The Negative Impact of Heavy Metals on The Environment and Human Health

Heavy metals are very hazardous and have become a big concern for health practitioners over the previous years. Population growth, Industrialization, and urbanization have brought about the emergence of manufacturing industries to feed the growing population. Smoke and fumes from chimneys of industries have resulted in long range atmospheric emissions which have made ecological pollution of heavy metals become a global issue, even affecting human population living in remote areas with less anthropogenic influence.

Bad human activities have caused heavy metals that were constrained within certain boundaries and incapable of causing harm to inhabitants of the ecosystem to be deposited at a very high rate into the environment. Industrial undertakings such as mineral extraction and smelting have contributed to environmental pollution by heavy metals Mineral extraction industries produce harmful metal pollutant which includes copper (Cu), lead (Pb), cadmium (Cd), zinc (Zn), nickel (Ni), arsenic (As) and iron (Fe). These metals have harmful impacts on the ecosystem. Heavy metals are commonly present in untreated waste water as a result of mining activities, smelting, electroplating and metal finishing industries. Due to this, the effects of heavy metals on the environment, health and the economy have attracted global attention. 

It’s estimated that 71% of the earth surface is covered by water bodies. These water bodies are often polluted by industrial growth, urbanization and technological advancement. Heavy metal industries are the most harmful chemical intensive industries likened to others. Agricultural soils regularly irrigated with industrial effluents (IEs) are easily polluted with toxic metals. Heavy metals have high solubility in marine eco-system and are easily absorbed by aquatic organisms. Once these metals get to the food chain, they ultimately enter into the system of human and cause malfunction of the organs. This poses severe wellbeing risk to humans if large volumes of heavy metals are ingested beyond permitted levels. Foodstuffs contaminated with excessive quantity of toxic metals can result in the emergence of serious health situations like cancer, tissue damage, skin damage, organ failure, aches, reduced immune system, etc. 

Heavy metals may appear in marine environment by natural and or anthropogenic processes. Heavy metals get into aquatic environment through atmospheric rainfall, surface runoff, mineral mining, urban sewages, agriculture and industrial discharges. Many studies have been done on dissolved heavy metal concentrations and their risks to aquatic environment. Therefore it can be stated that heavy metals does not only pollute our marine systems but also threatens our source of drinking water. There are a lot of processes available in heavy metal remediation from industrial sewages. Thus, it is essential to treat metal polluted wastewater prior to its release to the environment. Heavy metal uptake from inorganic effluent can be attained by physicochemical treatment methods such as chemical precipitation, chemical coagulation, ion exchange, membrane filtration, and electrochemical method. These processes have significant shortcomings, which are for instance, imperfect removal, high-energy requirements, and production of venomous sludge. Various biological treatments, both aerobic and anaerobic can be used effectively for toxic metal remediation.

Industries across the globe are major contributors of heavy metals. The amount of wastewater generated by domestic, industrial and commercial sources have increased in relation with the increasing population, urbanization, improved living standards of humans, and economic development. In many low income countries, both urban and non-urban areas of most developing countries depends, at least to a certain extent on sewage water from industries as a source of irrigation water for their agriculture activities. However, the quality of the wastewater used and the nature of its use vary hugely between countries across the world. In most low income countries in Africa, Asia and Latin America, the wastewater generated in the aforementioned sources tends to be untreated, as compared to middle income countries such as Tunisia and Jordan, which treat it wastewater before used for secondary purposes.

Heavy metals refer to metals and metalloids whose densities are greater than N5 g/cm Examples of such heavy metals include chromium (Cr), lead (Pb), cadmium (Cd), and mercury (Hg). Heavy metals are constituents that exist naturally in the earth's crust, but improper activities of man have drastically altered their geochemical cycles and biochemical balance. Arsenic (As) is usually classified as a heavy metal due to its chemical properties and environmental behavior. Heavy metals found in the environment may either be originated from nature or anthropogenic activities. Anthropogenic activities such as mineral resources development, metal processing and smelting, chemical production, factory emissions and sewage irrigation, have been proven to be the primary sources of heavy metal pollution. Among the list of major soil pollution being man-made or natural sources, heavy metals are of key importance due to their long-term toxicity effect. Heavy metals unlike some organic materials do not degrade over time and are essential for living at certain levels, they show toxic effect if they exceed the limit level. 

Heavy metals that contaminate soil can be introduced into the food chain by plant absorption and through their direct use or consumption by humans causes serious environmental risk. Heavy metals taken into the human body in larger quantities than the permitted limit values proposed by the World Health Organization (WHO) are known to cause carcinogenic, teratogenic, toxic, or cardiovascular problems. Therefore, industrial waste metal pollution in areas of agricultural deeds are of vital concern that needs attention and remediation.