Heavy Metal Contamination and Health Risk Assessment in the Vicinity of a Tailing Pond in Guangdong, China

Abstract

Abstract:The purpose of this study was to assess heavy metal contamination and health risks for residents in the vicinity of a tailing pond in Guangdong, southern China. Water, soil, rice, and vegetable samples were collected from the area in the vicinity of the tailing pond. Results showed that surface water was just polluted by Ni and As, while groundwater was not contaminated by heavy metals. The concentrations of Pb, Zn, Cu, Cd, Ni, and As in the paddy soil exceeded the standard values but not those of Cr. In vegetable soils, the concentration of heavy metals was above the standard values except for Ni and As. Soil heavy metal concentrations generally decreased with increasing distance from the polluting source. Leafy vegetables were contaminated by Pb, Cr, Cd, and Ni, while the non-leafy vegetables were contaminated only by Cr. There was a significant difference in heavy metal concentrations between leafy vegetables and non-leafy vegetables. Almost all the rice was polluted by heavy metals. Diet was the most significant contributor to non-carcinogenic risk, which was significantly higher than the safe level of 1. The total cancer risk was also beyond the safe range (10 −6 -10 −4 ). Results revealed that there is a risk of potential health problems to residents in the vicinity of the tailing pond.

Heavy Metal Pollution and Human Health Risk Assessment of Farmlands around Enyigba Lead-Zinc Mining Site, Ebonyi State, Nigeria

“…This study employed USEPA [4] to assess the human health risks associated with exposure to heavy metals in the study area via (i) direct ingestion of soil particles (ii) inhalation of soil particles (iii) dermal absorption of soil particles and (iv) diet of vegetables (T. occidentalis and A. hybridus) in adults and children. The intake defined as chronic daily intake dose (CDI in mg/kg/day) of heavy metals during the exposure duration via the different exposure pathways is given in the equations in Table 1 [4] while the meaning and the value of exposure parameters is given in Table 2 [2,7]. Human health risks of heavy metals via the different exposure route may lead to non-carcinogenic risks or carcinogenic risks [4] and can be computed using these equations:…”

“…Non-carcinogenic risk = CDI/RfD (6) Carcinogenic risk = CDI x SF (7) Where CDI is the chronic daily intake dose (mg/kg/day) of heavy metals via different routes as evaluated, RfD is the oral reference dose (mg/kg/day) of heavy metals and SF is the carcinogenic slope factor (kg.day/mg). The value of the exposure parameters (RfD and SF) via various routes [2,7,9] is shown in Table 3. 1.00 X 10 -3 1.00 X 10 -5 1.00 X 10 -3 6.10 Cr 3.00 X 10 -3 6.00 X 10 -5 2.86 X 10 -5 41.00 Ni 2.00 X 10 -2 5.40 X 10 -3 2.06 X 10 -2 0.84 Cu 4.00 X 10 -2 1.2 X 10 -2 4.02 X 10 -2 Pb 3.5 X 10 -3 5.25 X 10 -4 3.52 X 10 -3 Fe 7.00 X 10 -1 7.38 X 10 -1 7.00 X 10 -1 Zn 3.00 X 10 -1 6.00 X 10 -2 3.00 X 10 -1…”

“…Arable farmland soils contaminated with heavy metals can pose serious threat to the ecosystem and human health through different exposure routes. Heavy metals have been reported to cause varying degrees of toxicity in humans ranging from non-carcinogenic to carcinogenic risks [1,2].…”

Assessment of heavy metal release into the soil after mine clearing in Halgurd-Sakran National Park, Kurdistan, Iraq

“…The excess of heavy metals in soils is a significant environmental pollutant that threatens natural ecosystems; thus, it is important to understand their impacts (Kabata 2010). Soil characteristics govern heavy metal mobility through the impact of their chemical speciation and solubility (Liang et al 2017). Most heavy metals occur naturally in soils as a result of geological processes such as weathering and erosion and the alteration of the geological subsurface materials (Moor et al 2001).…”

“…Thus, evaluation of soil pollution requires in-depth knowledge of the spatial distribution on contaminants (Barbieri et al 2017). A polluting metal, which is stable in soil and not absorbed by plants, or insoluble, will have an effect through other processes (Liang et al 2017) such as inhalation, ingestion and dermal contact or the food chain. Consequently, these heavy metals can be transferred to human bodies, animals and plants (Wang et al 2012), which are harmful and tend to bio-accumulate in the food chain (Barbieri et al 2014) that pose risks to humans and ecosystems.…”