An Interesting Viewpoint in Environmental Science and Technology.

[NNadir]

I came across this "viewpoint" in today's issue of the scientific journal Environmental Science and Technology:

Potentially Toxic Element”─Something that Means Everything Means Nothing
Xiaokai Zhang, Damià Barceló, Robert J. Clougherty, Bin Gao, Hauke Harms, Boris Tefsen, Meththika Vithanage, Hailong Wang, Zhenyu Wang, and Mona Wells Environmental Science & Technology 2022 56 (17), 11922-11925

A character in a famous William Shakespeare play commented that “a great cause of the night is lack of the sun”. (1) Shakespeare used the comment as a statement and a humorous device, which we refer to here as we wish to address reasons why there is perhaps more humor and less illumination in the increasing use of the phrase “potentially toxic element”. Usage of this phrase gained momentum after a 2002 International Union of Pure and Applied Chemist’s publication criticizing the use of the term “heavy metal” to describe metals/metalloids “and their compounds [that] have highly toxic or ecotoxic properties”. (2) The 2002 paper was a scholarly work that carefully analyzed the use of heavy metal in the context of existing definitions, intended meaning, and possible consequences of using a phrase not unequivocally defined to describe hazardous substances. Throwing the proverbial baby out with the baby’s bathwater, we now have the alternative of a less useful phrase. While “toxic element” certainly addresses the concept of toxic and that not all heavy metals are strictly speaking metals, what is not “potentially” toxic? People have died from star fruit poisoning, carrot juice addiction, and water intoxication. (3?5) This global descriptor admits nothing to differentiate the relatively benign iron (Fe), or even sodium (Na), from lead (Pb) and cadmium (Cd), that is, metals toxic at relatively low dosages and simultaneously most frequently referred to as “potentially toxic elements”...

... As the famous ecological economist Herman Daly pointed out “One way to render any concept innocuous is to expand its meaning to include everything... Any definition that excludes nothing is a worthless definition”; that is, a definition that means everything, means nothing. (6)...

The article continues:

Unquestionably, toxicity is a function of exposure and bioavailability, and bioavailability in turn depends on concentration and speciation. In the last 20 years, some of the authors of this Viewpoint have published numerous papers confirming this and attesting to the value of taking bioavailability into account in risk assessment. (9?11) Our own research recognizing that bioavailability is a prerequisite to toxicity in no way abrogates other facts: in environmental research on contaminants with no known nutritive value, such as Cd and Pb, toxic effect is the key driver. The World Health Organization, the United States Environmental Protection Agency, the European Environment Agency, and the Ministry of Ecology and Environment of the People’s Republic of China all refer to Cd and Pb and a small number of other metals/metalloids as toxic, because they are toxic at low doses. Pb specifically has been described as “one of the most toxic elements in existence”, (12) presenting an impending global health crisis due to increasing levels of environmental Pb and concomitantly no safe level of Pb exposure. (13) Cd is one of a relatively elite and small number of items on the list of known carcinogens, as classified by the International Agency for Research on Cancer. Many environmental criteria limiting acceptable amounts of these and other toxic metals/metalloids are still based on total concentration, (14) because bioavailability is neither a simple nor an immutable quantity and because these toxic substances are highly subject to mobilization, for instance, in acidic conditions such as the human digestive tract. (15)...

...There are various alternative terms that may be used instead of heavy metal,a thus there is no reason why the question should be framed as heavy metal or the Newspeak of “potentially toxic element”. It seems only reasonable that experts should clarify what they mean by terms used, while also considering the merits of the environmental precautionary principle, that is, being careful not to diminish or downplay risks of pernicious environmental toxins. After all, this is not a purely academic discussion. Pb tops the list earning the moniker “potentially toxic element”, (7) this in a world where an estimated one-third of children globally are actually, not potentially, lead-poisoned, (19) resulting in a loss of intelligence recently estimated to actually, not potentially, value 1,154 billion U.S. dollars. (20) According to the Pure Earth Institute, there is widespread exposure to dangerous forms of Pb, and the World Health Organization ranks it as one of two contaminants posing an actual, not potential, risk that exceeds the sum of all other Top Ten Chemicals of Concern. Those affected are predominantly living in lower-income countries. (19) Humor aside, on behalf of millions of people and large swaths of ecosystems actually affected, in an effort to be more illuminating, we might all reflect a bit longer before rushing to take refuge in the imprecise and flawed descriptor “potentially toxic element” over long-standing and commonly understood terms already in use. If everything toxic becomes potentially toxic, then nothing remains that is toxic.

Interesting perspective.

[littlemissmartypants]

1. ❤️