Heavy metals
Introduction
Heavy metals are a group of elements that have particular physical and chemical properties. They are generally defined as metals with relatively high densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, heavy metals may be defined on the basis of density, whereas in physics the distinguishing criterion might be atomic number, while a chemist would likely be more concerned with chemical behavior.
Characteristics
Heavy metals are generally defined as those metals which possess a specific density of more than 5 g/cm3. They are often toxic or poisonous at low concentrations and are considered to be an environmental hazard. The toxicity of these metals, even at such low concentrations, is due to the fact that they can accumulate in biological systems and may induce cancer and other risks.
Classification
Heavy metals can be classified into three categories: Class I, Class II, and Class III. Class I heavy metals such as lead, mercury, and cadmium are highly toxic and can cause damage to living organisms even at low concentrations. Class II heavy metals, which include copper, zinc, and nickel, are less toxic and are essential for the proper functioning of the body. Class III heavy metals, such as aluminium, are not very toxic but can become toxic at high concentrations.
Sources and Uses
Heavy metals are naturally occurring elements and they are present in the Earth’s crust. They cannot be degraded or destroyed. To a small extent they enter our bodies via food, drinking water and air. As trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the metabolism of the human body. However, at higher concentrations they can lead to poisoning. Heavy metal poisoning could result, for instance, from drinking-water contamination (e.g. lead pipes), high ambient air concentrations near emission sources, or intake via the food chain.
Heavy metals are used in many different areas of modern industry. They are used in the production of many different types of products, including electronics, automobiles, and jewelry. They are also used in the production of a variety of chemicals and materials, including paints, pigments, and fertilizers.
Environmental Impact
Heavy metals can have a significant impact on the environment. They can contaminate soil and water, and they can also accumulate in plants and animals, leading to health problems in humans who consume contaminated food or water. The environmental impact of heavy metals is a major concern for many environmental scientists and policymakers.
Health Effects
Exposure to heavy metals can have a variety of negative health effects. These can range from mild symptoms such as nausea and vomiting, to more serious conditions such as organ damage, neurological damage, and even death. The specific health effects can vary depending on the type of heavy metal, the level of exposure, and the individual's overall health.
Prevention and Treatment
There are a variety of methods that can be used to prevent and treat heavy metal poisoning. These include avoiding exposure to heavy metals, using protective equipment when working with heavy metals, and seeking medical treatment if exposure occurs. Treatment for heavy metal poisoning can include chelation therapy, which uses medications to remove the heavy metals from the body.