**2. Sources of heavy metal pollution**

According to the FAO, the following are the sources of heavy metals: mining effluents, industrial effluents, domestic effluents, urban stormwater, leaching of metals from solid waste dumps and garbage, metal inputs from rural areas, batteries, pigments, paints, glass, fertilizers, textiles, dental and cosmetic products, atmospheric sources, and petroleum industrial activities [9]. More causes of heavy metal contamination include the preparation of nuclear fuels, the smelting of copper, and the electroplating of chromium and cadmium [10, 11]. Tiny particles of cadmium, lead, and zinc that have been liberated allow these dangerous metals to float on the wind and land on top of soil or edible plants [12]. PVC goods, color pigments, various alloys, and today's most frequently rechargeable nickel-cadmium batteries all use cadmium compounds as stabilizers [13]. Cadmium metal is mostly utilized as an anticorrosion substance and also be found in phosphate fertilizers as a contaminant [14]. Agricultural sewage sludge and fertilizer application are two anthropogenic sources of cadmium that can contaminate soil and increase crop cadmium uptake [15]. All living creatures' primary source of heavy metals is food [16]. In general, methylmercury exposure in fish is the main way that living things are exposed to it, along with dental

amalgam [11, 16]. The electrochemical method used to produce chlorine uses mercury as an electrode, and the chlor-alkali business is a significant source of mercury use in this process [17]. Methylmercury, an extremely stable form of organic mercury, is present and builds up in the food chain [18, 19].
