**3. Conclusions**

The heavy metal toxicity and their environmental impact is a global issue due to their transportation through air, soil, and water. Based on various factors such as concentration and different major sources are the possible ways of entering the heavy metals through drinking water, air and foods. In minimum traces these metals are required for cellular, metabolic and hormonal functioning in humans but if the limitation exceeds its leads to the cause of severe hazardous effects in health. The toxicity of these metals is affecting the soil vastly by killing microorganisms present in soil which are very helpful to enhance fertility and nutrition levels of soils. According to the IARC, arsenic toxic effects are the cause of cancers in prostate glands, liver, blood, and skin. Mercury is the major reason for causing carcinogenic effects on the brain, lung, skin, and colorectal parts. The adverse effects of lead are the reason for intestinal, central nervous system, and lung cancers. The toxic effects of cadmium cause gastric, breast, lung, and renal cancers in humans.

Another diagnosis was identified in china, extreme high levels of lead toxicity in children were due to the pretty dish and in women, high lead levels in the blood is due to the usage of food storage cans. Cadmium is the major cause of Alzheimer disease and due to high usage of phosphate fertilizers they are accumulating in soils and entering into food chains. WHO states that mercury is hazardous toxic metal affecting aquatic life severely and consumption such mercury affected foods by human leads to several harmful diseases such as Minamata and cause several physiological effects.
