Health risk assessment induced by trace toxic metals in tap drinking water: Condorcet principle development

Acute exposure to trace metals (TMs) in water is hazardous to human health. The average concentrations (C_avg.) and carcinogenic (CAR) and non-carcinogenic (non-CAR) risks of eight TMs to World Health Organization's (WHO) guidelines and national standard limits (NSLs)were determined. The C_avg. and (the range) of As, Hg, Cd, Pb, Co, Cr, Ni, and Zn were measured as 4.29 ± 0.57 μg L^-1 (1.12-10.27 μg L^-1), 0.22 ± 0.10 μg L^-1 (ND-1.05 μg L^-1), 0.31 ± 0.18 μg L^-1 (ND-1.80 μg L^-1), 4.66 ± 0.32 μg L^-1 (0.10-14.22 μg L^-1), 24.61 ± 4.65 μg L^-1 (3.11-67.25 μg L^-1), 16.86 ± 5.54 μg L^-1 (5.12-34.61 μg L^-1), 14.07 ± 4.37 μg L^-1 (3.79-31.39 μg L^-1), and 268.42 ± 75.82 (87.29-561.22 μg L^-1), respectively. The C_avg. of Co and Hg exceeded the WHO and NSLs. The non-CAR risk assessment was used to order the TMs according to the total target hazard quotient (TTHQ) As > Pb > Cr > Co > Zn > Hg > Ni > Cd. None of the investigated age groups are at risk As there is a low C_avg of all trace metals (i.e., the THQ is > 1). The age groups were ranked based on THQ and incremental lifetime cancer risk (ILCR) As < 1 year, >1-10 years, > 11-19 years, and > + 20 years. The ILCR of As for all the age groups was >10^-4, whereas for Pb it was <10^-6. Cumulative carcinogenic risk (CCR) for As and Pb was at a safe threshold risk (>10^-4) for all the age groups.