Non-carcinogenic risk assessment of exposure to heavy metals in underground water resources in Saraven, Iran: Spatial distribution, monte-carlo simulation, sensitive analysis
Introduction
Groundwater aquifers are the second richest source of freshwater worldwide. Today, at a pace with population growth and rising earth temperature, water shortage is the main issue for many both developing and developed countries all over the world (Mohammadi et al., 2020). Groundwater plays a vital role in human life, such as the economy, production, food production, and also politics. Unfortunately, the rapid growth of cities and industries and increased disposal of hazardous waste have deteriorated the quality of ground and surface water resources (Shams et al., 2020; Fiore et al., 2019). Furthermore, an ever-increasing utilization of pesticides and fertilizers for agricultural purposes poses a risk for groundwater resources (Yousefi et al., 2019; Dettori et al., 2019). In Iran, ground waters are used also significantly for irrigation, drinking, and industrial purposes (Dashtizadeh et al., 2019). Consuming polluted water with heavy metals (HMs) can increase the risk of human. These metals have some properties such as the capability of bioaccumulation, toxicity, and stability in natural environments, making them a threat to water resources' health. HMs are natural components of the Earth's crust and hence can be released by natural resources, but, generally, the most HMs pollution is caused by human activities. In this regard, several factors are involved, such as soil erosion, corrosion of bedrocks and volcanic rocks, mining activities, improper disposal of industrial wastewater, industrial and agricultural activities (Mohammadi et al., 2019). Some heavy metals are essential for life, but some others, such as Cadmium (Cd), Cchromium (Cr), and Lead (Pb), can harm human health. Cr is a natural element in the Earth's deposits. Few amounts of this HM are required for the body's normal function, but high concentrations can damage vital organs such as kidneys. Pb is a toxic HM cause extensive environmental contamination and health problems. Exposure to high Pb concentrations brings about health problems such as arterial pressure and behavioral complications (Esmaeilzadeh et al., 2019; Vasseghian et al., 2020). Generally, infants and children are the more vulnerable populations to this metal. Furthermore, exposure to extraordinary levels of Cd will induce health issues such as skeletal complications. Various researches have shown that Cd is exceptionally toxic, and its exposure can cause cancer (Vasseghian et al., 2020; Järup et al., 2000). Therefore, knowing the HMs and their potential contamination origins is a fundamental tool for human health risk management and prevention. Given the various effects of heavy metals on human health, the health risk assessment (HRA) (an integrated approach that evaluates health risks posed to humans through exposure to specific substances in environments)can be applied as a tool to estimate the potential risks of exposure to these toxics (Jafarzadeh et al., 2020; Fallahzadeh et al., 2018). The Monte Carlo simulation (MCS) technique is a widely used way to evaluate probabilistic risk. The MCS technique is applied to assess both the variability and uncertainty of data. In the probabilistic risk assessment (PRA) method (using MCS) all input parameters are considered to calculate the risk to achieve all the consequences related to pollutants (Kaur et al., 2020a; Karami et al., 2019). Several studies have been conducted carried out in Iran, and other studies from different countries used this methodology to assess the health risk of HMs in drinking water resources. Some studies have shown the high risk of HMs by drinking water resource in many countries of the world. For instance, according to Alidadi et al. (2019), and Fallahzadeh et al. (2019), carcinogenic and non-carcinogenic risk due to Cr, Cd, Pb, and As (Arsenic) in Iran were reported to be high (Alidadi et al., 2019; Fallahzadeh et al., 2017). Also, Khandare et al, 2020, and Khalid et al. 2020, evaluated the health risk of HMs in some areas of India and Pakistan, respectively. They reported that the carcinogenic and non-carcinogenic risk in study area were high (Khandare et al., 2020; Khalid et al., 2020). Xiaodong He, investigate the occurrence and potential sources of CrVI as well as associated health risks in surface water in the middle Chinese. The results of the performed health risk assessment suggest that the inhabitants in the study area face high carcinogenic risks induced by CrVI(He and Li, 2020). According to literature review, limited studies have been conducted to investigate the HMs concentration and their health effects on the residents of our study area. In the study area, there are several active mines, hence, there is a possibility of HMs penetrating water resources through these mines.
So, this research was designed to measure the content of the HMs including Cd, Pb, and Cr, in eighty-nine active wells located in rural regions of Saravan County, Sistan, and Baluchestan Province, Iran. We also applied probabilistic health risk assessment approaches as Monte-Carlo simulation. Besides, spatial distribution HMs concentration was illustrated using the inverse distance weighted technique.
Section snippets
Study area
Saravan County covers an area of about 9739 square kilometers (Fig. 1). This area is situated in South-East Iran (27°22′15″ N and 62°20′03″ E). This region has warm weather and an annual mean temperature of 22.1 °C; the maximum and minimum temperatures in a year are 45.3 °C and −7 °C, respectively. The mean precipitation of the area is estimated to be 70–130 mm per year. The most important agricultural product of Saravan is the date. Other crops include cereals (wheat, barley, and rice), fruits
Groundwater contamination by the HMs
Table 3 summarizes the HMs contamination in groundwater walls of Saravan County. The origin of HMs contamination in water supplies are a wide variety of pollution resources including domestic and industrial wastewater discharge, soil erosion, chemical pesticides in agriculture, mining, and other factors (Saleh et al., 2019).
As shown in Table 3, the Cr concentration ranges from 0.49 to 20 (μg/L) (Fig. 2 (a)). This metal can be discharged into the environment by agriculture fertilizers and
Conclusion
In the present study, the concentration and spatial distribution of HMs: Cr, Cd and Pb were studied in underground water supplies of Saravan city. Probabilistic and deterministic approaches were also implemented to evaluate human health risk in four exposed populations, including adults, teenagers, children, and infants. Based on the findings, the concentrations of Cr, Pb, and Cd were in the range of 0.49–20, 0.1 to 58.34, and 0.11–12.8 μg/L, respectively. The mean HQ calculated due to exposure
Credit author statement
Naghmeh Jafarzadeh: experiment, Formal analysis and Writing – original draft. Ali Meshkinian: experiment, Formal analysis and Writing – original draft, Hossein Kamani: study design, Supervision and Methodology and writing final manuscript. Ali Akbar Mohammadi: study design, Supervision and Methodology and writing final manuscript. Gea Oliveri Conti: Writing – review & editing
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments:
This study is the result of a research project with Grant Number 10235 approved by the Zahedan University of Medical Sciences with the ethics code IR.ZAUMS.REC.1400.066 from the Vice Chancellor for Research of Zahedan University of Medical Sciences. Therefore, thanks are owed to Zahedan University of Medical Sciences for its supports.
References (53)
- et al.
Assessment of the potential health risks associated with the aluminium, arsenic, cadmium and lead content in selected fruits and vegetables grown in Jamaica
Toxicol. Rep.
(2017) - et al.
Exposure and risk assessment of BTEX in indoor air of gyms in Tehran, Iran
Microchem. J.
(2019) - et al.
Spatial distribution variation and probabilistic risk assessment of exposure to chromium in ground water supplies; a case study in the east of Iran
Food Chem. Toxicol.
(2018) - et al.
Consumption of water from ex-mining ponds in Klang Valley and Melaka, Malaysia: a health risk study
Chemosphere
(2018) - et al.
Cadmium in soils and groundwater: a review
Appl. Geochem.
(2019) - et al.
Carcinogenic and non-carcinogenic health risk assessment of heavy metals in drinking water of Khorramabad, Iran
Methods (Duluth)
(2019) - et al.
Sensitivity analysis of environmental models: a systematic review with practical workflow
Environ. Model. Software
(2016) - et al.
Health risk assessment for exposure to nitrate in drinking water from village wells in Semarang, Indonesia
Environ. Pollut.
(2016) - et al.
Speciation of as (III) and as (V) in water samples by graphite furnace atomic absorption spectrometry after solid phase extraction combined with dispersive liquid–liquid microextraction based on the solidification of floating organic drop
Talanta
(2014) - et al.
A systematic literature review for some toxic metals in widely consumed rice types (domestic and imported) in Iran: human health risk assessment, uncertainty and sensitivity analysis
Ecotoxicol. Environ. Safety
(2019)