"Is Sodium Lauryl Sulfate safe?"
Sodium lauryl sulfate is a common detergent used in toothpaste.
It was featured in a famous internet hoax nearly 20 years ago.
Colgate toothpaste has it, supposedly proven to cause cancer.
At least, by buying Colgate rather than Crest,
you wouldn’t be supporting Satan, or so claimed another famous hoax.
The hoax that sodium lauryl sulfate in toothpaste and haircare products
was linked to cancer became so widespread,
the American Cancer Society was forced to publish a response to shampoo-poo the link.
“Radical e-mails have been flying through cyberspace…”
stating sodium lauryl sulfate causes cancer, and it’s simply not true.
So, I just ignored it all these years, until I was doing research
on canker sores; you know, those painful shallow gray ulcerations
you can get inside your lip or cheek, also known as aphthous ulcers?
They can often be set off by trauma, like if you accidently stab yourself
with a toothbrush or something.
And so, they recommend to try to avoid biting your lip,
and also to avoid sodium lauryl sulfate-containing toothpaste—
not because of cancer, but apparently for irritation,
which at least makes a little more sense.
Why would a detergent, a soap chemical, be carcinogenic,
though you could imagine how it might theoretically at least
dissolve off some protective layer from the inside of your mouth or something;
so, I decided to look into it.
Although SLS has been used as a foaming agent in toothpastes since the 1930s,
our story begins 25 years ago with an abstract presented at a conference
on the possible effects of sodium lauryl sulfate on recurring canker sores.
They took 10 men and women getting more than one sore a week,
nearly 18 on average over a 3-month period,
using a regular SLS- containing toothpaste,
and then they switched them to using an SLS-free toothpaste for another 3 months.
And, they went from 18 canker sores down to around 5;
that’s like a 70% decrease.
And indeed, what they thought was happening is that the sodium lauryl sulfate
was adversely affecting the protective mucus layer that lines our mouth.
You always have to be cautious about published abstracts, though.
You always want to make sure that they actually go on to publish their findings
in a peer-reviewed medical journal.
And indeed, in this case they did; so, you can confirm that, yes indeed,
it was a double-blind study.
Yes indeed, they used the exact same toothpaste,
just one with the regular concentration of SLS and the other SLS-free,
but still, just 10 patients?
It was considered a preliminary study, but with apparently such a dramatic effect,
a series of experiments were performed to see what might be going on,
as simple as just applying some SLS at the concentration found in toothpaste
onto someone’s gums with a Q-tip for 90 seconds
and measuring the spike in blood flow to the area,
which is a sign of inflammation, presumably because the detergent
was penetrating and irritating the gums.
Yeah, but does it actually damage the tissue?
Researchers smeared some toothpastes on the gums of some dental hygienists,
2 minutes twice a day for four days,
and, while the SLS-free toothpaste didn’t cause any problems,
the ones with the typical amount of sodium lauryl sulfate
caused desquamation among most of them,
in other words, a sloughing off or peeling of the topmost layers
of the inside lining of their mouths.
No wonder it might make canker sores worse.
It’s funny, if you go back to the original American Cancer Society debunking,
their response was sodium lauryl sulfate is not a known carcinogen;
it’s just a known irritant.