Assessment of toxic metals in groundwater and saliva in an arsenic affected area of West Bengal, India: A pilot scale study

Communities in many parts of the world are unintentionally exposed to arsenic (As) and other toxic metals through ingestion of local drinking water and foods. The concentrations of individual toxic metals often exceed their guidelines in drinking water but the health risks associated with such multiple-metal exposures have yet to receive much attention. This study examines the co-occurrence of toxic metals in groundwater samples collected from As-rich areas of Nadia district, West Bengal, India. Arsenic in groundwater (range: 12-1064μgL^-1; mean ± S.D: 329±294μgL^-1) was the most important contaminant with concentrations well above the WHO guideline of 10μgL^-1. Another important toxic metal in the study area was manganese (Mn) with average concentration of 202±153μgL^-1, range of 18-604μgL^-1. The average concentrations (μgL^-1) of other elements in groundwater were: Cr (5.6±5.9), Mo (3.5±2.1), Ni (8.3±8.7), Pb (2.9±1.3), Ba (119±43), Zn (56±40), Se (0.60±0.33), U (0.50±0.74). Saliva collected from the male participants of the area had mean concentrations of 6.3±7.0μg As L^-1 (0.70-29μgL^-1), 5.4±5.5μg Mn L^-1 (0.69-22μgL^-1), 2.6±3.1μg Ni L^-1 (0.15-13μgL^-1), 0.78±1.0μg Cr L^-1 (<DL-5.9μgL^-1), 0.94±0.90μg Pb L^-1 (<DL-4.2μgL^-1), 0.56±0.37μg Se L^-1 (0.11-1.5μgL^-1) and 194±54μg Zn L^-1 (112-369μgL^-1). The high concentrations of salivary As and Mn are believed to be indicative of intake from the groundwater. The clustering of salivary As and Mn in principal component analysis further indicated influence of the common exposure source. Zinc and selenium comprised a separate component presumably reflecting the local deficiencies in intakes of these essential elements from drinking water and foodstuff. Thus the study reveals that the concentration of other metals beside As must be monitored in drinking water before implementation of any policies to provide safe water to the affected communities.