Spatial pattern of arsenic concentration and associated noncarcinogenic health risk assessment: a case study on Gangni Union of Chuadanga district of Bangladesh

Abstract

Groundwater is one of the world’s most important sources of fresh drinking water. Various contaminants mix with groundwater and alter its natural composition, such as arsenic. This study aimed to ascertain the present condition of arsenic concentration, its spatial pattern, and its relationship with tube well depth in the Gangni Union in the Chuadanga district of Bangladesh. Additionally, the study tried to assess the associated noncarcinogenic health risks imposed by oral ingestion of arsenic. Systematic sampling was used to collect water samples (n=100) along with depth information from the sample tube wells. Water samples were analyzed with the pre-calibrated Hach EZ, Dual-Range Arsenic Test Kit (Range: 0.00–0.5 mg/l). Both geostatistical (spatial autocorrelation, Hotspot analysis, and IDW) and statistical (descriptive and correlation statistics) methods were used. The resultant arsenic content of the samples tested ranges from 0.0004 (mg/l) to 0.10 (mg/l). Arsenic levels in almost 42% of the samples exceeded the WHO standard, 21% exceeded the Bangladesh standard, and 37% were within the tolerable standard. Geostatistical analysis shows that approximately 63% of the total area is arsenic contaminated. Furthermore, hotspot analysis reveals that the northeastern and southeastern parts of the study area are more arsenic-contaminated than the other parts. Noncarcinogenic health risk assessment shows that children have a higher average daily dose (ADD) range (8.33E-06-0.00181) than adults (2.78E-06-0.0006). Similarly, the hazard quotient (HQ) value is also higher for children (0.0277–6.033) than for adults (0.0092–2.011). The result of Pearson’s correlation coefficient, r (98) = − 0.7580, p = 0.000, shows a negative linear relationship between concentration values and depth, meaning that increasing depth will reduce arsenic contamination from tube well water.