I have been assured by more than one biologist that it would be impossible to bring peanut butter to the market today because of the enormous public health threat posed by aflatoxin contamination. Unlike pesticides, herbicides and fertilizer, aflatoxin is the entirely natural metabolite of a naturally occurring fungus which gows on peanuts. Regulated to a degree on commercially produced peanut butter, the highest rates of aflatoxin contamination are usually found in healthfood stores in natural peanut butter ground on site. But there is in fact no known "safe" level of aflatoxin, which means that even Skippy and Peter Pan is riddled with cancer causing toxins that can strike down your primary school student in twenty or thirty or forty years.

At the very least, peanut butter should carry a warning label that says "this product may contain up to 5ppm of aflatoxin by law. There is no accepted safe level of aflatoxin, which is known to cause liver cancer." That statement would be completely true and additionally, not the slightest bit misleading. Oddly, peanut butter carries no such warning label. One wonders why. Oh, right, wouldn't want to adversely affect peanut growers...

a minor correction... in the states it's actually 2 parts per billion (and in the eu it's 1 ppm, last i checked). the us standard is definitely to protect peanut farmers.

but, as a biologist myself, i would speculate that either of these standards is sufficient to protect public health. yes, there is no level of such a serious carcinogen that has truly no effect, but i'd expect it's safe.

such levels are easily attained by proper drying facilities, even in humid areas, as i can say from personal experience.

care to share what *kind* of biologists you're asking anyway?

Quite so, a slip of the finger. But the point isn't whether it's 5ppm (invisible) or 2ppb (invisible) it's that aflatoxin does cause liver cancer, and sure, it's not many-- in a statistical view anyway. But out of a global population of 6b, how many liver cancers would you expect a year from peanut butter? Ten? A hundred? Even a thousand? Like the aflatoxin itself, invisible statistically-- but not to those affected.

Biologist biologists. One's a cancer researcher at NIH, one's a prof at a New England college (the college is highly rated and so is the prof) and a third is a garden variety biologist in between jobs.