Levels of Metals in Soils of Ait Ammar Iron Mine, Morocco: Human Health Risks

Research Article

Austin J Environ Toxicol. 2017; 3(1): 1017.

Levels of Metals in Soils of Ait Ammar Iron Mine, Morocco: Human Health Risks

Nouri M1,2*, El Rasafi T2 and Haddioui A2

1Department of Biology, University of Sultan Moulay Slimane, Morocco

2Team of Genetics and Plant Biotechnology, University of Sultan Moulay Slimane, Morocco

*Corresponding author: Mohamed Nouri, Department of Biology, University of Sultan Moulay Slimane, Beni-Mellal, Morocco

Received: February 17, 2017; Accepted: May 18, 2017; Published: May 25, 2017


The concentrations of metals were determined in soil samples collected in Ait Ammar (OuedZem, Morocco). The mean Cd, Cr, Cu, Fe, Pb and Zn contents in the mining topsoil samples (2.12, 135, 34.9, 214, 9.13 and 90.8 mg kg-1, respectively). Human health risks developed from metal ingestion, dermal absorption and inhalation of soils were also evaluated. For non-carcinogenic risks, united Hazard Index (HI) values for children surpassed the safe level (HI=1) for Cr (13.1). Values for HI in adults (1.74) also surpassed the safe level for Cr. The HI values for Pb and Cd for children were 0.69 and 0.68, respectively. Cancer risk due to Cr surpassed the tolerable range (1E-06 to1E-04) for children (1.05E-03) and for adults (1.42E-04). Cancer risks due to Pb and Cd were within acceptable ranges for both children and adults. Furthermore, Oral ingestion of soil particles contributed more highly to both carcinogenic and non-carcinogenic risk from Cr than either dermal absorption or inhalation in both children and adults.

Keywords: Metals; Ait ammar iron mine; Inhalation; Dermal; Ingestion; Risk assessment 


Mining is one of the actually bases of heavy metals in the ecosystem, and the process itself presents serious potential sources of pollution [1]. Heavy metal pollution has been a fundamental problem in the surrounding area of abandoned mine sites. These heavy metals have a potential to pollute topsoil. They can be dispersed and collected in plants and animals, and taken in by human beings as consumers. Human health risk assessment has been employed to define if exposure to a chemical, at any dose, could cause an increase in the incidence of adverse effects to human health [2]. In residential areas, surplus accumulation of heavy metals in topsoil can immediately threaten the safety of exposed inhabitants via ingestion, inhalation and dermal contact [3].

The possible toxicity of pollutants is determined by the speciation of the elements implicated. In risk assessment, oral exposures are characteristically specified in terms of the external dose or intake, instead of in terms of absorbed dose or uptake. Intake is characteristically described as the method by which an element crosses the outer exposure surface of a human without passing an absorption barrier, while uptake is the method by which an element crosses an absorption barrier into human or animal.

Risk assessment practices are well advanced and recognized in the USA. Lots of examinations have accepted human risk assessment methods by considering exposure scenarios of metal intake through polluted soil [2]. Risk assessment processes have mainly concentrated on urban areas [4,5], industrial areas [6], petrochemical plants [7] or areas of mining activities [8].

Heavy metal contact can be severe in infants and young children because of their rapid growth capabilities. The contact to children is also higher as compared to adults because of their playing activities, licking objects which may be polluted and hand to mouth habit [9].

The human health risk models including carcinogenic and non-carcinogenic risks elevated by US EPA have proved successfully and adopted worldwide. Human health risk assessment (HQ and HI) studies on various exposure ways in urban and industrial environments have recently been given great importance [10]. The adverse health effects through life can be assessed by utilizing threshold RfD value. The chances of severe health effects will be lowest if the average value of Average Daily Dose (ADD) is inferior to that of the Reference Dose (RfD) and the chances will be higher if the average value of ADD is higher than that of RfD [11].

The human health risk assessment has been suggested by USEPA and numerous scientists have utilized it for the evaluation of exposure rate of metals on human health [12,13].

The present study is evaluated the risk to human health from metals in the soil surrounding an abandoned iron mine. The study area (Ait Ammar mine site) is known by the presence of high levels of metals in soil [14]. These elements may affect the health of residents in the Ait Ammar village via their entry into the food chain of domestic livestock (cow and sheep), and the consumption of muscle, liver and kidney tissue from animals grazing over the mining area [15]. The present study (1) investigated the contamination levels and dispersion patterns of metals in soil, and (2) characterized the potential health risks in adults and children via the exposure pathways of soil ingestion, inhalation and dermal absorption.

Materials and Methods

On July 19, 2010, surface soil was collected at the site of Ait Ammar iron mine (33° 04’ N; 6° 38’ W), which is located in the Khouribga Province, Morocco. The region's climate is Mediterranean, arid to semi-arid [14]. Four sampling transects (T1, T2, T3, and T4) were selected based along the direction of iron deposits. Five sampling sites were selected along each transect, with the most distance point being 300-600 m from the first transect point (Figure 1). So, five sampling rounds (R1, R2, R3, R4 and R5) were determined based along the distance of iron deposits (e.g. R1 contained T11, T21, T31 and T41).