What is a heavy metal in chemistry?
Heavy metals are defined as metallic elements that have a relatively high density compared to water [1]. With the assumption that heaviness and toxicity are inter-related, heavy metals also include metalloids, such as arsenic, that are able to induce toxicity at low level of exposure [2].
What is heavy metals PDF?
Heavy metals are naturally occurring elements that have a high atomic weight and a density at least five times greater than that of water. These metallic elements are considered systemic toxicants that are known to induce multiple organ damage, even at lower levels of exposure.
Is heavy metal a chemical contaminant?
Heavy metals are well-known environmental pollutants due to their toxicity, persistence in the environment, and bioaccumulative nature. Contamination of aquatic and terrestrial ecosystems with toxic heavy metals is an environmental problem of public health concern.
What is the difference between toxic metal and heavy metal?
Toxic metals sometimes imitate the action of an essential element in the body, interfering with the metabolic process resulting in illness. Many metals, particularly heavy metals are toxic, but some heavy metals are essential, and some, such as bismuth, have a low toxicity.
What are heavy metals?
The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. Examples of heavy metals include mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (Tl), and lead (Pb).
What are heavy metals used for?
Heavy metals are relatively scarce in the Earth’s crust but are present in many aspects of modern life. They are used in, for example, golf clubs, cars, antiseptics, self-cleaning ovens, plastics, solar panels, mobile phones, and particle accelerators.
What are heavy metals in the environment?
Heavy metals normally occur in nature and are essential to life but can become toxic through accumulation in organisms. Arsenic, cadmium, chromium, copper, nickel, lead and mercury are the most common heavy metals which can pollute the environment.
What is heavy metal contamination?
The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. Heavy metals have been used by humans for thousands of years.
Why are heavy metals toxic to humans?
The main mechanism of heavy metal toxicity include the generation of free radicals to cause oxidative stress, damage of biological molecules such as enzymes, proteins, lipids, and nucleic acids, damage of DNA which is key to carcinogenesis as well as neurotoxicity.
What elements are considered heavy metals?
Some elements regarded as heavy metals are essential, in small quantities, for human health. These elements include vanadium, manganese, iron, cobalt, copper, zinc, selenium, strontium and molybdenum.
What are some examples of heavy metal?
Lead
What is the definition of heavy metal in chemistry?
The chemical definition of a heavy metal is a chemical element with a specific gravity that is at least 5 times the specific gravity of water. Examples of heavy metals include cadmium, chromium , lead, mercury, nickel, zinc and many more.
Why are heavy metals called heavy metals?
Gold is called a heavy metal because of its high density, which comes from the fact that each of its atoms is individually very heavy.