การประเมินความเสี่ยงทางนิเวศวิทยาและสุขภาพของการปนเปื้อนของธาตุที่อาจเป็นพิษในสิ่งมีชีวิตในอ่างเก็บน้ำจันทนาล

Potentially toxic elements (PTEs) are classified into essential and nonessential elements. Generally, humans require low concentrations of essential elements such as Zn, Fe, Cu, Ca, and Se. However, exposure to a high level of such elements is considered dangerous to humans. The nonessential elements, such as Hg, Cd, As, Pb, and Ni, are health hazards even in minimal amounts. PTEs are crucial environmental pollutants and become a global concern due to their toxicity, inherent persistence, non-biodegradability, and accumulative properties [1–4]. Researchers are currently working on finding the sources of contamination of heavy metals in aquatic animals and propose this problem to the authorities for further action [5–9]. PTEs can affect and damage human health even at a lower concentration. They can accumulate in the environment and increase their concentrations as transported through the food chain, causing human toxicity [10, 11]. So far, expanded industry, urbanization, population growth, agriculture, and other human activities have resulted in significant heavy metal pollution worldwide, particularly in emerging countries [12]. Heavy metals, originating from anthropogenic and natural sources, enter the environment through various processes and cause severe threats to the ecosystem and human health [13, 14]. To a small amount, they enter human bodies via food, drinking water, and air and bioaccumulate over a while [15, 16]. The primary source of heavy metals in the natural water bodies is the weathering of minerals [17].

Moreover, significant anthropogenic sources of heavy metal contamination in the environment are human activities (e.g., mining, sewage sludge disposal, application of pesticides, and inorganic fertilizers in agriculture), deforestation, and climatic deposition [18–23]. The significant sources of heavy metal contamination are the open dumping of household and agricultural hazardous waste (e.g., batteries, empty bottles of pesticides, and herbicides) and other factors such as deforestation and climate change. As trace components, some heavy metals (e.g., cadmium, copper, zinc, lead) are necessary to sustain the human body's metabolism. However, at higher concentrations, they can begin to poison. Heavy metal poisoning could produce, for instance, from drinking-water contamination (e.g., lead pipes), high ambient air concentrations near discharge sources, or intake via the food chain [22–25]
​​​​​​​The Chan Thnal reservoir is one of the potential fish habitats and also a primary source of water and protein for the Krang Chek people and others. The Chan Thnal reservoir never dries even though the dry season is one of the reasons it has many fish species and nursery ground for many aquatic species. Currently, the ecosystem receives untreated effluents from households, commercial markets, schools, animal farms, and agriculture. Many studies have attempted to assess the contamination status of river and estuarine environments in Bangladesh [4, 12], Pakistan [33],  Malaysia [28, 34], Taiwan [35], Nigeria [26, 30, 36], Ghana [15], China [27, 37, 38], and Egypt [39]. However, there was no report on the potential human health risk due to heavy metal contamination in the fish species harvested and consumed from the Chan Thnal reservoir. Therefore, this study aimed to fill this knowledge gap by assessing the concentration of heavy metals in some selected fish species, their bioaccumulation status, and the human health risk for local adult and children consumers.