"Heavy metals" a meaningless term? (IUPAC Technical Report)

Abstract

Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without theAbstract: Over the past two decades, the term "heavy metals" has been widely used. It is often used as a group name for metals and semimetals (metalloids) that have been associated with contamination and potential toxicity or ecotoxicity. At the same time, legal regulations often specify a list of "heavy metals" to which they apply. Such lists differ from one set of regulations to another and the term is sometimes used without even specifying which "heavy metals" are covered. However, there is no authoritative definition to be found in the relevant literature. There is a tendency, unsupported by the facts, to assume that all so-called "heavy metals" and their compounds have highly toxic or ecotoxic properties. This has no basis in chemical or toxicological data. Thus, the term "heavy metals" is both meaningless and misleading. Even the term "metal" is commonly misused in both toxicological literature and in legislation to mean the pure metal and all the chemical species in which it may exist. This usage implies that the pure metal and all its compounds have the same physicochemical, biological, and toxicological properties, which is untrue. In order to avoid the use of the term "heavy metal", a new classification based on the periodic table is needed. Such a classification should reflect our understanding of the chemical basis of toxicity and allow toxic effects to be predicted.

Assessment of Heavy Metals on Occupationally Exposed Workers from Hair Analysis

“…Ullah [13] defined heavy metals as the generic term for metallic elements which have density five times greater than density of water, but as stated by Duffus [14], the term "heavy metals" has been given wide range of meaning by many authors, and it has never been defined by any authoritative body such as IUPAC. However, "heavy metals" is often used as a group name for metals and metalloids that have been associated with contamination and potential toxicity or ecotoxicity.…”

Concentración iónica y metales pesados en el agua de riego de la cuenca del río Ayuquila-Tuxcacuesco-Armería

“…No pueden ser degradados o destruidos fácilmente de forma natural o biológica ya que no tienen funciones metabólicas específicas para los seres vivos (Méndez et al, 2009), agrupan sustancias como cadmio y mercurio, principales contaminantes, además de níquel y plomo, entre otras. Pueden incorporarse a un sistema de abastecimiento de agua por medio de residuos industriales que son vertidos sin previos tratamientos, y posteriormente se depositan en lagos, ríos y distintos sistemas acuíferos (Duffus, 2002). En los cultivos, la acumulación de metales pesados se da por medio de su absorción por el agua de regadío contaminada, por la tierra mediante las raíces o por la deposición en el follaje de partículas aerotransportadas (Mor & Ceylan, 2008).…”

Bioaccumulation of zinc in Rana tigrina in different aquatic habitats

“…The term heavy metal is used for elements which are toxic. At the same time, many authors (Phipps, 1981;Duffus, 2002) have critically called the term heavy metals as meaningless and objectionable. Heavy metals are natural constituents of freshwater and marine system and are found in very trace amounts.…”