Saccharin

Saccharin is the oldest artificial sweetener, discovered in 1879, and it is the only one this site covers whose story runs the full length from accusation to retraction with the paperwork still visible at both ends.

The listing

In 1981 the National Toxicology Program listed saccharin as “reasonably anticipated to be a human carcinogen” in its second Report on Carcinogens. The basis was specific: increased bladder tumours in animals fed sodium saccharin, “especially male rats”.

That listing is why a generation of Americans remembers a warning on the pink packet, and why the word saccharin still carries an association that none of the newer sweeteners do.

The retraction, and why

Saccharin was delisted in the ninth Report on Carcinogens in 2000, after a formal review with three separate scientific peer reviews and public comment. The reasoning is worth quoting because it is a model of how a mechanism changes a conclusion:

“Mechanistic studies indicate that the observed urinary bladder cancers in rat studies are related to urinary pH, osmolality, volume, presence of precipitate and urothelial damage with attendant hyperplasia following dietary concentrations of 3% or higher with inconsistent findings at lower dietary concentrations. The factors thought to contribute to tumor induction by sodium saccharin in rats would not be expected to occur in humans.”

In plain terms: at very high dietary concentrations, rat urine forms a precipitate that physically damages the bladder lining, and the damage drives the tumours. Human urine does not do that. The tumours were real, and they were an artefact of rat physiology at doses no person eats.

NTP added the honest caveat rather than an all clear: “Although it is impossible to absolutely conclude that it poses no threat to human health, sodium saccharin is not reasonably anticipated to be a human carcinogen under conditions of general usage as an artificial sweetener.”

Ten years later the EPA followed, removing saccharin from its hazardous constituent, hazardous waste and hazardous substance lists after determining that it does “not present a significant risk to human health or the environment”.

The regulation nobody went back to

Here is the part that makes this page worth reading rather than just reassuring.

The food additive regulation permitting saccharin was written under the shadow of the 1970s finding and it was never rewritten. It still permits saccharin only “if the substitution for nutritive sweeteners is for a valid special dietary purpose”, and it still sets hard limits: 12 milligrams per fluid ounce in beverages, 20 milligrams per teaspoon of sugar equivalence for table use, 30 milligrams per serving in processed foods.

And it still contains this: “Authority for such use shall expire when the Commissioner receives the final reports on the ongoing studies in Canada and publishes an order on the safety of saccharin and its salts based on those reports and other available data.”

A permission that expires on the arrival of a Canadian report, in a regulation still in force decades later. The science moved and the text did not.

What it means when you meet it

The practical consequence of that unrevised regulation is that saccharin is legally confined to special dietary foods in the US, which is why you meet it in tabletop sweeteners and diet drinks and almost nowhere else. It is not in the general food supply the way Sucralose and Aspartame are.

For a child, that restriction is most of the answer. The milligram limits are set per serving and per teaspoon of sugar equivalence, and the intended use is dietary substitution rather than ordinary sweetening. A product a child is likely to be given is unlikely to contain it, and where it does, the amounts are capped by the regulation rather than by the manufacturer.

The lesson worth carrying

This is the clearest case on the site of a finding that was correct and a conclusion that was not.

The rats did get tumours. The study was not fraudulent or badly run. What was missing was the mechanism, and once the mechanism was understood, the same data supported the opposite conclusion. That is the shape of the argument on hazard and exposure, and it is worth holding on to when you meet the next ingredient that something was found in.