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Persistent Pollutants


January 24, 2020 | A version of this story appeared in Volume 98, Issue 4


Letters to the editor

Sweet research

“Innovation Comes to the Sugar Wars” (C&EN, Oct. 21, 2019, page 28) properly addresses the link of sugar consumption with the alarming increase of endocrine and cardiovascular conditions and the measures being taken to warn consumers about the quantity of sugar in foodstuffs. The article, however, falls short of exposing scientifically based criticism of artificial sweeteners—most notably, the detriment to the gut microbiota (Nature 2014, DOI: 10.1038/nature13793; Food Chem. Toxicol. 2019, DOI: 10.1016/j.fct.2019.110692). New, “anticipated” solutions must also be treated with care. Randomized and controlled trials are still due to prove the long-term comprehensive safety and efficacy of newly explored sugars and sweet-taste blockers.

Jorge Cruz
London, Ontario

Details on PFAS


Re. the C&EN article on per- and polyfluoroalkyl substances (PFAS) in the Nov. 25, 2019, issue (page 22): Too much emphasis is placed (in headlines) on Ian Cousins’s committee plan. The PFAS rubric covers too many different kinds of molecules to be generalized. We should ban this acronym unless used with proper adjectives. Yes, a handful of nonpolymeric PFAS have been shown to have adverse and toxicological effects on lab animals. I read the dental floss paper and found it lacking in scientific rigor (for example, no chemical analysis of water extractables from dental floss). Of course we should ban harmful chemicals from widespread consumer and environmental use, but to say that all PFAS—namely, all polyfluorinated substances—must be banned is absurd. Animal tests indicate that PFA-sulfonic acid compounds in firefighting foams should be phased out. Water-soluble PFAS in stain-proof sprays can more easily be banned immediately. But we must not ban all high-molecular-weight perfluoropolymers. Rep. Dingell’s H.R. 535 and Rep. Dean’s H.R. 2600 are not informed by adequate scientific findings in polymer science. I agree with Steve Korzeniowski that fluoropolymers (of high molecular weight) are not bioavailable. Small, water-soluble perfluoro-molecules and telomers with “sticky” ends are bad actors, and PFAS that accumulate in body organs are a problem. In summary, please differentiate among different classes of PFAS. Details matter.

Geoffrey Lindsay
Temecula, California



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