HEAVY METAL CONTAMINATION IN THE CULTIVATED VEGETABLES AND FARMED TILAPIA AND SHRIMP IN SOUTHWEST BANGLADESH: A STUDY TO HIGHLIGHT PROBABLE HEALTH RISKS (Completed -KU RIC Funded)

Nowadays, heavy metal contamination of aquatic ecosystems and the associated places has resulted in great consideration worldwide, particularly in developing nations like Bangladesh (Islam et al. 2016, Lipy et al. 2020, Zakir et al. 2020 and Ahsan et al. 2022). Due to their toxicity, prolonged persistence, bioaccumulation, and biomagnifications in the food chain, metals, and metalloids are constantly entering water bodies and constituting significant risks to the well-being of humans and the environment (Islam et al. 2016, Lipy et al. 2020, Zakir et al. 2020, Khatun et al. 2021 and Hossain et al. 2022, Ahmed et al. 2023). The presence of these poisonous metals in Bangladesh's fields and farms, which eventually find their way into daily foods, is causally associated with several human-induced events, including irrigation from wastewater, sewage utilization, utilization of metal-contaminated agrochemicals, hazardous metal-rich chicken and fish diets, and improper handling of food during storage and transport (Zakir et al. 2020, Khatun et al. 2021 and Ahsan et al. 2022). The occurrence of these harmful contaminants in ecosystems is also influenced by natural sources such as geogenic, atmospheric, and dry and wet deposition (Lipy et al. 2020 and Ahsan et al. 2022). Because the supply of feed ingredients is often contaminated with hazardous metals in various ways, the fish feed manufacturing sectors have been unable to maintain feed quality (Sen et al. 2011).

Non-degradable toxic metals even at a low level may contribute to hazardous effects in water bodies by adsorption, accumulation, or integration at certain levels into abiotic elements, and lastly, by following the path of bio-accumulation into aquatic organisms (Biswas et al. 2021). The food web has been reported to be the primary mechanism of heavy metal acquisition in aquatic habitats (Biswas et al. 2021), and fish species as well as other inhabitants of the ecosystem, such as phytoplankton, zooplankton, crustaceans, microorganisms, and algal cells, are progressively being extinct (Khatun et al. 2021). Because of their high potential for transferring into the gastrointestinal tract of humans through absorption and then other parts of the body, eating metal-contaminated aquatic species like fish and shrimp may have a negative impact on human well-being (Lipy et al. 2020, Biswas et al. 2021 and Khatun et al. 2021).

heavy metals (e.g., Fe and Cu) function as micronutrients and are essential for normal metabolic activities in both plants and animals in even small amounts (Khatun et al. 2021 and Shaaban et al. 2021). Certain substances can be dangerous to humans and other living things when exposed to high levels (Hossain et al. 2022). Long-term contact with hazardous substances is known to have a negative influence on health and may even be fatal (Khatun et al. 2021). But metals and metalloids may seriously threaten human and ecological health, owing to their toxicity, long persistence, bioaccumulation, and biomagnifications in the food chain (Islam et al. 2014). The elements that are of concern include Cr, Ni, As, Cd, and Pb. Cr and Ni are known to cause a variety of pulmonary adverse health effects, such as lung inflammation, fibrosis, emphysema, and tumors (Forti et al. 2011), while high intake of Cu can cause adverse health problems such as liver and kidney damage (WHO 1995). Lead has been associated with pathological changes in organs and the central nervous system, leading to decrements in intelligence quotients (IQ) in children. Cadmium is toxic to the cardiovascular system, kidneys, and bones. (Fang et al. 2014), while inorganic arsenic, a human carcinogen, is the most toxic form of arsenic (EU 2002). It must be noted that although metals can change their chemical form, they cannot be degraded or destroyed. Therefore, the risk assessment of these metals via daily dietary intake is a very important issue (Marti-Cid et al. 2008).

The southwest region of Bangladesh is the hotspot of fish culture, where nowadays spoters are practicing intensive aquaculture and using chemical feeds. Besides, they are practicing extensive fertilizer and insecticide use during the cultivation of crops as well as vegetables. They are using wastewater for irrigation purposes as well as a supply of water for fish culture. As a result, there is a higher possibility of contaminating toxic metals in cultivated vegetables and fish. As metals can bioaccumulate in the food chain, intake of this contaminated diet may cause a potential health risk to men. However, few studies focused on investigating the concentration of heavy metals in vegetables, fish, water, and sediment (Islam et al. 2014, Sarkar et al. 2016, Bhuyan et al. 2016, Kundu et al. 2017, Das et al. 2017, Ahmed et al. 2019 and Akter et al. 2020). Though several studies have been done on heavy metal analysis in fishes or feed separately, it has become imperative to investigate the contamination of heavy metals in cultivated vegetables and fishes along with possible contamination sources such as respective commercial feeds, water, and sediments and take account of associated possible health risks.

Objective(s)

Objectives of the study are:

a)   Quantify heavy metal concentration in farmed bagda shrimp (P. monodon), golda shrimp (M. rosenbergii), and tilapia (O. mossambicus),

b)   Evaluate the concentration of heavy metals in selected cultivated vegetables,

c)   Determine the heavy metal concentration in possible sources such as fish feed, water and sediments,

d)   Calculate the health risk to humans upon consumption of contaminated foodstuffs based on Hazard Index (HI), Target Hazard Quotient (THQ) and Target Carcinogenic Risk (TR),

• Research Project