Health risk assessment techniques to evaluate non-carcinogenic human health risk due to fluoride, nitrite and nitrate using Monte Carlo simulation and sensitivity analysis in Groundwater of Khaf County, Iran

Abstract

ABSTRACT This study aimed to assess the groundwater quality and human health risks of nitrate, nitrite, and fluoride contamination in rural areas of Khaf County, Iran. For this aim, 28 groundwater samples were collected from open dug wells during August 2018. Twelve parameters (pH, EC, TDS TH, Cl-, SO4 2-, HCO3 −, NO3 −, F−, Ca2+, Mg2+, and Na+) have been used to evaluate the water quality index. Also, point estimation using HQ formula and sensitivity analysis using the Monte Carlo Simulation (MCS) method, by 10,000 repetitions in Oracle Crystal Ball®, were applied to determine the additional risk of non-carcinogenicity in Nitrate, Nitrite, and Fluoride in four groups: infant, children, teenager, and adult. WQI showed that 7%, 60%, 10% and 21% of groundwater samples fall within the class of excellent, good, poor, and very poor quality, respectively. The HQ values of nitrate for infant, children, teenagers, and adults in 32%, 14%, 10% and 7% of the samples from rural areas were above the safe limit of 1. The HQ values of nitrite were mostly acceptable for infants, children, teenagers, and adults in all the rural areas because the mean HQ values of fluoride were lower than 1. Also, the calculated HQ values of fluoride for infants, children, and teenagers in 60.7%, 21.4% and 10% of the rural areas were above the safe limit. The results of HQ point estimation showed that nitrate and fluoride had non-carcinogenic risk in most exposed population groups, but exposure to nitrite did not have non-carcinogenic risk. The results of sensitivity analysis, to determine the most effective parameter in increasing non-carcinogenic risk, showed that the concentration parameter of Nitrate, Nitrite, and Fluoride had the most effect on increasing sensitivity in the four studied exposed groups.