakistan

Groundwater contamination by arsenic (As) is a major health/environmental concern due to its high toxicity to humans. Despite substantial research, there is scarce data in many countries regarding spatial distribution and As levels in groundwater, as well as its possible accumulation in humans/animals and associated health hazards. In this study, a total of 124 drinking water, 20 animal milk, 21 human hair, and 14 human nail samples were collected and analyzed for As contents from four tehsils (Bahawalnagar, Chishtian, Haroonabad and Minchi-nabad) of District Bahawalnagar. Geostatistical analysis and risk assessment models were used to predict the spatial distributions and health hazards of As in drinking water. Arsenic groundwater contents ranged between below detection limit (BDL) to 31.5 mu g.L-1 with a mean of 7.6 mu g.L-1. About 6 water samples (5%) contained As level > World Health Organization (WHO) limit. All these samples containing As contents > WHO limit were collected from Chishtian tehsil. In the case of milk samples, mean As contents were 75 mu g.L-1 with a range of 42-111 mu g.L-1. Arsenic was also detected in human hair (mean value of 640 mu g kg- 1 and range 71-2139 mu g kg -1). However, As contents were BDL for all the nail samples. Risk assessment indices (cancer risk and hazard quotient) revealed possible health hazards due to their high values (3.0 and 0.0013, respectively). The principal component analysis (PCA) revealed that the potential sources of As release in the groundwater of study area do not match with those of other water variables. Hence, there is a need to monitor the groundwater quality of the Chishtian tehsil for any potential negative health impacts, as well as the possible sources of As in the ground-water of the study area.

Automated summary

Groundwater contamination by arsenic is a major concern, and this study found that Chishtian tehsil in Bahawalnagar district had arsenic levels exceeding the World Health Organization limit. Arsenic was also found in milk and human hair samples. Risk assessment revealed potential health hazards associated with the high arsenic levels in the groundwater.