Before this discussion goes too far, it would be wise to place this
particular food additive into a rational perspective. I would direct
readers, who have an interest in this, to a chapter on naturally occurring
cyanide sources, see Chapter 6 “Glycosides” (pages 173-234) in Natural
Toxicants in Feeds and Poisonous Plants edited by Peter R. Cheeke and Lee R.
Shull, published by AVI Publishing Co., Westport, CN (1985). While the book
is 15 years old, cyanide analysis hasn't changed that much in the
intervening period.
The reported lethal dose for cyanide is in the range of 0.5 mg to 3 mg/Kg
(see the above chapter pg 179). Assuming the customary 70 Kg human being,
this places the lethal quantity of cyanide in the range of 35 mg to 210mg.
In the area of toxic compounds, at least those occurring in nature, this isn
’t really very toxic. There are far worse poisons out there folks! Compare
this with PSP toxins, where the estimated lethal dose is about 2 mg;
palytoxin (another marine biotoxin) is somewhere in the microgram range,
Botulism toxin is probably in the picogram range. Now we're talking real
toxins!
But let’s get back to our cyanide. Let’s take the lethal dose range and
assume a dose somewhere near the lowest level, e.g., 70 mg or a dose of 1
mg/Kg. Assuming 13 ppm permitted YPS expressed as the anhydrous salt, i.e.,
without the water of hydration (that’s 10 moles of water per mole of YPS),
about 50% of the molecular weight of anhydrous YPS is cyanide. This means
that about 6.5 ppm of the 13ppm total permitted is cyanide. Let us assume
the absolutely worse case scenario and that all of the YSP is somehow
converted instantaneously into hydrogen cyanide (HCN), keeping in mind that
the blast would probably kill you. This would require about 11 Kg of salt
(that's about 24 pounds of salt)! Now I know that we Americans consume salt
in prodigious quantities but I don’t think we come even close to consuming
that much AT ONE SITTING! I doubt that the average person even has 24
pounds of salt in their home at one time. And if we did, I doubt it would
be out laying around in the sunshine (living here in the Seattle area, this
would be nearly impossible). Since we consume about 2 grams (that’s being
good) to 10 grams (that’s being really naughty) of salt per day our intake
of cyanide would be about 13 to 65 MICROGRAMS.
But what does this mean in terms of risk? Let’s go back to the Glycosides
chapter in order to compare the amount of YSP to what is found in other
typical foodstuffs. Again, check out page 179 in that chapter. For example,
Lima Beans contain 10-300 milligrams CN/100g plant tissue. Assuming you eat
about 1 oz or about 30 grams of Lima Beans, you would potentially be getting
a dose of 3 to 100 milligrams of CN—keep in mind that these are MILLIGRAMS
not MICROGRAMS. The relative risk of CN poisoning would be about a 1000
times greater than exposure to salt. Unfortunately, I really like those lima
beans!
Frankly, I am not worried about the small amount of YSP that may or may not
be present in my table salt. Nevertheless, if there were another
anti-caking agent (the aluminum silicates, for example) that had a lower
risk than it should be selected—that’s just good risk management, good
marketing, and "common sense". What I am objecting to in this whole
discussion, is suggesting “courses of action” that are based in fear,
exaggerated or just plain based on ignorance. If we, collectively, want to
get rid of YSP—fine, but let’s base it on sound toxicology and a clear
understanding of all the risks.
One last point, Marion Dewitt raises the point that YSP is used in salt used
for road de-icing. He states that the levels permitted there are 100 ppm
YSP. Frankly, I have some issues with using salt on roads because of the
damage to my car and its impact on the environment, but then I happen to
live in an area where we don’t get much snow and ice. I won’t go through
the same calculations because this is an issue for another listserver, not a
seafood one. But my guess is that if we did math, we would find that there
are other far greater risks presented if we didn’t use the salt (for
example, crashes due to the slippery conditions). I leave that to others.
Jack Wekell
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